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+metadata, and any other content or labor, has been confirmed to be
+in the PUBLIC DOMAIN IN THE UNITED STATES.
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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #60277 (https://www.gutenberg.org/ebooks/60277)
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-The Project Gutenberg EBook of Aërial Navigation, by Albert Francis Zahm
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Aërial Navigation
-       A Popular Treatise on the Growth of Air Craft and on
-       Aëronautical Meteorology
-
-Author: Albert Francis Zahm
-
-Release Date: September 13, 2019 [EBook #60277]
-
-Language: English
-
-Character set encoding: UTF-8
-
-*** START OF THIS PROJECT GUTENBERG EBOOK AËRIAL NAVIGATION ***
-
-
-
-
-Produced by ellinora, Robert Tonsing, and the Online
-Distributed Proofreading Team at http://www.pgdp.net (This
-file was produced from images generously made available
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-
-                             AËRIAL NAVIGATION
-
-                            A POPULAR TREATISE
-                      ON THE GROWTH OF AIR CRAFT AND
-                        ON AËRONAUTICAL METEOROLOGY
-
-                                    BY
-
-                  ALBERT FRANCIS ZAHM, A.M., M.E., PH.D.
-
-      SECRETARY OF THE AËRO CLUB OF WASHINGTON; GOVERNOR OF THE AËRO
-    CLUB OF AMERICA; GENERAL SECRETARY OF THE INTERNATIONAL CONFERENCES
-              ON AËRIAL NAVIGATION IN 1893 AND 1907; OFFICIAL
-           AMERICAN DELEGATE TO THE AËRONAUTIC CONGRESS OF 1900;
-               FORMERLY LECTURER ON MECHANICS IN THE UNITED
-                 STATES BUREAU OF STANDARDS, AND PROFESSOR
-                  OF MECHANICS IN THE CATHOLIC UNIVERSITY
-                                OF AMERICA
-
-                              [Illustration]
-
-                            NEW YORK AND LONDON
-                          D. APPLETON AND COMPANY
-                                   1911
-
-                            COPYRIGHT, 1911, BY
-                          D. APPLETON AND COMPANY
-
-          _Published September, 1911_
-
-                  Printed in the United States of America
-
-
-
-
-                                PREFACE
-
-
-The purpose of this work is to portray in popular terms the
-substantial progress of aëronautics from its earliest beginning to
-the present time. Beyond the introductory account, little note is
-taken of experiments, however picturesque or clever, which constitute
-no advance in the art, or lead to no useful result. At times some
-minutiæ are presented to complete the story of an important series of
-achievements; but the unproductive efforts of impractical zealots,
-however prominent or widely known in their day, receive scant, if any,
-attention. Failures and tragedies where introduced, are described for
-the lessons involved rather than for any curious interest investing
-them. The griefs and grotesque follies of aëronautic imbeciles form a
-long story, but a futile and unprofitable one, of slight concern in the
-evolutionary history of a veritable science.
-
-A general history of aërial locomotion would naturally be divided
-into four parts, treating respectively of passive balloons, power
-balloons, passive flyers, and power flyers; but in this work a separate
-treatment has not been allotted to passive flyers because of their too
-backward state of development. Passive gliders which maneuver in the
-air merely by virtue of gravitational force, or acquired momentum, are
-familiar enough; but the much more interesting passive flyers of human
-construction, adapted to rise without motive power considerably beyond
-their initial level, or to soar far aloft, and sail long distances by
-virtue of favorable winds, are still in their infancy. It may be hoped,
-however, that the vulture’s art which now is well nigh overlooked,
-because of the triumphant advance of dynamic flight, will soon receive
-such attention that future treatises may relate human achievements
-in soaring that shall rival the dexterous and marvelous feats of
-the condor and albatross, even as the majestic sweep of the dynamic
-aëroplane now rivals the powerful rowing flight of the strongest birds
-of prey.
-
-Following the story of the evolution of air ships, a brief account
-of the medium they navigate has been added. In particular, the
-circumstances which affect the density and motion of the air have been
-studied; for the density of the air determines the static lift of air
-ships; the density and speed of impact of the air together determine
-the dynamic lift and the resistance to progression; while the velocity
-of the air current conditions the possible speed of travel in any
-direction. It is important, therefore, that the aëronautical student
-should have some acquaintance with the general properties of the air
-which affect its density, and some knowledge of the generation and
-prevalence both of the great currents of the atmosphere, and of the
-local winds and invisible turmoils which so nearly concern the safety
-and effective progress of the aërial navigator.
-
-The French units of measurement have been freely used, as well as the
-English. This seems advisable because the official rules and records
-of international aëronautic events are partly expressed in the metric
-system. Moreover, the navigation of a universal medium seems to call
-for such universal standards. Indeed a peculiar mission of world travel
-is to eliminate provincialism, and to promote universalism of thought,
-of sentiment, and of custom.
-
-In order to lighten the book for the popular reader, some interesting
-historical facts and much important quantitative data are placed in the
-Appendices, where they may be available to the technical or special
-student.
-
-It is a pleasant duty to acknowledge here my obligations to the U.
-S. Signal Corps, the Smithsonian Institution, and the U. S. Weather
-Bureau, for much assistance in collecting the materials for this work.
-Dr. W. J. Humphreys, of the U. S. Weather Bureau, has very kindly read
-the manuscript for the chapters on the atmosphere.
-
-My thanks are due also to the _Scientific American_ and to
-_Aëronautics_ for the use of photographs for the illustrations, as also
-to the manufacturers of various aircraft, and to Mr. W. J. Hammer, Mr.
-Carl Dientsbach, and Mr. A. S. Levino.
-
-                                                          A. F. ZAHM.
-
-    COSMOS CLUB
-  WASHINGTON, D. C.,
-    January, 1911.
-
-
-
-
-                               CONTENTS
-
-
-  CHAPTER                                                           PAGE
-                             INTRODUCTION
-
-  INTRODUCTION                                                         3
-
-
-                                PART I
-
-                         GROWTH OF AËROSTATION
-
-     I.—EARLY HISTORY OF PASSIVE BALLOONS                             29
-
-    II.—PRACTICAL DEVELOPMENT OF PASSIVE BALLOONS                     54
-
-   III.—EARLY HISTORY OF POWER BALLOONS                               78
-
-    IV.—INTRODUCTION OF GASOLINE-DRIVEN DIRIGIBLES                   101
-
-     V.—PRACTICAL DEVELOPMENT OF NON-RIGID DIRIGIBLES                115
-
-    VI.—DEVELOPMENT OF RIGID DIRIGIBLES                              145
-
-
-                                PART II
-
-                          GROWTH OF AVIATION
-
-   VII.—MODEL FLYING MACHINES                                        173
-
-  VIII.—NINETEENTH CENTURY MAN-FLYERS                                202
-
-    IX.—AËROPLANES OF ADEQUATE STABILITY AND POWER                   235
-
-     X.—ADVENT OF PUBLIC FLYING                                      256
-
-    XI.—STRENUOUS COMPETITIVE FLYING                                 283
-
-   XII.—FORCING THE ART                                              307
-
-
-                               PART III
-
-                        AËRONAUTIC METEOROLOGY
-
-  XIII.—GENERAL PROPERTIES OF FREE AIR                               347
-
-   XIV.—GENERAL DISTRIBUTION OF HEAT AND PRESSURE                    363
-
-    XV.—PERMANENT AND PERIODIC WINDS                                 376
-
-   XVI.—CYCLONES, TORNADOES, WATERSPOUTS                             394
-
-  XVII.—THUNDERSTORMS, WIND GUSTS                                    422
-
-
-                              APPENDICES
-
-     I.—STRESS IN A VACUUM BALLOON                                   443
-
-    II.—AËRONAUTIC LETTERS OF BENJAMIN FRANKLIN                      446
-
-   III.—SUCCESSFUL MILITARY DIRIGIBLE BALLOONS                       456
-
-    IV.—THE RELATIONS OF WEIGHT, SPEED, AND POWER OF FLYERS          478
-
-     V.—CURTISS’ HYDRO-AËROPLANE EXPERIMENTS                         481
-
-  INDEX                                                              487
-
-
-
-
-                            LIST OF PLATES
-
-
-                                                                  FACING
-                                                                    PAGE
-
-  PLATE I                                                             66
-          Glaisher and Coxwell.
-          Parseval Kite Balloon.
-
-  PLATE II                                                            98
-          Haenlein’s Gas-driven Dirigible.
-          Wölfert’s Benzine-driven Dirigible.
-          Santos-Dumont’s Dirigible, _No. 16_.
-
-  PLATE III                                                          116
-          The _Lebaudy_.
-          _La Patrie._
-          Lebaudy’s _Morning Post_.
-
-  PLATE IV                                                           124
-          _La Ville de Paris._
-          _Colonel Renard._
-
-  PLATE V                                                            128
-          _Zodiac III._
-          _Zodiac IV._
-
-  PLATE VI                                                           130
-          _La Belgique._
-          Italian Military Dirigible _No. I bis_.
-
-  PLATE VII                                                          132
-          _Clément-Bayard I._
-          _Clément-Bayard II._
-
-  PLATE VIII                                                         138
-          _U. S. Signal Corps Dirigible I._
-          _Gross II._
-
-  PLATE IX                                                           140
-          _Parseval I._
-          _Parseval II._
-
-  PLATE X                                                            146
-          _Gross III._
-          Zeppelin Airship Structure.
-
-  PLATE XI                                                           160
-          Zeppelin Dirigible Resting on the Water.
-          Zeppelin Dirigible over Zürich.
-
-  PLATE XII                                                          182
-          Henson’s Aëroplane.
-          Ader’s Aëroplane.
-
-  PLATE XIII                                                         186
-          Stringfellow’s Aëroplane (Front).
-          Stringfellow’s Aëroplane (Side).
-
-  PLATE XIV                                                          192
-          Phillips’s Tethered Aëroplane.
-          Phillips’s Aëroplane.
-
-  PLATE XV                                                           194
-          Langley’s Steam Model.
-          Langley’s Gasoline Model.
-          Langley’s Two Surface Gasoline Model.
-
-  PLATE XVI                                                          212
-          Lilienthal’s Monoplane Glider.
-          Lilienthal’s Biplane Glider.
-          Pilcher’s Monoplane Glider.
-
-  PLATE XVII                                                         218
-          Chanute’s Five-Deck Glider.
-          Herring in Chanute Biplane.
-          Herring’s Compressed-air Biplane.
-
-  PLATE XVIII                                                        226
-          Maxim’s Aëroplane.
-          Langley’s Large Aëroplane.
-
-  PLATE XIX                                                          246
-          First Wright Glider.
-          Second Wright Glider.
-
-  PLATE XX                                                           248
-          First Wright Aëroplane (Rear).
-          First Wright Aëroplane (Side).
-
-  PLATE XXI                                                          252
-          Montgomery’s Aëroplane.
-
-  PLATE XXII                                                         258
-          Santos-Dumont’s Biplane.
-          Santos-Dumont’s _Demoiselle_.
-
-  PLATE XXIII                                                        260
-          Farman Biplane, 1908.
-          Farman Biplane, 1909.
-          Harmon in Farman Biplane.
-
-  PLATE XXIV                                                         264
-          The _Red Wing_.
-          Curtiss Biplane.
-          Curtiss Biplane with Pontoons.
-
-  PLATE XXV                                                          268
-          Blériot Flying Over Toury-Artenay Circuit.
-          Blériot Monoplane _No. VIII_.
-          Blériot Monoplane _No. IX_.
-
-  PLATE XXVI                                                         272
-          Wright Biplane of 1908.
-          Standard Wright Biplane of 1910.
-          Wright Racing Biplane of 1910.
-
-  PLATE XXVII                                                        286
-          _Blériot XI_ With Moisant Aviator on Mexican Border.
-          _Blériot XII._
-
-  PLATE XXVIII                                                       288
-          _Antoinette_ Monoplane of 1909.
-          _Antoinette_ Monoplane of 1910.
-
-  PLATE XXIX                                                         302
-          Esnault-Pélterie Monoplane, Early Pattern.
-          Esnault-Pélterie Monoplane of 1910.
-
-  PLATE XXX                                                          304
-          Grade Monoplane.
-          Cody Biplane.
-
-  PLATE XXXI                                                         332
-          Fabre Hydro-aëroplane.
-          Paulhan Hydro-aëroplane.
-          Moisant Metal Monoplane.
-
-  PLATE XXXII                                                        482
-          Curtiss Starting from the Water.
-          Curtiss Biplane for Land and Water.
-          Curtiss Triplane Risen from the Water.
-
-
-
-
-                     LIST OF ILLUSTRATIONS IN TEXT
-
-
-  FIG.                                                              PAGE
-
-   1.—Da Vinci’s designs for human flying-gear                         9
-
-   2.—A possible air-scout                                            12
-
-   3.—Blanchard’s flying-machine                                      17
-
-   4.—Lana’s proposed vacuum balloon                                  24
-
-   5.—Montgolfier’s experimental balloon                              34
-
-   6.—Charles’ first hydrogen balloon                                 36
-
-   7.—Montgolfier’s passenger balloon                                 39
-
-   8.—Charles’ passenger balloon                                      43
-
-   9.—La Flesselle                                                    50
-
-  10.—_The Great Balloon of Nassau_                                   55
-
-  11.—Car of Nadar’s balloon                                          61
-
-  12.—Diagram of a modern spherical balloon with ripping panel        75
-
-  13.—Blanchard’s dirigible balloon, 1784                             80
-
-  14.—Robert Brothers’ dirigible, 1784                                82
-
-  15.—General Meusnier’s proposed dirigible, 1784                     85
-
-  16.—Rufus Porter’s dirigible, 1820                                  87
-
-  17.—Jullien’s model dirigible, 1850                                 88
-
-  18.—Giffard’s steam dirigible, 1852                                 89
-
-  19.—Dupuy de Lome’s dirigible, 1872                                 92
-
-  20.—Renard’s dirigible, _La France_, 1884                           94
-
-  21.—_La Ville de Paris_                                            121
-
-  22.—_Le Petit Journal_, Zodiac type                                128
-
-  23.—_Clément-Bayard II_, 1910                                      133
-
-  24.—_Morning Post_ dirigible, 1910                                 135
-
-  25.—Route of British military dirigibles from France to England,
-        1900                                                         137
-
-  26.—Da Vinci’s helicopter                                          175
-
-  27.—Da Vinci’s parachute                                           176
-
-  28.—Veranzio’s parachute                                           178
-
-  29.—Lenormand’s parachute, 1784                                    179
-
-  30.—Paper traveling parachute                                      181
-
-  31.—Wenham’s aëroplane, 1866                                       185
-
-  32.—Penaud’s aëroplane toy, 1871                                   187
-
-  33.—Tatin’s aëroplane model, 1879                                  188
-
-  34.—Hargrave’s model screw monoplane, 1891                         190
-
-  35.—Hargrave’s kite                                                191
-
-  36.—Launoy and Bienvenu’s helicopter, 1784                         198
-
-  37.—Forlanini’s helicopter, 1878                                   200
-
-  38.—Le Bris’ aëroplane, 1855                                       204
-
-  39.—Mouillard’s aëroplane                                          208
-
-  40.—Blériot’s Toury-Artenay aëroplane circuit, 1908                269
-
-  41.—Map of the “Circuit de l’Est”                                  330
-
-  42.—Diagram of Curtiss hydro-aëroplane                             333
-
-  43.—The Etrich monoplane of 1910                                   336
-
-  44.—Summer and winter average vertical temperature gradients       369
-
-  45.—General circulation of the atmosphere                          378
-
-  46.—Normal Wind direction and velocity for January and February
-        (Köppen)                                                     381
-
-  47.—Normal Wind direction and velocity for July and August
-        (Köppen)                                                     383
-
-  48.—Trade and counter-trade winds                                  384
-
-  49.—Velocity diagram in horizontal section of a cyclone            398
-
-  50.—Funnel-like cloud sometimes observed in a tornado              409
-
-  51.—Vertical section of the St. Louis, Mo., tornado of May 27,
-        1896                                                         411
-
-  52.—Horizontal section of St. Louis tornado of May 27, 1896        412
-
-  53.—Vertical section of short tornado                              414
-
-  54.—Vertical section of a tall tornado                             415
-
-  55.—Vertical section of a hail tornado                             417
-
-  56.—Universal anemograph                                           428
-
-  57.—Records of wind variation in horizontal and vertical
-        direction                                                    429
-
-  58.—Records of Wind speed obtained by Langley                      433
-
-
-
-
-                             INTRODUCTION
-
-
-
-
-                             INTRODUCTION
-
-                          FANCY AND FOLK-LORE
-
-    Of silver wings he took a shining pair,
-      Fringed with gold, unwearied, nimble, swift;
-    With these he parts the winds, the clouds, the air,
-      And over seas and earth himself doth lift.
-    Thus clad he cuts the spheres and circles fair,
-      And the pure skies with sacred feathers clift;
-    On Lebanon at first his feet he set
-      And shook his wings with rosy may-dews wet.
-                                   TASSO, CANTO I, XIV.
-
-
-How beautiful! May we hope ever to journey thus, on wings actuated by
-human power? It is an old question, once dear to the philosopher and
-fool alike, but now important mainly to the fool. Or say more kindly it
-is the affair of untechnical inventors—the amateur, the rustic, the man
-of chimerical dreams. For the wise aëronaut now numbers that project
-among the roseate illusions of his youth.[1]
-
-Ovid relates a story, doubtless credible in his day, of a clever
-craftsman who with his son flew bravely aloft, the very first time they
-put on wings. Daedalus, a Greek architect, having fled from Athens for
-murder, went with his son Icarus to the island of Crete, where he built
-the celebrated labyrinth for Minos, the king. He offended that monarch
-and was cast into prison. In order to escape he made wings for himself
-and his son, with which they flew far over the sea. But Icarus, in his
-elation, soared too near the sun, ruined his wings, fell into the sea
-and was drowned. For proof of this we have the Icarian Sea, named after
-the unfortunate boy. Also we have Ovid’s charming poem:
-
-    In tedious exile now too long detain’d
-    Daedalus languish’d for his native land;
-    The sea foreclosed his flight, yet thus he said;
-    “Though earth and water in subjection laid,
-    O cruel Minos, thy dominion be,
-    We’ll go through air; for sure the air is free.”
-    Then to new arts his cunning thought applies,
-    And to improve the work of nature tries.
-    A row of quills, in gradual order placed,
-    Rise by degrees in length from first to last;
-    As on a cliff the ascending thicket grows;
-    Or different reeds the rural pipe compose:
-    Along the middle runs a twine of flax,
-    The bottom stems are join’d by plaint wax;
-    Thus, well compact, a hollow bending brings
-    The fine composure into real wings.
-        His boy, young Icarus, that near him stood,
-    Unthinking of his fate, with smiles pursued
-    The floating feathers, which the moving air
-    Bore loosely from the ground, and wafted here and there:
-    Or with the wax impertinently play’d,
-    And with his childish tricks the great design delay’d.
-        The final masterstroke at last imposed,
-    And now, the great machine completely closed;
-    Fitting his pinions on, a flight he tries,
-    And hung self-balanced in the beaten skies.
-    Then thus instructs his child: “My boy, take care
-    To wing your course along the middle air:
-    If low, the surges wet your flagging plumes;
-    If high, the sun the melting wax consumes.
-    Steer between both: nor to the northern skies,
-    Nor South Orion, turn your giddy eyes,
-    But follow me; let me before you lay
-    Rules for the flight, and mark the pathless way.”
-    Thus teaching, with a fond concern, his son,
-    He took the untried wings, and fix’d them on:
-    But fix’d with trembling hands; and, as he speaks,
-    The tears roll gently down his aged cheeks;
-    Then kiss’d, and in his arms embraced him fast,
-    But knew not this embrace must be the last;
-    And mounting upward, as he wings his flight,
-    Back on his charge he turns his aching sight;
-    As parent birds, when first their callow care
-    Leave the high nest to tempt the liquid air;
-    Then cheers him on, and oft, with fatal art,
-    Reminds the stripling to perform his part.
-    These, as the angler at the silent brook,
-    Or mountain shepherd leaning on his crook,
-    Or gaping ploughman, from the vale descries,
-    They stare, and view them with religious eyes,
-    And straight conclude them gods; since none but they
-    Through their own azure skies could find a way.
-    Now Delos, Paros, on the left are seen,
-    And Samos, favour’d by Jove’s haughty queen;
-    Upon the right, the isle Lebynthos named,
-    And fair Calymne for its honey famed.
-    When now the boy, whose childish thoughts aspire
-    To loftier aims, and make him ramble higher,
-    Grown wild and wanton, more embolden’d flies
-    Far from his guide, and scars among the skies:
-    The softening wax, that felt a nearer sun,
-    Dissolved apace, and soon began to run:
-    The youth in vain his melting pinion shakes,
-    His feathers gone, no longer air he takes:
-    “Oh! father, father!” as he strove to cry,
-    Down to the sea he tumbled from on high,
-    And found his fate; yet still subsists by Fame,
-    Among those waters that retain his name.
-    The Father, now no more a father, cries:
-    “Ho, Icarus! where are you?” as he flies;
-    “Where shall I seek my boy?” he cries again,
-    And saw his feathers scatter’d on the main;
-    Then cursed his art; and funeral rites conferr’d
-    Naming the country from the youth interr’d.
-
-How tender and apprehensive that gentleman’s farewell, compared with
-the modern vogue in like circumstances! Of the two Americans at Berlin
-who fell four thousand feet in a balloon, it is not recorded that they
-either kissed or wept.[2] But some Teutonic Ovid may yet adorn the tale
-with quaint embellishments.
-
-Taking more serious note of Daedalus, it will be observed that he
-has had few imitators. It is because he never really flew, and no
-one else can fly, in such manner. That is to say, no man can achieve
-practical flight on wings actuated by his own muscular power. It may be
-physically possible for an athlete putting forth herculean energy for
-a few seconds to sustain himself on wings of enormous spread; but in
-every lightest zephyr he would be as helpless as a thistle seed.
-
-The actual area of wing required for a man of given weight and power
-may be roughly estimated; at least its lower limit of size can be
-determined. Lord Rayleigh,[3] on purely theoretical ground, has
-computed that a man operating a screw propeller 280 feet in diameter,
-moving without frictional loss, could sustain his weight for a period
-of eight hours a day at a comfortable rate of work. But that estimate
-does not include the weight of the propeller. By exerting ten times his
-normal power the man could support his weight with a 28-foot propeller.
-
-The physical basis of the computation is the same for every type of
-flyer, whether bird, man, or machine. Its weight must be sustained by
-hurling the air downward. The humming bird in its aërial pause, the bee
-floating beside a blossom, rests on a down-driven column of air. The
-home-gliding eagle at dusk may encounter a medium in stillest repose,
-but he leaves behind him a down-flowing wake, viewless, maybe, but none
-the less real. In all cases the downward impulse per second given to
-the air must equal the weight supported by its reaction. If the wings
-be very extensive a proportionate mass of air may be struck down, and
-yield support with so much the less exertion.
-
-Horizontal flight promises little more than direct screw lift, with the
-feeble energy of the human muscle. The best modern aëroplanes carry
-less than 100 pounds per horse power, while an average man must weigh,
-with a light machine, not less than 200 pounds, and must therefore
-exert upwards of two horse power during flight. Such an output of
-energy would exhaust a powerful athlete in a few seconds. Hence from
-every point of view it appears that Daedalean flight, which still has
-its devotees in some form, was and always will be utterly impracticable.
-
-Ruskin finds another objection to the disciples of the winged arm.
-In his disquisition on the equilibrium of angels he complains that
-those of the traditional two-wing type are devoid of gravitational
-balance. Such creatures vex the imagination with apprehensions for
-their stability; hence they cannot be entirely beautiful. The centroid
-of an angel is in the small of its back, whereas the center of wing
-support is well forward; therefore the horizontal poise is absurd and
-unæsthetic. The scientific artist, consequently, views with pain the
-picture of a fair lady floating level through space supported only at
-her front end.
-
-Milton adroitly forestalls this censure. In the conception of his
-glorious Raphael, he provides consummately for uniform and adequate
-support:
-
-        Six wings he wore, to shade
-    His lineaments divine; the pair that clad
-    Each shoulder broad, came mantling o’er his breast
-    With regal ornament; the middle pair
-    Girt like a starry zone his waist, and round
-    Skirted his loins and thighs with downy gold,
-    And colors dipped in Heaven; the third his feet
-    Shadowed from either heel with feathered mail,
-    Sky-tinctured grain. Like Maia’s son he stood,
-    And shook his plumes, that heavenly fragrance filled
-    The circuit wide.
-
-Leonardo da Vinci, who was a gifted engineer as well as an artist,
-devised a flying gear for man which shows some dynamic improvement over
-the mechanism of the old-time angels, flying gods, and hobgoblins. As
-shown in the accompanying sketch, it provided for gravitational balance
-by use of an expanding tail projecting well to the rear. Moreover, the
-propulsion was to employ both arms and legs. This design is considered
-very remarkable for the time in which it was produced, probably a few
-years before the discovery of America; and yet it is but one of Da
-Vinci’s quaint aëronautical inventions, as will appear later.
-
-A less futile scheme of aviation may be to saddle the birds. If one
-eagle can float a child, a few may possibly carry a man. They are
-physically able; they are inexpensive; they are unwearied, nimble,
-swift. Some harness, some tuition may be required; but these come
-to the industrious. Apparently, such locomotion is a sport worth
-developing; a royal art, if you please; for who would not course the
-sky in a purple palanquin borne by imperial eagles?
-
-Kai Kaoos, the King of Persia, is credited with a voyage of this kind,
-as described in the _Shah-Nemeh_, or _King-Book_, written in the tenth
-century:
-
-  “To the king it became a matter of great concern how he might
-  be enabled to ascend the heavens, without wings; and for that
-  purpose he consulted the astrologers, who presently suggested a
-  way in which his desires might be successfully accomplished.
-
-[Illustration: FIG. 1.—DA VINCI’S DESIGNS FOR HUMAN FLYING-GEAR.]
-
-  “They contrived to rob an eagle’s nest of its young, which they
-  reared with great care, supplying them with invigorating food.
-
-  “A frame of aloes-wood was then prepared, and at each of the
-  four corners was fixed perpendicularly a javelin surmounted
-  on the point with the flesh of a goat. At each corner again
-  one of the eagles was bound, and in the middle the king was
-  seated with a goblet of wine before him. As soon as the eagles
-  became hungry they endeavored to get at the goat’s flesh upon
-  the javelins, and by flapping their wings, and flying upwards
-  they quickly raised the throne from the ground. Hunger still
-  pressing on them, and still being distant from their prey,
-  they ascended higher and higher in the clouds, conveying the
-  astonished king far beyond his own country. But after a long
-  and fruitless exertion, their strength failed them, and, unable
-  to keep their way, the whole fabric came tumbling down from the
-  sky, and fell upon a dreary solitude in the Kingdom of Chin,
-  where Kai Kaoos was left a prey to hunger, alone, and in utter
-  despair.”
-
-One might prefer a single bird, which could be ridden bareback by a man
-or woman of common equestrian skill. The early philosophers, therefore,
-sought with some care for such a creature. The following is related by
-Bishop Wilkins:
-
-  “Cardan and Scaliger doe unanimously affirm, that there is
-  a bird amongst the Indians of so great a bignesse, that his
-  beak is often used to make a sheath or scabbard for a sword.
-  And Acosta tells us of a fowl in Peru called Condores, which
-  will of themselves kill and eat up a whole calf at a time. Nor
-  is there any reason why any other body may not be supported
-  and carried in the air, though it should as much exceed the
-  quantity of these fowls as they do the quantity of a flie.
-  Marcus Polus mentions a fowl in Madagascar which he cals a
-  Ruck, the feathers of whose wings are 12 paces, or threescore
-  foot long, which can with as much ease scoop up an elephant as
-  our kites do a mouse. If this relation was anything credible,
-  it might serve as an abundant proof for the present quaere.”
-
-As the roc has proved a myth, one questions whether a saddle bird
-may not be evolved by judicious breeding. But opposed to this is the
-square-cube law of the Greek geometer, by which a learned geologist
-demonstrated that nature has reached the limit of her resources in the
-production of large flyers, the ostrich, for example, being too bulky
-to navigate at all. As a last resource, then, the human dwarf may
-breed his weight downward to accommodate the bird. Assuredly, the most
-powerful flyer can carry the lightest human dwarf without difficulty.
-
-Such aërial cavalry has been projected occasionally, and if fairly
-developed might have interesting employment. Its military value, to
-say nothing of its civil uses, would be considerable. An aërial scout
-that could hide in a tree top, or small cloud, then flit home with full
-intelligence of the enemy, would be effective and unique. In aggressive
-warfare it would serve the plan of that ingenious Englishman who
-proposes to repel a German invasion by dispatching birds to peck holes
-in the enemy’s war balloons. But here the dwarf might be omitted, if
-the birds were taught to have a definite interest in attacking aërial
-cruisers with their beaks, or with steel-armed spurs like those of the
-Spanish fighting cock, or with talons treated chemically to strike
-fire. Sparrows with sulphur-pointed toes could easily annihilate an
-aërial squadron at all combustible.
-
-Recurring to the geologist, it may be added that, having discovered the
-major limit of feathered navigators, he concluded, as a corollary, that
-human flight is forever impossible. That was in the latter eighties.
-In 1901 a versatile astronomer adduced the same law to prove that an
-aëroplane could not be made to carry a man. Presently, learning that
-this had been achieved, he proved, in a second mellifluous paper, that
-an aëroplane could not carry, several men.[4] Having erred twice, he
-wrote a final article announcing that a flyer is fatuous, anyhow,
-because she cannot repair her engines in the sky!
-
-[Illustration: FIG. 2.—A POSSIBLE AIR-SCOUT.]
-
-Of the numerous daring and industrious inventors who, during remote
-generations, have launched themselves in the air on some species of
-rigid or vibrant wings, a few were men of considerable equipment in
-philosophy, or mechanics, and enjoyed a sufficient measure of success
-to deserve passing notice; though it seems that no man before the
-middle of the eighteenth century made a permanent contribution to the
-real art of mechanical flight, if we except the ingenious suggestive
-devices of Leonardo da Vinci. However skilfully their flying apparatus
-may have been planned, or operated, the results were lost to the world,
-due to inaccurate or inadequate description. Such inventors were J. B.
-Dante, in the fifteenth century, and the Marquis de Bacqueville, in the
-seventeenth. Each of these made one, or more, considerable flights, if
-we may credit the unwavering testimony of their contemporaries; but
-neither has left a sketch of his device, nor a school of followers to
-continue his spectacular practice.
-
-Jean-Baptiste Dante, a shrewd observer and profound mathematician, who
-flourished toward the end of the fifteenth century, a contemporary of
-Da Vinci and Columbus, is reported by the historians of that day to
-have sailed successfully through the air on nonvibrant wings designed
-by himself after a careful study of the great soaring birds. Perching
-above a steep crag on the shore of Lake Trasimene, he set his wings
-to the wind at a nice angle, as one sets the sails of a vessel; then,
-lifted by the swelling breeze, he rose grandly aloft and floated far
-over the waters. Again and again he repeated the experiment, until
-the fame thereof secured for him a request to make the demonstration
-at the marriage fêtes of the illustrious general, Barthelmi Alviano.
-He accepted the invitation, and, starting from the top of the highest
-tower in the city of Perugia, he sailed over the public square,
-and balanced himself for a long time in space, amid the shouts and
-acclamations of the multitude, attracted to Perugia by the novelty of
-his performance. But, sad to relate, the very first time he performed
-these wonderful maneuvers above the solid ground instead of the lake,
-one of the levers used to alter the impact angle of his wings gave way,
-disturbing his aërial poise, and causing him to pitch down upon Notre
-Dame church, breaking one of his legs. After this he taught mathematics
-at Venice, where he died of fever at the age of forty years.
-
-In 1742, the Marquis de Bacqueville, at the age of sixty-two years,
-announced that on a certain day he would fly from his house on the
-Seine, traverse the river, and land in the Garden of the Tuileries. A
-great multitude assembled, crowding both shores and the two bridges.
-At the appointed moment the Marquis appeared with his pinions, and
-launched himself from the terrace. He sailed forth in majestic and
-serene poise, on graceful wings not unlike those of the traditional
-angels. He was gliding directly toward the Tuileries, and he enjoyed a
-happy cruise quite to the middle of the river. Then something happened;
-his movements became fitful and uncertain; he plunged downward and
-broke his leg on a laundry boat. The reason for his stopping there can
-only be surmised, for he had nothing to report. He did not quite fulfil
-his program, but he flew nine hundred feet delightfully, and he landed
-without getting wet.
-
-Commentators have marveled as to the nature of the mechanism used by
-Dante and by De Bacqueville. Historians have strongly attested the
-fact of the flights, but have overlooked the means. The inventors must
-have employed aërial gliders of some kind, for adequate motive power
-was not available before the end of the nineteenth century. Even as
-an experiment in gliding, or soaring, the achievement of Dante was
-most daring and wonderful, eclipsing the best performances up to the
-twentieth century. It is strange that in that period of science the
-survivor of such an experience, and a college professor, should not
-have left to the world a careful account of such an extraordinary
-performance. The alleged flights, however, were unquestionably
-feasible, even in that remote period, for the construction of an
-aërial glider is a simple task not beyond the capacity of craftsmen
-in the fifteenth century A.D., or even the fifteenth century
-B.C., directed by a skilful designer.
-
-Besides the wing-armed scheme of flight credited to Daedalus, and
-contemplated by Da Vinci, various other plans were evolved in
-succeeding years. Aërial chariots and flying machines were devised for
-the more advantageous use of muscular energy. In all these, of course,
-the passenger could be both power plant and captain of the ship.
-
-One of the earliest authenticated devices of this kind was the
-invention of Blanchard, described by him in the _Journal de Paris_,
-August 28, 1781, nearly two years before the invention of the hot-air
-balloon, of which he became later an enthusiastic votary. As his device
-is but one of a large number that appeared before the close of the
-nineteenth century, and the advent of light motors, the reader who
-wishes fuller acquaintance with man-driven airships may be referred
-to Mr. Chanute’s book, entitled _Progress in Flying-Machines_, which
-describes a large variety of such inventions, and discusses the merit
-and weakness of each.
-
-Blanchard prefaces the description of his machine by answering some
-criticisms of his project, apparently ventured by his neighbors. “They
-object to me,” he writes, “that flying is not the business of man, but
-rather of the feathered birds. I reply that feathers are not at all
-necessary to the bird for flight; any fabric suffices. The fly, the
-butterfly, the bat, etc., fly without feathers and with fanlike wings
-of material resembling horn. It is, then, neither the material nor
-the form that causes flight, but the volume and the celerity of the
-movement, which should be as lively as possible.
-
-“They object, moreover, that a man is too heavy to lift himself alone
-with wings, much less in a vessel which of itself presents enormous
-weight. I reply that my ship is extremely light; as to the man’s
-weight, I pray that attention be given to that which M. de Buffon says
-in his _Histoire Naturelle_, on the subject of the condor; this bird,
-though of enormous weight, easily lifts a two-year-old heifer weighing
-at least a hundred pounds, the whole with wings of about thirty to
-thirty-six feet expanse.”
-
-He then describes the vessel as a little ship four feet long by two
-feet wide, having on either side two posts, each supporting a wing ten
-feet long, the whole forming a parasol twenty feet in diameter. The
-construction was illustrated by an engraver, who had seen the vessel
-and was convinced of its practicability. In conclusion, the inventor
-writes that people shall see him cleave the air with more speed than
-the crow, and that without losing his breath, being protected by a
-pointed mask of peculiar construction. But, as he failed to make good
-his promises, he was subjected to ridicule, as well as praise, by the
-local press, one of the caricatures portraying him in the act of making
-an ascension before a concourse of bulging-eyed savants and long-eared
-jackasses, wearing spectacles to accentuate the appearance of wisdom
-and solemnity.
-
-The scientific coterie of Paris were apparently impatient of the
-attention shown Blanchard by the press and people. Accordingly, in May,
-1782, the distinguished astronomer, De Laland, of the French Academy,
-administered a mild rebuke to the editors of the _Paris Journal_.
-“Gentlemen,” he wrote, “you have given so much time to air ships and
-divination rods that one might eventually think that you believe in
-these follies, or that the scientists who coöperate with your journal
-have nothing to say to dispel these absurd pretensions. Permit me,
-therefore, gentlemen, to occupy some lines in your journal to assure
-your readers that if the savants are silent it is only because of their
-contempt.
-
-[Illustration: FIG. 3.—BLANCHARD’S FLYING-MACHINE.]
-
-“It has been demonstrated to be impossible for a man in any manner
-whatever to raise himself, or even to sustain himself, in the air. M.
-Coulomb, of the Academy of Sciences, at one of our meetings a year ago,
-read a paper in which he showed clearly, by calculating the power of
-a man, determined by experiments, that he would require wings two or
-three thousand feet long moved three feet per second; hence no one but
-an ignoramus would make an attempt of this kind.”
-
-Not many months after this lofty deliverance, Blanchard took De Lalande
-up in a balloon—“the dead borne by the dumb.”
-
-Coulomb’s calculation that a man’s pinions should be half a mile long
-must have been discouraging to those inventors who believed in him;
-for, granting that such wings could lift a man, who could lift the
-wings? And at that date the steam engine was only beginning to develop;
-the petroleum engine was hardly thought of. No wonder that people
-turned eagerly to the balloon when it finally appeared.
-
-There has been some controversy as to what person first clearly
-conceived a feasible design for a balloon. The conception was
-certainly not new to the world in 1783, when Joseph Montgolfier made
-his classical experiment. Indeed, prior to that date three distinct
-principles of aërial flotation had been entertained by natural
-philosophers; first, that a boat could be so formed of heavy material
-as to ride on the upper surface of the atmosphere, as a metallic vessel
-floats on the water; second, that a closed hull, comprising a partial,
-or complete, vacuum, could be made light enough to rise; third, that
-a bag could be made buoyant by filling it with material lighter than
-air. Of course, it is now clear to men versed in mathematics that only
-the light-gas principle is mechanically applicable. But the vacuum
-principle still has adherents among inventors who are too “practical”
-to understand, or trust, exact computation; and the first principle,
-though now discarded by everyone, was plausible enough, even to
-accomplished scientific men, before the experiments of Torricelli, and
-his invention of the barometer, made in 1643. It may, therefore, be
-interesting to notice some of the proposed, or reported, air ships
-based upon these various principles. The following is from _Mendoza,
-Viridario, libri III, probl. 47_:
-
-  “Any brass vessel full of air, which otherwise would sink, is
-  sustained on the surface of the water, though naturally of
-  much greater specific gravity; consequently a wooden ship, or
-  one of any other material, placed on the summit of an aërial
-  superficies and filled with elementary fire, will be sustained
-  in that position till the gravity of the vessel becomes greater
-  than the sustaining power of the fire it contains.”
-
-This is a clear scientific exposition of a plan for navigating the
-atmosphere on its upper surface, assuming a distinct upper surface
-to exist. In commenting on this passage, the Jesuit Schottus, in his
-_Magia Universalis_, uses an expression which indicates his belief that
-a vessel can be made to _float in the air_ by filling it with ether, or
-the element of fire. He says:
-
-  “In such terms has this matter been treated by Mendoza (died
-  1626); nor is there any improbability involved in his view,
-  whether the element of fire be placed above the air, or, what
-  is still more credible, the ether—that is, the purest air.
-  Although any wood, iron, copper, lead, and such like metals are
-  weightier than an equal volume of water, and for that reason
-  will sink in water when placed there alone, yet if fabricated
-  into hollow shapes, and filled with our impure and heavy air,
-  they swim upon waters, and are adapted to the construction of
-  ships, and are sustained by water without danger of immersion;
-  thus, although these bodies are of greater specific gravity
-  than our air, nevertheless, when shaped into a boat and filled
-  with that very light material, they can _float in the air_,
-  and are suitable material for the construction of small ships,
-  because the entire work composed of the little ship and the
-  ether can be made lighter than an equal volume of our impure
-  air, even in the highest region.”
-
-As Roger Bacon proposed a similar device in 1542, Mendoza’s was not
-entirely new and may not have been original. Bacon, describing his
-aërial vessel, says: “It must be a large, hollow globe of copper, or
-other suitable metal, wrought extremely thin, in order to have it
-as light as possible. It must then be filled with ‘ethereal air or
-liquid fire,’ and then be launched from some elevated point into the
-atmosphere, where it will float like a vessel on water.”
-
-In the year 1646 another learned Jesuit published a book, _Ars Magna
-Lucis et Umbræ in Mundo_, in which he relates an episode indicating
-that one of his order had made use of a hot-air balloon to intimidate
-some ignorant pagans. The following demonstration, if reported by a
-modern missionary, would be accepted as a matter of course; why, then,
-should we gravely question the story, since it describes an achievement
-quite possible at the time, assuming that the necessary materials were
-available? And even assuming the report to be fictitious, still it is a
-scientific description of a practicable hot-air balloon, presented and
-credited by a learned scholar and accomplished mathematician more than
-a century before the balloon was publicly exhibited by the illustrious
-Frenchmen. He writes:
-
-  “I know that many of our fathers have been rescued from the
-  most imminent dangers amongst the barbarians of India by such
-  inventions. These were cast into prison, and whilst they
-  continued ignorant of any means of effecting their liberation,
-  some one, more cunning than the rest, invented an extraordinary
-  machine, and then threatened the barbarians, unless they
-  liberated his companions, that they would behold in a short
-  time some extraordinary portents, and experience the visible
-  anger of the Gods. The barbarians laughed at the threat. He
-  then had constructed a dragon of the most volatile paper, and
-  in this he enclosed a mixture of sulphur, pitch, wax, and so
-  artistically prepared all his materials, that, when ignited, it
-  would illumine the machine, and exhibit the following legend
-  in their vernacular idiom, _The Anger of God_. The body being
-  formed and the ingredients prepared, he then affixed a long
-  tail, and committed the machine to the heavens, and, favored
-  by the wind, it soared aloft towards the clouds. The spectacle
-  of the dragon so brilliantly lit was terrific. The barbarians,
-  beholding the unusual motion of the apparition, were smitten
-  with the greatest astonishment, and now, remembering the
-  threatened anger of Deity and the words of the father, they
-  were in fear of expiating the punishment he had prognosticated
-  for them. Therefore, without delay, they threw open the gates,
-  they suffered their prisoners to go forth in peace and enjoy
-  their freedom. In the meantime the fire seized on the machine
-  and set it in a blaze, and with an explosion, which was
-  interpreted as an expiring declaration of satisfaction, it,
-  apparently of its own accord, vanished from sight, as if it
-  had accomplished its supernatural mission. Thus the fathers,
-  through the apprehension which this natural manifestation
-  inspired, obtained that which could not be purchased with a
-  large amount of gold.”
-
-Perhaps the reader will permit another anecdote, not entirely for its
-scientific value, but because he may like to compare the attitude of
-people toward aërial navigation in the dark ages with the attitude of
-his neighbors at the opening of the twentieth century. In two histories
-by Jef le Ministre and De Colonia, of the town of Lyons, the following
-account is given:
-
-  “Toward the end of Charlemagne’s reign, persons who lived
-  near Mount Pilate in Switzerland, knowing by what means
-  pretended sorcerers traveled through the air, resolved to try
-  the experiment, and compelled some poor people to ascend in an
-  aërostal. This descended in the town of Lyons, where they were
-  immediately hurried to prison, and the mob desired their death
-  as sorcerers. The judges condemned them to be burned; but the
-  Bishop Agobard suspended the execution, and sent for them to
-  his palace, that he might question them. They answered: ‘Qu’ils
-  sont du pays meme, que des personnes de consideration les ont
-  forcés de se laisser conduire, leur promettent qu’ils verroient
-  des chose merveilleuses; et qu’ils sont veritablement descendu
-  par l’air.’ Agobard, though he could not believe this fact,
-  gave credence to their innocence, and allowed them to escape.
-  On this occasion he wrote a work on the superstition of the
-  time, in which he demonstrated the impossibility of rising in
-  the air; that it is an error to believe in the power of magic;
-  and that it has its existence in the credulity solely of the
-  people.”
-
-One of the first men to make an aërial model like a fire balloon was
-the celebrated Brazilian, Bartholomeo-Lourenco de Gusmao, who in his
-day was nicknamed the “flying man,” and who is reported to have made
-a remarkable experiment in aërial locomotion at Lisbon. The following
-account of it is found in a manuscript of Ferreira:
-
-  “Gusmao made his experiment on August 8, 1709, in the court of
-  the Palace of the Indies, before his majesty and a large and
-  distinguished audience, with a globe which lifted itself softly
-  to the height of the hall of the Ambassadors, then descended in
-  like manner. It was borne up by certain materials which burned
-  and which the inventor himself had ignited.”
-
-All the details of this description, which was written a generation
-or more before the Montgolfier experiment, suggest at once a hot-air
-balloon. But a note printed in 1774 and cited by Cavallo explains that
-the globes must have been transported by gas. It is certain that early
-in 1709 Gusmao applied to the King for a patent and sole right to some
-such invention, desiring an injunction and severe penalty against
-all infringements. The application sets forth a machine capable of
-journeying through the air faster than over land or sea, competent
-to carry messages five or six hundred miles a day to troops, or the
-most distant countries, and even adequate to explore regions about the
-poles. Quite a modern promoter Señor Gusmao. The King in reply issued
-the following decree:
-
-  “Agreeably to the advice of my council, I order the pain of
-  death against the transgressor. And in order to encourage the
-  suppliant to apply himself with zeal toward improving the
-  machine which is capable of producing the effects mentioned by
-  him, I also grant him the first Professorship of Mathematics in
-  my University of Coimbra, and the first vacancy in my College
-  of Barcelona, with the annual pension of 600,000 reis during
-  his life.”
-
-The “patent” seemed liberal enough, and yet Gusmao never resumed
-his aërial experiments. He was accused of magic, and may have
-feared persecution on that account; accordingly he engaged in naval
-construction till 1724, when he left Portugal.
-
-The first vacuum balloon was proposed by the Jesuit father, Francis
-Lana, and described in his book _Podromo dell’Arte Maestra Brecia_,
-which appeared in 1670. Though not a practical project like Gusmao’s,
-it was very ingenious, and marks an interesting phase in the evolution
-of the fundamental idea of the air ship, or “balloon” as it was called
-by the inventor, who then coined the word now in common use. Lana
-proposed to use four copper spheres each 25 feet in diameter and
-1/225 inches in wall thickness, quite well exhausted of air, to give
-ascensional force which he computed at 1,200 pounds aggregate for the
-four spheres. From these he would suspend the passengers in a boat
-having a mast and sail to propel the ship in time of favorable wind.
-Having computed the buoyancy according to well-known physical laws, he
-could see no possible objection to his project “unless,” he writes,
-“it be that God would never permit this invention to be practically
-applied, in order to prevent the consequences that would ensue
-therefrom in the civil and political government of men.”
-
-[Illustration: FIG. 4.—LANA’S PROPOSED VACUUM BALLOON.]
-
-Of recent years inventors having less delicate scruples about
-embarrassing Providence, have revived Lana’s project with
-improvements. It has been proposed to replace the sail by a
-motor-driven propeller, and to ensure the hull against collapse from
-the prodigious external air pressure—a ton per square foot—by ample
-internal bracing. Even within the past twelve months this scheme has
-been soberly advocated by several technical journals and by the author
-of an elaborate book on aërial warfare. To a mathematician this is
-amusing, when not too pathetic; for it can be rigorously proved that
-no vacuum balloon of present day material, whatever its design, can
-possibly resist crushing if made light enough to float.
-
-In 1887 Walter Wellman described in the _Associated Press_ a steel
-vacuum balloon 144 feet in diameter and 654 feet long in which a
-Chicago doctor proposed to carry passengers to the North Pole, at
-incredible speed, if they would furnish him $130,000 to meet the
-expenses of construction. “Here is a most excellent opportunity,” wrote
-Wellman, “for all who would like to win fame by being one of the party
-which shall set foot upon that icy _ignis fatuus_ of many nations and
-two centuries.” Two decades later Mr. Wellman organized, after his own
-ideas, an aërial expedition to the North Pole; but he no longer favored
-starting from Chicago in a vacuum balloon with a party of stockholders.
-
-It may be added that the inventor of the great steel vacuum balloon,
-after organizing the Trans-Continental Aërial Navigation Company, and
-failing to raise all of the $130,000, sought aid from the national
-government. Here was an interesting situation; a doctor ignorant
-of mechanics, with the plans for a mammoth and impossible balloon,
-appealing for aid to a congress, supremely shy of air ships, even
-though recommended by its ablest military advisers. But in this case
-there was a capable lobby. The bill for this physically impossible
-balloon actually passed the House, and was finally defeated only by
-the timely effort of a few scientific men who, by easy calculation,
-proved the absurdity of the invention. As the reader may like to see a
-mathematical proof of the impossibility of a vacuum balloon, since such
-projects arise frequently, the argument is given in Appendix I.
-
-
-
-
-                                PART I
-
-                         GROWTH OF AËROSTATION
-
-
-
-
-                               CHAPTER I
-
-                   EARLY HISTORY OF PASSIVE BALLOONS
-
-    Oh, that I could as smoke arise,
-    That rolls its black wreathes through the air;
-    Mix with the clouds, that o’er the skies
-    Show their light forms, and disappear:
-    Or like the dust be tossed
-    By every sportive wind till all be lost!
-                                           —ÆSCHYLUS.
-
-
-If desire is sometimes the mother of invention, doubtless the wish to
-“mix with the clouds,” or “as smoke arise,” suggested to man his first
-means of aërial locomotion. Indeed this is openly avowed by Joseph
-Montgolfier. “Smoke rises in the chimney; why not encage this smoke,
-and have an available force.” But before describing his fundamental
-experiments of 1783, let us notice the less conspicuous ones,
-though not less philosophical, of his immediate predecessors in the
-development of aëronautic science.
-
-It has been seen, that many years before 1783, inventors had clearly
-conceived the true principle of the balloon, and would be glad to
-avail themselves of an element of sufficiently low specific gravity
-for aërial flotation. The desired opportunity came when, in 1766,
-Henry Cavendish published his experiments, proving that hydrogen is
-many times lighter than air. Immediately after this, Dr. Black, the
-famous chemist and natural philosopher of Edinburgh, conceived the
-idea that a thin light vessel filled with hydrogen should be able to
-float and rise in the atmosphere, ideas that he conveyed to his friends
-and expressed in his lectures a year or two after the appearance of
-Cavendish’s publication. But he contented himself with merely pointing
-the way to an obviously practicable invention, leaving, as a university
-professor should, the development of the scientific idea to inventors
-and constructive engineers.
-
-Intermediate between Dr. Black, the pure scientist, and the Montgolfier
-brothers manufacturers, came Tiberius Cavallo, an Italian philosopher
-living in England, who made the first small hydrogen balloons. In
-a note presented to the Royal Society of London, June 20, 1782, he
-relates experiments that seem to entitle him to all the credit of
-inventing the balloon except success on a practical scale. He made
-hydrogen soap bubbles which rose beautifully in the air, an experiment
-that has been repeated throughout the world in every chemical
-laboratory since his day. He made a variety of gum bubbles and varnish
-bubbles inflated with hydrogen; but curiously enough these failed
-to rise, though it is known that such bubbles can be made to float
-handsomely.[5] He inflated carefully prepared gold-beater skin and
-failed, though gold-beater skin balloons, both large and small, are now
-a marketable commodity. Finally he constructed paper balloons which he
-tried to float by use of hydrogen, but without success, though a year
-later the Montgolfier brothers easily made paper bags arise with hot
-air, and Professor Charles ascended in a large silk balloon inflated
-with hydrogen.
-
-The cause of Cavallo’s interesting failures reveals itself in his own
-account of one of his pioneer experiments. In his _History and Practice
-of Aërostation_, he relates that he constructed, of fine Chinese paper,
-a cylindrical balloon having short conical ends and a calculated
-buoyancy of twenty-five grains, when properly inflated with hydrogen.
-This bag, carefully deflated of air by compression between the hands,
-he suspended above a large bottle connected with it by a glass tube,
-and supplied with materials for generating hydrogen; in this case a
-mixture of dilute sulphuric acid and iron filings. When the hydrogen
-was evolving quite rapidly, he expected to see the paper sac expand
-and fill out with proportionate speed; but to his surprise it remained
-perfectly flat, while the room filled with the strong and disagreeable
-odor of the “inflaminable air.” He then realized that the carefully
-made sac of paper, which could be so easily inflated with air, was very
-permeable to hydrogen, allowing it to escape instantly, as through
-porous cloth, or netting.
-
-Cavallo desisted when the goal was within reach. His plans were
-practicable, but he abandoned them too readily. Why did he not varnish
-his balloon when it leaked? He could thus so easily have inaugurated
-the art of aërial navigation. But after salting the bird’s tail he let
-it escape.
-
-Various accounts have been given of the steps by which the Montgolfiers
-were led to their invention of the balloon. They are said to have
-studied and discussed projects for aërial locomotion a decade before
-hitting upon their first successful device; at one time filling a paper
-bag with smoke ineffectually; again with steam, and again trying, but
-in vain, to employ hydrogen. The following apparently reliable account
-is given by a friend of the Montgolfiers, Baron Gernando, in his
-biographical notice of Joseph Montgolfier, having obtained the story
-from the inventor himself.
-
-Joseph Montgolfier found himself at Abignon, and it was at the time
-when the combined armies held the siege of Gibraltar. Alone, in the
-chimney corner, dreaming, as usual, he was contemplating a sort of cut
-that represented the work of the siege; he grew impatient observing
-that one could not reach the body of the place either by land or
-sea. “But could not one arrive there through the air? Smoke rises in
-the chimney; why not store this smoke in such a manner as to form an
-available force?” His mind calculated instantly the weight of a given
-surface of paper, or taffeta; he constructed without delay his little
-balloon, and saw it rise from the floor, to the great surprise of his
-hostess, and with a peculiar joy. He wrote on the spot, to his brother
-then at Annonay: “Prepare immediately a supply of taffeta and cordage,
-and you shall see the most astonishing thing in the world.”
-
-A quainter story is told by Brisson in his _Dictionary of Physics_. He
-says: “I can only repeat what the citizen Montgolfier himself told me,
-when he came to Paris to announce his discovery; that the citizeness
-Montgolfier having placed a skirt on an open-wicker basket, such as
-women use to dry linen, the skirt was lifted to the ceiling. It is from
-this fact that the citizens Montgolfier started.”
-
-Whatever the preliminaries, the Montgolfier brothers finally made the
-experiment of holding a paper bag over a fire fed with wet straw and
-wool. It is doubtful whether they purposed to fill it with smoke, or
-with hot air or an electrical cloud. They knew that a cloud of some
-kind rises from such a fire, and they wanted to harness it. Their
-first balloon took fire and went up as smoke. But they were rich
-paper manufacturers, and soon had another balloon of 700 cubic feet
-capacity. This rose from the fire to a height of 1,000 feet, carrying
-no fuel with it. Thus two practical[6] men had made fire lift a paper
-sac; let the Academy explain how. The baby Aërostation was born.
-
-How fortuitous the primal steps of science! Galvanism from the twitch
-of a frog’s leg; aërostation from the puff of a petticoat! There had
-been no year in thirty centuries when people could not easily have
-built a hot-air balloon. All the materials were available; only a
-little thought was wanting. A simple sketch sent to a Roman tailor,
-or tent-maker, could have furnished a woven bag competent to lift
-passengers from the heart of the Coliseum, to the wonder and delight
-of a hundred thousand spectators. Yet the genius that could design the
-Coliseum, or cover its vast enclosure with canvas, failed to think of
-the magic bag that would have enhanced so much the ingenious shows of
-a show-loving people. That device was an inspiration destined to a
-common Frenchman at no uncommon period of science. The hydrogen balloon
-arrived in the natural and logical order of scientific progression;
-but the hot-air bag might have presented itself at any time since the
-birth of weaving. It was a happy thought, like the ophthalmoscope,
-or jack-knife—quaint modern creations of constant use or comfort to
-mankind.
-
-The public inauguration of aëronautics occurred on June 5, 1783, at
-Annonay, the home of the Montgolfier family, 36 miles from Lyons.
-The states of Vivarais being assembled at that place, were invited
-to witness the ascension. The Deputies and many spectators found in
-the public square an enormous bag which, with its frame, weighed 300
-pounds, and would inflate to a ball 35 feet in diameter. When told
-that this huge mass would rise to the clouds they were astonished and
-incredulous. The Montgolfiers, however, lit a fire beneath and let the
-bag speak for itself. It gradually distended, assuming a beautiful
-form, and struggling to free itself from the men who were holding it.
-At a given signal it was released; it ascended rapidly, and in ten
-minutes attained a height of 6,000 feet. It drifted a mile and a half
-and sank gently to the ground.
-
-[Illustration: FIG. 5.—MONTGOLFIER’S EXPERIMENTAL BALLOON.]
-
-When the French Academy learned of this event they desired to have
-an ascension in Paris, and at once started a public subscription to
-defray the expense of constructing and inflating a balloon. They
-placed the work in charge of the physicist Charles, after inviting the
-Montgolfiers to Paris, and finding they could not come immediately.
-Charles proved more than a substitute; he became a fertile inventor and
-a rival in the new field. Aided by the skill of the Robert brothers, he
-made a silk globe varnished with dissolved rubber, and filled it with
-hydrogen, which is many times lighter than hot air. The operation of
-filling occupied three days, consuming 500 pounds of sulphuric acid and
-half a ton of iron. The globe was 13 feet in diameter, and designated
-a “balloon,” or big ball. This had next to be moved from the place of
-filling, in the Place des Victoires, to the Champ de Mars, two miles
-distant, in order to have space enough to accommodate the increasing
-crowd of spectators. Accordingly, on the 26th it was conveyed thither,
-in the dead of night, preceded by lighted torches, surrounded by a
-cortege, and escorted by foot and horse guards. Impressive and weird,
-indeed, was this nocturnal caravan of troops and towering globe
-advancing slowly through the dark and silent streets. The astonished
-cab drivers knelt humbly, hat in hand, while the procession passed.
-
-The ascent of this, the first hydrogen balloon, was a popular and
-a memorable event. The field was lined with troops. The curious
-spectators had thronged every thoroughfare and darkened every housetop.
-It was an all day festival, inaugurating a peculiarly French science,
-with French animation. The booming of cannon announced to all Paris
-the impending flight of the balloon. At five o’clock, in the presence
-of 50,000 spectators, and in a shower of rain, the balloon rose more
-than half a mile and entered the clouds. The people overwhelmed with
-surprise and enthusiasm, stood gazing upward, despite the rain,
-observing every maneuver till the vessel had ascended and faded from
-view.
-
-[Illustration: FIG. 6.—CHARLES’ FIRST HYDROGEN BALLOON.]
-
-The landing of this little balloon did not leave it in a condition to
-exhibit proudly to future generations. After drifting three quarters
-of an hour, it fell in a field near Gonesse, a village fifteen miles
-from the place of ascension, apparently ruptured from overdistention.
-The villagers flocked about it with curiosity and trepidation, ignorant
-of its nature, whether of bird kind or monster; and doubtful of its
-origin, whether natural or satanic. They fell upon it with flails and
-pitchforks. When struck it smelt strongly of sulphur, indicating a
-diabolic source. They finally hitched it to the tail of a horse which
-galloping away in terror, badly damaged it. Whether this destruction
-was wrought through fear or rustic hilarity, it induced the government
-of France to issue a notice to the public explaining the innocuous
-nature of a simple balloon.
-
-In the meantime Joseph Montgolfier, having reached Paris, had
-constructed a waterproof linen balloon 46 feet in diameter and
-ornamented in oil colors, which was to be publicly launched at
-Versailles. On September 19, 1783, the king and queen, the court and a
-vast throng of people of every rank and age, assembled to witness the
-ascension. Montgolfier explained to them every detail, and finally lit
-the fire, about one o’clock. The great bag gradually expanded, rounding
-out in eleven minutes to a beautiful globular form, tugging upward with
-a force of seven hundred pounds. Beneath was suspended a wicker cage
-containing the first aërial passengers—a sheep, a rooster and a duck.
-The vessel rose majestically above the applauding multitude to a height
-of fourteen hundred feet, and drifted some two miles in eight minutes,
-descending gradually in the wood at Vaucresson. The animals were tipped
-out on landing; but, when found by two game-keepers, they were none the
-worse for their strange journey. The sheep was grazing and the cock
-crowing, says one report, while another relates that the sheep had
-trampled on the rooster and lamed him.
-
-Stephen Montgolfier now wishing to send up human passengers, made a
-balloon of 100,000 cubic feet capacity. It was shaped like a full lemon
-pointing upward, with a cylindrical neck below, 16 feet in diameter.
-Around this neck was a wicker balcony three feet wide, to carry the
-aëronauts, bundles of straw for fuel, pails of water and sponges to
-extinguish incipient conflagrations, here and there in the balloon,
-during a journey. Through stokeholes in the side of the neck sheaves
-of straw could be forked to the grate suspended centrally below by
-radial chains. During inflation the base of the balloon rested on a
-platform, and its top was supported by a rope stretched between two
-poles. The vessel when completed, in a garden of the Faubourg St.
-Antoine, was 85 feet high by 48 feet across, and weighed 1,600 pounds.
-About its zone, painted in oil, were elegant decorations; portraits,
-cyphers of the king’s name, fleur-de-lis, with fancy borders below and
-above; while higher still, on the arching dome of the bag, were all the
-signs of the celestial zodiac.
-
-The handsome vessel was now ready; but what daring captain should
-navigate her? King Louis proposed two prisoners who were under sentence
-of death, and had to be killed somehow. But the brave Pilâtre de
-Rozier protested indignantly: “Eh quoi! de vils criminels auraient
-les premiers la gloire de senlever dans les airs! Non, non, cela ne
-sera point.” He stirred up the city, and finally prevailed, through
-the entreaties of the Marquis d’Arlandes, who secured from the king
-permission to accompany his friend.
-
-After some days of preliminary practice in maneuvering the tethered
-balloon, these gentlemen were ready for an aërial voyage. On November
-21, 1783, the balloon was inflated in the garden of La Muette palace,
-and stocked with enough straw for an hour’s journey. When all was ready
-Pilâtre de Rozier and the Marquis d’Arlandes stepped with eager courage
-into the gallery taking opposite sides to ensure proper balance. At two
-o’clock they rose splendidly, amid the acclamations of a vast throng
-of spectators, and at the height of 280 feet, removing their hats,
-saluted the surprised multitude. Encountering a south blowing wind,
-they drifted five miles in some twenty minutes, and landed safely in a
-field. The apparatus was soon assembled on a cart and returned to the
-Faubourg St. Antoine, where it was originally constructed. The details
-of this first human voyage in a balloon are very interesting and well
-told in a letter written by the Marquis d’Arlande to a member of the
-French Academy.
-
-[Illustration: FIG. 7.—MONTGOLFIER’S PASSENGER BALLOON.]
-
-“At this time M. Pilâtre said: ‘You do nothing, and we shall not
-mount.’ ‘Pardon me,’ I replied. I threw a truss of straw upon the
-fire, stirring it a little at the same time, and then quickly turned
-my face back again; but I could no longer see La Muette. Astonished,
-I gave a look to the direction of the river.... M. Pilâtre then said,
-‘See, there is the river, and observe that we descend.’ ‘Well, then,
-my friend, let us increase the fire;’ and we worked away. But instead
-of crossing the river, as our direction seemed to indicate, which
-carried us over the house of the Invalides, we passed along the island
-of Cygnes, reëntered over the principal bed of the river, and advanced
-up it as far as the gate de la Conference. I said to my intrepid
-companion: ‘See, there is the river &c.’ I stirred the fire, and took
-with the fork a truss of straw, which from being too tight, did not
-take fire very easily. I lifted it and shook it in the middle of the
-flame. The next moment I felt as if I were lifted up from under the
-arms, and said to my companion, ‘Now we mount, &c.’ At the same time
-I heard a noise toward the top of the machine, as if it were going to
-burst; I looked, but did not see anything. However, as I was looking
-up, I felt a shock, which was the only one I experienced. The direction
-of the motion was from the upper part downwards. I said then: ‘What
-are you doing? Are you dancing?’ ‘I don’t stir,’ said he. ‘So much the
-better,’ I replied, ‘it is then a new current, which, I hope, will push
-us over the river.’ In fact, I turned myself in order to see where we
-were, and I found myself between l’École Militaire and les Invalides,
-beyond which place we had already gone about 2,500 feet. M. Pilâtre
-said at the same time: ‘We are on the plain.’ ‘Yes,’ said I, ‘and
-we advance.’ ‘Work on,’ said he. I then heard another noise in the
-machine, which appeared to be the effect of a rope breaking. This fresh
-admonition made me examine attentively the interior of our habitation.
-I saw that the part of the machine which was turned toward the south
-was full of round holes, many of which were of a considerable size. I
-then said: ‘We must descend,’ and at the same time I took the sponge
-and easily extinguished the fire, which was round some holes that I
-could reach; but leaning on the lower part of the linen, to observe
-whether it adhered firmly to the surrounding circle, I found that the
-linen was easily separated from it, on which I repeated that it was
-necessary to descend. My companion said: ‘We are over Paris.’ ‘Never
-mind that,’ said I, ‘but look if there appears any danger for you on
-your side—are you safe?’ He said: ‘Yes.’ I examined my side, and found
-that there was no danger to apprehend. Farther, I wetted with a sponge
-those cords which were within my reach. They all resisted, except two,
-which gave way. I then said: ‘We may pass over Paris.’ In doing this,
-we approached the tops of houses very sensibly; we increased the fire,
-and rose with the greatest ease. I looked below me, and perfectly
-discovered the Mission Étranger. It seemed as if we were going toward
-Saint-Sulpice, which I could perceive through the aperture of our
-machine. On rising a current of air made us leave this direction, and
-carried us toward the south. I saw on my left a sort of forest, which
-I took to be the Luxembourg; we passed over the Boulevard, and then I
-said: ‘Let us now descend.’ The fire was nearly extinguished; but the
-intrepid M. Pilâtre, who never loses his presence of mind, and who
-went forward, imagining that we were going against the mills that are
-between Petite Gentilly and the Boulevard, admonished me. I threw a
-bundle of straw on the fire, and shaking it in order to inflame it more
-easily, we rose, and a new current carried us a little toward our left.
-M. Rozier said again: ‘Take care of the mills’; but as I was looking
-through the aperture of the machine, I could observe more accurately
-that we could not meet with them, and said: ‘We are there.’ The moment
-after, I observed that we went over a piece of water, which I took
-for the river, but after landing, I recollected that it was the piece
-of water, &c. The moment we touched the ground, I raised myself up to
-the gallery and perceived the upper part of the machine to press very
-gently on my head, I pushed it back, and jumped out of the gallery, and
-on turning toward the machine, expected to find it distended, but was
-surprised to find it perfectly emptied and quite flattened, &c.”
-
-While the foregoing experiment was in progress, plans were matured for
-the construction of a hydrogen balloon large enough to support two
-passengers and remain aloft many hours, without the need of carrying
-dangerous fuel. This type of balloon, called a _Charlière_, after its
-inventor, was destined largely to supersede the hot-air type, known
-as the _Montgolfière_, and indeed, to replace it entirely for free
-voyages of considerable endurance and for most power voyages. The
-construction after the plan of Professor Charles was delegated to two
-very intelligent mechanics, the Robert brothers who also had succeeded
-in dissolving caoutchouc, and thus producing a very superior balloon
-varnish. The project was first announced in the _Journal de Paris_ of
-the 19th of November 1783. As usual in those days of public enthusiasm,
-a subscription was opened to defray the expenses of the experiment,
-estimated to cost about ten thousand francs.
-
-[Illustration: FIG. 8.—CHARLES’ PASSENGER BALLOON.]
-
-This balloon was a truly scientific creation, which advanced
-aërostation from tottering infancy almost to full prime. The bag was
-a sphere 27½ feet in diameter made of gores of varnished silk. A net
-covered the upper half and was fastened to a horizontal hoop girding
-the middle of the globe, and called the “equator.” From the equator
-depended ropes which supported, just below the spherical bag, a wicker
-boat measuring eight feet by four, covered with painted linen and
-beautifully ornamented. The balloon had at the bottom a silk neck 7
-inches in diameter, to admit the gas during inflation, and at the top,
-a valve which could be opened by means of a cord in the boat to let
-out gas during a voyage, so as to lower the balloon, or to relieve
-excessive pressure. In the boat were carried sand ballast to regulate
-the height of ascension, a barometer to measure the elevation, anchor
-and rope for landing, a thermometer, notebook, provisions, and all the
-paraphernalia of a scientific voyage. Barring the fancy boat, this is
-almost a description of a good modern balloon.
-
-The inflation and ascension occurred in the Garden of the Tuileries,
-where the limp bag was initially suspended from a rope stretched
-between two trees. For three days and nights the hydrogen, drawn from
-twenty barrels containing iron and dilute sulphuric acid, poured upward
-through the silken neck into the distending globe, which swelled in
-volume to 1,400 cubic feet. Finally on a beautiful day, the first of
-December 1783, the Tuileries and all the neighborhood were crowded with
-spectators. A numerous guard of soldiers, stationed about the apparatus
-and grounds, preserved order. The fashion and nobility of Paris were
-there, in ample splendor, attracted by the novelty and importance
-of the experiment, and the fame of the inventor. Shortly before two
-o’clock Professor Charles presented to his friend, Montgolfier, a pilot
-balloon six feet in diameter, saying, “It is your prerogative to blaze
-the way through the sky.” The pilot balloon was released, showing to
-everyone the direction of the aërial currents. Charles and Roberts
-stepped into the boat, seated themselves, and quickly rose into the
-sky. The multitude gazed in silent wonder. Presently they observed two
-pennants waving high above them, though the navigators were scarcely
-visible; whereupon they burst forth into wild enthusiasm and thunderous
-applause.
-
-Immediately a cavalcade set out in hot pursuit of the venturesome
-sailors. It was the first chase after an air ship, and a most vigorous
-one. The balloon drifting northwestward at a speed of fifteen miles
-an hour, crossed the Seine, passed over several towns and villages,
-to the great astonishment of the inhabitants, and landed in a field
-near Nesle. Here it was securely held by friendly peasants, to await
-the advent of the official witnesses. Presently these arrived, drew
-up a certificate of descent and signed it. The Duke de Chartres, and
-the Duke de Fitz-James, who had followed less swiftly, now rode up
-and signed the formal document, to the great gratification of the
-aëronauts. The aërial journey had been a most delightful one, lasting
-about two hours and covering nearly thirty miles.
-
-After receiving the felicitations of his friends, Charles determined
-to reascend, in order to obtain further scientific observations. Owing
-to leakage and loss of buoyancy, he must now leave behind his pleasant
-companion. He had proposed replacing with earth, or stones, a part
-of Mr. Robert’s weight, but, finding none at hand, he signaled the
-peasants to let go, whereupon he rose with unusual speed. The remainder
-of this first and very remarkable scientific voyage is well told by the
-navigator himself:
-
-  “In twenty minutes I was 1,500 fathoms high; out of sight of
-  all terrestrial objects. I had taken the necessary precautions
-  against the explosion of the globe, and prepared to make the
-  observations which I had promised myself. In order to observe
-  the barometer and thermometer, placed at the end of the car,
-  without altering the center of gravity, I knelt down in the
-  middle, stretching forward my body and one leg, holding my
-  watch in my left hand, and my pen and the string of the valve
-  in my right, waiting for the event. The globe, which, at my
-  setting out, was rather flaccid, swelled insensibly. The air
-  escaped in great quantities at the silken tube. I drew the
-  valve from time to time, to give it two vents; and I continued
-  to ascend, still losing air, which issued out hissing, and
-  became visible, like a warm vapor in a cold atmosphere. The
-  reason of this phenomenon is obvious. On earth, the thermometer
-  was 47°, or 15° above freezing point; after ten minutes’ ascent
-  it was only 21°, or 11° below. The inflammable air had not
-  had time to recover the equilibrium of its temperature. Its
-  elastic equilibrium being quicker than that of the heat, there
-  must escape a greater quantity than that which the external
-  dilatation of the air could determine by its least pressure.
-  For myself, though exposed to the open air, I passed in ten
-  minutes from the warmth of spring to the cold of winter; a
-  sharp dry cold, but not too much to be borne. I declare that,
-  in the first moment, I felt nothing disagreeable in the sudden
-  change. When the barometer ceased to fall, I marked exactly
-  18 inches 10 lines (20-01 in. English), the mercury suffering
-  no sensible oscillation. From this I deduce a height of 1,524
-  fathoms (3,100 yards), or thereabouts, till I can be more exact
-  in my calculation. In a few minutes more, my fingers were
-  benumbed by the cold, so that I could not hold my pen. I was
-  now stationary as to the rising and falling, and moved only in
-  an horizontal direction. I rose up in the middle of the car
-  to contemplate the scene around me. At my setting out the sun
-  was set on the valleys; he soon rose for me alone, who was the
-  only luminous body in the horizon, and all the rest of nature
-  in shade; he, however, presently disappeared, and I had the
-  pleasure of seeing him set twice in the same day. I beheld,
-  for a few seconds, the circumambient air and the vapors rising
-  from the valleys and rivers. The clouds seemed to rise from the
-  earth and collect one upon the other, still preserving their
-  usual form, only their color was gray and monotonous from the
-  want of light in the atmosphere. The moon alone enlightened
-  them, and showed me that I was tacking about twice; and I
-  observed certain currents that brought me back again. I had
-  several sensible deviations; and observed, with surprise, the
-  effects of the wind, and saw the streamers of my banners point
-  upwards. This phenomenon was not the effect of the ascent or
-  descent, for then I moved horizontally. At that instant I
-  conceived, perhaps a little too hastily, the idea of being able
-  to steer one’s course. In the midst of my transport I felt a
-  violent pain in my right ear and jaw, which I ascribed to the
-  dilatation of the air, in the cellular construction of those
-  organs, as much as to the cold of the external air. I was in a
-  waistcoat and bareheaded. I immediately put on a woolen cap,
-  yet the pain did not go off but as I gradually descended. For
-  seven or eight minutes I had ceased to ascend; the condensation
-  of the internal inflammable air rather made me descend. I now
-  recollected my promise to return in half an hour, and, pulling
-  the string of the valve, I came down. The globe was now so much
-  emptied, that it appeared only a half globe. I perceived a
-  fine ploughed field near the wood of Tour du Lay, and hastened
-  my descent. When I was between twenty or thirty fathoms from
-  the earth I threw out hastily two or three pounds of ballast,
-  and became for a moment stationary, till I descended gently
-  in the field, about a league from the place whence I set out.
-  The frequent deviations and turnings about make me imagine
-  that the voyage was near three leagues, and I was gone about
-  thirty-three minutes. Such is the certainty of the combinations
-  of our aërostatic machine, that I might have kept in the air at
-  least for twenty-four hours longer.”
-
-Further interesting details of the first balloon experiments at Paris
-are furnished by Dr. Benjamin Franklin, then American Minister to
-France, in his letters written to Sir Joseph Banks, President of
-the Royal Society of London, and presented in Appendix II of this
-book. These quaint and substantial stories are well worth perusal
-as the expressions of a great diplomat and philosopher who, in the
-midst of social and political activities, found time for scientific
-correspondence with his friends in both hemispheres.
-
-Aërial navigation was now become a practical art which should advance
-rapidly in popularity, in both Europe and America. Very soon ascensions
-were made everywhere, for private amusement and for public exhibitions.
-Not a few were made for scientific, for military and for topographical
-purposes; thus giving the art a utilitarian as well as a sporting
-feature. It will be interesting to note some of the more conspicuous
-ascensions, voyages and improvements made in passive balloons
-subsequently to the invention of _Montgolfières_ and _Charlières_.
-
-The largest hot-air balloon ever constructed, _La Flesselle_, was
-launched from the suburbs of the city of Lyons on January 19, 1784,
-just two months after the ascent of the first human passengers. It was
-also one of the most troublesome to assemble and keep in repair. Day by
-day, for more than a week, the balloon was inflated for the purpose of
-attaching the ropes to support the great gallery. But the wind blew
-dreadfully at times; rain and snow fell on the machine; frost and ice
-covered the huge bag; many rents ensued, demanding frequent repairs.
-On one occasion, when fed too freely with flame from straw sprinkled
-with alcohol, the monstrous ship rose so vigorously as to drag fifty
-men with it some distance along the ground. Finally on the 19th of
-January, when the weather moderated, the operators built small fires
-under the scaffold below the balloon, and thawed away the ice from
-the drenched and frozen bag. Then they stocked its gallery with straw
-and pitchforks, with fire extinguishers, and other provisions for the
-journey. The inflation beginning about noon, occupied but seventeen
-minutes. The balloon swelled out rapidly, with the roaring flames
-ascending inside, and at last stood forth huge and majestic before
-the admiring multitude—a towering thing of magic growth, 100 feet in
-diameter by 130 feet high.
-
-The ascension of this gigantic vessel was immensely spectacular; but
-it was also most adventurous and foolhardy. The great bag, which at
-best was made of poor materials, was in bad repair after its frequent
-inflations. But of the six passengers in the gallery not one could be
-induced to remain behind to lessen the risk to the others. Their pilot,
-M. de Rozier, remonstrated with them; the proprietor M. C. Flesselle
-wished them to cast lots; but no one would abandon the journey. So,
-with fear and reluctance, the pilot ordered the mooring ropes to be
-cut. Just as the ascent began, a seventh passenger, M. Fontaine, sprang
-into the gallery and sailed aloft with the others. By vigorous stoking
-the aërial sailors urged their fiery vessel upward three thousand feet,
-whence, apparently without fear, they waved their hats to the vast
-throng below.
-
-[Illustration: FIG. 9.—LA FLESSELLE.]
-
-The spectators were now in a frenzy of excitement. For more than a week
-they had vacillated between hope and disappointment; but now they saw
-the huge ship soaring into the sky, perhaps on her way to destruction.
-They heard the blast of martial music and the booming of mortars. Then
-the accumulated emotion of the multitude burst forth. Exclamations
-of joy, shrieks of fear, thunders of applause resounded above the
-sea of people. Finally the balloon began to burst, a dangerous rent
-running vertically along her side. The machine descended with great
-rapidity, to the alarm of everyone. It is reported that not fewer than
-sixty thousand people ran to the place of landing, with the greatest
-apprehension for the lives of the travelers. But the adventurous men
-stepped forth from the gallery, after a fifteen minutes’ voyage,
-without hurt of any kind, save an insignificant scratch borne by Joseph
-Montgolfier, who on this occasion made his first and last ascension.
-This was also the first and last ascension of that gigantic fire
-balloon; for although it furnished a world of delirious emotion and
-excitement, the trouble of inflating the vessel was too great to be
-repeated.
-
-The crossing of the English Channel by balloon had been contemplated
-many months by various adventurous spirits; and at length, on a fine
-day, the seventh of January, 1785, this feat was attempted by two
-intrepid men, the French aëronaut, M. Blanchard, and an American
-physician, Dr. Jeffries, who had graduated at Harvard in 1763, and
-was practicing medicine in England. Starting from the perpendicular
-cliff at Dover Castle, at one o’clock, they sailed in the direction of
-Calais, having with them only thirty pounds of sand ballast. This was
-too little for so long a voyage; but it would doubtless carry them a
-few miles, in the favorable breeze then blowing. To their surprise,
-the atmosphere seemed to grow lighter as they advanced over the water,
-letting them sink too freely. As they approached mid-channel they
-were compelled to discharge all their ballast in order to maintain
-their level. But the balloon still descended, seemingly attracted by
-the water. Then they ejected a parcel of books to gain a moment’s
-relief. When three-fourths across the Channel they sighted the French
-Coast, which now they yearned to see at closer range; for the balloon
-was contracting and sinking rapidly. They threw out from the boat
-everything available, wings, anchors, cords, provisions; yet they saw
-the vessel persistently approaching the sea. Finally they cast off part
-of their clothing, fastened themselves to the cords suspended from
-the balloon-ring, and prepared to cut away the boat. But presently
-approaching the coast near Calais, they began to rise; then ascended
-rapidly, soaring in a magnificent arch above the high grounds. At
-last they descended gradually above the forest of Guines, seized the
-branches of a tree to stop their flight, and at three o’clock were
-happily landed. It was a thrilling voyage of two hours, and made a
-profound impression at the time. As a mark of appreciation the King
-presented Blanchard a sum of 12,000 francs and a pension of 1,200
-francs per year. The people erected a monument on the place of landing
-to commemorate this extraordinary voyage.
-
-This splendid achievement incited two Frenchmen to attempt a counter
-voyage which ended disastrously. On June 15, 1785, Pilâtre de Rozier
-and M. Romain set out from Boulogne on a voyage from France to
-England, in a compound balloon composed of a hydrogen balloon forty
-feet in diameter, below which was suspended a fire balloon ten feet
-in diameter. They hoped by judicious stoking of the lower balloon to
-obviate the sinking tendency suffered by Blanchard and Jeffries. But
-the smaller globe proved a fatal auxiliary. Scarcely a quarter of an
-hour after launching, the whole apparatus was aflame at an altitude of
-3,000 feet, and presently fell in charred and hideous fragments upon
-the seashore. M. Romain still showed some signs of life, but Pilâtre
-de Rozier was completely dead and all his bones were broken. They were
-the first martyrs in the cause of the new science. Poor De Rozier
-knew on starting that his apparatus was in bad condition, but he had
-received for the purpose a sum of money from a distinguished patron,
-and therefore felt obliged in honor to attempt the voyage. He was
-twenty-eight years old and engaged to be married to a young lady in the
-convent at Boulogne, who eight days after the catastrophe which robbed
-her of her fiancé, died brokenhearted and in convulsions.
-
-
-
-
-                              CHAPTER II
-
-               PRACTICAL DEVELOPMENT OF PASSIVE BALLOONS
-
-
-The next important advance in practical ballooning was made by the
-substitution of coal gas for hydrogen. This was England’s contribution
-to an art which previously had not greatly flourished west of the
-Channel. It was a contribution following the natural growth of science;
-for in 1814 coal gas began generally to be used for lighting London,
-and seven years later for inflating balloons. This valuable innovation
-was made by the famous aëronaut, Charles Green, on the occasion of his
-first ascension, made July 19, 1821, the coronation day of George IV.
-The new method largely superseded the old, extending throughout the
-world with the spread of gas lighting; and it gave a powerful stimulus
-to aëronautics by rendering inflation cheap and convenient. Mr. Green
-himself made 526 ascensions during his life, or at the rate of one
-cruise a month for nearly forty-four years. In due time, every country
-had its professional aëronauts, and finally its amateurs, who, forming
-themselves into aëro clubs, devoted themselves to racing in free
-balloons, inflated quite usually from a city gas supply.
-
-In 1836 Mr. Robert Holland organized an expedition designed to test the
-utmost capabilities of the balloon of his day, particularly in points
-of endurance and control. Engaging as pilot the first aëronaut of the
-age, Mr. Charles Green, and employing the largest gas balloon that ever
-had been constructed, stocked with provisions enough to last three
-men a fortnight, he invited a third person, Mr. Monck Mason, to join
-them on a cruise from London to wherever the wind would take them, but
-preferably to land near Paris, as the balloon was to be delivered there
-after the voyage.
-
-[Illustration: FIG. 10.—THE GREAT BALLOON OF NASSAU.]
-
-The vessel selected for that famous cruise was _The Great Balloon of
-Nassau_, then recently built by Mr. Green and representing all that his
-skill and experience could devise. It was of pear shape, formed of
-the finest crimson and white silk, “spun, wove and dyed expressly for
-the purpose,” and comprising when distended a volume of 85,000 cubic
-feet. From its stout balloon-ring six feet in diameter was suspended a
-wicker car measuring nine feet long by four wide, having a seat across
-either end, and a cushioned bottom to serve as a bed, if such should be
-needed. Across the middle of the car was a plank supporting a windlass
-for raising or lowering the guide-rope, that is a heavy rope which
-could be trailed over land, or water, to keep the balloon at a nearly
-constant level without expenditure of ballast, and to check its speed
-on landing. This valuable device invented by Mr. Green in 1820, was
-now to receive adequate trial, which, indeed, formed one of the chief
-purposes of the cruise. Other paraphernalia of the voyage were food
-and drink, warm clothing, lamps, trumpets, telescopes, barometers, a
-quicklime coffee-heater, a grapnel and cable, and a ton of sand ballast
-in bags.
-
-The voyage proved well worthy of the elaborate preparations. At
-one-thirty o’clock on November 7th, the three navigators arose
-from London, in presence of a mighty multitude, and drifted in a
-southeasterly direction traversing the cultivated plains of Kent, and
-in two hours passed the environs of Canterbury. Here they dropped
-a parachute with a letter for the Mayor, which he duly received.
-Continuing their journey they floated leisurely above the tree tops,
-talking to the inhabitants of the country, startling the fleet-winged
-quail, terrifying a colony of rooks, and finally reaching Dover at
-sundown, where they again dropped a letter for the Mayor of the city,
-which also was duly delivered.
-
-Without a moment’s pause they drifted over the Channel into the
-gathering darkness. Before them rose a huge wall of vapor and black
-clouds standing on the bosom of the sea; behind them the twinkling
-lights and the music of breakers rolling on a hospitable shore.
-Presently they were immersed in a region of absolute silence and
-impenetrable darkness. At times this deep stratum would slowly
-dissolve, revealing a glimpse of the dusky ocean and a passing ship;
-then some huge wreath of vapor would involve them in bottomless gloom,
-without perspective, without apparent motion, without a sound to cheer
-or mark their dubious course. Now to avoid the risk of settling too
-near the sea, as Blanchard and Jeffries had done, they were preparing
-to let down the guide-rope with floating ballast attached, when
-suddenly they emerged from the pall of darkness, and were greeted by
-the glittering lights of Calais, and the gentle sound of waters dashing
-upon the beach. They had crossed the Channel in one hour, and were
-soaring serenely three thousand feet above the ocean, not having to
-lower the guide-rope to preserve their elevation.
-
-Now came the preparations for a night voyage over an obscurely defined
-land route. A simple rope one thousand feet long without ballast was
-allowed to trail beneath them. A lamp was lit. Coffee was heated by the
-slacking of quicklime. An ample store of viands and wine was spread on
-the board in the middle of the car. The strenuous period of thought and
-labor was past, and now three hungry men sat leisurely at dinner, after
-a fast of twelve long hours. However sparing of bones and bottles,
-which later might serve as ballast, they were not economical of food
-and wine that evening. For the present they had only to live and be
-happy as bachelors. Muffled in soft garments, well fed, abundantly
-served with divine beverages, hot or cold; what finer picture of
-masculine comfort and delight?
-
-They were now floating tranquilly in the vast solitude of heaven, over
-a teeming continent mantled in night and mystery. Far along earth’s
-sable surface gleam the scattered fires of many villages; and above
-it the lovelier fires of a moonless sky. Unseen, unsuspected, they
-survey kingdoms and cities, trailing their long rope serpent-like
-over woodland, field and quiet homestead. Now on the horizon before
-them looms a greater fire, like a distant conflagration, widening as
-they approach. Gradually it expands into a model city, shooting out
-long lines of illuminated streets; here the public squares, markets
-and theatres; there the rumbling iron mills with blazing furnaces.
-They are above Liege at her festive hour, murmuring with animation
-and busy life. Again they drift into the dark regions of slumber,
-lapped in silence and deep tranquillity, where the lights of men are
-extinguished, and the stars, redoubling their lustre, gleam whitest
-silver in heaven’s jetty dome. Midnight involves the world; an abyss
-of darkness enfolds it; their solitary lamp seems to melt its way
-through solid space of blackest marble. For hours they undulate over
-the rolling hills, rising and falling a thousand cubits, held always to
-earth by the trailing rope. At times they are so near as to trace the
-landscape dimly; here a white tract covered lightly with snow, here a
-dark valley or forest, here a tortuous river, probably the Rhine, with
-its multitudinous thunder of waters. But in all that weird and obscure
-wandering no joyous note of human or animal life ascends ere dawn to
-cheer their solitary course in the sky.
-
-At last the paling of the morning star, and a faint tingeing of the
-eastern cumuli, announce the expected day. With sudden bound the
-great ship mounts aloft twelve thousand feet, into the glory of the
-blazing sun, new risen among clouds of amber and purple. Far below,
-twilight and mist still mantle the half-awakened world, presenting a
-stupendous panorama, vast as an empire. Presently down they plunge into
-the vaporous and obscure atmosphere, drifting carelessly, but soon
-reascending into the splendor of morning. Thus after making the sun
-rise three times and set twice, they float contentedly along the misty
-landscape, marveling what region lies below them, whether a barren
-wilderness, or the abode of civilized life, with human comforts and a
-ready means of transportation. A hot breakfast would be very welcome
-now; for they had accidentally dropped the lime pot and had spent the
-latter half of the night without warm beverage in a region where oil
-and water had frozen.
-
-At length through the clearing vapor they perceive the country well
-tilled and populous; a good place to land to shorten their route to
-Paris, and avoid the wide plains of Poland or Russia. They raise the
-guide-rope, lower the cable and anchor, open the valve, and descend
-in a grassy field near Weilburg, in the Duchy of Nassau. It is now
-seven-thirty o’clock, just eighteen hours since starting; and they
-have traveled five hundred miles, the longest aërial voyage thus
-far recorded. Very soon they are surrounded by a wondering crowd of
-pipe-puffing, shaggy-headed, German peasants, by whose willing aid they
-finally deflate the balloon, pack it in the bottom of the car, and
-mount it on a one-horse cart for Weilburg. Thence the aëronauts, after
-a week of festivities in their honor, and distinguished attentions from
-the highest officials of the town, embarked with their balloon for
-Paris. This famous craft now bore its permanent title; for a few days
-previously the lovely daughter of the Baron de Bibra, with seven other
-young ladies and Mr. Green, had stood within the air-inflated vessel,
-poured a generous libation of wine, and christened the hardy cruiser
-_The Great Balloon of Nassau_.
-
-It was in truth a great balloon in various ways; in solidity and
-strength, in workmanship, in completeness of appointment, in endurance
-and control. Having accomplished that long journey without a sign
-of weakness or defect, it was still in prime condition, proudly
-heading for the farthest verge of Europe. It had not, of course, the
-instrumental equipment of a modern balloon; but it did possess the
-elements essential for a long and hard cruise. Since the day of its
-launching many additions have been added to the art, but these, for
-the most part, are special adjuncts. The more important features of a
-good balloon are practically the same to-day as when they were first
-introduced by Professor Charles and sturdy old Mr. Green.
-
-A still more elaborate and colossal air ship was the _Geant_,
-constructed in 1863, for A. Nadar of Paris. It was made of a double
-layer of white silk, had a volume of 215,000 cubic feet and a buoyancy
-of 4½ tons. The car was a wicker cabin 13 feet wide by 7 feet high,
-with a wicker balcony round the top so that the roof could be used
-as an observation deck—a delightful place to loll in the starlight,
-or watch the morning sun “flatter the mountain tops with sovereign
-eye.” The closed car comprised two main rooms with a hallway between
-them, one containing the captain’s bed and baggage, the other having
-three superposed berths for passengers. Minor divisions of the car
-were reserved for provisions, a lavatory, photography and a printing
-press, the latter to be used for the dissemination of news from the
-sky, as the navigators floated from state to state. A compensator
-balloon of 3,500 cubic feet, just below the main bag and connected
-with it, received the escaping gas during expansion with increase of
-temperature or altitude, and gave it back on contraction. In fact
-as well as in name, Nadar’s vessel was a giant. Curiously enough, he
-called it the “last balloon,” for he expected to realize enough money
-by exhibiting it, to inaugurate successful flying by means of the
-helicopter, and thus banish ballooning from the world of futile effort
-to the domain of bygone dreams and chimæras.
-
-[Illustration: FIG. 11.—CAR OF NADAR’S BALLOON.]
-
-The first ascension, made on Sunday, October 4, 1863, was one of
-magnificent promise. In the midst of a vast holiday throng on the Champ
-de Mars, the great globe towered aloft nearly two hundred feet, held to
-earth by one hundred men and twice as many sand bags. In the car were
-fifteen notable passengers including one lady, the fair young Princess
-de la Tour d’Auvergne, in morning toilet and a pretty hat. “Lachez
-tout!” shouts Captain Nadar, the effervescent photographer of Paris.
-Away they soar, heading for St. Petersburg, with provisions enough to
-sail beyond the polar sea.
-
-The captain was now in supreme control, with the key to the victual
-and liquor room in his pocket, and his twelve commandments duly signed
-by all aboard. They had pledged themselves not to gamble, not to carry
-inflammable materials, not to smoke unduly, not to throw bottles
-overboard, not to quit the balloon without permission, but to descend
-if so ordered, etc. They had sailed at five o’clock in the evening and
-all was going merrily. But presently trouble came. The valve rope gave
-way, the vessel was sailing in the dark, and the Godards declared she
-was drifting to sea, whereas she was drifting in quite the opposite
-direction. To be on the safe side they threw out the anchors by
-permission of the commander. One anchor broke, but the other took hold
-and checked the balloon in spite of the strong wind blowing. At last
-after three violent bumps on the ground they landed near Meaux at nine
-o’clock in the evening, one passenger sustaining a broken knee, the
-others various bruises. It was a grand adventure and all were pleased.
-
-Two weeks later a second voyage was begun in similar style, and again
-from the Champ de Mars, this time in the presence of the King of
-France and the young King George of Greece; but now Nadar took along,
-not the Princess with the pretty hat, but Madame Nadar, his wife. To
-entertain the crowd before starting, thirty-two persons were first sent
-aloft 300 feet and drawn back to earth. Finally at five o’clock Sunday
-evening, October 18th, a party of nine passengers soared proudly
-northward, well provisioned as before, and eager for a long voyage.
-They disappeared in the gathering night, leaving their friends much
-concerned for their safety and ultimate destination. At half past eight
-they were over Compiegne, seventy-eight miles away, drifting near the
-ground to say “All goes well” and have the good tidings transmitted
-to Paris. At nine they crossed the Belgian frontier; at midnight they
-were over Holland; at sunrise they skirted the Zuyder Zee and entered
-Hanover; at eight they were coursing headlong toward Nienburg and the
-North Sea in the current of a swift west wind.
-
-They were now in great peril. If they went to sea they might all be
-drowned; if they came to earth at such horizontal speed they should
-be terribly pounded. Choosing the latter evil, they opened the valve
-and threw down the grappling irons. “To the ropes,” shouted the Godard
-brothers. Assembling on deck all clung to the suspension ropes to
-mitigate the shock of landing. Nadar put his arm about his wife to
-protect her. The anchors snatching a tree, uprooted and dragged it
-along; then caught and tore off the roof of a house; threshed into
-a telegraph line pulling down the wires and poles; struck into some
-firmer obstacle and broke off completely, leaving the huge monster
-to sweep unchecked in the violent ground current. Owing to trouble
-with the valve, the gas could not be liberated quickly; the great
-vessel again and again plunged to earth and rebounded high in air,
-its ponderous basket crashing through heavy timber, and breaking
-down whatever opposed its course. For nine miles they pounded over
-the plain by Nienburg toward the sea, dashing into pools, bogs and
-thickets, their limbs sprained or broken, their bodies bruised, their
-faces splashed with mud. Presently through loss of gas the rebounding
-ceased, the basket dragged along the earth squeezing some of the
-passengers beneath it, and dumping others out on the ground, leaving
-them behind. Those remaining tried to assist Madam Nadar to land, but
-they were tumbled out and she was caught under the basket from which
-she was extricated with much difficulty, when the balloon was finally
-halted. Thus their memorable voyage of seventeen hours, covering 750
-miles, had a terrific, though not fatal ending. One had a broken femur,
-another a dislocated thigh, others numerous scratches and contusions.
-But no complaint was uttered; for the afflictions were regarded as
-natural concomitants to such interesting sport. After some days tender
-nursing by the Germans, and solicitous inquiries from the King of
-Hanover, they returned to Paris; some indeed on their backs, but for
-all that, none the less admired by their countrymen, as survivors of a
-marvelous adventure.
-
-Another valiant English leader in aërostation was James Glaisher,
-member of the British Association for the Advancement of Science.
-As one of a committee of twelve appointed by that body in 1861, to
-explore the higher strata of the atmosphere by means of the balloon,
-he volunteered his services as an observer, when no other capable man
-could offer to do so. With a professional aëronaut, Mr. Coxwell, and a
-new balloon specially constructed for the work, cubing 90,000 feet, he
-made eleven ascensions for the society, four from Wolverhampton, seven
-from Woolwich. Incidentally he made seventeen other ascents of various
-altitude; not at the expense of the committee, but as a scientific
-passenger in public balloon ascents advertised beforehand.
-
-The objects of the enterprise were first to study the physical
-conditions of the atmosphere; secondly to study the effect of the
-higher regions upon the passengers themselves, and some pigeons,
-which they carried along; thirdly to make some observations in
-acoustics and magnetism, particularly to determine the period of
-oscillation of a magnet at various altitudes. The specific study of
-the atmosphere itself was to comprise observations at all altitudes,
-of the temperature of the air, its pressure, and percentage of
-moisture; observations of the velocity and direction of the wind,
-the constitution of the clouds, their height, density and depth, the
-constitution and electrical properties of the air. They were also to
-collect samples of the air at different elevations, which later might
-be examined in the laboratory. Thus the voyages were systematically
-planned for scientific research, and were the first thorough attempts
-in England, though similar efforts had been made previously in France.
-It may be added that Glaisher’s observations were the most important
-made during the first century of aëronautics, and may be found fully
-detailed by that hardy investigator himself in the British Association
-Reports for 1862-66.
-
-Mr. Glaisher’s most interesting voyage of that memorable series
-occurred on September 5, 1862. Starting from Wolverhampton at three
-minutes after one o’clock, they soared swiftly upward, passing through
-a cloud eleven hundred feet thick and emerging in a glorious field
-of sunlight with an amethystine sky above and a boundless sea of
-vapor beneath; a sea of rolling hills and mountain chains, with great
-snow-white masses steaming up from their surface. They had left the
-noisy bustle of earth in the comfortable temperature of 59°; in three
-quarters of an hour, they were five miles aloft in a deadly silent
-atmosphere, two degrees below zero, and approaching one third its usual
-density, the balloon neck white with hoar frost, the men gasping for
-breath. Here the observations became increasingly interesting but
-immensely more difficult. They are graphically told in the following
-extract from Mr. Glaisher’s classical report:
-
-  “I asked Mr. Coxwell to help me to read the instruments, as I
-  experienced a difficulty in seeing. In consequence, however,
-  of the rotatory motion of the balloon, which had continued
-  without ceasing since the earth had been left, the valve-line
-  had become twisted, and he had to leave the car and mount into
-  the ring above to adjust it. At this time I looked at the
-  barometer, and found it to be 10 inches, still decreasing
-  fast; its true reading therefore, was 9¾ inches, implying a
-  height of 29,000 feet. Shortly afterwards I laid my arm upon
-  the table, possessed of its full vigor, and on being desirous
-  of using it, I found it powerless; it must have lost its power
-  momentarily. I tried to move the other arm, and found it
-  powerless also. I then tried to shake myself, and succeeded
-  in shaking my body. I seemed to have no limbs. I then looked
-  at the barometer; whilst doing so my head fell on my left
-  shoulder. I struggled and shook my body again, but could not
-  move my arms. I got my head upright, but for an instant only,
-  when it fell on my right shoulder, and then I fell backwards,
-  my back resting against the side of the car, and my head on
-  its edge; in this position my eyes were directed towards Mr.
-  Coxwell in the ring. When I shook my body I seemed to have full
-  power over the muscles of the back and considerable power over
-  those of the neck, but none over either my arms or my legs; in
-  fact I seemed to have none. As in the case of the arms, all
-  muscular power was lost in an instant from my back and neck. I
-  dimly saw Mr. Coxwell in the ring and endeavored to speak, but
-  could not; when in an instant intense black darkness came, the
-  optic nerve finally lost power suddenly. I was still conscious,
-  with as active a brain as at the present moment whilst writing
-  this. I thought I had been seized with asphyxia, and that I
-  should experience no more, as death would come, unless we
-  speedily descended; other thoughts were actively entering my
-  mind, when I suddenly became unconscious as in going to sleep.
-  I cannot tell anything of the sense of hearing; the perfect
-  stillness and silence of the regions six miles from the earth
-  (and at this time we were between six and seven miles high) is
-  such that no sound reaches the ear.
-
-PLATE I.
-
-[Illustration: GLAISHER AND COXWELL.]
-
-[Illustration: PARSEVAL KITE BALLOON.]
-
-  “My last observation was made at 1 h. and 54 m., at 29,000
-  feet. I suppose two or three minutes fully were occupied
-  between my eyes becoming insensible to seeing fine divisions,
-  and 1 h. 54 m., and then that two or three minutes more passed
-  till I was insensible; therefore I think this took place at
-  about 1 h. 56 m. or 1 h. and 57 m. Whilst powerless I heard
-  the words, ‘temperature’ and ‘observation,’ and I knew Mr.
-  Coxwell was in the car speaking to me, and endeavoring to
-  arouse me, therefore consciousness and hearing had returned. I
-  then heard him speak more emphatically, but I could not see,
-  speak or move. I heard him again say, ‘Do try—now do.’ Then I
-  saw the instruments dimly, then Mr. Coxwell, and very shortly
-  saw clearly. I rose in my seat and looked round, as though
-  waking from sleep, though not refreshed by sleep, and said to
-  Mr. Coxwell, ‘I have been insensible;’ he said, ‘You have;
-  and I, too, very nearly.’ I then drew up my legs, which had
-  been extended before me, and took a pencil in my hand to begin
-  observations. Mr. Coxwell told me he had lost the use of his
-  hands, which were black, and I poured brandy on them.
-
-  “I resumed my observations at 2 h. 7 m., recording the
-  barometer reading at 11.53 inches, and temperature −2°. I
-  suppose three or four minutes were occupied from the time of my
-  hearing the words ‘temperature’ and ‘observation’ till I began
-  to observe; if so, then returning consciousness came at 2 h.
-  and 4 m., and this gives seven minutes for total insensibility.
-  I found the water in the vessel supplying the wet-bulb
-  thermometer, which I had by frequent disturbances kept from
-  freezing, was one solid mass of ice; and it did not all melt
-  until after we had been on the ground some time.
-
-  “Mr. Coxwell told me that whilst in the ring he felt it
-  piercingly cold; that hoar-frost was all round the neck of the
-  balloon. On attempting to leave the ring he found his hands
-  frozen, and he had to place his arms on the ring and drop
-  down; that he thought for a moment I had laid back to rest
-  myself; that he spoke to me without eliciting a reply; that
-  he then noticed my legs projected and my arms hung down by my
-  side; that my countenance was serene and placid, without the
-  earnestness and anxiety he had noticed before going into the
-  ring, and then it struck him I was insensible. He wished to
-  approach me, but could not, and he felt insensibility coming
-  over himself; that he became anxious to open the valve, but in
-  consequence of having lost the use of his hands he could not,
-  and ultimately did so by seizing the cord with his teeth and
-  dipping his head two or three times until the balloon took a
-  decided turn downwards. This act is quite characteristic of
-  Mr. Coxwell. I have never yet seen him without a ready means
-  of meeting every difficulty, as it has arisen, with a cool
-  self-possession that has always left my mind perfectly easy,
-  and given me every confidence in his judgment in the management
-  of so large a balloon.
-
-  “No inconvenience followed the insensibility; and when we
-  dropped it was in a country where no conveyance of any kind
-  could be obtained, so that I had to walk between seven or eight
-  miles.
-
-  “The descent was at first very rapid; we passed downwards three
-  miles in nine minutes; the balloon’s career was then checked,
-  and we finally descended in the center of a large grass-field
-  belonging to Mr. Kersall, at Cold Weston, seven-and-a-half
-  miles from Ludlow.
-
-  “I have already said that my last observation was made at
-  a height of 29,000 feet; at this time (1 h. 45 m.) we were
-  ascending at the rate of 1,000 feet per minute; and when I
-  resumed observations we were descending at the rate of 2,000
-  feet per minute. These two positions must be connected, taking
-  into account the interval of time between, viz. 13 minutes,
-  and on those considerations the balloon must have attained
-  the altitude of 36,000 or 37,000 feet. Again, a very delicate
-  minimum thermometer read—12, and this would give a height of
-  37,000 feet. Mr. Coxwell, on coming from the ring, noticed that
-  the center of the aneroid barometer, its blue hand, and a rope
-  attached to the car, were all in the same straight line, and
-  this gave a reading of 7 inches, and leads to the same result.
-  Therefore these independent means all lead to about the same
-  elevation, viz. fully SEVEN MILES.
-
-  “In this ascent six pigeons were taken up. One was thrown out
-  at the height of three miles, when it extended its wings and
-  dropped as a piece of paper; a second, at four and five miles,
-  and it fell downward as a stone. A fourth was thrown out at
-  four miles on descending. It flew in a circle, and shortly
-  alighted on the top of the balloon. The two remaining pigeons
-  were brought down to the ground. One was found to be dead, and
-  the other, a ‘carrier,’ was still living, but would not leave
-  the hand when I attempted to throw it off, till after a quarter
-  of an hour it began to peck a piece of ribbon which encircled
-  its neck, and was then jerked off the finger, and flew with
-  some vigor toward Wolverhampton. One of the pigeons returned to
-  Wolverhampton on Sunday the 7th, and it is the only one that
-  has been heard of.”
-
-This was the loftiest ascent ever made up to that time; and thus
-Glaisher, or rather Coxwell, who was in the ring above him, could be
-called the “highest man” of the first century of aëronautics. Their
-greatest elevation, however, is now generally estimated at much less
-than seven miles, and probably below six miles, due allowance being
-made for inaccuracies of estimate made by Mr. Glaisher. His results,
-nevertheless, were considered valuable, revealing as they did, that the
-balloon may be used safely up to the neighborhood of five miles; that
-the temperature of the atmosphere does not, as previously supposed,
-decline one degree for each 300 feet of ascent, but often declines
-more rapidly, and sometimes even increases with the elevation for
-considerable stretches; that the moisture percentage is extremely
-slight at an altitude beyond five miles; that at all elevations
-attainable by man the dry- and wet-bulb thermometers can be used
-effectively, etc.
-
-A still loftier ascent was made by Professor Berson of Germany,
-aided by the respiration of oxygen. On July 31, 1901, accompanied by
-Dr. Süring, he ascended from Berlin in the balloon _Preussen_ to an
-elevation of 10,800 meters, which at present constitutes the world’s
-record for altitude. The balloon had a capacity of 300,000 cubic feet,
-and left the ground two thirds filled with hydrogen, and carrying 8,000
-pounds of ballast in the form of sand bags attached to the sides of the
-basket, so that they could be cut loose with the slightest physical
-effort.
-
-The _Preussen_ was one of the largest passive balloons ever
-constructed. In cubic capacity it was comparable with the colossal
-_Montgolfière_, _La Flesselle_, already described, and the huge free
-balloon _Le Geant_, constructed by Nadar in 1863. But all were
-eclipsed by the great balloon of Henri Giffard. This latter measured
-450,000 cubic feet, and even to-day ranks as the largest captive
-balloon ever constructed. It was a familiar object at the Paris
-Exposition of 1878, where it was installed by the famous inventor
-Henri Giffard, to give sightseers a bird’s-eye view of Paris. It could
-take up forty persons at one time, or eight more than once ascended in
-Nadar’s _Geant_.
-
-No serious attempt has been made to surpass the altitude flight of
-Professor Berson and Dr. Süring; for though it is easily possible to
-carry human beings to a greater height than seven miles, the results
-seem hardly to justify the cost. To ascend very much higher would
-require an enormous and costly balloon, and to ensure the comfort
-of the passenger might require an air-tight car, or armor supplied
-continuously with fresh air, or oxygen. Such a suit, or car, however,
-can be made very light, since its pressure must naturally be internal;
-and it would admit of an extremely rapid change of elevation without
-discomfort to the passenger. A steel bottle weighing fifty pounds,
-and filled with compressed air, or oxygen, would supply a passenger
-several hours, and allow him to breathe under normal pressure. The
-total weight of a bottle and air-tight car, or suit, need not exceed
-the weight of a man. Moreover, the ballast could be largely dispensed
-with, thus admitting of a very rapid ascent from the earth. A celluloid
-car would have the advantage of transparency, though it might become
-too brittle at very low temperatures. A suit, or car, with glass
-portholes would serve in lieu of a celluloid car for transparency. The
-usual balloon and basket, carrying a steel bottle, furnishing air at
-normal pressure to a man in a rubberized silk suit is a sufficiently
-simple and practicable device; the air entering the suit near his
-mouth and leaving below through a check valve regulated to maintain the
-desired internal pressure. An air-tight silk fabric capable of enduring
-safely a tensile stress of 150 pounds per running inch would answer the
-purposes. But at present there seems to be no incentive to attempt a
-balloon trip exceeding the heights already attained, unless it be that
-of notoriety or sentiment.
-
-The French meteorologists have devised a much simpler and cheaper
-method of exploring the upper atmosphere, by use of small balloons
-carrying recording instruments. An ordinary silk or gold-beater
-skin balloon, partly inflated, ascends to a great height with the
-instruments, drifts away losing gas, and on landing is found by some
-one who returns it according to written directions accompanying the
-craft. Another method, introduced by Professor Assman, is to employ
-closed rubber balloons which at great altitudes burst by the expansion
-of the hydrogen within them, and allow the instruments to descend
-in parachutes softly to the ground. Instrument-carrying balloons of
-the above type are called “sounding balloons,” or _balloons sondes_,
-whereas if they carry no instruments, but merely show the course of the
-wind, they may be called “pilot balloons.” Such sounding balloons have
-been used to explore the temperature of the atmosphere to an altitude
-of 18 miles.
-
-In the preceding pages some extended balloon voyages have been
-described. These were considered very long in their day, but in recent
-years have been surpassed frequently, first by the professional
-aëronauts, then by the amateurs and members of various aëronautic
-clubs practicing aërostation as a sport, and stimulated by attractive
-prizes. But the man who achieved the longest balloon flight during the
-first century of the art, seems to have been Mr. John Wise, America’s
-foremost pioneer balloonist.
-
-Mr. Wise was a rare composite of showman, scientist, sport and
-dare-devil, who during the four decades succeeding his first ascension
-at Philadelphia in 1835, made no fewer than 440 voyages. At first the
-aërial art captivated him by the beauty and sublimity of the natural
-panoramas witnessed from on high; then he amused himself by dropping
-things from the basket and hearing them whistle through space; and
-finally he coquetted with the balloon itself, in various ways to
-observe the result. On one occasion the neck was choked and the
-valve could not be operated, so that when the hydrogen expanded with
-increasing altitude, it overstretched the cover and started a rent in
-the side of the bag. The balloon descended rapidly, but landed without
-injurious shock.
-
-The audacious aëronaut then decided to make an ascension and
-deliberately burst the balloon, by confining the gas in it and throwing
-out ballast. But first he tried the experiment on a dog, taking him up
-4,000 feet, dropping him in a small collapsed balloon and watching him
-settle slowly to earth. Then rising to an altitude of 13,000 feet he
-stood debating whether to follow the example of the dog. The balloon
-quickly ended the question by exploding at the top. The hydrogen rushed
-out with a tempestuous sound, and the great vessel sank swiftly with a
-moaning noise of the wind in her rigging. In a few seconds the bag was
-empty and collapsed on the top of the net thus forming an effective
-parachute. After an exciting fall of more than two miles, Mr. Wise
-landed on a farm, with a lively thump, which overturned the basket, and
-threw him sprawling on the ground. It was fine sport; he decided at
-once to advertise a repetition of it, and thus was led by degrees to
-the invention of the ripping panel.[7]
-
-Mr. Wise firmly believed that a steady wind from west to east prevails
-at a height of two miles. He wished to use this for long voyages, and
-even contemplated crossing the Atlantic; for he trusted his varnish to
-hold hydrogen a fortnight if need be. Accordingly in 1873 the New York
-_Daily Graphic_ paid the cost of a balloon to carry him and two others
-on that hazardous voyage. The bag had a capacity of 400,000 cubic feet,
-but was too frail in construction to receive Mr. Wise’s approval, and
-actually burst during inflation when slightly more than three fourths
-full. Fortunately, perhaps, for Mr. Wise, he never had an opportunity
-to attempt the trans-Atlantic voyage; but on one occasion he enjoyed a
-memorable cruise in the great west wind which so took his fancy. Rising
-from St. Louis on June 23, 1859, he sailed northeastwardly for twenty
-hours, and landed at Henderson, N. Y., having traversed a distance of
-809 miles, measured directly. But in attempting another long voyage
-with two companions, in September, 1879, he passed over Lake Michigan,
-where all were drowned.
-
-In recent years Mr. Wise’s long voyage has been exceeded several
-times. In 1897 M. Godard sailed from Leipsic to Wilna, a distance of
-1,032 miles in 24½ hours; but this was not an official flight nor in a
-direct course as the crow flies. In October, 1900, M. Balsan voyaged
-from Vincennes, France, to Rodom, Russia, a distance of 843 miles in
-27 hours and 25 minutes, and De la Vaulx starting from the same point
-landed at Korosticheff, Russia, having traversed 1,193 miles in 35¾
-hours. This latter is the longest balloon flight thus far recorded. A
-close second to this record was made by A. R. Hawley in his spherical
-balloon _America_, aided by Augustus Post, in the Gordon Bennett
-International Balloon Race of 1910. Sailing from St. Louis, October
-17th, they drifted 1,172.9 miles from their starting point, and landed
-in a great forest at Peribonka River, North Lake Chilogoma, Canada,
-where they were lost for several days.
-
-[Illustration: FIG. 12.—DIAGRAM OF A MODERN SPHERICAL BALLOON WITH
-RIPPING PANEL.]
-
-Quite as eventful was the ocean voyage of Walter Wellman, who left
-Atlantic City October 15, 1910, for Europe in a motor balloon with a
-drag rope, or equilibrator, voyaged with favorable wind to a point
-140 miles northeast of Nantucket Island, then was driven by adverse
-wind toward Bermuda, and finally rescued by a passing steamer, after
-69 hours in the air and a journey of about one thousand miles. A full
-account of this strange voyage is given in the New York _Times_ of
-October 19, 1910, and in the _Scientific American_ of subsequent date.
-
-The recent advances in aërostation, though not radically changing the
-balloon itself, contribute much to its usefulness and convenience.
-Improvements have occurred in the means of inflation and deflation,
-in devices for making topographical and meteorological observations,
-as also for transmitting and receiving signals. Hydrogen shipped in
-steel tubes is now available for easy and rapid inflation, the process
-of obtaining it on a large scale making it practically as cheap as
-illuminating gas. The ripping panel, invented in 1844 by America’s
-foremost pioneer aëronaut, John Wise, is a simple and an excellent
-practical device. This is a long patch running longitudinally above the
-equator[8] of the balloon, feebly sewed to the envelope, and having a
-cord, called the “ripping cord,” extending down to the car along the
-outside or inside of the bag, so that the pilot on coming to earth
-can let out the gas quickly by tearing a rent in the balloon, thus
-flattening it promptly on the earth’s surface, so as to avoid dragging
-and bumping if any wind prevails. During an ascension the rise or fall
-of the vessel may be instantly noted on the dial of the statoscope,
-the temperature, pressure and moisture of the atmosphere may be read
-on recording instruments, messages may be sent by telegraph and
-telephone either by wire or through space, and sky or landscape may
-be photographed if there be sufficient light. The bag itself has been
-improved by making it of special fabrics formed of several layers of
-silk, or cotton, with thin layers of rubber vulcanized between them
-to render the cloth impermeable, also the bag, when not designed to
-cleave the wind, is usually given a spherical form which is the figure
-of greatest volume for a given surface, the figure originally used by
-the inventor of the gas balloon; but when designed to be tethered in
-a wind, it is given a longish shape and a tail so that it may ride
-the wind like a kite. This type of balloon, though first proposed by
-Douglass Archibald about 1845, was first made a practical invention by
-Captain von Sigsfeld and Major von Parseval. In a certain sense it is a
-tethered motor-balloon, just as a kite is a tethered aëroplane.
-
-
-
-
-                              CHAPTER III
-
-                    EARLY HISTORY OF POWER BALLOONS
-
-
-Directly after the first launching of human passengers in a crude
-aërostat, numerous schemes for controlling the course of a balloon were
-evolved. Apparently mere flotation afforded less contentment to the
-early pioneer aëronauts than to the free balloonists of the present
-hour. Many were eager to apply propelling mechanism to their gas bags,
-expecting thus to achieve practical locomotion through the air, even a
-generation before the advent of practical steam navigation. Magnificent
-dreams they had, indeed, but none the less futile. Few suspected the
-enormous power required to propel swift balloons of the very best shape
-and size; still fewer realized the impossibility of driving spherical
-bags at a practicable velocity.
-
-On the other hand, it must be said, to the credit of that era of
-investigators, that certain noted scientists, after computing the power
-required to drive a balloon at high speed, promptly recognized the
-inadequacy to that task, of any motors then available. In conjunction
-with favorable aërial currents something might be effected; that they
-fully grasped; for they knew that the wind frequently has different
-directions at different levels. They believed, therefore, that by
-causing the craft to rise or fall to a suitable stratum, by use of
-various then known devices, it could be made to travel in any direction
-at the will of the pilot. Likewise they deemed that the rise and fall
-of a balloon, due to change of buoyancy, could be used to propel it, if
-sails attached to the vessel were set obliquely to the motion, so as to
-receive fair pressure; or if the balloon were made flat, or longish, so
-as to glide horizontally, like a kite or parachute.
-
-Several devices for changing the altitude of the balloon were proposed
-or tried. If the vessel were a _Montgolfière_, the mere increase or
-lessening of the fire would promptly cause it to rise or fall. If a gas
-bag were employed it could be sent up or down by casting out ballast
-or opening the valve; or again, as proposed by Pilâtre de Roziere, by
-having a _Montgolfière_ underneath the gas balloon, and lifting or
-depressing the whole by altering the intensity of the flame. Finally,
-an air balloon within a gas balloon was proposed by the Roberts, and a
-gas balloon within an air balloon was proposed by General Meusnier, in
-either of which combinations, a change of level could be effected by
-pumping air into, or letting it escape from, the air bag. All of these
-devices can be effected and practically operated by a competent balloon
-maker and pilot; and yet they have not enabled man to realize his dream
-of navigating the air in all directions without motive power.
-
-The first attempts at balloon propulsion could not be seriously
-regarded by trained engineers, even at the inception of aëronautics;
-but still, as infantile steps in the new art, they may deserve passing
-notice.
-
-Blanchard, on March 2, 1784, made the first real effort to steer a
-balloon, using for that purpose a spherical gas bag and car provided
-with aërial oars and a rudder. As he was about to ascend, however,
-from the Champs de Mars, a young officer with drawn sword persisted in
-accompanying the pilot, thus compelling Blanchard to leave his wings
-on earth to allow sufficient buoyancy for himself and his obtrusive
-guest. His first trial was, therefore, frustrated; but subsequent ones
-made with that inadequate contrivance also proved futile under the best
-circumstances; for the scheme was evidently puerile, though tried by
-various grown-up men besides M. Blanchard.
-
-[Illustration: FIG. 13.—BLANCHARD’S DIRIGIBLE BALLOON, 1784.]
-
-A no less simple and quaint device for propulsion was that of the
-two physicists, the Abbé Miolan and Janinet. The balloon was a
-_Montgolfière_ with a large hole in one side, through which the hot air
-was to escape with such strong reaction as to drive the bag forward, on
-the principle of a lawn sprinkler, or of Newton’s reaction wagon. The
-projectors failed, however, to make an ascent, and the crowd becoming
-furious destroyed the balloon.
-
-A more reasonable plan for practical navigation was devised and tried
-by the Robert brothers. A melon-shaped balloon, fifty-two feet long by
-thirty-two feet in diameter, was made of silk and inflated with pure
-hydrogen. Beneath was suspended a longish car of light wood covered
-with sky-blue silk. This elegant ship was to be rowed through heaven by
-means of six silken oars actuated by sturdy sailors. A silken rudder
-should guide her at pleasure when the winds were asleep, or softly
-playing in the placid sky. She was a fairy bark, indeed, a soaring
-castle lovely to behold.
-
-After a preliminary trial, accompanied by their patron, the Duke de
-Chartres, they were ready for a substantial journey. On September 19,
-1784, the vessel was inflated and taken to the Garden of the Tuileries,
-in front of the palace, where its cords were held by Marshall Richelieu
-and three other noblemen. At eleven forty-five the two Roberts and
-their brother-in-law arose and drifted beyond the horizon on a seven
-hours’ cruise. Before coming to earth, they plied the oars vigorously,
-and described a curve of one kilometer radius, thus deviating 22° from
-the feeble wind then prevailing. In a lighter wind they could deviate
-still more. They considered, therefore, that the experiment was a
-complete success. They had constructed the first elongated balloon,
-and had “solved the problem of aërial navigation.” In very happy mood,
-therefore, they landed at dusk among the delighted inhabitants of
-Artois, where they were graciously met and hospitably entertained by
-the Prince de Ghistelles-Richbourg.
-
-[Illustration: FIG. 14.—ROBERT BROTHERS’ DIRIGIBLE, 1784.]
-
-The Robert brothers were the first to employ in practice an air bag
-inside a gas bag. This was held within the balloon by ropes and
-connected with the outer atmosphere by a tube, the idea being to
-regulate the internal pressure of the balloon by introducing air into,
-or withdrawing it from, the smaller bag. But during an ascension with
-their patron, the Duke de Chartres, they entered a violent eddy which
-tore away the oars and rudder, at the same time agitating the balloon
-so violently that the internal air bag broke its sustaining cords and
-fell upon the bottom of the gas bag, thus throttling the connection
-with the external atmosphere. The vessel rose swiftly and the gas
-expanded dangerously near to the bursting pressure. At a height of
-16,000 feet the Duke de Chartres, perceiving the imminent danger of
-an explosion of the envelope, drew his sword and cut a rent ten feet
-long in its lower part. A part of the gas immediately rushed forth,
-and the balloon sank rapidly, but after the discharge of the ballast,
-landed safely without further mishap. The Duke acted wisely enough,
-but he was afterwards ridiculed for his apparent lack of courage. If
-he had possessed more bravery and less caution he might have allowed
-the balloon to burst and descend as a parachute, thus anticipating the
-spectacular performance of John Wise, in 1838.
-
-Simultaneously other inventors were evolving designs of no less
-importance in the ultimate perfection of the dirigible. In a letter
-written to Benjamin Franklin on May 24, 1784, Francis Hopkinson of
-Philadelphia proposed to build a balloon of spindle shape and to drive
-it by means of a wheel-like propeller at the stern, consisting of vanes
-set at an angle to the line of progression, like the common smokejack.
-This proposed craft, the harbinger of the modern screw-driven motor
-balloon, far antedated the screw-driven boat and the submarine torpedo
-which it most resembles.[9]
-
-While Blanchard and other aëronauts were paddling their globose bags
-in search of favorable winds, vainly hoping thereby to direct their
-course in the air, General Meusnier of the French army, and member of
-the Academy of Sciences, made a systematic study of the requirements
-for practical air navigation. After some research on forms suitable
-for aëronautic hulls, he designed a power balloon having a pointed
-car suspended from a bag of goose-egg form, this latter embodying his
-idea of the best shape for a balloon that must cleave the air swiftly
-and resist deformation. The propulsion was to be effected by means of
-three coaxial screw propellers, supported on the rigging between car
-and bag, and actuated by eighty men, for lack of a light artificial
-motor. He thus hoped to obtain a moderate velocity which, combined with
-skillfully selected air currents, would enable the ship to reach her
-destination in ordinary weather.
-
-[Illustration: FIG. 15.—GEN. MEUSNIER’S PROPOSED DIRIGIBLE, 1784.]
-
-General Meusnier introduced important special features in the design of
-dirigibles for preserving their form and poise. He insisted that the
-bag and boat should be so rigidly connected that one could not swerve
-from alignment and relative position with the other. He also emphasized
-the necessity of preserving the vessel from deformation during flight,
-in order to diminish its resistance. To that end he proposed to provide
-the hull with a double envelope, the inner one thin and light but
-impermeable to hydrogen; the outer one strong and air-tight; the space
-between the two envelopes to be pumped full of air under pressure
-sufficient to preserve the form of the bag when beating its way swiftly
-against a buffeting wind. This was an important invention which in
-later years was adopted in many of the most powerful motor balloons—for
-all, indeed, except those of the rigid type. He also proposed the
-use of stabilizing planes to control the poise of the vessel, thus
-anticipating the Lebaudy brothers by more than a century. Like the
-Robert brothers he proposed to raise or lower the vessel in search of
-suitable currents, by altering the quantity of air in the space between
-the inner and outer envelope, by use of hand bellows.
-
-Apparently General Meusnier and his colleagues were endowed with
-constructive genius sufficient to have developed a practical motor
-balloon, had they been able to secure a light engine. Lacking this the
-early aëronauts could do little more than describe their projects, and
-await the growth of the collateral arts and sciences. Accordingly no
-substantial advance in motor balloons beyond Meusnier’s designs was
-effected till after the middle of the nineteenth century; and until
-then the art of aëronautics remained in the hands of showmen. Hundreds
-of projects, indeed, were advanced, some exciting considerable interest
-and expectation, but nevertheless of such paltry value as hardly to
-deserve comment. One notable exception to these was the invention of
-Porter in America.
-
-In 1820 Rufus Porter, a Yankee inventor, and later the original
-founder of the _Scientific American_, patented an air ship of very
-promising appearance for that early day. Its hull was a long, finely
-tapering symmetrical spindle, suspending a car of similar shape by
-means of cords, which were vertical at its middle but more and more
-slanting toward its ends. Midway between the hull and car was a large
-screw propeller actuated by a steam engine in the car. A model of
-this dirigible exhibited in Boston and New York, some years later, is
-reported to have carried its own power, at fair speed, and to have
-obeyed its helm satisfactorily.
-
-[Illustration: FIG. 16.—RUFUS PORTER’S DIRIGIBLE, 1820.]
-
-The inventor, being too poor to develop his air ship alone, did
-little with the patent during its life; but in 1850 he organized
-a stock company to realize the needed funds. From the sale of 300
-five-dollar shares he expected to raise $1,500, and with this sum
-build an “aëroport,” 150 feet long, capable of carrying five persons
-sixty miles an hour, the whole to be completed in six weeks. Once
-this was in operation he would easily command funds sufficient to
-build a full-sized vessel adapted to regular passenger service. For,
-after careful calculation, he reported that: “It appears certain that
-a safe and durable aërial ship (or aëroport) capable of carrying 150
-passengers at a speed of ninety miles an hour, with more perfect safety
-than either steamboat or railroad cars, may be constructed for $15,000,
-and that the expense of running it would not exceed $25 per day.”
-
-The language and project seem very modern, even at the present
-time, and might well be copied now by a promoter of that identical
-project. But it must be observed that the most successful European
-experimenters, after spending hundreds of thousands of dollars on giant
-air ships, have not yet attained one half the speed contemplated by
-that ambitious and chimerical Yankee. The picture was handsome and
-alluring, none the less. It may even be said to excel in outward design
-any of the air-ship plans produced in either hemisphere before the
-middle of the nineteenth century.
-
-In 1850 a clockmaker and skillful workman, Jullien by name, exhibited
-in the Hippodrome, at Paris, a torpedo-shaped model balloon of
-gold-beater’s skin, provided with a screw propeller at either side
-of its bow, and a double rudder at its stern. It measured 23 feet in
-length and weighed 1,100 grammes complete. The propellers were actuated
-by spring power, and proved able to drive the tiny vessel against a
-moderate wind. The most suitable form for the bag was determined by
-towing models through water.
-
-[Illustration: FIG. 17.—JULLIEN’S MODEL DIRIGIBLE, 1850.]
-
-Aërodynamically considered, this tiny motor balloon was by far the best
-in design of any that appeared during the first century of aëronautics.
-It may be regarded as the harbinger of the swiftest modern French
-balloons. It was also an inspiration to Henri Giffard who assisted
-Jullien in constructing his clever model, and shortly afterwards built
-the first dirigible ever driven by a heat engine.
-
-The illustrious Henri Giffard was perhaps the first aëronautical
-engineer adequately endowed and circumstanced to realize, on a
-practical scale, General Meusnier’s well pondered and truly scientific
-plans for a motor balloon. He had studied in the college of Bourbon,
-and had worked in the railroad shops of the Paris and St. Germain
-railway. He had further equipped himself by making free balloon
-ascensions, under the auspices of Eugene Godard, for the purpose of
-studying the atmosphere; and by building light engines, one of which
-weighed 100 pounds, and developed three horse power. Finally in 1851 he
-patented an air ship, consisting of an elongated bag and car, propelled
-by a screw driven by a steam engine. He had not the means to build such
-a vessel, but he had the genius and training necessary to construct it,
-and at the same time enough enthusiasm and persuasive power to induce
-his friends, David and Sciama, to loan him the requisite funds.
-
-[Illustration: FIG. 18.—GIFFARD’S STEAM DIRIGIBLE, 1852.]
-
-Giffard’s first dirigible was successful in both design and operation.
-It consisted of a spindle-shaped bag covered with a net whose cords
-were drawn down and attached to a horizontal pole, from which the car
-and motor were suspended, and at the end of which was a triangular
-sail serving as a rudder. To guard against fire, the furnace of the
-vertical coke-burning boiler was shielded by wire gauze, like a miner’s
-lamp, and the draft, taken from its top through a downward pointing
-smoke pipe, was ejected below the car by force of exhaust steam, from
-the engine, thus obviating, as Giffard asserted, all danger from the
-use of fire near an inflammable gas. The car hung twenty feet below
-the suspension pole, and carried a three horse-power engine driving a
-three-blade propeller 11 feet in diameter, making 110 turns a minute.
-The motor complete, including the engine and boiler without supplies,
-weighed 110 pounds per horse power. The bag measured 143 feet long, 39
-feet in diameter, and 75,000 cubic feet in volume. Giffard reports of
-his first voyage, made from the Hippodrome in Paris at five fifteen
-o’clock, September 23, 1852, that although he could not sail directly
-against the strong wind then blowing, he could attain a speed of six
-to ten feet per second relatively to the air, and he could easily
-guide the vessel by turning her rudder. He continued his journey till
-nightfall, then made a good landing, near Trappes, and by ten o’clock
-was back in Paris.
-
-This vessel was but a prelude to mightier projects. After some further
-experience with dirigibles of moderate size, Giffard designed a
-colossal air ship calculated for a speed of forty-four miles an hour.
-Its hull was to be of torpedo shape, measuring 2,000 feet in length,
-100 feet in diameter, and 7,000,000 cubic feet in volume. It was a
-most audacious project, one worthy of the genius and energy of that
-illustrious engineer, the most original and daring inventor known in
-the aëronautical world during the nineteenth century.
-
-Stimulated by this huge enterprise, Giffard’s first step was to pay his
-debts and make a fortune. He soon acquired a hundred thousand francs
-from the sale of small high-speed engines of his own construction, and
-with this, settled his account with David and Sciama. Next he realized
-several million francs from his world-famous injector, a device by
-which steam flowing from a boiler is made to drive in feed-water
-against the same pressure.
-
-He now made definite plans to build a motor balloon of one and a half
-million cubic feet capacity, driven by a condensing engine drawing
-steam from two boilers, one fired with oil, the other with gas from
-the balloon, so as to keep the vessel from rising with loss of weight.
-His designs were complete, and everything was provided for. He had
-deposited a million francs in the Bank of Paris to defray the estimated
-cost. But, in the words of Tissandier,[10] “above the human will and
-foresight are the fatal laws of destiny to which the strongest must
-submit.” The great inventor was visited with a painful affliction
-of the eyes; his sight waned, unfitting him for work; he became
-disconsolate, pined away with pain and grief, and in 1882 ended his
-life by taking chloroform.
-
-Giffard was succeeded in France, first by Dupuy de Lome; then by
-Gaston Tissandier, well-meaning projectors of steerable balloons, but
-too cautious to effect an important advance in the art. The first of
-these gentlemen, an eminent marine engineer, in 1872, completed a gas
-balloon for the French government, resembling the one designed by
-General Meusnier in 1784, and like that also driven by muscular power
-actuating a screw, and kept rigidly inflated by use of an internal
-balloon, or ballonet. The car was suspended from the bag by a close
-fitting cover instead of a net, in order to lessen the resistance, and
-it was kept in alignment by use of crossed suspension cords. A speed
-of but six miles an hour was attained by the industrious work of eight
-men operating an ample screw propeller. A decade later Tissandier, with
-a balloon of like design, but driven by the power of an electric motor
-and bichromate of potash battery, attained a speed of six to eight
-miles an hour.
-
-[Illustration: FIG. 19.—DUPUY DE LOME’S DIRIGIBLE, 1872.]
-
-The two vessels were safe but of no practical value, for lack of
-sufficient power to cope with the wind. Their motors were fundamentally
-unadapted to the purpose of swift propulsion, and incapable of
-development to very great lightness and strength. Furthermore, the
-vessels themselves were unsuitably designed for speed; their shape
-being one of too much resistance, and their dynamic balance being
-that of a pendulum, or clumsy parachute, rather than that of a vessel
-adapted to cleave the air with celerity, grace and steadiness. If there
-had been danger of fire from placing the motor and screw near the gas
-bag, that might justify or excuse the clumsiness of design in the craft
-of De Lome and of Gaston Tissandier; but, having perfectly safe motors,
-it is astonishing that they did not place the center of mass and the
-line of thrust more nearly in the line of resistance. This obvious
-requirement was duly recognized by several of their contemporaries,
-notably by Hänlein in Germany, and by Captain Renard of the French War
-Department, and had been observed by Jullien.
-
-Captain Charles Renard proved to be a worthy inheritor of the dreams,
-experience and inventions of the first century of aëronautical
-votaries. He did not, indeed, have the picturesque madness displayed
-by some of his predecessors; he did not project schemes of marvelous
-originality or boldness; but he manifested uncommonly good judgment
-and excellent scientific method in combining the researches and
-contrivances of others with those of himself and his collaborator,
-Captain Krebs. As a consequence they produced the first man-carrying
-dirigible that ever returned against the wind to its starting point,
-and the first aërial vessel whose shape and dynamic adjustment even
-approximated the requirements of steady and swift navigation in a
-surrounding medium presenting various conditions of turbulence or calm.
-Captain Renard had been studying and designing dirigibles since 1878
-in coöperation with Captain La Haye and Colonel Laussedat, president
-of an aëronautic commission appointed by the Minister of War; and had
-endeavored to secure from the latter an appropriation sufficient to
-construct a dirigible; but his request was at first denied, owing
-to the waste of funds on similar projects in 1870. However, with the
-help of Gambetta, who promised a sum of $40,000, Renard was enabled to
-proceed. In the meantime he had been made director of the laboratory at
-Chalais Meudon, seconded by Captain Krebs.
-
-[Illustration: FIG. 20.—RENARD’S DIRIGIBLE, _La France_, 1884.]
-
-These officers first worked out the separate elements in the design of
-their motor balloon before proceeding to build on a practical scale.
-They chose the torpedo form for their gas bag, thereby ensuring in
-the hull itself, projectile stability, and diminution of resistance.
-They placed the car near the envelope, thus minimizing the disturbing
-moment of the screw thrust, and the resistance of the suspension cords.
-They employed an extraordinarily powerful electric motor actuating a
-large screw so as to obtain a strong thrust with the least effort.
-In addition they adopted the best ideas of their predecessors in
-aëronautical design; the internal ballonet of Meusnier, and the
-close fitting cover of De Lome, with crossed suspension cords. But
-unfortunately they used an electric motor instead of some light engine.
-Finally, having carefully computed its requisite dimensions, they
-proceeded to construct the elegant air ship, _La France_, which was
-tested in 1884 and aroused anew the hope of ultimately conquering the
-air.
-
-Further details of this successful ship are of interest. Its hull
-was 165 feet long, 27.5 feet in greatest diameter, at one fourth the
-distance from its front end, and cubed 66,000 feet, thus having a
-buoyancy of two long tons. It was kept rigid under varying conditions,
-by means of a ballonet filled with air driven in by a common fan blower
-coupled to the motor. Beneath the envelope, a long narrow rectangular
-car made of bamboo, covered with silk, was suspended from the cords
-of the balloon cover which embraced the hull throughout nearly its
-entire length. The car was 108 feet long and 6 to 7 feet across,
-carried at its forward end the propeller, at its rear a rectangular
-rudder, and between them the aëronauts and the batteries and electric
-motor. A sliding weight was used to alter the poise of the ship, and a
-guide-rope to soften its descent.
-
-The electric motor and battery which furnished the propulsive power
-were designed expressly for such use, and were considered at the time
-to be remarkably light and effective. The motor, which was designed
-with the assistance of M. Gramme, weighed 220.5 pounds, and developed
-nine horse power. The battery, composed of chlorochromic cells, was the
-result of the researches of Renard himself. Having made a careful study
-of the best geometrical arrangement of the parts of the cell, Renard
-found that this battery would deliver to the shaft one horse power for
-each eighty-eight pounds of its weight. Thus the power plant rivaled
-in lightness the steam engine of Giffard, and at the same time was free
-from danger; but apparently it could not be much reduced in weight,
-whereas Giffard’s steam-power plant could be reduced tenfold, as shown
-by Renard’s contemporaries.
-
-The trials of _La France_ in 1884-85 were most successful and
-encouraging; not that they represented or pointed to the complete
-mastery of aërial navigation, but because they so far surpassed all
-previous achievements. The vessel moved through the air as steadily as
-a boat on the water, and obeyed her rudder perfectly, heading against
-the wind, or at any angle to it, or turning entirely about, at the will
-of the aëronauts. On her first voyage from Chalais, August 9, 1884, she
-traversed a distance of four and one half miles in twenty minutes, made
-various evolutions in the air with the greatest ease, and returned to
-her point of departure. The following account of this voyage is given
-by Renard:
-
-  “As soon as we had reached the top of the wooded plateaus which
-  surround the valley of Chalais, we started the screw, and had
-  the satisfaction of seeing the balloon immediately obey it and
-  readily follow every turn of the rudder. We felt that we were
-  absolutely masters of our own movements, and that we could
-  traverse the atmosphere in any direction as easily as a steam
-  launch could make its evolutions on a calm lake. After having
-  accomplished our purpose, we turned our head toward the point
-  of departure and we soon saw it approaching it. The walls of
-  the park of Chalais were passed anew, and our landing appeared
-  at our feet, about 1,000 feet below the car. The screw was
-  then slowed down, and a pull at the safety-valve started the
-  descent, during which, by means of the propeller and rudder,
-  the balloon was maintained directly over the point where our
-  assistants awaited us. Everything occurred according to our
-  plan, and the car was soon resting quietly on the lawn.”
-
-Six other similar voyages were made within the two years following,
-and we have as a result, that in five out of the seven trials, the
-balloon returned to its point of departure. Its failure to return in
-the other two trials was due, in the one case, to the breaking down of
-the motor; in the other, to the resistance of a strong wind which made
-it necessary to land at a distance from the starting point. The last of
-these remarkable voyages was performed in presence of the Minister of
-War, on September 23, 1885. The balloon started from Calais and sailed
-against the wind directly to Paris, passed over the fortifications,
-described a graceful curve and returned to its place of departure,
-recording an average speed of 14.5 miles an hour.
-
-The torpedo form of hull, chosen by Renard and Krebs, has two important
-advantages; one is projectile stability, the other is economy of
-propulsive power. Owing to the blunt bow and long tapering stern, the
-center of mass is well forward, while the center of side wind pressure
-is more to the rear. As a consequence, if the vessel should encounter a
-quartering wind-gust, or have her nose slightly turned from the course,
-she would promptly right herself like a dart or an arrow. If on the
-contrary, the hull were a symmetrical spindle, the vessel would move
-forward in unstable equilibrium, and, once slightly diverted from her
-course, would tend to deviate further, like an arrow with unloaded head.
-
-The second advantage mentioned is also worth attention, viz.: that at
-ordinary transportation speeds a longish spindle has less resistance
-with a blunt bow than with a very sharp one. Renard and Krebs did
-not account for this fact; but the present writer, by determining
-separately the skin friction and the impactual resistance of the air,
-proved that in sharpening the bow beyond a certain best form, its
-friction increases faster than its head resistance diminishes, the
-most suitable shape being that of a torpedo whose nose has a radius
-of curvature of about two diameters, and its stern a radius of about
-twelve diameters.
-
-While the successors of Giffard in France were thus engaged in
-developing dirigibles driven by muscular or electric power, a few
-German experimenters were applying gas and benzine engines to such
-vessels, with better promise of ultimate practical success and
-usefulness. The first of these was Hänlein, who in 1872 advanced the
-meritorious project of driving a well shaped balloon by means of a gas
-engine taking its fuel from inside the balloon, and making good the
-loss by pumping air into the ballonet. This balloon was of far better
-design for swiftness and kinetic stability than the contemporary one of
-Dupuy de Lome. Its hull was a well pointed cylinder 164 feet long, 30
-feet in diameter and of 85,000 cubic feet capacity, made air-tight by
-a thick coating of rubber inside, and a thin one outside. The car was
-rigidly suspended near the envelope and carried a 6 horse-power Lenoir
-gas engine actuating a large screw. Notwithstanding that the buoyancy
-was small, owing to the use of coal gas, this air ship attained a speed
-of 15 feet per second. By employing hydrogen, a much larger engine
-could have been carried, entailing a much swifter speed. During its
-trial the balloon was kept near the earth’s surface, held loosely by
-ropes in the hands of soldiers. The air ship was remarkably successful
-for that early date, and had the potency of greater achievement
-than its contemporaries in France; but owing to lack of funds its
-capabilities were not fully developed. If it had been inflated with
-hydrogen, and propelled by use of gas and petrol, so that the loss
-of weight would compensate for the loss of buoyancy, it might have
-anticipated the speed and endurance of the best air ships built toward
-the close of the nineteenth century, or later.
-
-PLATE II.
-
-[Illustration: HAENLEIN’S GAS-DRIVEN DIRIGIBLE.]
-
-[Illustration: WÖLFERT’S BENZINE-DRIVEN DIRIGIBLE.]
-
-[Illustration: SANTOS-DUMONT’S DIRIGIBLE, _NO. 16_.
-
-_Photo E. Levick, N. Y._ ]
-
-In 1879, Baumgarten and Wölfert in Germany built a dirigible equipped
-with a Daimler benzine motor, but otherwise not possessing any special
-merit. An ascension was made at Leipsic in 1880, but owing to improper
-load distribution the vessel reared on end and crashed to earth. After
-further experiments, an ascension was made on the Templehofer field,
-near Berlin, in 1897, but this ended disastrously; for the benzine
-vapor ignited; the fire spread to the balloon, and the vessel fell
-flaming to the earth, killing Wölfert and his assistant. Baumgarten had
-died some years before.
-
-In 1897, an aluminum air ship invented by an Austrian engineer, named
-Schwartz, was launched on the Templehofer field. Its hull was of
-cylindrical form with conical ends, made of sheets 0.008 thick, and
-stiffened with an internal frame of aluminum tubes. Being leaky and
-inadequately driven, it voyaged but four miles, drifting with the wind,
-then fell to earth with considerable shock. The pilot, a soldier of the
-Balloon Corps, escaped by jumping, before the vessel struck ground, but
-the frail unbending hull was soon demolished by the buffeting of the
-winds as it lay stranded on the unyielding earth. This was the second
-air ship built after the plans of poor Schwartz, the first having
-collapsed on inflation. He had, however, the credit of being the first
-to drive a rigid air ship with a petrol motor, and thus to inaugurate
-a system of aërial navigation capable of immense development, in
-the hands of sufficient capital and constructive skill. Thus the
-rigid type, conceived and crudely tried by Marey Monge and Dupuis
-Delcourt in the early part of the century, began to approach practical
-realization toward the end of the century.
-
-The process of inflating with hydrogen such a rigid hull is
-interesting. Schwartz’s plan, carried out by Captain Von Sigsfeld,
-was to place the hydrogen in one or more sacs inside the hull, thus
-expelling the air and filling the space, then withdrawing the sacs and
-leaving the hydrogen within. A better plan is to have a single sac
-inflated with air just filling the hull like the lining of an egg, then
-to force the gas between the lining and metal wall of the hull, thus
-expelling the air from the sac, which when completely collapsed can be
-removed. Practically the same result can be obtained by use of a thin
-fabric covering one half the inner wall, like the lining of an egg.
-Further provision can easily be made for manipulating the ballonet in
-such a case.
-
-
-
-
-                              CHAPTER IV
-
-              INTRODUCTION OF GASOLINE-DRIVEN DIRIGIBLES
-
-
-We have now traced the art of balloon guidance and propulsion from its
-earliest inception to the close of the nineteenth century. It was a
-period of extravagant hope and chimerical scheming, but withal a period
-fruitful in devices of fundamental value. The best experiments paid no
-dividends, but they prepared the way for really useful vessels. The
-methods of manipulation and control had been sufficiently developed
-to answer immediate needs. The air ship was at least dirigible, if
-not practical. It kept its shape, obeyed its rudder, rose and fell
-according to the operator’s will. It was, however, a fair-weather
-machine, beautiful in appearance, but helpless in any considerable
-wind. Speed was now the desideratum, and the attainment of this
-involved new difficulties. The storm-proof balloon was still a dream.
-
-Naturally one inquires what velocity makes a dirigible air ship really
-practical, assuming all other requirements satisfied. The minimum
-allowable speed depends largely upon the locality and season. On Long
-Island an assured velocity of forty to fifty miles an hour would
-seem desirable; for there the winds are swift and the water near. In
-Washington, or Berlin, thirty miles an hour is enough, though each
-additional mile per hour must be regarded as a considerable gain on
-a small margin of progress in facing a stiff breeze. Colonel Renard
-has estimated, from a study of the wind records near Paris, that a
-dirigible is practically useful in that locality if it can maintain a
-speed of twenty-eight miles an hour for ten or twelve hours; since in
-that case it can maneuver 81 days in 100.
-
-Renard’s own graceful ship attained a speed of but half that much. In
-order, therefore, to give his vessel the desired usefulness its speed
-must be doubled. This would require an eightfold[11] increase of motive
-power without increase of weight. Evidently then the cardinal requisite
-was a light durable motor of extraordinary output. Such motors
-fortunately were now coming into the market, owing to the development
-of gasoline engines for automobile racing.
-
-The year 1898 witnessed the commencement of two famous systems of
-navigation by the lighter than air, one in France, the other in
-Germany, destined quickly to revolutionize the art, and to establish
-it on a practical basis. The leading exponents of these two systems
-were Señor Don Alberto Santos-Dumont, a rich young Brazilian living in
-Paris, and Count Ferdinand von Zeppelin, Germany’s stanch old admiral
-of the air. Both achieved success by applying the gasoline engine to
-the propulsion of elongated balloons, but by very different methods.
-Santos-Dumont, apparently ignoring, or fearing to adopt, the excellent
-hull and car designed and used by Renard, began where Tissandier left
-off, with a symmetrical hull and low-hung car, thus producing a safe
-aërial pendulum, if not a racing machine; then by degrees he gradually
-felt his way to something more efficient. Zeppelin began with a long
-cylindrical hull pointed at the ends, rigidly framed like that of
-Schwartz, and supporting its car and propellers well aloft near the
-line of resistance. His was a bold and effective design but difficult
-to execute. Santos-Dumont scored the first success, and startled the
-world by his spectacular flights; but ere long he was surpassed by
-other builders of non-rigid balloons. Zeppelin won his success slowly
-and by heroic perseverance in the face of enormous obstacles, finally
-emerging as the most successful and illustrious figure in the history
-of aëronautics. The achievements of these two pioneers and colleagues
-make the first decade of the twentieth century memorable in the annals
-of aërial navigation.
-
-Santos-Dumont, who spent his early years on his father’s large coffee
-plantation in Brazil, had, during boyhood, dreamed of navigating the
-air, and in 1897, at the age of twenty-four, made in France his first
-ascension in a spherical balloon. While living at Paris during that
-year he gave much time to motorcycling, automobiling and operating
-spherical balloons, of which he possessed two constructed after his own
-ideas; one, the smallest in the world, designed for solitary voyages,
-the other large enough for more than one person, intended for social
-excursions. Thus by way of amusement, and probably by impulse rather
-than deliberate purpose, he was equipping himself to become both the
-designer and the pilot of his future dirigibles.
-
-Having acquired experience and skill in operating both balloons and
-engines, the young enthusiast set about realizing his boyhood dream
-of navigating the air independently of the course of the wind. His
-first dirigible was designed to carry his weight of 110 pounds and a
-3½ horse-power petroleum engine taken from his tricycle, and reduced
-in weight to 66 pounds. The hull was a cylinder of varnished Japanese
-silk, 82½ feet long including its pointed ends, 11½ feet in diameter
-and 6,354 cubic feet in gas capacity. A ballonet, or air pocket,
-occupied the lower middle of the envelope. The basket for the little
-pilot, engine, and two-blade propeller was suspended far below the
-hull, to which its cords were attached by means of small wooden rods
-inserted into hems along each side of the envelope, for a great part of
-its length. The poise of the vessel was controlled by shifting weights
-fore and aft, while the turning right and left was effected by means
-of a silk rudder stretched over a steel frame. On the whole it was a
-crude and primitive affair, but of considerable interest as the first
-dirigible of a young man destined to give a strong impulse to the
-development of motor balloons of the non-rigid type.
-
-After some preliminary tests, the little air ship and pilot soared away
-from the Zoölogical Garden in Paris, on September 20, 1898, rising in
-the face of a gentle wind, to the wonder and delight of a large crowd
-of witnesses, some of them professional aëronauts and very skeptical
-as to the outcome of this venturesome experiment. The ship maneuvered
-round and round overhead of the applauding throng, steering readily in
-all directions. Then the green navigator ascended a quarter of a mile
-and merrily continued his evolutions in the direction of the Longchamps
-race course. But when he wished to descend he observed the envelope
-contracting in volume, and was appalled to find that he could not
-pump air into the ballonet fast enough to keep the hull distended. It
-became swaybacked, and “all at once began to fold in the middle like a
-pocket-knife; the tension cords became unequal and the balloon envelope
-was on the point of being torn by them.” As he was falling swiftly
-toward the grassy turf at Bagatelle, he called to some boys who were
-flying kites, to grasp his guide-rope and run against the wind. They
-understood and ran so swiftly with the canted balloon that it played
-kite, and descended with a moderated fall, landing the frightened
-aëronaut safely on the turf.
-
-Except for the doubling of his long balloon, Santos-Dumont’s first
-voyage was satisfactory, and he returned to Paris elated. He had found
-it easy to steer in all directions. He could change his level hundreds
-of feet without discharge of gas or ballast, by merely canting his
-balloon, and allowing it to run obliquely up or down grade. He had
-stemmed the wind and gone whither he pleased, at such speed as to make
-his clothes flutter. And best of all he had found no danger in using a
-gasoline motor near an inflammable gas bag. The mere buckling of the
-long bag was a trifle, to be remedied by using an air pump adequate to
-maintain the flabby thing well inflated. He felt, therefore, that he
-had the conquest of the air well in hand, and that he was drifting into
-air ship construction as a life work. Small wonder that he continued
-his conquests till he had built, in less than one decade, fourteen
-motor balloons.
-
-_Santos-Dumont No. 2_ was closely patterned after its predecessor,
-but was a little larger and carried a rotary fan worked by the motor,
-to keep the balloon plump by filling the air pocket, or ballonet. On
-May 11, 1899, an ascension was made from the old starting place, but
-in rainy weather. As the vessel rose its hull contracted faster than
-air could be pumped into the ballonet, the long bag doubled worse than
-before, and dropped into the trees with its chagrined but fearless
-rider.
-
-The _No. 3_, which followed, was a short, thick vessel, 66 feet long
-by 25 feet in diameter, having in outward appearance the features of
-Dupuy de Lome’s very stable and very slow dirigible. It was apparently
-a safety ship for a scared young man who had not yet learned fully to
-appreciate Renard’s elegant design. It served for a few pleasant trips,
-while the inventor was screwing up courage to build another cylindrical
-vessel, and gradually realizing the advantage of an elongated car such
-as Renard had employed in _La France_. Not only was the hull short
-and thick, but it was further secured from buckling by a horizontal
-stiffening pole placed between it and the basket, and from which the
-latter was hung. After some voyages in _No. 3_, which the captain found
-very tractable, and probably capable of fifteen miles per hour, he was
-ready to begin a new vessel.
-
-The _No. 4_ was a compromise between the better features of _No. 3_
-and its predecessors. The elongated hull and ballonet were resumed,
-and the stiffening pole was elaborated into a longish car resembling
-Renard’s, but of triangular cross section. On this long trussed frame
-were placed the motor, propeller, rudder and the rider in his basket.
-A seven horse-power engine turning, at one hundred revolutions per
-minute, a screw propeller having two blades, each 13 feet across, gave
-a thrust of 66 pounds. Frequent trials of the ship during the summer
-of 1900, in presence of the Exposition crowds, brought the inventor
-into extraordinary prominence, and secured for him the “Encouragement
-Prize” of the Paris Aëro Club, consisting of the yearly interest on
-one hundred thousand francs, this being one of M. Deutsch’s numerous
-foundations for the promotion of aëronautics.
-
-In the spring of 1900, M. Deutsch de la Meurthe had established another
-prize which Santos-Dumont now greatly coveted, and hoped ere long to
-win. This was a cash sum of one hundred thousand francs to be awarded
-by the Scientific Commission of the Aëro Club of France to the first
-dirigible that, between May 1 and October 1, 1900, 1901, 1902, 1903,
-1904, should voyage from Saint Cloud to and around the Eiffel tower,
-and return within half an hour. The distance to the tower and back,
-not counting the turn, was nearly seven miles, and the estimated speed
-required to fulfill the conditions for winning the prize, even in calm
-weather, was 15½ miles per hour.
-
-As Santos-Dumont thought his _No. 4_ scarcely swift enough to win
-the Deutsch prize, he enlarged it by inserting an additional length
-of sixteen feet at its middle, supplied it with a stronger car, and
-applied a larger engine, naming the new vessel so formed, his _No.
-5_. Its hull was 109 feet long, 17 feet in largest diameter and cubed
-nearly 20,000 feet. A four cylinder air-cooled petroleum motor driving
-a screw propeller having two blades, each 13 feet across, gave a thrust
-of 120 pounds, at 140 revolutions per minute, and produced such draft
-as to give the inventor pneumonia. Among other novelties water ballast
-was used, and piano wires replaced the old-time suspension cords.
-
-The _No. 5_ proved so powerful and swift that on July 13, 1901,
-Santos-Dumont attempted to win the Deutsch prize. Starting from the
-Aëro Club grounds at Saint-Cloud in presence of official witnesses,
-at half past six in the morning, when the air is usually stillest,
-he turned the Eiffel Tower in the tenth minute, thus gaining twenty
-minutes for the home stretch. But on his return he encountered an
-unexpected head wind, and after a terrific struggle reached the
-timekeepers at Saint-Cloud in the fortieth minute.
-
-To add to the romance of this voyage, the genii of the upper elements
-stopped his motor, shortly after his return, and the bold sailor in his
-shining ship landed in a stately chestnut tree very near the house
-of the Princess Isabel, daughter of Dom Pedro. She very thoughtfully
-arranged a breakfast for him and sent it up in a basket, where he was
-at work disengaging the balloon, at the same time inviting him to call
-and relate to her the story of his voyage. A few days later she sent
-him a medal of St. Benedict “that protects against accidents.” He wore
-the medal, and on his very next trial escaped without a scratch from an
-appalling accident which might have terminated fatally. He continued to
-wear the gift of that gracious princess, on a thin gold chain circling
-his wrist, and many a time thereafter endured unscathed the most
-dreadful accidents, as if he possessed a charmed life.
-
-On August 8, 1901, the dauntless aëronaut again sailed for the coveted
-prize, at the same still morning hour, sacred to duels and aërial
-contests. In nine minutes he turned the tower and headed bravely for
-home. But soon a leaky valve let the balloon shrink and the wires
-sag into the whirring propeller, which therefore had to be stopped.
-Santos-Dumont now had the choice of drifting back against the tower
-and destroying his vessel high in air, or of descending at once, by
-allowing the balloon to sink without discharge of ballast. He chose
-the latter course, hoping to land on the Seine embankment; but instead
-his balloon struck the top of the Trocadero hotel, exploded and fell
-in fluttering shreds into the courtyard. Some firemen who had been
-watching the flight from a distance, came with a rope and found
-the long car leaning like a ladder against the wall of the court,
-the balloon shreds hanging from it in graceful folds, and Captain
-Santos-Dumont perched aloft in his wicker basket wearily waiting for
-St. Benedict’s further aid. As usual, he was rescued intact.
-
-On the evening of his fall on the roof of the hotel Santos-Dumont
-issued specifications for his famous _No. 6_, which surpassed
-all its predecessors in safety and speed. It had the shape of an
-elongated ellipsoid with pointed ends, measured 110 feet in length,
-20 feet in major diameter, 22,239 cubic feet in volume, and had an
-absolute ascensional force of 1,518 pounds. It was driven by a twelve
-horse-power four-cylinder water-cooled engine which gave the propeller
-a thrust of 145 pounds. To insure against buckling of the gas bag, an
-air pump connected with the motor, kept the ballonet under constant
-pressure, regulated by an escape valve through which the excess of
-air passed outward. To secure the envelope against rupture, due to
-the expansion of the hydrogen at unusual elevations, a stronger valve
-was used to let the gas escape from the envelope into the atmosphere.
-Thus the air escape valve kept the pressure constant in the partially
-distended ballonet, and consequently also in the surrounding gas
-envelope itself; while the stronger gas valve in the envelope opened
-only in an emergency, when the gas pressure had fully collapsed the
-internal air pocket and was threatening to explode the envelope. With
-all its improvements this new vessel was finished and inflated by
-August 4, being a work of twenty-two days, and after some preliminary
-trials was ready to try for the Deutsch prize.
-
-The day of triumph followed quickly. On October 19, 1901, at 2.45
-P.M., Santos-Dumont again headed for the Eiffel Tower in presence of
-the official witnesses. In spite of a wind of six meters per second
-striking him sidewise, he held his course straight for the goal, and
-turned it in the ninth minute, as in his preceding attempt. On the
-return he had to struggle against a quartering wind and the caprice
-of his motor, which sometimes threatened to stop, and again spurted
-so actively as to turn the ship upward at a steep angle. The mighty
-throng below, in the Auteuil race track and the Bois de Boulogne, sent
-up immense applause, then suddenly held its breath in alarm, as the
-vessel pitched violently. But the hardy little rider was self-possessed
-and at home on his vaulting Pegasus. Alert to every prank he held his
-course straight for the timekeepers and passed over their heads at
-exactly twenty-nine and one-half minutes after starting.
-
-His unmercenary disposal of the two rich awards which he had won seemed
-no less commendable than the dauntless industry which achieved such
-rapid success. The Deutsch prize amounting in all to one hundred and
-twenty-five thousand francs he divided into two unequal parts. The
-greater sum of seventy-five thousand francs he gave to the prefect
-of police of Paris, to be used for the deserving poor; the remainder
-he distributed among his employés. The Encouragement Prize of four
-thousand francs a year, mentioned before, he also declined to retain,
-but instead he founded with the money a new prize at the disposal of
-the Aëro Club. As a second reward for his triumphal voyage around the
-Eiffel Tower, he received from the Brazilian government one hundred
-and twenty-five thousand francs and a beautiful gold medal bearing
-appropriate and very complimentary inscriptions.
-
-Now that the stimulus and excitement of striving for the Deutsch prize
-was over, the ardent inventor was free to develop and test his air
-ships in a deliberate and scientific manner. He therefore set about
-building specialized types of motor balloons, and practicing with them
-over all kinds of territory, smooth and rough. Within the next six
-years he constructed eight more air ships making altogether fourteen,
-besides his various free balloons, to say nothing of the aëroplanes and
-hydroplanes which he found time to develop. But before indulging in
-these new luxuries he would have more experience with his _No. 6_.
-
-When the cold weather set in, following his victorious flight about
-the Eiffel Tower, Santos-Dumont went with his _No. 6_ to Monaco, to
-practice air cruising over the Mediterranean. The Prince of Monaco
-had erected for him an “aërodrome,” or balloon shed, facing the sea
-and very near shore. On pleasant days the daring pilot would cruise
-up and down the bay, not far from shore, trailing his guide-rope over
-the waves with the greatest ease, and to the applause of thousands of
-spectators. But on February 14, 1902, he set forth on a pleasure cruise
-over the bay with insufficient gas pressure, and thus came to grief.
-The bag grew flabby; the hydrogen poured to its higher end; the vessel
-reared up so steeply that the propeller had to be stopped to avoid
-its cutting the envelope. Rather than drift at the mercy of the wind,
-the pilot opened the valve and sank slowly to the water where he was
-rescued by a boat. On the following day the parts of his _No. 6_ were
-fished out of the sea and sent back to Paris. His few days’ practice
-had taught him the delights of guide-roping over the waters, and his
-accident induced him in future to sew unvarnished silk partitions
-across his balloons, to prevent the hydrogen passing too suddenly from
-one end to the other.
-
-Returning to Paris he built for himself an “aërodrome,” provided
-with great sliding doors like the one at Monaco, and equipped with a
-hydrogen plant, constructive appliances, and everything needed for
-the rapid rebuilding or repair of air ships. It stood in a vacant lot
-surrounded by a high stone wall and was made of posts covered with red
-and white canvas, so that it looked like a great striped tent. Inside,
-the central stalls were 31 feet wide, 165 feet long, and 44½ feet
-high,[12] the whole enclosure having accommodation for seven dirigibles
-all inflated and ready for instant service. When completed, in the
-spring of 1903, it was at once used to harbor three new air ships.
-These were the _No. 7_, designed for racing contests; the _No. 9_,
-called the Runabout, a minim air ship used for calls and short pleasure
-trips; and the _No. 10_, called the Omnibus, intended for several
-persons, with ample supplies for a considerable journey.
-
-The _No. 7_, which excelled its predecessors in length and bulk, was
-intended greatly to outstrip the best of them in velocity. The first
-air ship had attained fourteen miles per hour, the _No. 6_, nearly
-twenty miles an hour in winning the Deutsch prize, and over twenty
-miles per hour on subsequent occasions, though provided with a motor
-rated at only 12 horse power. The new vessel which had little greater
-resistance than _No. 6_, was to carry four times the internal pressure,
-or about 12 centimeters of water, and to be propelled by an engine of
-60 horse power. The inventor expected therefore to attain a speed of
-between forty and fifty miles per hour. A very lofty expectation for
-that day, and one still unrealized for many years.
-
-The racing air ship, or _No. 7_, was of cigar form, supporting a long
-car beneath, and generally resembling the _No. 6_, but slightly more
-tapering. Her length was six times her major diameter, and her volume
-45,000 cubic feet. The envelope was made of two layers of the strongest
-French silk, four times varnished, and was built exceptionally thick
-at the stern, where the differential outward pressure is greatest in
-flight. The propulsion was effected by a 60 horse-power water-cooled
-four-cylinder Clément engine actuating two screw propellers 16½ feet
-in diameter, one in front the other at the rear of the car. The poise
-and maneuvering were to be controlled in the usual way, by means of the
-rudder and shifting weight. The inventor seemed not to realize that
-the bow of his vessel was too sharp to cleave the air with minimum
-resistance, though his predecessor, Jullien, in 1850, had discovered
-experimentally that a torpedo form is better for speed than the
-symmetrical spindle form used by Santos-Dumont in his racing vessel. He
-did, however, in time, learn that the torpedo form of hull is better
-for stability of forward motion, and hence adopted that form in his
-little _Runabout_.
-
-The _No. 9_ was a thick torpedo-shaped air ship originally cubing only
-7,770 feet, though later enlarged to 9,218 feet. It was so thick as
-to appear nearly egg-shaped. In order to make it respond promptly to
-the rudder Santos-Dumont drove it through the air blunt end foremost,
-but with apparent regrets, thinking that it would cleave the air
-more easily than sharp end foremost. In this he was mistaken; for
-the writer has shown that a body of such shape encounters much more
-resistance—roughly one hundred per cent more—when driven sharp end
-foremost than when driven blunt end forward. This fact furnishes one
-reason why most whales and swift fishes have blunt bows and long
-tapering sterns. However this be, the practical man felt his way to
-success, whether right or wrong in his theory of resistance. When
-actuated by a three horse-power Clément motor, weighing 26½ pounds, the
-little air ship carried its jaunty pilot twelve to fifteen miles an
-hour on many a merry trip about Paris and its environs.
-
-The _No. 10_, or _Omnibus_, was a well shaped vessel of nearly eighty
-thousand cubic feet capacity, and amply provided with steering
-devices. Its hull tapered slightly from front to rear, terminating
-in projectile-shaped ends, and had a length of nearly six times its
-major diameter. Underneath was suspended a long car provided with
-aëroplane surfaces, in addition to the usual rudder, for controlling
-its movements.
-
-Its arrow-like appearance was suggestive of some of the greatest German
-balloons of the decade. Indeed, the _Omnibus_, if well powered, might
-have proved a very swift vessel, in addition to a powerful carrier.
-But she was designed merely for easy going passenger service, for the
-purpose of popularizing aëronautics and stimulating its growth.
-
-Santos-Dumont now had three typical air ships, a spacious and well
-equipped “aërodrome,” and ample facilities for advancing the science
-of motor balloons on a moderate scale. He could not, however, maintain
-the ascendency in this branch of science in France; for he encountered
-the rivalry of great wealth employing highly trained engineering and
-constructive talent. He could, however, still promote the art as a
-pioneer and a popularizer. This he continued to do. With his little
-_Runabout_ he would one day guide-rope along the boulevard, another
-day take up a little boy, another day send up a beautiful young lady
-to navigate the air alone for a short distance, another day voyage
-over the military parade grounds and with his revolver fire a salute
-of twenty-one shots to the President of France, and give exhibitions
-to arouse the interest of the War Department. But he could not keep
-pace with the new giants in aëronautics, and he did not attempt
-it. Nor did he ever build a vessel of sufficient power, speed and
-durability to be purchased by the French nation. That honor went to his
-opulent contemporaries who had not failed to take cognizance of his
-contributions to the aërial art.
-
-
-
-
-                               CHAPTER V
-
-             PRACTICAL DEVELOPMENT OF NON-RIGID DIRIGIBLES
-
-
-In 1899 the Lebaudy brothers, wealthy sugar refiners in Paris,
-commissioned their able engineer, Julliot, to make investigations
-and develop plans for a large and swift air ship. This he did with
-the assistance of Surcouf, a well-known manufacturer of balloons at
-Billancourt, Paris. Emulating the example of Santos-Dumont and certain
-German aëronauts in making their plan, they adopted the light petroleum
-engine for motive power, but experimented on a larger scale, thus
-creating a new era in military aëronautics in France. Their first
-vessel was the _Jaune_ whose bag was built at Surcouf’s place, and
-its mechanical part at the Lebaudy Sugar Refinery. When launched,
-in 1902, it so pleased the owners that they determined to continue
-the experiments on a larger scale. Their second air ship, called the
-_Lebaudy_, after fulfilling various tests, was accepted by the French
-government and formed the beginning of its modern aërial fleet.
-
-Moisson, near Paris, where the balloons were kept, now became quite an
-aëronautical center. Here, under military supervision and the skillful
-management of the aëronaut Juchmes, other dirigibles were built in
-rapid succession. Of these the _Patrie_ was launched in 1906, and the
-_République_ in 1908, both fine swift vessels capable of voyaging many
-hours and carrying many passengers. The Lebaudy vessels were the first
-air ships of the “semi-rigid type,” in which the long and flexible
-envelope, or hull, is provided with a rigid keel or floor, from which
-the car is suspended with its machinery and passengers. They are,
-therefore, of unusual interest both for their scientific design and for
-the stimulus they imparted to the growth of aërial fleets. For this
-reason they may well be studied in some detail.
-
-The first Lebaudy air ship, called the _Yellow_, because of its color,
-had an envelope constructed of a rubber-treated cotton fabric, made in
-Hanover and covered with a yellow coating of lead chromate, to ward off
-the sun’s actinic rays from the rubber, and thus prevent deterioration.
-Her hull, which was cigar shaped and inflated with hydrogen, measured
-183 feet in length, 32 feet in diameter, and 80,000 cubic feet in
-volume. She was propelled by a 40-horse-power Daimler motor actuating
-twin screws, and attained a maximum speed of twenty-six miles an hour.
-During her first year’s service she made many ascensions, returning to
-her starting point twenty-eight times out of twenty-nine. Her longest
-voyage, made at Moisson, June 24, 1904, was sixty-two miles in two
-hours and three quarters, with an average speed of twenty-two miles
-an hours. But in November, 1902, while landing in a high wind at the
-end of her voyage from Paris to Chalais-Meudon, she was wrecked by
-colliding with a tree. Her motor, however, was uninjured, and a new
-envelope was at once prepared.
-
-The second vessel, called the _Lebaudy_, and brought out in 1904,
-though resembling her predecessor, had a number of improvements in
-detail. Her hull was somewhat larger than the _Jaune_, and no longer
-pointed at the stern, but rounded off to an ellipsoidal shape, and
-provided, like the rear of an arrow, with guiding, or steadying planes.
-It measured 190 feet in length and 94,000 cubic feet in volume. It
-was provided with two windows for internal inspection, and had an air
-bag of 17,650 cubic feet, divided into three parts. This air bag was
-inflated by a rotary fan near the main body, driven by the motor during
-flight, and by a storage battery when at rest. Suitable horizontal
-and vertical sails were used to steady and guide the vessel; also a
-guide-rope and anchor were carried. The car, suspended by steel ropes,
-ten feet below the hull, carried the passengers and supplies; also
-the motor actuating twin propellers, one on either side. At night an
-abundance of light was available, each passenger carrying a small lamp
-fastened to his clothes, the car itself bearing a powerful acetylene
-projector in its front, and two other lamps of 100 candle power each,
-to illumine the vessel. It was an elaborate affair, costing fifty to
-sixty thousand dollars, and was the outcome of experiments costing ten
-times that sum.
-
-PLATE III.
-
-[Illustration: THE _LEBAUDY_.
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: _LA PATRIE._
-
-(Courtesy E. L. Jones.)]
-
-[Illustration: LEBAUDY’S _MORNING POST_.]
-
-The _Lebaudy_, with these various improvements, gave much satisfaction
-to her owners, and received favorable recognition from the French War
-Department. During the thirty ascensions and voyages of her first
-year’s service, she proved herself a swift vessel, easy to control,
-very stable, and safe to land on solid ground. The Minister of War,
-who had followed her developments with much interest, appointed a
-commission to test her value for military service, with a view to her
-adoption by the government. The test required that the balloon remain
-in active service three months, always being anchored in the open, and
-that it perform certain prescribed maneuvers and voyages. In one of
-these it sailed with three persons on July 3, 1905, from Moisson to
-Meaux, an air-line distance of 57 miles in two hours and thirty-five
-minutes, at an average speed of 22 miles an hour, thence to Chalons,
-61 miles in three hours and twenty minutes. Here it was anchored to
-some trees, but presently was caught in a strong wind, lifted high in
-the air, then dashed violently against other trees, with the complete
-destruction of its envelope. Within eleven weeks it was repaired
-in the military riding school at Toul, nearby; then, after some
-evolutions, returned to its harbor at Moisson. Other maneuvers were
-made subsequently, in which five officers were carried at one time,
-and interesting experiments were tried, such as dropping a sand bag
-upon a given spot, photographing fortifications, etc. The Minister of
-War, accompanied by two officers and other passengers, made a trip on
-October 24th, which was the seventy-sixth voyage of this stanch vessel.
-On November 10th, the hard-worked and successful air ship went into
-winter quarters, being now the property of the French government, and
-the first of her modern aërial cruisers.
-
-The _Patrie_ and the _République_, planned on the general lines
-of the _Lebaudy_, but in ascending scale of magnitude, were built
-expressly for the French government, and experienced brilliant if
-ill-fated careers. Both vessels had whale-shaped hulls, with rather
-sharp-pointed noses and rounding sterns. The original volume of the
-_Patrie_ was 111,250 cubic feet, which was later increased to 128,910,
-by the insertion of a cylindrical section at the major diameter of the
-hull. The _République_ had a volume of 2,000 cubic feet more than the
-_Patrie_, and a length of 200 feet, or a little less than the enlarged
-_Patrie_. She also had a diameter of 35½ feet as against 33¾ in the
-sister vessel. As the technical reader may like more complete details
-of these two noted air ships, a fuller account is given in Appendix III.
-
-The _Patrie_ was a swift and graceful ship which, during its brief
-activities in 1906-7, made many remarkable trips at an altitude of
-about half a mile, and frequently maneuvered with the troops. She
-sailed with excellent stability, had a speed of about 28 miles an hour,
-and, with four men, had a radius of action of 280 miles. In November,
-1907, carrying four passengers, she voyaged from Paris to Verdun,
-on the German frontier, where she was to be stationed. In spite of
-a quartering wind, the total distance of 175 miles was traversed in
-seven hours and three quarters, or at an average overground speed of
-25 miles an hour. But while at Verdun, after some maneuvers, she was
-too insecurely anchored to the ground by means of iron stakes. A strong
-wind came, tore out the pickets, and overpowered the soldiers, some
-two hundred in number, who were trying to hold the vessel. As she was
-pulling them along the ground, they were ordered to let go. The huge
-ship bounded high into the air, soared across France, England, Wales,
-and part of Ireland, then far out over the Atlantic where she vanished,
-leaving no trace behind.
-
-The _République_ also had a brilliant but ephemeral career, from July,
-1908, to September, 1909. She surpassed the _Patrie_ not only in bulk
-and buoyancy, but also in power and speed. She had an 80-horse-power
-motor as against the _Patrie’s_ motor of 60 to 70 horse power. She
-could carry eight to nine men, had a speed of about thirty miles an
-hour, and a radius of action of 500 miles. She made a number of long
-flights and manifested satisfactory steadiness and stability. But on
-September 25, 1909, while maneuvering near Paris, one of her propellers
-broke and tore a great gash in her envelope. At once, with outrushing
-gas and collapsing hull, the great ship fell 500 feet crashing to the
-earth, a total wreck, and killing her crew of four officers. This
-disaster illustrated forcibly the advantage of the cellular system of
-balloon construction, and drew more favorable attention to the rigid
-type of air ship cultivated in Germany.
-
-The famous firm that produced the _République_ brought forth, in
-1909, two other fine vessels patterned after it, the _Russie_ and _La
-Liberté_, built respectively for Russia and France. The _Russie_ made
-her first voyage on May 29th, ascending 600 feet with eight passengers,
-and maneuvering under perfect control. After her official trial,
-in June, she was sent to St. Petersburg, being the first dirigible
-furnished to a foreign government by a private concern. The _Liberté_
-was launched the last week in August and, after various practice and
-official tests, was accepted by the French government two months later.
-On a notable voyage, made on September 20th, she sailed ten hours with
-her Panhard motor constantly working.
-
-The escape of the _Patrie_ was a loss keenly felt by the French people,
-but soon compensated by the generosity of M. Deutsch de la Meurthe.
-This liberal patron of aëronautics had a dirigible of excellent design,
-whose hull, based on the plans of Colonel Renard, was contrived and
-built by E. Surcouf, director of the Astra aëronautic establishment,
-along with H. Kapferer, while its other parts were built by Voisin,
-both of Billancourt. In September preceding the accident to the
-_Patrie_, he had offered the use of his air ship, the _Ville de Paris_,
-to his government, which accepted the gift with the understanding that
-it was not to be delivered except in case of war or emergency. When,
-therefore, in November, 1907, the disaster occurred to the _Patrie_,
-M. Deutsch at once placed his dirigible in the hands of the military
-authorities.
-
-[Illustration: FIG. 21.—_La Ville de Paris._]
-
-The _Ville de Paris_ showed considerable resemblance to her prototype,
-the _France_ of 1884, but differed from that elegant vessel in various
-important features. Her hull was shaped like a wine bottle with its
-thickest end, or bow, brought to a sharp projectile point, and its
-other end furnished, like an arrow, with four fixed guiding surfaces
-to steady its flight. These guiding surfaces were elongated, finlike,
-cylindrical sacs, inflated as shown in the illustration. The hull
-measured 200 feet long, 34½ feet in major diameter, 112,847 cubic feet
-in volume. Heavy bands of canvas with their edges sewed along the
-sides of the balloon served as flaps for the attachment of the cords
-suspending the long car beneath. With this long suspension the weight
-of the car was more evenly distributed over the envelope than in the
-Lebaudy balloons. An interesting improvement in this air ship was the
-stabilizing planes, placed above the car, fore and aft, to lift or
-depress aëroplanelike, thus enabling the pilot to raise or lower the
-vessel, also to alter her trim, or to check her pitching. As might be
-expected, her flight was very steady, but as the motor developed only
-70 to 75 horse power, her velocity did not exceed twenty-five miles per
-hour. In January, 1908, she made a run of 147 miles in seven hours, six
-minutes, with an average speed of 21 miles an hour. Further details of
-construction are given in Appendix III.
-
-We now have had examples of the three leading types of motor balloons;
-the rigid, the semirigid, the flexible. The rigid type, as exemplified
-in the Schwartz and Zeppelin air ships, is characterized by its
-solidly trussed hull of invariable size and form to which all other
-parts are directly attached. The semirigid type, exemplified in the
-Lebaudy vessels, has a flexible hull, generally of woven fabric, with
-a trussed floor or platform for its ventral part, from which the car
-is suspended. The flexible type, as seen in the _Ville de Paris_, the
-_France_, and its predecessors, consists of a flexible hull entirely
-devoid of stiffening framework, together with a car, usually quite
-long, suspended from the bag directly. These are all of the important
-kinds in use at present. A combination of balloon and aëroplane has
-been tried by Santos-Dumont, Malecot, and others, but thus far has
-not resulted in a very successful and distinct type. Of the many
-powerful, swift, and elegant balloons which sprang into being after
-the success of the Lebaudy vessels, all could be classified under the
-above three types. Neither kind proved preëminently the fittest for
-all service, but the semi-rigid and flexible balloons multiplied most
-rapidly; partly, no doubt, because of their cheapness and convenience
-of management. We may review briefly this new crop of air ships, before
-turning to the novel and huge rigid vessels of Count von Zeppelin.
-
-The _Ville de Paris_ was followed, in 1909, by the _Clément-Bayard_,
-a slightly larger vessel of very similar pattern, constructed for the
-Russian government for $40,000. It also, like the _Ville de Paris_,
-was built by the Astra Society. The most striking feature of this new
-balloon was its curious stern with its bulblike steadying surfaces.
-These fin surfaces were not flat, as in the _Patrie_, nor cylindrical,
-as in the _Ville de Paris_, but of pear form, with the blunt ends
-pointing rearward and inflated like the rest of the hull. Apparently
-these tail bags were not economical of power, since, as is well
-known, a pear shape encounters greater resistance when moving sharp
-end forward than when moving blunt end forward. However this be, the
-stabilizing force proved very effective. The vessel was driven by a
-Clément-Bayard motor of 100 horse power actuating a wooden screw placed
-in front of the long car, as in the _France_. A speed of 30 miles an
-hour was attainable, and the ship could accommodate eight passengers.
-On one occasion it made a round trip from Sartrouville, traversing 125
-miles at an average speed of 27 miles an hour. It was acquired by the
-Russian government on August 23, 1909, having on that day completed
-its third official test, and satisfied the requirement of rising 1,550
-meters and voyaging two hours at a height of 1,200 meters. Two notable
-incidents of that voyage were that the air ship made a new record for
-altitude, and on landing was caught by a squall which tore it from the
-hands of thirty men, after which, owing to motor failure, it drifted
-freely across country, tripped on a willow, and fell into the Seine,
-whence it was rescued after considerable pains and labor.
-
-Other vessels presently built by the Astra Society may be listed,
-together with their size in cubic meters, as follows: _Ville de
-Bordeaux_, 3,300 m^3;[13] _Ville de Nancy_, 3,300 m^3; _Colonel
-Renard_, 4,000 m^3; _España_, 4,000 m^3; _Clément-Bayard II_, 6,500
-m^3; _Transaerienne I_, 6,500 m^3; _Flandre_, 6,500 m^3 (228,579
-cubic feet). These were among the most noted air ships produced in
-France toward the close of the first decade of the twentieth century.
-On the whole they proved to be swift and stable ships adapted either
-for military use, or for exhibitions and sport, and even for regular
-transportation of passengers.
-
-The _Ville de Nancy_ was one of the conspicuous dirigibles of the
-summer of 1909. It was constructed primarily for use at the Exposition
-at Nancy, and was owned by the Compagnie Générale Transaerienne, an
-aërial passenger transportation society organized at Paris, in
-March, 1909, with a capital of one million francs. This society planned
-to inaugurate an aërial line from Paris to Bordeaux, in 1910, equipped
-with other vessels of the Astra construction, more powerful than the
-_Ville de Nancy_, and capable of transporting a dozen passengers.
-
-PLATE IV.
-
-[Illustration: _LA VILLE DE PARIS._
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: _COLONEL RENARD._
-
-_Photo E. Levick, N. Y._]
-
-The _Ville de Nancy_ was slightly smaller and slightly more powerful
-than the _Clément-Bayard I_, besides differing in minor details. It
-measured 55 meters in length, 10 meters in greatest diameter, and
-cubed 33,000 meters, as against the 35,000 meters of its predecessor.
-It was driven by a 100-horse-power Bayard-Clément motor actuating a
-Chauvière screw propeller at the front of the car. The car itself was
-made of steel tubes covered with fabric, and near the engine with
-sheet aluminum. The tail bags were an evident improvement on those of
-the previous air ships, being less blunt at the rear, and therefore
-less adapted to generate a retarding suction. They were still rather
-bulbous, however.
-
-This splendid vessel made various interesting voyages during the
-summer of 1909, the first on June 27th, piloted by Surcouf and
-Kapferer, directors of the Astra Society. On July 14th, she maneuvered
-at Longchamps, side by side with the _République_, thus contrasting
-nicely with the ship designed by Julliot. It was the first time two
-dirigibles navigated together in regular maneuver. The _Ville de Nancy_
-was naturally the swifter, having greater power and less bulk than
-the other. About the middle of July she sailed from Sartrouville to
-Nancy, where she was to sail about the Exposition grounds and make
-daily excursions, carrying passengers for 100 francs per trip. These
-voyages proved very popular, being the first of their kind, and in
-themselves quite attractive. As the vessel was endowed with excellent
-stability and had manifested high speed, she was well suited to be the
-first regular passenger air ship, and the herald of the aërial liners
-projected to cruise between Paris and Bordeaux.
-
-The _Colonel Renard_ was closely patterned after the _Ville de Nancy_,
-but was larger and more powerful. She measured 212 feet in length,
-140,000 cubic feet in volume and carried an engine of 120 horse power,
-driving a Chauvière propeller. On July 13th she made her first trip,
-cruising one hour with notable facility, then reëntered the hangar[14]
-of the Astra Society, at Beauval near Meaux. Thence, on August 23d, she
-sailed for Rheims to compete in the aëronautical races, arriving after
-a very successful cruise. On August 29th, she circled the ten kilometer
-rectangular course at Betheny, near Rheims, five times in 1 hour, 19
-minutes, 40 seconds, thus winning the Prix des Aëronats,[15] of 10,000
-francs offered for the vessel that should accomplish, in the least
-time, those five rounds, aggregating 50 kilometers. The showing was not
-remarkable, but the vessel could sail much faster in a straightaway
-voyage.
-
-The prize-winning _Renard_ was quickly followed by the _España_, a
-vessel of the same size and pattern, built for the Spanish government
-by the same capable firm. During October this fine air ship made
-several trial trips, carrying seven men. On November 2d she made
-a splendid official test voyage of five hours, sailing from the
-Astra aërodrome, at Beauval, to Paris and return, a distance of 250
-kilometers in 5 hours and 10 minutes, or at the average rate of 31
-miles an hour for the entire course. On November 5th, she started on a
-ten-hour voyage, with five men and fuel for fifteen hours; but after
-five hours, stopped her engine, and came to earth, owing to the bending
-of the main shaft of the motor.
-
-Besides the great auto balloons designed by Julliot and Surcouf, of
-which the _République_ and _Colonel Renard_ are examples, a number of
-convenient cruisers were brought forth in 1909 by the Zodiac Company.
-One of the leading spirits in this enterprise was the famous Count de
-la Vaulx, well known for his auto balloon designs and his long voyages
-in sphericles. The chief merit of these modest air ships, which ranged
-in volume from 25,000 cubic feet upwards, was cheapness and facility of
-demounting and shipment. They were intended to popularize the art among
-the masses, by giving everyone a chance to make a voyage at no great
-expense. Besides their applicability to sport, touring, and public
-uses, some were designed for considerable speed and endurance; which
-qualities, together with their demountability and partial independence
-of hangars, were expected to give them military value. They were of
-the flexible type, so arranged that the various parts were easily
-detachable, so as to be packed for transportation, by wagon or car.
-The smaller ones might be called semi-navigables, since they had the
-organs of a swift motor balloon, but, like the common sphericles,
-could easily be demounted and hauled home—a likely issue on a day of
-any considerable wind. The first one cost $5,000, cubed 25,000 feet
-and, with its 16-horse-power engine, traveled 13 miles per hour. Its
-hull had the form of a whale with docked and rounded tail. From this
-body hung an elongated car with a screw at the rear and elevating
-planes in front. Others of similar make, but larger, followed in rapid
-order, their common mission being that advocated by Santos-Dumont, in
-the early part of the decade, when he produced his _Runabout_ and
-_Omnibus_—to give everybody a ride.
-
-[Illustration: FIG. 22.—_Le Petit Journal_, ZODIAC TYPE.]
-
-PLATE V.
-
-[Illustration: _ZODIAC III._]
-
-[Illustration: _ZODIAC IV._]
-
-The _Zodiac I_ was quickly followed by vessels _II_ and _III_, cubing
-respectively 1,200 and 1,400 meters. The _No. II_ had a speed of
-twenty, or more, miles per hour, and carried two passengers when
-inflated with coal gas, three with hydrogen. The _No. III_, of torpedo
-form, measured 133 feet long, 28 feet in major diameter, carried four
-persons, and sailed 25 miles an hour with her 40-horse-power Ballot
-engine. On August 29th, piloted by Count de la Vaulx, she competed with
-the _Colonel Renard_, at Rheims, for the _Prix des Aëronats_, making
-five rounds of the ten kilometer course in one hour and twenty-five
-minutes, this being at the average speed of 22 miles an hour. On
-October 30th, again piloted by the same renowned aëronaut, she sailed
-from Brussels to Anvers, rounded the lofty Cathedral spire, and
-returned to her aërodrome, traversing a distance of sixty kilometers in
-one hour and twelve minutes, or with an average speed of 31 miles an
-hour, a good showing for so small an air ship.
-
-A very handsome dirigible, named the _Belgique_, was constructed early
-in 1909, by the skillful aëronautical engineer, Louis Godard, of Paris,
-in collaboration with the prominent Belgian engineer and sportsman,
-Robert Goldschmidt. It was a flexible balloon of elegant torpedo form,
-measuring 175 feet long, 30 feet in major diameter, and 106,000 cubic
-feet in volume. It was propelled by two 60-horse-power Vivinus engines
-actuating two screws, made of fabric stretched over radial sticks,
-and placed at either end of the spindle-shaped car. The control was
-provided for by ample keel surface, an elevating plane in front,
-and ingeniously designed fins on the rear of the hull to steady the
-motion. The entire structure showed much originality and skill. When
-the dirigible was tested near Brussels, on June 28th, it was piloted
-by Louis Godard, the famous expert in sphericals, accompanied by
-Goldschmidt. Godard’s début in this capacity was reported as excellent.
-
-The Italian government brought forth, in the summer of 1909, a swift
-and elegant auto balloon showing considerable originality of design.
-It has a porpoise-shaped hull of 2,500 cubic meters capacity, divided
-into seven compartments, so as to obviate the accident which wrecked
-the _République_. An ample keel along the rear bottom, and large
-aëroplane surfaces at the stern, serve to guide and steady the vessel.
-Propelled by twin screws well above a short car, she readily attained
-thirty miles an hour, carrying four persons. On October 31st, starting
-on her seventeenth voyage, she cruised from the aëronautic park, Vigna
-de Vale, near Rome, to Naples and back to Rome by ten o’clock at
-night, having sailed over the edge of the Mediterranean Sea and over
-the French squadron in the bay, remaining fourteen hours in the air
-and traversing 520 kilometers, or 323 miles. It was one of the finest
-voyages of the year. Further details of this Italian military dirigible
-_No. I bis_, together with illustrations, are given in _Aërophile_ for
-January 15, 1910, together with its prototype the dirigible _No. I_,
-which maneuvered so successfully in 1908.
-
-England and America all along had pursued an oriental, or
-semicivilized, policy toward the auto balloon, languidly watching
-the progress elsewhere, and hoping some time to enjoy the fruition,
-if not the glory, of the costly and successful experiments made in
-other countries. In 1909, however, the British government appropriated
-nearly $400,000 for aëronautics, and the United States House of
-Representatives voted $500,000, but promptly reversed its action,
-and gave nothing, though it may be said that even then there was a
-growing sentiment in favor of a more liberal policy. The movement to
-secure the beginning of an aërial fleet in England is summarized in the
-following paragraph.[16]
-
-PLATE VI.
-
-[Illustration: _LA BELGIQUE._]
-
-[Illustration: ITALIAN MILITARY DIRIGIBLE _NO. I BIS_.]
-
-  “The naval authorities were entrusted with the building of a
-  rigid ship, whilst to the military department was delegated the
-  work of building non-rigid and semi-rigid ships. A national
-  air-ship fund was organized by the _Morning Post_ with the
-  object of purchasing a French Lebaudy semi-rigid dirigible
-  which would be presented to the War Office; whilst Mr. Arthur
-  du Cros and other members of the Parliamentary Aërial Committee
-  arranged for a _Clément_ non-rigid air ship of new design, to
-  sail from Paris to London, and also to qualify for purchase as
-  a unit of the British aërial fleet.”
-
-The non-rigid auto balloon ordered from Clément, and afterwards known
-as the _Clément-Bayard II_, was the masterpiece of that skilful
-designer, and occupied his best thought and energy for eighteen
-months, aided by his devoted and capable engineer, Sabathier. She
-was completed in the Clément-Bayard factory at Lamotte-Breuil in
-April, 1910, and during the next five months made thirty-two test
-ascensions and practice voyages. In particular she took a conspicuous
-part in the military maneuvers at Picardie during the early half of
-September, where with wonderful precision and airworthiness she made
-forced voyages in fair weather and foul, remaining, when so desired,
-in continuous communication with the land office by means of wireless
-telegraphy. Finally, on a fair day, September 16th, the tried and
-perfected vessel was brought forth from her hangar for the long
-contemplated voyage to London, her machinery and rigging in trimmest
-order, and her car furnished with supplies for twenty hours, or thrice
-the anticipated time of transit.
-
-The voyage was a glorious achievement for aëronautics, and for the
-enthusiastic constructor and his devoted aids. Starting at seven
-o’clock in the morning, with seven men aboard, including happy Clément,
-Sabathier, and an English delegate, the whalelike cruiser sailed
-directly to London with admirable regularity, covering the entire
-distance of 242 miles in six hours, or at the rate of forty miles
-an hour, which is better time than could be made by land and water.
-Enthusiastic cheers from the English spectators greeted the arrival of
-this French dirigible, built for the English government. Then quietly
-the English soldiers took the vessel in hand, as if performing a
-familiar duty, and housed her in the _Daily Mail_ hangar, at Wormwood
-Scrubs. Thus simply and without unusual incident terminated the first
-motor-balloon cruise between the two countries, and one of the finest
-voyages in the history of aëronautics.
-
-In outward appearance the _Clément-Bayard II_ closely resembled her
-predecessor, except for the absence of empennage on her envelope. In
-the whalelike elegance of her hull she was, in fact, a reversion to the
-trim and efficient model of Renard’s dirigible of 1884, which in turn
-was a fair copy of Jullien’s model of 1850, all having excellent forms
-for speed and stability. But the new vessel was of greater size and
-power than her predecessor. Her net buoyancy was sufficient to carry
-twenty passengers. Her average speed tested in a round-trip voyage was
-about 50 kilometers or 31 miles per hour when her two motors developed
-200 horse power, and 55 kilometers or 34 miles per hour when the
-engines developed their maximum effort of 260 horse power. The details
-of construction were so elaborate and important, and so representative
-of the best aëronautical workmanship of the time that a full account of
-their chief features is presented in Appendix III. In passing it may be
-added that some time before sailing to England the _Clément-Bayard II_,
-because of her excellent workmanship and maneuvers, received the first
-prize at the review of dirigibles by the French Minister of War.
-
-PLATE VII.
-
-[Illustration: _CLÉMENT-BAYARD I._
-
-(Courtesy E. L. Jones.)]
-
-[Illustration: _CLÉMENT-BAYARD II._
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: FIG. 23.—_Clément-Bayard II_, 1910.]
-
-The dirigible to be purchased with the money secured by the popular
-subscription organized by the _Morning Post_ was ordered from the
-Lebaudy factory at Moisson in July, 1909, to be delivered directly
-through the air to Farnborough before November 6, 1910. This
-stipulation was severe enough, but furthermore the vessel was to
-be a considerable departure from any thus far built at that famous
-factory, and was to be the largest air ship yet constructed in France.
-As usual the general design of the huge balloon was entrusted to the
-distinguished aëronautical engineer, Henri Julliot, and this was a
-certain guarantee of its successful operation.
-
-The general features of this great military dirigible resemble those
-of her prototype, the _Patrie_, differing chiefly in the shape of her
-hull and the method of stiffening. The hull itself was more longish
-than the _Patrie’s_, but had the same sharp prow and blunt stern; for
-a blunt stern offers better support to the empennage planes, though
-it increases the resistance more than a tapering stern. The trussed
-framing to stiffen the ship was no longer a platform inserted in the
-base of the hull, but a long trussed beam of cruciform cross section,
-made of steel tubing and suspended intermediately between the hull and
-car.
-
-The hull was of excellent workmanship and bold design. The envelope
-was of rubberized tissue, measured 338 feet in length, 39.4 feet in
-diameter and cubed 353,000 feet. Its length was, therefore, 8.5 times
-its diameter, an extraordinary proportion for a balloon of the flexible
-type. The hull was provided with three ballonets, two ripping panels,
-and various valves, as shown in the scale drawing.
-
-[Illustration: FIG. 24.—MORNING POST DIRIGIBLE, 1910.]
-
-The car, made of steel tubing and large enough for twenty persons,
-carried two Panhard-Levassor motors of 135 horse power each, actuating
-two Chauvière wooden screws, sixteen feet in diameter, placed on either
-side, well outward and upward, the transmission gear permitting either
-engine, or both, to drive the screws at one time. Below the car and
-well forward was a ground keel, or post, on which the whole vessel
-could pivot with the wind, when riding at anchor, while a shorter
-ground post was placed at the rear of the car.
-
-The controlling surfaces were adequate and skillfully arranged. To
-maintain steadiness and directness of flight, fixed empennage planes,
-both horizontal and vertical, were provided, some attached to the stern
-of the hull, others at the rear of the trussed suspension beam. To
-direct the up and down movement, ailerons placed well to the front and
-rear of the long framing, were turned about conjunctively in opposite
-directions, thus causing the vessel to raise or lower her bow. Needless
-to say, all these navigation appliances worked with ample force and
-effectiveness from the beginning of the earliest tests.
-
-After four preliminary ascensions the great air ship started from
-Moisson to her destination at Farnborough, having on board Henri
-Julliot, Louis Capazza, the pilot, Alexander Bannerman, director of
-the aëronautic military school at Aldershot, and five other men. It
-was a triumphant and glorious voyage, one of the most splendid in
-the history of aërostation. Piloted by aid of chart and compass, and
-by signal fires and captive balloons arranged along her route, the
-vessel followed a direct course, without check or hindrance, crossing
-a wide part of the English Channel and arriving before the hangar at
-Aldershot, where the British soldiers awaited her, and where she was
-safely landed, having made the whole voyage of 230 miles in 5.5 hours,
-at a level varying between five hundred and two thousand feet. As
-shown by the accompanying map, about one third of the route lay over
-the Channel, or, more accurately, 78 miles, which was traversed in two
-hours. Thus the whole journey was accomplished at an average speed
-of nearly forty-two miles an hour, or in less time than it could be
-effected in any other way than through the air.
-
-[Illustration: 15 Novembre 1910
-
-FIG. 25.—ROUTE OF BRITISH MILITARY DIRIGIBLES FROM FRANCE TO ENGLAND,
-1910.]
-
-The United States War Department, in 1908, started an aërial squadron
-by purchasing from Thomas S. Baldwin, for $10,000, a tiny air ship of
-the flexible type, a trifle larger than Santos-Dumont’s _Runabout_, but
-in fact the smallest military dirigible then in existence. It had a
-rubberized gray silk cylindrical hull slightly tapering toward the rear
-and terminating in ogival ends, its length being 96 feet, its major
-diameter 19½ feet. From this was suspended, by means of netting and
-steel cables, a longish car having at the rear a double rudder working
-about a vertical hinge, at the front an elevating plane and an 11-foot
-wooden screw driven by a Curtiss 20-horse-power water-cooled engine.
-With two men aboard, this vessel readily attained over twenty miles an
-hour in a straightaway course, and at times more nearly thirty miles an
-hour. Its total ascensional force was 1,350 pounds, of which 500 were
-available for men, ballast and supplies.
-
-Santos-Dumont’s most strenuous disciples outside of France were found
-among the German military officers. These advocated and promoted both
-the semirigid and the flexible types of auto balloon, with such ability
-as to match the best productions of the foremost French designers.
-The most successful pioneers of these two types in Germany were
-respectively, Major von Gross, commander of the balloon battalion at
-Tegel, near Berlin, and Major Von Parseval of the Bavarian army, and
-director of the Society for the Study of Motor Air Ships.
-
-Beginning in 1907, a number of Gross auto balloons were built in
-succession, for the German Aëronautical Battalion, by Master Engineer
-Basenach, under the supervision of its commander, Major Gross. The
-first was intended only as a model, though it was large enough for
-two passengers. It cubed 63,000 feet, but having an engine of hardly
-more than 20 horse power, was necessarily slow. It was succeeded by
-the _Gross I_, and others, all having rigid ventral parts, like the
-_Patrie_, but with hulls of rather better form for speed and bulk
-combined, having blunter bow and longer stern.
-
-PLATE VIII.
-
-[Illustration: _U. S. SIGNAL CORPS DIRIGIBLE I._
-
-(Courtesy U. S. Signal Corps.)]
-
-[Illustration: _GROSS II._
-
-(Courtesy E. L. Jones.)]
-
-The second Gross air ship, built in 1908, cubed 176,000 feet, and
-attained a speed of 27 miles per hour, driven by two 75-horse-power
-Daimler motors. On September 11th of that year, with four persons
-aboard, she made a round trip from Berlin lasting 13 hours, covering
-176 miles, and attaining altitudes up to 4,000 feet. This was one of
-the finest voyages known at the time. This air ship was purchased by
-the German government, named _Gross I_, and sent to Metz. A detailed
-description is given in Appendix III.
-
-The _Gross II_, brought forth in April, 1909, resembled her predecessor
-in build, but had greater power and speed. Her hull cubed 176,000
-cubic feet, had a blunt bow, full body and sharp stern, was provided
-with horizontal and vertical keels, a sliding weight, and a ballonet
-at either end. She was propelled by two Körting engines of 75 horse
-power each, actuating two three-blade propellers. Under the action of
-her keels and stabilizing planes and rudder, her motion was steady and
-precise. A special feature of this air ship was the wireless telegraph
-equipment by which she could send messages in all directions over a
-range of 300 miles or more. She made many practice voyages during the
-season of 1909, sometimes alone, again in concert with other auto
-balloons and with troops. In August she made a fine voyage of sixteen
-hours, from Tegel to Apolda and return, traversing 470 kilometers.
-
-The above described vessel was followed by others, large and small.
-The _Gross III_ measured 70 meters long, cubed 7,500 meters, and was
-propelled by four Körting motors aggregating 300 horse power. This was
-a splendid vessel, and one of extraordinary speed.
-
-Various auto balloons of the Parseval type were designed by Major Von
-Parseval of the Bavarian army, who also was one of the inventors of the
-kite balloon. Satisfactory experiments with his air ship were made as
-early as 1906. These formed the basis of larger vessels, subsequently
-constructed in the same factory of August Riedinger of Augsburg,
-for the Motor Air Ship Study Society, of which Parseval was general
-manager. This society, organized practically at the command of the
-Emperor, purchased the Parseval patents and began the development of
-auto balloons as a business enterprise, soon furnishing a series of its
-flexible air ships to the German army.
-
-After the experiments of 1906, the Parseval air ship was enlarged from
-2,500 to 2,800 cubic meters, its length becoming 52 meters and its
-major diameter 8.7 meters. Its hull was of cylindric form, with rounded
-bow and egg-shaped stern; had two air bags—one fore, the other aft—and
-at the stern carried two fixed horizontal planes and a vertical rudder.
-From this envelope the car, made largely of aluminum, was hung by steel
-cables, and on its bottom had trolley wheels resting on suspension
-cables joining the front and rear parts of the hull. The vessel was
-propelled by a 50-horse-power Mercedes motor actuating a four-blade
-screw propeller 13 feet in diameter, mounted between the car and hull.
-This screw was made of thin steel tubes covered with shirting. Among
-the merits of Parseval’s air ship may be mentioned its lightness and
-demountability, and its kite-like effect on the air, got by canting
-the hull while the car, rolling on the suspension cables, allowed
-the screw mounted above it to thrust horizontally. The canting was
-effected by giving one ballonet more air than the other, thus causing
-its end of the hull to sink. The speed was about twenty-five miles per
-hour.
-
-PLATE IX.
-
-[Illustration: _PARSEVAL I._
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: _PARSEVAL II._
-
-(Courtesy E. L. Jones.)]
-
-The second _Parseval_ was of greater bulk and power than her
-predecessor. Her hull which was of cylindric form, with round prow
-and pointed stern, measured 190 feet long, 30.5 feet in diameter, and
-113,000 cubic feet in volume. She resembled her predecessor in the
-arrangement of the two ballonets, and in the “loose,” or trolley,
-system of suspension of the car. The propeller was a unique patented
-device of Von Parseval’s. It had four cloth blades so weighted with
-lead as to stand out firmly under centrifugal force, assuming an
-effective shape for propulsion, though limp and deformed when at rest.
-Various interesting evolutions were performed by this vessel in the
-autumn of 1908, including tests imposed by the military authorities,
-as a condition of purchase by the government, one requirement being a
-voyage of one hour at an altitude of 1,500 meters; another requirement
-being a continuous cruise of twelve hours. These tests completed,
-the Motor-Luftschiff-Studien-Gesellschaft sold its proud ship to the
-Vaterland for 210,000 marks.
-
-About the same time the War Department purchased the _Gross I_, already
-described, and Zeppelin’s third great ship, naming it _Zeppelin I_.
-Germany thus began her program of developing a great aërial fleet,
-by acquiring three powerful and well tried ships, each capable of
-remaining all day in the air, and having a radius of action of several
-hundred miles. They were frequently called upon to make test voyages in
-all kinds of weather, to maneuver with the troops, to pass in review
-before the Emperor, at times conveying prominent officers and members
-of the noblest families, including Prince Henry and the Crown Prince,
-who manifested a fondness for navigating about their newly opened
-empire of the sky. But sometimes the tests were crucial. On September
-11, 1908, both the _Gross_ and _Parseval_ were summoned to Potsdam by
-His Majesty. They set forth from their sheds, at Tegel, in face of a
-strong wind. After journeying some distance they each had to abandon
-the voyage, the _Gross_ returning home, and the _Parseval_ falling to
-the ground owing to an accident.
-
-The third Parseval air ship was brought forth on February 18, 1909, by
-the Luftfahrzeug-Gesellschaft, an aëronautical firm founded by merging
-the Motor-Luftschiff-Studien-Gesellschaft with the A. E. G. This vessel
-closely resembled her predecessor, but possessed greater size, power,
-and perfection of detail. Her hull at first measured 224 feet long,
-47 feet in diameter, and 198,000 cubic feet in volume, but later was
-enlarged to 235,000 cubic feet by increasing its diameter.
-
-Her car, which could accommodate twelve passengers, was framed of steel
-tubing covered with canvas, and was divided into two parts, separated
-by the big gasoline cylinder running athwart ship, the passenger cabin
-being to the fore, the engine room aft. Here were stationed the two
-engines, of 120 horse power each, actuating reversible right and left
-_Parseval_ screws 13 feet in diameter, located to the rear, well aloft
-and outward on either side. In the forepart of the passenger cabin was
-space for the pilot and his navigating appliances; his chart desk, his
-valve controls, his statoscope, manometers, etc.
-
-The great ship with her nine tons burden was to have sailed from
-Bitterfeld to Frankfort, for the Aëronautical Exposition, but owing
-to excessive gales, she was sent by rail. Once there, she made many
-excursions, at times carrying passengers at a schedule rate, reported
-to be 200 marks for a voyage of one to two hours. In October she made
-an inter-city excursion covering a distance of nearly 500 miles, during
-which she passed four nights in the open air, finally returning in
-good form to Frankfort. On October 27th she made a farewell tour about
-Frankfort, then voyaged along the Main and down the Rhine valley to
-Cologne, there to participate in the aëronautic military maneuvers,
-together with the _Parseval I_, the _Gross II_ and the _Zeppelin
-II_. Having passed creditably through these and other operations in
-the autumn, she was eventually stationed at Tegel, as a part of the
-national fleet.
-
-The fourth _Parseval_, a smaller vessel, was built for the Deutscher
-Aëro Club early in 1909. Her hull cubed 113,000 feet, and her framing
-was made of the strongest materials, carefully hollowed, to eliminate
-undue weight. At the rear of the car, on either side, were two
-100-horse engines, driving two _Parseval_ propellers at a common speed,
-whether both engines were in operation, or only one. In many respects
-she resembled her immediate predecessors, and her little successor
-_Parseval V_ of 1,200 cubic meters capacity and 30 meters length, built
-for the Imperial Automobile Club.
-
-The maneuvers at Cologne constituted the first grand demonstration of
-the new fleet of military dirigibles, and proved a severe test of the
-powers of the air ships, even when manned by experienced crews and
-commanded by regular military officers. Two companies of the balloon
-corps battalion were in attendance. Large provisions of hydrogen loaded
-on wagons, each carrying 100,000 cubic feet, were kept in readiness to
-be attached to an express train and rushed at the first alarm to any
-balloon in need of replenishing. On Sunday, October 31, three of the
-dirigibles representing each type, _Zeppelin IV_, _Parseval I_, _Gross
-II_, left Cologne together, by official order, and returned after
-flights of 7, 10 and 11 hours respectively, covering in the aggregate
-930 miles. Again, leaving Cologne shortly before noon on November 3d,
-they went down the Rhine, simulated a concerted attack on the great
-fortress of Eherenbreitstein, and returned in the evening, each having
-covered 155 miles. And so on for many days they continued to execute
-maneuvers under military orders and in severe forced marches.
-
-
-
-
-                              CHAPTER VI
-
-                    DEVELOPMENT OF RIGID DIRIGIBLES
-
-
-Count Ferdinand von Zeppelin, the famous cavalry general of Würtemburg,
-and hero of the Franco-Prussian war, after retiring from the army,
-organized, in 1898, a limited liability company for the purpose of
-developing a new type of dirigible which he had long contemplated.
-It was to be a vessel far larger and swifter than any the world had
-yet seen. In the summer of 1900, after two years of industrious
-experimental research and active construction, he brought forth from
-his floating laboratory on Lake Constance, near Manzell, the first
-of those wonderful air ships which have aroused such expectation and
-enthusiasm in Germany. In outward appearance and in its chief features
-of design it typified the whole series of motor balloons thus far
-developed and navigated by that illustrious inventor. Many valuable
-improvements were added, as a result of trial and the advance of the
-collateral sciences; but the fundamental plans seem to have proved as
-practical as they were bold and original. One by one were surmounted
-the greatest obstacles, physical, financial and finally political; for
-the Prussian Ministry did not favor his project at first, and many
-aëronautical adepts were adverse to it. Those huge ships faced the fury
-of many a tempest; their dauntless builder endured the storm of hostile
-criticism; but in the end, builder and ships alike won the plaudits of
-a proud empire and of an astonished world.
-
-Outwardly a Zeppelin balloon may be described as a long cylinder with
-ogival ends and a V-shaped keel running the length of its bottom. From
-afar the cylinder and pointed ends appear circular in cross section,
-but they are sixteen-sided. About one-third the distance from either
-end of the great ship a small boat is suspended from the hull so
-closely that at those places the keel is omitted to make room. These
-two boats are rigidly connected with the hull and support it when the
-vessel rests on, or is towed along the water. Within them are the crew
-and petroleum engines, while above them and outward on each side of
-the hull, and fastened to it by outriggers, are two pairs of screw
-propellers, so placed as to exert their united thrust along the line
-of resistance. In some cases the crew can walk through the V-shaped
-keel from one boat to another, the passageway being illuminated here
-and there, by transparent covering, or windows of celluloid, along the
-sides and floor. Again an observer may climb up through the hull and
-take observations of the sky from above. Telephones, electric bells,
-and speaking tubes serve to transmit intelligence from one part of the
-vessel to another.
-
-The frame of the hull is formed of sixteen longitudinal beams, or
-girders, of trellised metal work running from prow to stern and
-riveted at regular intervals to cross bridges of similar trellised
-metal work, each cross bridge being a sixteen-sided wheel with
-trellised rims strengthened by radial rods running inward to a
-central flange of sheet aluminum. Thus the body of the vessel is
-divided into many compartments, each bounded by two wheels, and the
-surrounding longitudinal beams. Each compartment contains a hydrogen
-balloon, or sac, which fairly fills it and exerts a lift against
-the longitudinal beams and against a netting formed of ramie cords
-stretched from wheel to wheel, diagonally between beams at their
-inner corners. Similarly the outward corners of the beams are joined
-by strong diagonal wires for the purpose of rigidity, and the whole
-external frame is covered with a heavy fabric which forms the outer
-skin, or wall of the hull. Between this skin and the hydrogen bags
-are air spaces, as also between bag and bag. Thus the whole vessel is
-buoyed up by numerous thin hydrogen sacs, protected by the frame and
-outer skin from the direct sun, from foul weather, and from external
-shocks. The gas bags are also separated from each other by the bridge
-work and flanges of aluminum.
-
-PLATE X.
-
-[Illustration: _GROSS III._]
-
-[Illustration: ZEPPELIN AIRSHIP STRUCTURE.]
-
-Obviously there is a material advantage in having many gas cells and
-two propelling plants; for if one fails it may not prevent navigation.
-The tandem arrangement of bags separated by the wheel-like cross
-bridges also allows the balloon to rear any amount without material
-displacement of the gas, or dangerous increase of pressure; for it must
-be remembered that a single hydrogen sac extending the full length of
-an up-ended balloon of such length, would have an outward pressure of
-about thirty pounds per square foot greater at the top than at the
-bottom. The poise of the vessel is maintained by shifting weights, and
-also by use of fins, or rudders, when driving through the air; but
-those arrangements vary in the different machines. So much for the
-general features of these wonderful ships, of which four were built
-during the decade from 1898 to 1908, and several more since that period.
-
-The construction and trial of Count Zeppelin’s first air ship proved a
-formidable task, requiring all his resources of money and mechanical
-skill. As it rivaled in size and fluid displacement a large ocean
-liner, it could not well be launched and landed, except on the water.
-It was therefore housed in a wooden shed 472 feet long, floating on 95
-pontoons, and so anchored as to swing freely with the wind and assume
-its direction. This shed, as well as the ship, was very costly, and
-in an unfortunate hour was torn from its moorings by a tempest, which
-did other damage entailing great expense and time for repairs. The
-inventor’s resources were becoming strained; for, as reported, the shed
-cost $50,000, while the first balloon cost more than twice that sum.
-
-Finally, the first launching was officially set for June 30, 1900. The
-lake was thronged with people massed along the shores, and dotting
-its surface with every kind of craft, from the fisherman’s primitive
-boat to the handsomest private yacht, or launch. All day the expectant
-multitude waited, only to learn at dusk, that the inflation was not
-completed. Next day they tarried again till evening, and merely saw
-the raft on which the balloon rested, towed out of the floating house.
-On the third day, July 2d, those who waited were rewarded with an
-interesting spectacle. The long stiff air ship was drawn forth from
-its shed, like a ram rod from a gun. Count Zeppelin, with two men,
-occupied the front boat, while two others took the rear one. After
-careful adjustment the vessel was liberated, at eight o’clock, rose
-slowly and advanced over the water, accompanied by the droning of its
-propellers and the shouts of the delighted spectators, who realized
-that they might be witnessing the commencement of a new epoch in
-aërial navigation. But the voyage was not an unqualified success.
-The controlling mechanism became deranged, the framework was bent,
-and the propellers could not be worked properly. A gentle wind was
-blowing and the vessel drifted with it, having an independent speed
-of only thirteen feet per second, at best. At eight-twenty she reached
-Immenstadt and landed on the water, having voyaged three and one half
-miles, and having attained a height of thirteen hundred feet on a part
-of the journey.
-
-At that date the _Zeppelin I_ was by far the largest and most
-elaborate air ship ever constructed. Her hull measured 416 feet long,
-38 feet across, cubed nearly 400,000 feet, weighed 9 tons, and had a
-displacement of 10 tons. The trellised frame was made of aluminum, and
-its body comprised seventeen compartments, of which fifteen were 26
-feet long, and the other two 13 feet long. The outer cover was of linen
-treated with pegamoid and tightly stretched. The hydrogen sacs were of
-thin fabric. The propulsion was effected by two benzine motors, one in
-either boat, which together developed 32 horse power, each driving,
-by means of bevel gears and shafting, a pair of four-blade propellers
-3.77 feet in diameter, at 1,100 revolutions per minute. Steering
-sidewise was effected by means of vertical rudders, while the trim was
-controlled by horizontal rudders at either side of the vessel, as also
-by means of a sliding weight which could be drawn fore and aft by means
-of a winch. Naturally some of these details were superseded ere long by
-better devices suggested by subsequent experience.
-
-On October 17, 1900, _Zeppelin I_ made her second voyage, and with much
-better result. Starting from the same balloon house at Manzell, at
-four-forty-five, she promptly rose a thousand feet, and maneuvered in
-a seven-mile wind, steering in great curves at the will of the pilot.
-At times the speed was nearly twenty miles an hour, as determined by
-continuous observations of the balloon’s position, taken from three
-points of a triangle, together with the velocity of the wind on its
-course, duly recorded by an anemometer. Finally a landing on the water
-was made at six o’clock, without mishap.
-
-This last demonstration left the Count triumphant in other respects,
-but without sufficient funds to bring his invention into practical
-use. He must, therefore, look for additional money for the proper
-continuation of his great work. The financial task thus ensuing
-occupied much of his time during the next five years, but he finally
-secured capital enough to continue his experiments and to build a
-second airship. This was completed and ready for trial in the latter
-part of 1905.
-
-_Zeppelin II_ resembled its predecessor in appearance, but embodied
-many improvements suggested by the former trials. Its hull was 414
-feet long, 38 feet in diameter, held 367,000 cubic feet of hydrogen
-in its sixteen gas bags, and weighed with all appliances and cargo,
-about nine tons. It was, therefore, about ten per cent smaller than
-its predecessor; but at the same time it was far better powered than
-the earlier one, and more effectively controlled. Each boat carried
-an 85-horse-power Daimler benzine motor, actuating two enlarged
-propellers. Ample steering surfaces, operated by the helmsman in the
-front boat, served to turn the great ship about either of three axes
-and, at the same time, to displace her bodily up and down in the air,
-either by direct lift or by canting her hull so that her screw thrust
-and the pressure on her sides would produce the desired translation.
-
-Two trials of Zeppelin’s second air ship were made on the Borden-See,
-one on November 30, 1906, the other on January 17, 1907; but both
-met with serious accident. In the first trial the balloon was towed
-by a motor boat some distance, then cut loose in the wind, which
-was carrying it forward faster than the boat. But it soon became
-unmanageable and plunged into the water, suffering considerable damage.
-In the second trial it flew for a short time at a speed of thirty
-feet per second, when the engines were developing 36 horse power.
-Some maneuvering was effected in a strong wind, but presently the
-propellers stopped, the vessel dropped to the shore and was anchored on
-the ground. During the night it was so badly damaged by the wind that
-Count Zeppelin ordered it to be taken to pieces to furnish material for
-further construction.
-
-The loss of two mammoth air ships after such brief trial seemed
-enough to appall even a sturdy general of the Prussian army; but
-Count Zeppelin was too resolute to waste time in futile tears and
-hopeless dejection. Strong natures are usually stimulated by disaster,
-and aroused to fuller energy, to grimmer determination, if not to
-desperate hazard. However, not desperation, but buoyant hope and high
-expectation, based on ample experience, were now his ruling motive. Had
-not his ship attained thirty feet per second with less than one fourth
-her motive power? The year began with disaster indeed, but he intended
-it to terminate in glorious victory. And such, indeed, was the happy
-issue.
-
-October, 1907, witnessed the launching of _Zeppelin III_. She had the
-same length as her immediate predecessor, but she was a luckier vessel
-and better powered. On her official trial she voyaged at the height of
-half a mile, carrying eleven persons sixty-seven miles in two hours
-and seventeen minutes, or at more than twenty-nine miles per hour.
-This was a record velocity exceeding that of the best military balloon
-in France. At times she attained a velocity of fifty feet per second,
-thus considerably outspeeding the swiftest ocean liner. Moreover, her
-stability and steering qualities were excellent. With pardonable
-elation, therefore, the illustrious inventor could report to the
-Minister of War the complete success of his experiments. And with good
-reason the German government now granted financial aid to test more
-fully the merits of the rigid system of construction.
-
-With this assistance the industrious aëronaut erected a new floating
-house on the Borden-See at Friedrichshafen, and began the construction
-of a still larger air ship embodying further improvements in various
-details. _Zeppelin IV_ was 446 feet long, 42.5 in diameter, held
-460,000 cubic feet of hydrogen in her sixteen compartments, and had a
-total buoyancy of sixteen tons. She had a surplus buoyancy of over two
-tons, carried a crew of 18 men, and had an estimated range of action
-of eighteen hundred miles. When drawn from her shed in the autumn of
-1907, her great buoyant hull resting lightly on the water supported by
-her two floating cars, she had all the appearance of a royal passenger
-express ready for important service. In general features the vessel
-was like her three predecessors, but in the center of the keel, with
-transparent floors and windowed sides, was a special stateroom designed
-for passengers only. This seemed very suggestive, if not prophetic,
-of the future trend of aërial navigation. Moreover, the mechanism of
-propulsion and control were increased in power and effectiveness.
-In each boat-like car was a 110-horse-power Daimler benzine engine,
-actuating a pair of three-blade propellers about 15 feet in diameter.
-A large vertical rudder, mounted on the extreme end of the stern, and
-supplemented by a pair of smaller vertical rudders at either side of
-the stern, served to steer the vessel right and left. For steering
-up and down, as also for exerting a direct lift up or down, four
-superposed planes like a Venetian blind were placed at either side of
-the hull fore and aft, at about the same level as the propellers. In
-addition the hull was provided, like a feathered arrow, with fixed
-fin-like planes at the stern, both vertical and horizontal, for
-securing steadiness of flight.
-
-Several trials of this leviathan were made preliminary to her official
-government test which, if satisfactory, assured her purchase by the
-German government for $500,000. At the builder’s suggestion this test
-should include a voyage of 24 hours duration, a safe descent on land or
-water, an ascent to 4,000 feet, and the fulfillment of various secret
-requirements. In the autumn of 1907 a successful voyage of eight hours
-was easily accomplished. In the early part of the next summer, 1908, a
-series of voyages were made which aroused intense interest throughout
-the civilized world. On June 13th the great ship, starting from her
-harbor at Friedrichshafen, sailed over the Alps to Lucerne, steering
-in among the mountains; here buffeted by eddies, and cross currents,
-there stemming such stiff head winds that her shadow could hardly
-creep forward over the ground, again driving through a dark lowering
-hailstorm which pelted with ominous thunder on her resounding hull; but
-at length reaching Lucerne safely, then returning in triumph to her
-harbor at Friedrichshafen. For twelve hours the stanch vessel endured
-the elements, by no means hospitable, and in that period voyaged 270
-miles at an average speed of 22 miles an hour. It was a record journey
-and a triumph in the art.
-
-The following picturesque account of a flight in Count von Zeppelin’s
-gigantic air ship, written by Emil Sandt, appeared in the _Scientific
-American Supplement_ of August 15, 1908:
-
-  “Early in the morning Professor Hergesell, Freiherr von
-  Bassus, Dr. Stalberg, Herr Uhland, and myself set out in
-  Count Zeppelin’s launch for the shed in which the great air
-  ship is housed. When we arrived everything was in readiness
-  for us. Count Zeppelin is proud of the fact that his colossal
-  craft can be drawn in and out of the shed with very little
-  help. In seven minutes the huge gas bag had emerged, and a
-  few minutes later we were floating up to the sky. I took my
-  station in the central car or cabin, a comfortable room flooded
-  with the yellow light that filters through the translucent
-  balloon fabric of which the walls, the floor and the ceiling
-  are constituted. Comfortable seats suspended from fine chains
-  provide a seating capacity for a dozen passengers.
-
-  “For a great portion of their length the walls are provided
-  with celluloid panes. The floor is also transparent wherever
-  it is not used as a footway. Seated comfortably in the central
-  car, I could look down through my knees and see the green
-  earth, water, people, cities and castles far below. I could
-  also see birds circling around and fluttering anxiously,
-  evidently frightened by the strange giant of the air.
-
-  “We crossed over to the Ueberlinger See, traversed the
-  intermediate neck of land, and turned into the valley of the
-  Rhine at Konstanz. Here I left the central car and walked
-  toward the rear car along the keelway, which is flanked with
-  balloon cloth, and which is closed at the end of the keelway
-  by a celluloid door. I opened the door and stepped out on the
-  narrow aluminum gangway, which runs down sharply to the rear
-  car. The gangway has no protecting handrail. It is merely
-  ribbed to give a better foothold. That apparently flimsy
-  structure bridges a chasm of twenty feet between the end of the
-  keelway and the car. From below, the passage from the keelway
-  and the car must seem perilous indeed, but up in the air ship
-  itself no fear is felt. I stood on this narrow bridge and gazed
-  on the landscape. To the north I could see the Hohendtwiel.
-  Behind us lay the Swabian See glistening in the morning’s sun.
-  In the southeast I saw Thurgau wrapped in violet light. On the
-  horizon the lofty peak of the Saentis rose broad and jagged,
-  capped with ice and snow. Below us writhed the Rhine. I looked
-  across at the propellers. Count von Zeppelin had signaled full
-  speed ahead. The giant air ship trembled. The propellers seemed
-  like disks, revolving with furious speed and yet as transparent
-  as a locust’s wings. They gave out a note like that of a deep
-  organ, so loud that the human voice, even when lifted to a
-  shriek, could hardly be heard.
-
-  “I walked down to the rear car to obtain a better view. Here
-  the gigantic craft could be seen in a wonderful perspective.
-  The sensation was strange. The giant ship obediently sank and
-  rose. Obediently moved to the right or to the left, slavishly
-  following the slightest pressure of the human hand. Sometimes
-  its angle was such that the entire fabric seemed inclined like
-  a kite. At times the forward car lay below us; at times we had
-  to look up at it.
-
-  “As we neared the splendid falls of the Rhine at Schaffhausen,
-  the Count brought the air ship down, in order to ascertain
-  whether the eddies occasioned by the waterfall would have any
-  effect.
-
-  “We turned into the Reusstal, but were buffeted by the wind
-  all the way up the valley. To the south the sharp jutting
-  peak of Mount Pilatus hove in sight. Soon Lucerne appeared, a
-  jewel among cities. The lake itself shimmered brightly where
-  it was struck by the sun; its darker portions lay like an
-  emerald, held in a setting of heliotrope. It was like a melody
-  in colors. Below us in Lucerne itself there was a hubbub and
-  a great jubilation. The streets were crowded with gayly clad
-  people. The roads were a-swarm. Zeppelin guided his air ship
-  down, and allowed it to glide full speed over the city at the
-  height of a church steeple.
-
-  “We traveled over the Vierwaldstaetter See, and crossed to
-  Knessnacht, to Zug Lake, and up northward to Zug itself. Then
-  came the most difficult task which Professor Hergesell had
-  assigned to the air ship. The craft was to carry us straight
-  across to Lake Zurich, through a narrow pass where it would be
-  caught in a veritable cyclone. The motors groaned and rattled.
-  The propellers howled a deep groaning song. The air ship did
-  all that it could. The wind was dead against us, traveling
-  with a velocity of nearly thirty-one miles an hour. The Count
-  could easily have arisen and escaped the fury of the blast,
-  but it was his purpose not to avoid obstacles, but to court
-  them. Whenever the great air ship showed signs of swerving, it
-  was brought back to its course. Far below us in the valley the
-  sharply marked shadow of the air ship, crawling slowly from
-  tree to tree, showed us how hard it was struggling. There were
-  minutes when it seemed as if we stood stock still, despite the
-  infernal music of the propellers. Gradually the nose of the
-  craft was thrust forward; once more the air ship mastered the
-  winds. We had forced our way through the pass, and were dashing
-  on at full speed. The vast shadow below us traveled with the
-  velocity of a bird over the mountain, valleys, cliffs and rocky
-  points, over railway embankments and road, over water and land.”
-
-Two attempts were made in July, 1908, to complete the government test;
-but they proved abortive, and in the second one the hull was damaged by
-the wind pushing it sidewise against the shed, as it was being towed
-out by motor boat. This accident caused a delay of two weeks, much
-to the disappointment of the expectant populace. As a consequence
-Zeppelin resolved to begin the next attempt unheralded. He had the
-repairs made quickly and all was ready early in August.
-
-On Tuesday, August 4th, at six forty-five in the morning, the great
-twenty-four hour test for the government began, without previous
-announcement, but with fairest prospect of success. Sailing from
-Friedrichshafen, Zeppelin purposed to follow the Rhine as far down
-as Mayence, then return in a direct line to his starting point. All
-went splendidly at first. He passed Constance at seven o’clock in
-the morning, Basle at nine-thirty, Strassburg about noon, then with
-slower speed passed Mannheim at two-fifty and Darmstadt at four-thirty.
-At about six o’clock a descent was made at Oppenheim, eleven and a
-quarter hours after starting. The air ship had voyaged 270 miles at the
-average speed of 22 miles an hour. A wonderful demonstration it was
-for the inhabitants of that historic valley, and a glorious tour for
-the brave old sailor and his crew. Resuming the voyage, Mayence, the
-turning point, was reached at eleven o’clock at night, and the vessel
-was headed for home. But now the engines, being overworked, could
-not maintain the usual speed, which therefore was lowered to twelve
-miles an hour. Next morning at eight o’clock, after Stuttgart had been
-passed, a descent had to be made at the village of Echterdingen, to
-adjust and overhaul the machinery. Ninety-five miles of the return had
-been made in nine hours.
-
-It was most unfortunate that a landing had to be made without a harbor,
-particularly as a gale was in pursuit of the vessel. Ere long she was
-torn from her moorings by a squall, carried into the air, and set on
-fire, probably by an electric discharge. Immediately the great hull was
-enveloped in flame and completely destroyed, leaving a tangled network
-of distorted framing. It was a dismal termination to the greatest motor
-balloon voyage in the world’s history up to that date; for the vessel
-had been in the air continuously for twenty and three-fourths hours and
-had traveled 378 miles.
-
-The hardy and venerable hero of so many voyages and long continued
-experiments quite broke down at the sight of his grandest vessel in
-ruin. But an unlooked for and a sudden turn of events brought him the
-greatest triumph in his darkest hour. While the world expressed its
-grief and sympathy his loyal countrymen hastened to his relief in an
-admirable burst of enthusiasm. Within twenty-four hours the government
-had made him a grant of $125,000, and subscriptions offered in all
-parts of Germany brought the sum to over $500,000. By October, 1908,
-the total gift amounted to $1,500,000, which was paid to the Zeppelin
-Air Ship Company, formed for developing and building air ships on a
-large scale. A tract of 300 acres was secured at Friedrichshafen for
-an air ship factory. Here was erected the necessary shops, hydrogen
-plant, balloon harbor, and everything necessary to enable the company
-to construct several mammoth air ships each year. To these new grounds
-the Count’s former interests were gradually conveyed, while his old
-station, with its air ship dock on Lake Constance, was converted into a
-military post by the German government.
-
-After the destruction of _Zeppelin IV_, its predecessor, the Count’s
-third air ship, was again prepared for service and for new triumphs.
-Her hull was lengthened by the addition of a cylindrical section having
-the length of one compartment, or about 26 feet. This alteration gave
-a considerable increase of net buoyancy with but slight increase of
-resistance. The dimensions now were: length 446 feet, diameter 38
-feet, volume 423,768 cubic feet. The gas was contained in sixteen
-sacs, twelve in the cylindrical part and two at each end. The ship
-was propelled by two 85-horse-power engines, supplied with sufficient
-gasoline for a forty-one hour voyage at 25 miles per hour. The loss of
-gas by leakage was less by weight than the loss of fuel. The famous old
-cruiser, thus remodeled, was operated in the autumn of 1908 with her
-usual precision and grace; thus winning new distinction and renown. On
-one occasion she had as passengers the Crown Prince and the Kaiser’s
-brother, Prince Henry. The Emperor himself witnessed the demonstration,
-and decorated the Count, referring to him as “the greatest German of
-the century.” Soon afterward the ship was taken over by the government
-and assigned to the Prussian Battalion of Aëronauts, being christened
-_Zeppelin I_, since it was the first vessel of the kind taken into the
-military service.
-
-Beginning with March 9, 1909, the military _Zeppelin I_ was kept in
-active operation by the officers, and subjected to a wide variety of
-tests day by day. She was driven through rain and snowstorms, at all
-elevations up to a mile; she was anchored over land and over water,
-sometimes exposed for hours to a gale; she was steered in and out of
-her shed without the aid of her floating raft; she was sent on long
-trips, landed in the open country, by day and by night, and returned to
-harbor in safety. On one occasion she carried twenty-six passengers for
-over an hour and a half; again she made an endurance flight of thirteen
-hours. These maneuvers exhibited for the first time many capabilities
-of the ship, which all along had been stoutly affirmed by the inventor,
-but questioned by his critics.
-
-On April 1, 1909, at four o’clock in the morning, the renowned
-_Zeppelin I_, with the Count as helmsman, started through the rain
-and wind on a voyage from Friedrichshafen to Munich, a hundred miles
-distant. The ship followed the railway as far as Ulm, guided by the
-station lights, which were kept burning all night to mark the route. As
-she approached Munich, at the appointed hour of nine next morning, her
-approach was announced from afar by the droning of her machinery and
-propellers, whereupon she was welcomed by loud music from many bands
-and the joyous ringing of all the bells in the city. The Prince Regent
-of Bavaria and a great throng of applauding citizens awaited her at the
-Teresenhohe park. Presently the swift cruiser approached, sailing over
-the steeple tops like a monstrous arrow. She halted before the Regent
-and dipped her bow three times, in graceful salute. Then she circled
-widely over the city, intending to land at the Oberwiesenfeld Parade
-Grounds, where part of the garrison troops were drawn up to receive
-her. But now, while so near the goal, she found it difficult to stem
-the increasing gale, and unsafe to land; so, with her bow pointed to
-the city, and propellers humming furiously, she gradually yielded to
-the storm, and drifted slowly backward toward the northeast.
-
-The crucial hour had come for this stanch vessel and her audacious
-captain. They wrestled with the storm bravely and obstinately, but
-were beaten back steadily, with no port in view. The Count determined
-to weather the gale till it should spend its fury. He coolly sent an
-aërogram to Munich, saying that all was well and that he might reach
-the city late in the day. Observing a suitable place to land, near
-the village of Loiching, he pointed the prow of his ship downward,
-approached the earth and cast anchor. As the front car touched the
-ground it was grasped by the willing hands of thronging peasants and
-villagers. Presently the ship was taken in charge by a military
-relief party which the Count had hailed on the way, at Guendelkoven,
-and which had hastened to his aid in automobiles. Fifty soldiers, in
-regular shifts, that night held the bow of the vessel by a short leash.
-The anchor was firmly fastened, and additional ropes secured the bow
-to an unwheeled wagon loaded with stones. Thus all night long that
-mighty hull swayed to and fro in the passing storm, securely as a ship
-anchored at sea.
-
-PLATE XI.
-
-[Illustration: ZEPPELIN DIRIGIBLE RESTING ON THE WATER.
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: ZEPPELIN DIRIGIBLE OVER ZÜRICH.
-
-_Photo E. Levick, N. Y._]
-
-Next morning the vessel was well replenished and headed for home, by
-way of Munich. The return was easy, for the wind had nearly reversed
-its course. Sailing at 32 miles an hour, with a quartering current,
-the stormbeaten ship soon reached Munich, where she was hailed with
-boundless enthusiasm. The Prince Regent entertained the Count during
-his sojourn of three hours, and decorated him with a gold medal. The
-ship then sailed for Friedrichshafen, with the full speed of the wind
-and of her propellers, at one time attaining 68 miles an hour. At
-nightfall she landed gently on the lake near Manzell, having weathered
-that tempestuous voyage without serious mishap.
-
-This was a splendid proof of her stanchness; but a few days later
-she was put through other tests quite as severe, one being a night
-voyage of thirteen and a third hours, after a day of busy maneuvering.
-Following this came her still longer voyage, to Metz, where she was
-stationed as a frontier war vessel, and one of a considerable fleet
-contemplated by the German government.
-
-In the meantime the energetic Count had started his fifth vessel, or
-military _Zeppelin II_, which now was nearing completion at the works
-of the Zeppelin Air Ship Construction Company. Her hull measured 446
-feet in length, had a diameter of 42½ feet, and a volume of over
-half a million cubic feet. It also had a ladder running through one
-of the compartments to a platform on its top. Her motors of 220 horse
-power were taken uninjured from the wreck of the old _Zeppelin IV_ at
-Echterdingen.
-
-Without previous notice this new air ship set forth in a rain on the
-evening of May 29, 1909, headed toward Berlin, having on board the
-Count and seven other men. The purpose of the voyage was merely to
-exercise the ship; not to reach any definite goal; but by mistake she
-was reported on her way to Berlin, so that the Kaiser and his retinue
-waited some hours in vain to receive her. She voyaged bravely past
-Nuremberg and Leipsic to Bitterfeld, within 85 miles of the capital;
-then turned for home, the Count being unaware of the hopes he was
-disappointing. She returned successfully past Weimar and Stuttgart,
-then, near Goeppingen, descended on an open plain to take on gasoline
-from a neighboring petroleum refinery. As they were nearing the ground
-in a heavy rain, Count Zeppelin, who was acting as pilot, suddenly
-beheld, just before them, a half dead pear tree, with gaunt bare limbs.
-He gave a sharp order to starboard the helm; but his aëronaut, worn by
-too long service, thrust the helm to port, and the ship, impelled by a
-sudden gust, plunged head on against the tree. Her prow was wrecked,
-the frame and envelope being wrenched and torn for a distance of 100
-feet.
-
-The disaster seemed complete, but the dauntless Count was equal to the
-emergency. Twenty workmen were summoned from Friedrichshafen, sixty
-miles away, and sped to the rescue in automobiles. Electric wires from
-a nearby plant were stretched to furnish light for night repairs. The
-grounds were guarded by police and troops. The hull was detached from
-the tree; furnished with a temporary prow of young firs covered with
-balloon cloth; relieved of the forward motors and other impedimenta;
-furnished with fresh supplies; and, in exactly 28 hours from the
-mishap, was ready for the homeward voyage.
-
-Slowly the crippled air ship sailed for Friedrichshafen, followed by
-the white-haired inventor in an automobile, unmoved and triumphant.
-A mighty shout ascended from the immense crowd of witnesses who had
-assembled from many quarters. All Germany was elated and jubilant. The
-great voyage and the prompt recovery from apparent disaster were a
-triumph of the whole people, for they had helped their hero to build
-this ship, and now participated in his victory over the spite of
-fortune and the elements. The Emperor telegraphed his congratulations,
-affirming his renewed confidence in the rigid system. Without further
-difficulty the vessel reached her port at an easy gait of ten miles an
-hour, thus completing a memorable voyage of seven hundred miles—one of
-the most glorious in the history of aëronautics.
-
-If the citizens of Berlin were disappointed on this occasion,
-they had not long to wait for an aërial visit from the wizard of
-Friedrichshafen. On August 27th, at 4.45 A.M., his crew of five men
-sailed for Berlin via Nuremberg and Leipsic in his sixth air ship,
-his latest and largest, hurriedly finished for the Berlin voyage.
-It cubed 533,000 feet, and was driven by two Daimler engines of 150
-nominal horse power each. In the afternoon they reached Nuremberg,
-circled over the city and landed for the night. Starting at 2.15 next
-morning they battled their way toward Leipsic against a strong wind,
-and at 6.45 P.M. landed for the night at Bitterfeld, where they arrived
-with a broken propeller. Here Count Zeppelin joined them. The next
-morning, after a good night’s rest and some repairs, they started at
-half past seven, in a dense fog, which, however, soon cleared. Finally
-they arrived at Berlin at half past twelve o’clock, as the people were
-returning from church. They circled over the city, to the delight of
-the multitude of spectators who thronged the house tops, parks, and
-thoroughfares, finally reaching the parade ground at Tegel. Here,
-after saluting the Emperor, the happy navigator maneuvered before the
-imperial tribune, greeted by the thunderous Hoch! Hoch! of a hundred
-thousand throats, and the ringing of all the church bells of the
-nation’s capital. The venerable Count was graciously received by the
-Emperor and members of the royal family. After spending the day at
-Berlin, the crew sailed for Friedrichshafen, about midnight, where,
-after various accidents and delays, they arrived in safety on September
-6th.
-
-In some respects this was Von Zeppelin’s crowning voyage of the year,
-though effected with a hurriedly finished vessel, not yet thoroughly
-adjusted. In mechanical execution this journey was equaled on many
-other occasions; for those great air ships were kept in active service
-and were everywhere hailed with enthusiasm. Both the Emperor and his
-people were proud to number those grand cruisers among the nation’s
-aërial warships. With general commendation, therefore, was received
-the announcement that four large _Zeppelins_ were ordered for the use
-of the German navy. And not surprising was the announcement that other
-inventors were at work on designs for dirigibles of the rigid type.
-The projects of these new rivals, who began to appear in 1909, are set
-forth in the following account:[17]
-
-  “Count Zeppelin, who proved that air ships have a practical
-  future, is no longer undisputed ‘king of the air.’ His rivals
-  have taken his pattern, and improved it until soon air ships
-  will be able to keep afloat for many days and in that case to
-  cross oceans. A type of this modern ship is the first Schütte
-  leviathan of wood and steel bracing, now nearly finished at
-  Mannheim. It is expected to lift its twenty-four and one-fifth
-  tons one and a quarter miles, because its beam is sixty feet
-  as compared with the forty-four feet of the _Zeppelin II_.
-  The car is one hundred and thirty feet long, with a cabin to
-  accommodate thirty passengers. The new ship displaces nineteen
-  thousand cubic meters, as against fifteen thousand in the
-  _Zeppelin III_. It is expected to carry a cargo of five to six
-  tons supported by ten spherical sustaining chambers, and eight
-  ring-shape reservoir chambers connected by a secret apparatus.
-  These eight reservoirs automatically receive all expanding gas
-  that escapes from the sustaining chambers, thus conserving the
-  entire supporting power. Four motors of combined five hundred
-  and forty horse power will drive the propellers. Expert opinion
-  predicts a speed of thirty-seven to forty-three miles an hour,
-  three miles faster than the _Gross III_, at this writing the
-  fastest air ship in the world. The whole enterprise is backed
-  by Mr. Lanz, a rich manufacturer, who is president of the
-  German Air-Navy League. A wooden-braced ship of equal equipment
-  and size, designed by the Engineer Rettich, is well under way.
-
-  “Another rival of the _Zeppelin_, so far only projected, has
-  been designed by the Engineers Radinger and Wagner, and is
-  intended to be an advance in endurance. It should float for
-  fifty days without replenishing gas. It is planned to have a
-  rigid hull of hollow paper tubes and steel bracing and to be
-  thirty per cent lighter than a _Zeppelin_ built of aluminum,
-  in any equal size. Drum-shape compartments are to hold the
-  sustaining hydrogen, none of which is to be lost through
-  expansion by the sun, as any surplus will be compressed by
-  automatic pumps into the hollow tubes.[18] Having six thousand
-  meters less displacement than the _Zeppelin III_, it will carry
-  a reserve of seven hundred cubic meters of gas. Thirty-two
-  per cent of its weight-carrying capacity will be given up to
-  passengers, fuel, and baggage. Engines of two hundred and
-  forty-two combined horse power are expected to develop a speed
-  of forty to fifty miles an hour. Larger craft of the same type
-  would, of course, carry much heavier cargoes and have higher
-  speed. This type of ship, soon to be placed in the construction
-  cradle, is expected to cross the ocean easily with fifteen
-  passengers.”
-
-In keeping with the lively growth of these great ships was the
-formation of the German aërial transportation company, with a capital
-stock of $750,000, reported in _l’Aérophile_ for December, 1909. A line
-of large _Zeppelins_ was to connect Baden-Baden, Mannheim, Munich,
-Leipsic, Cologne, Düsseldorf, Berlin, Dresden, Essen and Frankfort.
-The first two auto balloons of this line were to be the _Zeppelin
-IV_ and _Zeppelin V_, to be put in commission in the spring of 1910.
-The _Zeppelin IV_ was to cube 706,000 cubic feet, and carry twenty
-passengers in three cars, each containing a motor. The _Zeppelin V_ was
-to be constructed of a remarkably light rigid alloy “electrometal,”
-and was to carry at least thirty passengers. This enterprise certainly
-formed an appropriate termination to the first decade of practical auto
-ballooning.
-
-The projected passenger line of the German Air Ship Society was
-inaugurated the following summer with serene audacity and fairy-like
-magnificence. The first ship employed, _Zeppelin VII_, was a huge
-vessel of unusual power, speed and elegance of appointment. She was
-485 feet long by 46 in diameter, cubed 690,000 feet, and carried three
-engines totaling 420 horse power and competent to drive her 35 miles
-per hour. Midway beneath her hull and rigidly joined to it, was a
-passenger car thirty-five feet long, having a vestibule at one end, a
-lavatory at the other, and five compartments between them, with seats
-for twenty persons. Beyond the ends of the car were open decks leading
-to the boats fore and aft containing the machinery.
-
-At three o’clock on the morning of June 22, 1910, with Count Zeppelin
-in charge, and a dozen passengers aboard, this majestic auto balloon
-sailed from Friedrichshafen up the Rhine Valley for Düsseldorf, three
-hundred miles, and after a prosperous voyage of nine hours, made an
-easy landing. Next morning at eight thirty she voyaged from Düsseldorf
-to Dortmund, thirty-seven miles north, sailing at a general height of
-one thousand feet, over some of the finest industrial parts of Germany.
-Then she returned to Düsseldorf with her delighted passengers who were
-all enthusiasm for the new mode of travel so auspiciously begun. Of the
-thirty-two persons aboard, the majority were regular public passengers
-who had paid fifty dollars each for the trip, several of them tourists
-from various countries, and ten of them women.
-
-The maiden voyage of this first air liner was a marvel and dream
-of delight to the fortunate few traveling in such celestial style.
-The comforts and splendors of the service quite surpassed their
-expectations. Seated in that fairy car of aluminum framing lined with
-mahogany and rosewood inlaid with pearl, they looked from spacious
-windows over the beautiful German landscape gliding beneath them, and
-enjoyed visions fit for itinerating gods. Along the shining waters of
-the Rhine, and over its castellated crags, and among its rolling hills
-terraced with luxuriant vineyards, now lapped in the glory of summer,
-and above stately cities murmuring with multitudinous life, they sailed
-in serenest comfort and security, marveling at their own strange
-career through the sky, and equally regarded with wonder by all the
-inhabitants below, not to say written and read about by millions in all
-parts of the civilized world. The delights of land and sea travel were
-happily mingled, without their inconvenience. Neither dust nor smoke
-was here, nor rattle of iron rails, nor lurching and rolling from heavy
-seas. Quite otherwise. The senses were charmed with the fanning of
-fragrant winds forever and uniformly blowing, with the melodious drone
-of the swift propeller wheels, with the green glories of the earth and
-purple splendors of the sky. When the tourist was sated with these he
-could turn to his book; when tired of his chair he could stroll to and
-fro in the car on a soft carpet, or along the trellised deck beyond;
-when his appetite called, he could answer with the choicest food and
-wine; for every convenience of an ample buffet was available. It was
-all so enchanting if only practical.
-
-Encouraged by these trials the company announced, and hoped to make,
-voyages at frequent intervals. But in this they promptly encountered
-difficulties. On June 28th the _Deutschland_ started from Düsseldorf on
-a four-hour cruise, with nearly a score of passengers, mostly newspaper
-representatives. But she remained in the air longer than intended.
-Passing Solingen she tried to reach Eberfeld, but ineffectually; nor
-could she find a landing place. Toward five o’clock she was caught in
-a great rising wind and carried one mile aloft like a passive balloon
-in a vortex or thunderhead. Here much gas was lost by expansion, and
-presently, as the ship emerged from a snow cloud in the upper vortex,
-with cooled gas and hull laden with precipitation, she descended at a
-terrible velocity. With crippled motive power, the vessel could not be
-supported dynamically by the impact of the air against her sustaining
-planes and against her canted hull, for lack of forward speed. At
-length with a terrific crash she struck upon the forest of Teutoberg,
-80 miles from Dusseldorf, a great tree trunk piercing the rear boat and
-projecting among the terrified crew. Here the vessel lodged with her
-stern and controlling gear badly wrecked, and here she was abandoned
-by the passengers, with her huge hull resting on the branches forty
-feet from earth. Ere long she was retrieved by a company of infantry
-who sawed down the trees, dismantled the ship, and returned the parts
-on railway trucks to Friedrichshafen, to be used in building another
-vessel.
-
-Thus in both civil and military aëronautics the pioneers had to endure
-many losses and grievous hardships; but the direst disasters often mark
-the way to the greatest victories.
-
-
-
-
-                                PART II
-
-                          GROWTH OF AVIATION
-
-
-
-
-                              CHAPTER VII
-
-                         MODEL FLYING MACHINES
-
-
-From time immemorial man has admired the aërial evolutions of
-wing-gifted creatures, and aspired to imitate them. But which
-evolutions should he attempt first? Which if any are practicable for
-the ponderous lord of creation? The question is still pertinent.
-
-Nature in her bounty bewilders us with wondrous models. All about
-and overhead, with exquisite art, they challenge us to float or fly.
-Before the flower-bell drifts the ruby-throat, his long bill in the
-honey-hearted bloom; now bulletlike he leaps through boundless space.
-Why not adopt that style of locomotion? Call your rainbow equipage to
-the door, and take the family forth in purple state, to the music of
-melodious wheels.
-
-If the humming bird will not serve, look above you. There rides
-the dark-winged master of aërial motion, throned like a god on the
-impetuous wind. Mark his majestic sweep as all day long, with unbeating
-pinion, he scours the wide plain and rugged regions of the hills,
-unwearied, reposeful, deliberate; now skimming the fragrant forest, or
-meadow; now scaling the precipice, or swinging above the abyss; now
-soaring cloudward beyond the range of human vision. There is a model
-for the ambitious and the brave!
-
-Or turn to mid ocean when the hurricane, shearing the tops of the
-arched billows, scatters them in foam and spray over the watery chaos,
-and the big ship strains in the storm. See the long-winged albatross,
-white vision of joy in the darkness, careering all playfully round
-the imperiled vessel, and above the monstrous waves; wheeling in glad
-curves, frolicking in the face of the tempest, riding, without toil or
-trepidation, the rudest[19] winds a thousand miles over the sea. What a
-jocund pace for man!
-
-Of all the charming modes of flight now possible to us it is certain
-that our ancestors could copy but one with any hope of success. Minus
-motive power they could not imitate the direct flight of the homing
-pigeon, much less the mid-air pause of the bumblebee floating round a
-daisy. Hence there remained to them only passive flight on nonvibrant
-wings. The gliding of vultures, of gulls, and of certain quadrupeds and
-fishes, they could imitate with profit; but when they essayed power
-flight they invariably and egregiously failed.
-
-The art of aviation presents two main groups of fliers. The first
-comprises the various man kites, parachutes, gliding machines, soaring
-machines. These may be called passive flyers, because they carry no
-motive power, but ride passively on the air by the force of gravity or
-a towline.
-
-The second group comprises the bird-like flap-wing machines, called
-orthopters by technical people; the screw-lift flyers, called
-helicopters; the aëroplanes, also called monoplanes, biplanes,
-triplanes, according to the number of superposed main lifting surfaces;
-and lastly the gyroplanes, whose sustaining surfaces may turn over and
-over, like a falling lath, or whirl round and round, like a boomerang.
-These all may be called dynamic, or power, flyers. The technical
-names, however, are not so important, as they are numerous; for the
-whole aëronautic nomenclature is in a formative, not to say chaotic,
-state. We may, therefore, like Adam, name the creatures as they pass
-before us for review or discussion.
-
-Disregarding the crude essays at human flight, recorded in the early
-literature and history of many peoples, we may notice first the well
-authenticated sketches of Leonardo da Vinci. His fertile mind conceived
-three distinct devices for carrying a man in the air. But he and his
-successors for nearly four centuries could do little more than invent.
-For lack of motive power they could not navigate dynamic flyers,
-however ingeniously contrived.
-
-[Illustration: FIG. 26.—DA VINCI’S HELICOPTER.]
-
-Da Vinci’s first design, as shown in Fig. 26, provides the operator
-with two wings to be actuated by the power of both arms and legs,
-through the agency of very ingenious harness. With this device
-an acrobat could fly forward and downward, to the delectation of
-a multitude; but he would have to be caught on something soft to
-escape injury. Since Leonardo’s day the experiment has been tried
-occasionally, with varied results, sometimes grotesque, sometimes
-tragic. He doubtless realized the impracticability of an orthopter
-actuated by human muscle, and yet he has had many followers. The
-orthopter is still a favorite device cultivated by a few persons who
-propose to work its wings by means of a gasoline motor. Doubtless the
-feat is physically possible, and may be accomplished in time.
-
-[Illustration: FIG. 27.—DA VINCI’S PARACHUTE.]
-
-Da Vinci’s second flyer was a helicopter, as shown in Fig. 26. An
-aërial screw 96 feet in diameter was to be turned by a strong and
-nimble artist who might, by prodigious effort, lift himself for a short
-time. Though various small paper screws were made to ascend in the air,
-the larger enterprise was never seriously undertaken. Many subsequent
-inventors developed the same project; but the fellow turning the screw
-always found it dreadful toil and a hopelessly futile task. Of late
-the man-driven helicopter has been abandoned, but the motor-driven one
-is very much cultivated. Scores of inventors in recent years, aided by
-light motors, have been trying to screw boldly skyward, and some have
-succeeded in rising on a helicopter carrying one man.
-
-Da Vinci’s third scheme for human flight, as shown in Fig. 27, was a
-framed sail on which a man could ride downward, if not upward. This
-device never fails to navigate with its confiding sailor. Sometimes
-he lands in one posture, again in another; but voyage he must, with
-the certainty of gravitation. Leonardo is, therefore, the father
-of the parachute. This, in turn, has had a varied offspring. The
-common parachute, the aërial glider, the soaring machine, or passive
-aëroplane, that rides the wind without motive power and without loss of
-energy.
-
-The foregoing sketches by the great artist were made toward the year
-1500, and there the science stood for nearly three centuries. Much
-speculation followed, but no substantial progress. Mathematicians
-proved by figures the inadequacy of the human muscle to achieve human
-flight. Dreamers demonstrated the same by launching themselves from
-high places, and breaking their bones on the unfeeling earth, before
-unpitying crowds. Finally came the balloon, giving a new impetus to an
-embryo art.
-
-The earliest of Da Vinci’s aëronautic ideas to be practically realized
-was the parachute. The exact date of its first employment is not
-exactly known. In the year 1617 Fauste Veranzio published in Venice
-a good technical description of the construction and operation of
-the parachute, accompanied by a clear illustration, as shown in
-Fig. 28. But the first authentic account of a parachute descent of
-a human being is that given by Sebastien Lenormand. This dauntless
-inventor, on December 26, 1783, descended from the tower of the
-Montpelier Observatory, holding in either hand an umbrella sixty inches
-in diameter. A few days later he sent to the Academy of Lyons the
-following description of his improved parachute, illustrated in Fig. 29:
-
-  “I make a circle 14 feet in diameter with a heavy cord; I
-  attach firmly all around, a cone of linen whose height is 6
-  feet; I double this cone with paper laid on the linen to render
-  it impermeable to air; or better, instead of linen, taffeta
-  covered with gum elastic. I place all about the cone small
-  cords, which are attached below to a wicker frame, and forming
-  with this frame an inverse truncated cone. Upon this frame I
-  place myself. By this means I avoid the ribs and handle of
-  the umbrella, which would add considerable weight. I am sure
-  to risk so little that I offer to make the experiment myself,
-  after once having tried the parachute with different weights to
-  make sure of its solidity.”
-
-[Illustration: FIG. 28.—VERANZIO’S PARACHUTE.]
-
-Previous to Lenormand’s experiments, Blanchard, the aëronaut, had
-dropped small parachutes from his balloon, sometimes carrying animals,
-but never a human being. For unaccountable reasons the world had to
-wait fourteen years longer to see a man make the new familiar parachute
-descent from a balloon. On October 22, 1797, in presence of a large
-crowd Jacques Garnerin ascended in a closed parachute to a height of
-3,000 feet, then cut loose. The people were astonished and appalled;
-but they soon saw the umbrella-shaped canvas spread open and oscillate
-in the sky with its human freight. As it was but eight yards in
-diameter, it descended rapidly and struck the ground with violence,
-throwing Garnerin from his seat. He escaped with a bruised foot,
-mounted a horse, and returned to the starting point, where he received
-a lively ovation.
-
-[Illustration: FIG. 29.—LENORMAND’S PARACHUTE, 1784.]
-
-After this experiment, parachute descents became popular the world
-over, and have been repeated up to the present time substantially
-without change. A slight improvement in the construction was made by
-cutting away the top of the canvas, thus allowing the air to escape
-sufficiently to check the oscillations; but no radical change in
-the design has come into general use. It would seem easy to have
-transformed the craft into a traveling parachute gliding down the sky
-like a great bird on out-stretched wings. Such a device would enable
-the aëronaut to sail some miles and direct his course in the air. If
-fair skill had been acquired it might have hastened the advent of human
-flight twenty years, so far as it is practicable without the aid of
-the internal combustion motor. For two decades ago Maxim produced an
-abundantly powerful steam engine; but could find no one to furnish him
-a manageable glider on which to mount it. Now, indeed, such gliders are
-available; but they were developed by aviators, not by balloonists, or
-parachutists, who should have effected that advance many years ago.
-
-Curiously enough, Nature has furnished a traveling parachute which
-seems never to have been imitated by man, though not difficult to
-copy. It is a large two-winged seed, which when dropped in any poise,
-immediately rights itself, and glides gracefully through the air. The
-seeds grow on a tree in India, bearing the name _Zanonia Macrocarpa_,
-and when shaken from its branches look like so many sparrows sailing
-earthward in wide curves. Artificial gliders of this type are easy to
-construct, and would make interesting toys. However, if man has not
-copied such natural models, he has done much better, by making his
-gliders concave below instead of concave upward, as are the beautiful
-Indian seeds.
-
-An interesting model of a traveling parachute, quite as efficient as
-the gauzy-winged seed, is shown in the accompanying figure. It is a
-sheet of paper twenty inches long by four inches wide, having a quarter
-inch strip of tin folded in its forward margin, and having its rear
-margin turned upward slightly, to steer the little craft from a too
-steep descent. In order to improve the stability of the paper plane,
-its sides may be bent upward. The model when dropped in any attitude
-quickly rights itself, and sails down a gently sloping course, the rear
-margin functioning as a rudder or tail.
-
-[Illustration: FIG. 30.—PAPER TRAVELING PARACHUTE.]
-
-One of the earliest trustworthy and scientific accounts of
-experimentation with an aërial glider was given by Sir George Cayley in
-_Nicholson’s Journal_, in 1809 and 1810. After a careful study of the
-principles of stability, he, in 1808, constructed a glider spreading
-300 square feet of surface and weighing with its load 140 pounds. It
-had wing surfaces slightly inclined to each other, and a tail inclined
-enough to determine a gentle downward course. “When any persons,” says
-Cayley, “ran forward in it with his full speed, taking advantage of a
-gentle breeze in front, it would bear him up so strongly as scarcely
-to allow him to touch the ground, and would frequently lift him up and
-carry him several yards together. It was beautiful to see this noble
-white bird sail majestically from a hill to any given point of the
-plain below it, with perfect steadiness and safety, according to the
-set of the rudder, merely by its own weight, descending in an angle of
-about 18° with the horizon.”
-
-Sir George Cayley made a brave start in the science of dynamic
-flight, marshaling to it all the mechanical resources of his day. He
-applied the most reliable data of fluid resistance then available. He
-formulated the laws of equilibrium and control of a flying machine
-quite as well as any of his successors for two generations. He
-estimated the propulsive power required to carry a man, and computed
-the weight of the newly invented Bolton and Watt steam engine capable
-of supplying that power. He even conceived the idea of burning a gas
-or inflammable vapor behind a piston, thus anticipating the modern
-aëronautical motor. But the project as a whole was too formidable at
-that time for the genius of this one man, or of his generation of
-colleagues. Sailing flight they could have practiced with profit to the
-advancement of aviation, but power flight on a practicable scale had to
-await the long evolution of the internal combustion engine.
-
-The next great advancement in the devices and principles of aviation
-was made by another Englishman, and a worthy successor to Sir George
-Cayley. In 1842 Mr. Henson patented the aërial equipage shown in
-the accompanying illustration. It was what in present-day parlance
-is called a monoplane, being in fact the first commercially planned
-aëroplane known to history. As seen at a glance it consisted of a large
-sustaining surface rigidly trussed and driven through the air by two
-propellers actuated by a steam engine. It was to be guided up and down
-by means of a horizontal rudder, and guided to the right and left by
-means of a vertical rudder, seconded by a keel cloth; both rudders
-being at the rear of the large plane. The machine was designed to be
-launched by running down an inclined plane or track. Fuller details
-of this first patent aëroplane are given in the following official
-description in the South Kensington Museum of a model aëroplane
-constructed by Henson and Stringfellow:
-
-  “The model consists of an extended surface, or aëroplane,
-  of oiled silk or canvas, stretched upon a bamboo frame made
-  rigid by trussing both above and below. A car is attached to
-  the underside of the aëroplane to contain the steam engine,
-  passengers, etc. It has three wheels to run freely upon when
-  it reaches earth. Two propellers, three feet in diameter,
-  are shown with their blades set at 45°. They are operated by
-  endless cords from the engine. Behind these is a fan-shaped
-  tail stretched upon a triangular frame capable of being opened
-  out, closed, or moved up and down by means of cords and
-  pulleys. By this latter arrangement ascent or descent was to be
-  accomplished. A rudder for steering sideways is placed under
-  the tail, and above the main aëroplane a sail was to be
-  stretched between two masts rising from the car, to assist in
-  maintaining the course. When in motion the front edge of the
-  machine was to be raised in order to obtain the required air
-  support. To start the model it was proposed to allow it to
-  run down an incline—e.g., the side of a hill, the propellers
-  being first set in motion. The velocity gained in the descent
-  was expected to sustain it in its further progress, the engine
-  overcoming the head resistance when in full flight. Experiments
-  were eventually made on the Downs near Chard, in Somerset, and
-  the night trials were abandoned, as the silk became saturated
-  from a deposit of dew. After many day trials, down wide
-  inclined rails, the model was found to be deficient in stable
-  equilibrium for open-air experiments, little puffs of wind
-  or ground currents being sufficient to destroy the balance.
-  The actual machine was never constructed, but in 1847-48 F.
-  Stringfellow built a model which is supposed to be the first
-  flying machine to perform a successful flight.”
-
-PLATE XII.
-
-[Illustration: HENSON’S AËROPLANE.]
-
-[Illustration: ADER’S AËROPLANE.
-
-_Photo E. Levick, N. Y._]
-
-The creation of Henson’s flying machine at that early period is one
-of the most original and fruitful achievements in the century-long
-development of the modern aëroplane. Barring the torsional wing-tips
-invented more recently, it hardly differs in principle from the
-successful monoplane of to-day. The same mode of propulsion, the same
-mode of sustention, the same mode of launching and lighting, the same
-mode of steering and control. What has been added since is not so much
-original invention as perfection of detail through the combined efforts
-of many designers. After Cayley, Henson, as nearly as any one person
-was the inventor of the flying machine. He did not bring his conception
-to practical maturity, nor was that to be expected; but he did lay
-down the broad lines which have led others to success. His ideas still
-feature every practical aëroplane, and particularly every successful
-monoplane. Indeed, it is now possible to construct an aëroplane from
-Henson’s description that will fly, even in breezy weather, with
-a stability practically as good as that of the early Voisin and
-Antoinette machines before the use of the aileron or torsional wing was
-practiced. It is all a question of wise proportioning and sufficient
-motive power.
-
-So much for Henson’s contrivance as an abstract invention. The
-concrete, full scale machine was to spread 6,000 square feet of
-surface, weigh 3,000 pounds, and be propelled by a high pressure steam
-engine of 25 or 30 horse power. The machine was not completed on a
-large scale, and wisely so; for it was inadequately powered, and,
-moreover, required many refinements of detail to make it entirely
-practical. These improvements had to be left to succeeding inventors
-with accumulated experience and resources.
-
-In 1844 Mr. Henson began the construction of a steam-driven model,
-in partnership with his friend, Mr. Stringfellow, who designed the
-motor for it. They experimented together for some weeks with only
-meager success, but gaining valuable experience. A model of the
-Henson-Stringfellow machine is on exhibition at the South Kensington
-Museum.
-
-In 1846 Stringfellow built a steam model aëroplane about the size of a
-large soaring bird, and weighing all together, with fuel and water, 6½
-pounds. A special feature of this model was that its main surfaces were
-sloped like the wings of a bird, _slightly concave below and feathered
-toward the back_; thus making it more efficient and stable in flight.
-With a good head of steam, and propellers whirling, the model ran down
-a stretched wire, leaped into the air “and darted off in as fair a
-flight as it was possible to make, to a distance of about 40 yards.”
-Thus the first power-driven aëroplane to fly successfully was the
-little steam model constructed by Stringfellow in 1846.
-
-[Illustration: FIG. 31.—WENHAM’S AËROPLANE, 1866.]
-
-In 1866, two decades after the flight of Stringfellow’s monoplane,
-Mr. F. H. Wenham, another Englishman illustrious in the annals of
-aëronautics, patented the multiplane; that is, an aëroplane comprising
-two or more superposed surfaces. This proved to be a valuable
-contribution to the art of aviation, and continues in use at the
-present time. The device furnished an increase of sustaining surface
-without enlargement of the ground plan. It moreover lends itself
-conveniently to a strong and simple trussing of the surfaces. Some
-designers protest that superposed surfaces blanket one another; but the
-advantages just named seem amply to compensate for this objectionable
-feature. If the surfaces be properly spaced, very little interference
-is found; moreover, any blanketing that may occur diminishes the drift
-as well as the lift,[20] though not necessarily in the same proportion.
-
-Wenham’s aëroplane is illustrated in Fig. 31. The rider lies underneath
-the multiple wings, so as to diminish the resistance to progression
-through the air. The apparatus could thus be used as an aërial toboggan
-for coasting down the atmosphere. To prolong the flights two flappers
-actuated by a treadle were to be employed, their ends being hinged at
-a point above the operator’s back. Though the device was patented, no
-very serious efforts were made to operate it practically. Once, indeed,
-the inventor took his glider to a meadow and mounted it, during a lull
-in the evening wind, but soon a gust caught him up, carried him some
-distance from the ground and toppled him over sidewise, breaking some
-of the surfaces. The machine disclosed some good working principles;
-but it was inadequately ruddered, and too feebly constructed, to
-weather the buffets of the prevailing ground currents.
-
-PLATE XIII.
-
-[Illustration: STRINGFELLOW’S AËROPLANE (FRONT).
-
-(Courtesy Smithsonian Institution.)]
-
-[Illustration: STRINGFELLOW’S AËROPLANE (SIDE).
-
-(Courtesy Smithsonian Institution.)]
-
-Adopting the scheme of superposed surfaces then recently devised
-by Wenham, Mr. Stringfellow in 1868 constructed the interesting
-steam-driven model shown in Plate XIII. This consists essentially of
-three superposed planes, rigidly connected by rods and diagonal wires,
-propelled by a pair of screws actuated by a high pressure steam engine,
-and guided by a tail. The three planes aggregated 21 feet in length and
-28 square feet in surface; totaling, with the tail, 36 square feet.
-The engine was rated at one third of one horse power. Its weight is
-not known, but may be roughly surmised from the fact that a separate
-engine exhibited simultaneously by Stringfellow weighed thirteen pounds
-per horse power. The model was entered for competition in the London
-Aëronautical Exhibition of 1868. In actual operation, however, it seems
-not to have excelled the monoplane of 1846; but still it is of much
-interest as being the prototype of the multiple-wing aëroplane now in
-common use. It seems to have been the first aëroplane having two or
-more sustaining surfaces joined by rods and stayed by diagonal cords
-after the manner of a Pratt truss. This historic little model was
-purchased by Professor Langley for the Smithsonian Institution, and
-is now to be seen suspended from the ceiling of the National Museum,
-beside Langley’s own models and Lilienthal’s epoch-making glider.
-
-[Illustration: FIG. 32.—PENAUD’S AËROPLANE TOY, 1871.]
-
-In 1871 M. A. Penaud produced the interesting toy aëroplane shown in
-Fig. 32. The model is propelled horizontally forward by a single screw,
-actuated by twisted rubber, and is fastened, as shown, to the middle of
-a long stick or backbone. The center of mass of the machine is well to
-the front, tending to plunge the model earthward like a heavy-headed
-arrow; but this down-diving is promptly checked by the tiny rudder
-which is so inclined as to counteract the diving proclivity. That is
-to say the rudder dips so as to receive the aërial impact on its upper
-surface; which impact increases with the speed of flight and causes
-the bow to rise, until the weight before the wings just balances the
-impact on the rudder at the rear. The equilibrium is thus automatic, on
-the principle expounded by Sir George Cayley sixty years earlier. This
-quaint little bird when liberated in the Garden of the Tuileries flew
-a distance of 131 feet in eleven seconds, much to the delight of some
-members of the French Society for Aërial Navigation. It may be added
-that Penaud, who was a most promising and clever aëronautical inventor,
-contemplated a twin-screw monoplane large enough to carry two men, but
-died in his early manhood, before the project could be realized.
-
-[Illustration: FIG. 33.—TATIN’S AËROPLANE MODEL, 1879.]
-
-In 1879 M. Victor Tatin made some very promising tests with the model
-shown in Fig. 33, so promising, in fact, as to convince many that human
-flight was even then practicable. This little flyer was a twin-screw
-monoplane mounted on wheels, and actuated by an oscillating compressed
-air engine, the whole machine weighing 3.85 pounds, and supported by a
-silk plane measuring 16 by 75 inches. The central body of the aëroplane
-was a thin steel tube three feet long by four inches in diameter
-containing the compressed air, and weighing only one pound and a half,
-though strong enough to endure a pressure of twenty atmospheres. When
-the model was allowed to run round a board walk 46 feet in diameter,
-tethered to a stake at the center, it quickly acquired a speed of 18
-miles an hour, rose in the air, and flew a distance of fifty feet.
-
-A remarkable deduction from the very careful measurements made with
-this machine was that it carried at the rate of 110 pounds per tow line
-horse power, when flying at an angle of 8 to 10 degrees. Mr. Tatin
-concluded: “These experiments seem to demonstrate that there is no
-impracticability in the construction of a large apparatus for aviation,
-and that perhaps even now such machines could be practically used in
-aërial navigation. Such practical experiments being necessarily very
-costly, I must to my great regret, forego their undertaking, and I
-shall be satisfied if my own labors shall induce others to take up such
-an enterprise.”
-
-Tatin’s faith in the practicability of a large aëroplane was later
-voiced by Mr. Chanute in his valuable book, _Progress in Flying
-Machines_, published in 1894, but now unfortunately out of print.
-Recalling that Maxim had recently produced a large motor weighing
-complete only ten pounds per horse power, he says: “Aviation seems to
-be practicably possible, if only the stability can be secured, and an
-adequate method of alighting be devised.” Since the above quoted facts
-and opinions were published, no competent man well informed in the
-science of aviation has for one moment doubted the feasibility of human
-flight.
-
-[Illustration: FIG. 34.—HARGRAVE’S MODEL SCREW MONOPLANE, 1891.]
-
-In 1891, twelve years after Tatin’s experiment, Lawrence Hargrave, of
-Sydney, Australia, made a similar compressed air monoplane, with a
-single-screw propeller, but without wheels for launching and lighting.
-The model, which is shown in Fig. 34, had a wing-spread of 20 square
-feet, weighed about three pounds, and flew 128 feet in eight seconds.
-The weight carried was at the rate of 90 pounds per horse power, a very
-encouraging result. Two years later he described a small steam engine
-which he had developed, weighing 10.7 pounds per horse power, and
-capable of driving the model about two miles, though he did not use it
-for that purpose, being engrossed with other researches.
-
-One interesting outcome of his numerous experiments was the Hargrave
-Kite, now more familiarly known as the box kite. A good example of
-his kites is the type shown in Fig. 35. This consists of two arched
-biplanes mounted tandem on a backbone, or connecting framework. The
-kite floats steadily, and was thought suitable for the body of a flying
-machine to be driven by an engine and propeller. Thus meteorology is
-indebted to aëronautics for its most useful kite.
-
-[Illustration: FIG. 35.—HARGRAVE’S KITE.]
-
-A very novel and interesting type of aëroplane model was tested by
-Mr. Horatio Phillips in 1893. After careful preliminary experiments
-with various forms of curved “sustainers,” or lifting surfaces, tested
-in a wind tunnel, to determine which were most suitable wing forms,
-he finally constructed the flying apparatus shown in Plate XIV. This
-consisted of a compound aëroplane composed of many superposed narrow
-curved slats, the whole resembling an open Venetian blind. These
-curved blades, or sustainers, measured 12 feet long, 1.5 inches wide,
-2 inches apart, and were held in a frame sharpened to cleave the air
-with slight resistance. The entire aëroplane spread 136 square feet
-of lifting surface, and was mounted on a truck as shown, carrying a
-steam engine and boiler, to actuate a two blade propeller 6 feet in
-diameter. The whole apparatus weighed 330 pounds, to which a dead load
-was usually added, and ran around a circular wooden track 628 feet in
-circumference, being tethered at the center, as in Tatin’s experiment.
-The apparatus readily lifted itself, when running at a speed of 28
-miles an hour, and carried at the rate of 72 pounds per horse power,
-the added load weighing at times nearly one fourth that of the machine
-itself. The ultimate purpose of the experiment was to prepare the
-way for a one-man aëroplane like that shown in the lower part of the
-figure. This latter model actually carried a man across a field in
-1904, but was found defective in longitudinal balance, because perhaps
-of its inadequate horizontal rudder. Apparently Mr. Phillips had in
-1904 a machine capable of well-balanced flight, if he had made the
-rudders large enough, and provided a mechanism for rotating the slats
-at either wing end, so as to control the lateral poise, as proposed by
-the present writer in 1893, for practically that same flier (see page
-229).
-
-Phillips’s aëroplane shows a distinct advance over its predecessors,
-even Wenham’s multiplane, because of the careful curving of the
-sustainers. Tatin’s flat wing machine had, indeed, shown a greater
-efficiency as a whole, but that was likely due to less proportionate
-body resistance. To Phillips we owe the introduction of superposed
-arched surfaces, now so commonly used in mechanical flight. Whether he
-was wise in using so many narrow wings, instead of a few broad ones,
-was a question to be answered by precise measurement.
-
-Prof. S. P. Langley, like Mr. Hargrave, made numerous flying models,
-trying, in turn, the power of twisted rubber, compressed air and
-steam. He constructed scores of gauzy winged contrivances which
-flitted about like huge butterflies or birds, till their mission
-was accomplished—that of illustrating a scientific principle to his
-inquiring mind. One by one they came into existence, enjoyed an
-ephemeral life, and then were consigned to the aëronautical attic of
-the Smithsonian Institution, a storehouse of quaint flying creatures.
-It was a most interesting collection which well merited preservation
-as the “juvenile” creations of an illustrious man. But the first
-experiments of Langley, like the similar ones of Hargrave, were of
-value chiefly as training to the inventor himself; they were not
-important advances in the art of aviation. Such advances were to follow
-the long preliminary training.
-
-PLATE XIV.
-
-[Illustration: PHILLIPS’ TETHERED AËROPLANE.]
-
-[Illustration: PHILLIPS’ AËROPLANE.]
-
-On May 6, 1896, Dr. Langley launched the picturesque steam model,
-which, to his mind, first proved conclusively the practicability of
-mechanical flight. It was the crowning success, and, as he thought
-then, probably the termination of his aëronautic labors. “I have
-brought to a close,” says he, “the portion of the work which seemed
-to be peculiarly mine—the demonstration of the practicability of
-mechanical flight—and for the next stage, which is the commercial
-and practical development of the idea, it is probable that the world
-may look to others. The world, indeed, will be supine if it does not
-realize that a new possibility has come to it, and that the great
-universal highway overhead is now soon to be opened.”
-
-As shown in Plate XV, Langley’s first successful steam flying machine
-is a tandem monoplane[21] with twin screws amidships. It measures
-nearly 13 feet from tip to tip of its wings, about 16 feet along its
-entire length, and weighs with motor and propellers 30 pounds. The
-boiler weighs 5 pounds, the engine 26 ounces, and the power developed
-was between 1 and 1.5 horse power. The model is therefore somewhat
-larger than a large condor, and very much more powerful.
-
-Being too small to carry a pilot, it was launched over water, to
-obviate wreckage on landing. The machine was capable of flying several
-miles continuously, but in the actual test on the Potomac River the
-flight was limited, in order to prevent the model passing beyond
-the shore. The flyer was placed on launching ways on the top of a
-houseboat, hurled rapidly forward by force of a spring, and liberated
-in space, with engine and propellers running at full speed. Its
-subsequent behavior has been graphically described by an eyewitness,
-Dr. Alexander Graham Bell, in the following passage, published in
-_Nature_, May 28, 1896:
-
-  “On the occasion referred to, the aërodrome, at a given signal,
-  started from a platform about 20 feet above the water, and
-  rose at first directly in the face of the wind, moving at all
-  times with remarkable steadiness, and subsequently swung around
-  in large curves of perhaps a hundred yards in diameter, and
-  continuously ascending till its steam was exhausted, when at
-  a lapse of about a minute and a half, and at a height which
-  I judged to be between 80 and 100 feet in the air, the whole
-  ceased turning, and the machine, deprived of the aid of its
-  propellers, to my surprise did not fall, but settled down so
-  softly and gently that it touched the water without the least
-  shock, and was in fact immediately ready for another trial.
-
-  “In the second trial, which followed directly, it repeated in
-  nearly every respect the actions of the first, except that the
-  direction of its course was different. It ascended again in the
-  face of the wind, afterward moving steadily and continually in
-  large curves, accompanied with a rising motion and a lateral
-  advance. Its motion was, in fact, so steady that I think a
-  glass of water on its surface would have remained unspilled.
-  When the steam gave out again it repeated for a second time
-  the experience of the first trial when the steam had ceased,
-  and settled gently and easily down. What height it reached at
-  this trial I can not say, as I was not so favorably placed as
-  in the first, but I had occasion to notice that this time its
-  course took it over a wooded promontory, and I was relieved of
-  some apprehension in seeing that it was already so high as to
-  pass the tree tops by 20 or 30 feet. It reached the water in
-  one minute and thirty-one seconds from the time it started, at
-  a measured distance of over 900 feet from the point at which it
-  rose.
-
-PLATE XV.
-
-[Illustration: LANGLEY’S STEAM MODEL.
-
-(Courtesy Smithsonian Institution.)]
-
-[Illustration: LANGLEY’S GASOLENE MODEL.
-
-(Courtesy Smithsonian Institution.)]
-
-[Illustration: LANGLEY’S TWO SURFACE GASOLENE MODEL.
-
-(Courtesy Smithsonian Institution.)]
-
-  “This, however, was by no means the length of its flight. I
-  estimated from the diameter of the curve described, from the
-  number of turns of the propellers, as given by the automatic
-  counter, after due allowance for slip, and from other measures,
-  that the actual length of flight on each occasion was slightly
-  over 3,000 feet. It is at least safe to say that each exceeded
-  half an English mile.
-
-  “From the time and distance, it will be noticed that the
-  velocity was between 20 and 25 miles an hour, in a course
-  which was constantly taking it ‘up hill.’ I may add that on a
-  previous occasion, I have seen a far higher velocity attained
-  by the same aërodrome when its course was horizontal.
-
-  “I have no desire to enter into detail further than I have
-  done, but I can not but add that it seems to me that no one who
-  was present on this interesting occasion, could have failed to
-  recognize that the practicability of mechanical flight had been
-  demonstrated.”
-
-In passing it may be added that in 1899 this model was again flown
-successfully, having superposed surfaces; for its inventor all along
-recognized the structural advantage of the bridge trussing in biplanes.
-If he preferred the monoplane, or single-tier arrangement, it was
-because the best flights were obtained with such models.
-
-Many persons now thought that Langley would do well to rest on his
-laurels, leaving to others the “commercial and practical development”
-of his ideas. But he had caught the aëronautic fever. Like many another
-poor son of fancy, he was haunted by magnificent dreams. Now, perhaps,
-was stirring in his mind that vision of his childhood when he lay on
-his back in the New England pasture and “watched a hawk soaring far
-up in the blue, and sailing for a long time without any motion of its
-wings, as though it needed no work to sustain it, but was kept up there
-by some miracle.” Mr. Andrew D. White declares that Professor Langley
-was a poet by nature. Whatever the dominant impulse, he followed his
-“aërodrome” like one possessed. It was the all engrossing pursuit of
-the latter years of his life, entailing how much vexation, toil and
-unjust censure!
-
-In 1898 the Board of Ordinance and Fortification, after carefully
-studying the flights of 1896, appropriated $50,000 to enable Professor
-Langley to build a one-man flyer. He first tested a gasoline driven
-aëroplane having one fourth the linear dimensions of the man-carrying
-one. In external appearance this model resembled the steam “aërodrome,”
-described above, but was considerably larger. It spread 66 square feet
-of surface, weighed 58 pounds, and developed 2½ to 3 horse power.
-When ready for the test, August 8, 1903, this beautiful white-winged
-creature was taken to the middle of the Potomac, 40 miles below
-Washington, mounted on the launching ways, swiveled into the eye of
-the wind and shot forth like a stone from a catapult, her engine and
-propellers humming merrily.
-
-The flight must have been very graceful and dignified, for it
-elicited commendation even from the squad of reporters present, men
-who customarily recorded such events with uncontrollable mirth and
-ridicule. Dr. Langley merely remarks: “This was the first time in
-history, so far as I know, that a successful flight of a mechanically
-sustained flying machine was seen in public.” It was also the first
-successful gasoline[22] aëroplane, and the forerunner of the host
-of flyers presently to spring up in all parts of the world. Its
-flight though very brief, owing to a surcharge of gasoline, was so
-satisfactory in all its dynamic features, that it seemed to justify an
-immediate launching of the one-man machine, with which like maneuvers
-were anticipated. As will appear in the sequel this prospect of fair
-sailing was beset with unsuspected shoals.
-
-We have now traced the growth of the aëroplane from its earliest
-conception to the present time, as exemplified by working models. First
-came the parachute of Da Vinci and others, whose sole function was
-to carry a weight softly to earth, with no provision for steadiness
-of motion, or control of direction. Then, in the beginning of the
-nineteenth century, arrived the gliders adjusted for steadiness,
-equilibrium and a predetermined slanting course in the air; beautiful
-passive birds, actuated by gravity, but riderless and awaiting the
-advent of artificial motive power. Then suddenly appeared Mr. Henson’s
-wonderful _project_; a large man-carrying aëroplane, provided with
-a motor, propellers, rudders, wheels for launching and landing—an
-impossible scheme for that day, but destined to be realized in
-the course of two generations. Henson’s idea was doubtless the
-most prolific in the history of aviation. After this followed the
-numerous instructive models, actuated by twisted rubber, steam,
-gasoline, compressed air—economic contrivances for ascertaining the
-secrets of propulsion, equilibrium and control, of the prospective
-man-flyer. These may be said to have demonstrated the practicability
-of man-flight, though many contemporaneous and allied experiments, to
-be noticed presently, all contributed to the triumphs subsequently
-achieved by the race of sanguine, daring and tireless inventors.
-
-[Illustration: FIG. 36.—LAUNOY AND BIENVENU’S HELICOPTER, 1784.]
-
-In this brief outline, the two other main types of flyers, the
-orthopters and helicopters, have been omitted. The orthopters, or wing
-flapping machines, have been very numerous, but have not yet approached
-practical success in use. Though a man-carrying orthopter has not yet
-been produced, an elegant pigeon-like model operated by rubber has been
-made by Pichancourt, which flies and balances nicely. The helicopters,
-or direct-lifting screws, have more than once raised their weight and
-that of the helicoptrist, or navigator. These latter, therefore, seem
-to be of sufficient interest to merit a short historical review.
-
-Leonardo da Vinci, the fertile pioneer in aviation, missed one novel
-device worthy even of his genius. He constructed aërial screws of
-paper, but he did not endow them with motive force. Such an achievement
-was in his power, and would have ranked him with Archytas of Tarentum,
-who 400 B. C. invented the kite, and an artificial dove said to have
-flown, no one knows how. Having escaped Da Vinci’s ingenuity, the power
-helicopter failed to materialize for three centuries, but finally
-appeared in France.
-
-In 1784 Launoy and Bienvenu, the first a naturalist, the second a
-mechanician, exhibited before the French Academy the interesting toy
-shown in Fig. 36. This was the first power-driven helicopter, and is
-said to have lifted itself in the air quite readily. As may be observed
-it consists of two coaxial screws rotating in opposite directions
-actuated by the power of an elastic stick, like a bow. The screws were
-each about one foot in diameter and made of four feathers; one screw
-being fastened to the top of the rotating shaft, the other fastened
-to the bow, which rotated in the contrary direction. The little model
-excited much interest, particularly as its inventors expected to build
-a man-carrying helicopter on the same plan. The larger project was
-obviously without merit; for no combination of springs can maintain
-flight for more than a few seconds even on the most favorable scale.
-
-A more powerful toy helicopter was produced by Mr. Horatio Phillips in
-England in 1842. This was a single aërial screw emitting jets of steam
-which compelled it to spin, on the principle of a lawn sprinkler, or
-a Hero engine. The whole apparatus weighed two pounds, and had screw
-blades inclined 20° to the horizon. The steam was generated by the
-combustion of charcoal, niter and gypsum, as in the fire extinguisher
-previously invented by the same ingenious man. The performance of this
-curious helicopter, is thus described by Mr. Phillips: “All being
-arranged, the steam was up in a few seconds, then the whole apparatus
-spun around like a top, and mounted into the air faster than any
-bird; to what height it ascended I have no means of ascertaining. The
-distance traveled was across two fields, where, after a long search, I
-found the machine minus the wings, which had been torn off from contact
-with the ground.”
-
-“The distance traveled was across two fields.” For vagueness this
-surpasses the poet’s measure—“as far as oxen draw the plow in a day.”
-It would be most interesting to have an exact description of this
-classical experiment, when for the first time a flying machine rose
-in the air propelled by a heat motor. It would be desirable also
-to know the possibilities of such a helicopter, particularly since
-Prof. Cleveland Abbe has proposed to employ a like agent to carry
-meteorological instruments into the higher atmosphere.[23]
-
-[Illustration: FIG. 37.—FORLANINI’S HELICOPTER, 1878.]
-
-A still more ambitious helicopter was that shown in Fig. 37 invented by
-Professor Forlanini, an Italian Civil Engineer, and launched in 1878.
-The lower screw was fastened to the frame of a steam engine, the upper
-screw was attached to the crank shaft. Steam was supplied from the
-globe shown beneath, which was two thirds filled with water, and well
-heated over a separate fire just before an ascension. As the globe was
-merely a reservoir of hot water and steam, carrying neither fuel nor
-furnace, its power waned rapidly. The best flight lasted about twenty
-seconds, attaining a height of 42 feet. The apparatus weighed 77
-pounds, spread 21.5 square feet of screw surface, and lifted about 26.4
-pounds per horse power.
-
-Many other helicopter models have been tried from time to time, with
-various sources of power, without, however, yielding any important
-results beyond those already given. But these were sufficiently
-encouraging. If a large machine could be made to lift as many pounds
-per horse power, it would be easy to build one competent to carry
-a man. That, indeed, has been done on several occasions. Of the
-various inventors who have built man-lifting helicopters M. Cornu and
-M. Bréguet, in France, seem to have been first to attain a measure
-of success. While their machines have raised a passenger directly
-from the ground, they have not yet maneuvered in horizontal flight
-with sufficient speed to be of practical service. However, a few
-helicoptrists in various countries are still industriously at work, and
-hope eventually to rival the aëroplanists in the mastery of flight.
-There will doubtless be room in the sky for both. Perhaps also there
-will be occupation and a mission for both.
-
-
-
-
-                             CHAPTER VIII
-
-                     NINETEENTH CENTURY MAN-FLYERS
-
-
-Having traced the growth of winged models from their earliest beginning
-to the time when they proved the possibility of mechanical flight, we
-may now study the evolution of larger machines, designed to carry human
-beings. Considering first the aëroplane, we may follow the two general
-methods advocated by various inventors for launching a man safely in
-the air, both of which led to success. The first of these may be called
-Henson’s method, the second Lilienthal’s, coupling them with the names
-of their distinguished pioneer exponents. Henson in 1842 proposed
-that the pilot should mount a full-power machine, run along a smooth
-course, and glide into the air without previous experience in the art
-of navigating. Lilienthal recommended careful preliminary training on a
-glider, by which the novice should acquire sufficient skill in parrying
-the wind to qualify him to manage a dynamic machine, under its more
-complex conditions of control. Others, more cautious still, contended
-that automatic equilibrium should be secured before a rider risked his
-bones on the aërial bronco; while still others thought the uncertain
-beast should be tethered to some point in the sky, say a balloon or
-taut wire, or the end of a pole; so that however he bucked, or reared,
-he should not fall over on his rider.
-
-We have noticed in the first chapter some picturesque man-flights,
-usually deplorable or tragic; and always fruitless for lack of
-scientific method in experimentation and report to the world. There can
-be no doubt that such flights were accomplished, mainly, of course,
-by the aid of gravity; but the difficulty is to ascertain the exact
-nature of any given performance, the specifications of the apparatus,
-and the principles of equilibrium and control. Gradually, however, the
-experimenters improved both in the construction of man-carrying devices
-and in the manner of imparting their results to their colleagues, or
-successors; and so the flying enterprise began to assume a progressive
-aspect, attended with that scientific dignity which invests secure
-and continuous advance in any branch of knowledge. Little of value,
-however, can be gleaned from any such flights made prior to the middle
-of the nineteenth century. From that time forward observers and
-inventors made definite and fairly methodical efforts to develop the
-art of gliding and soaring in the air, the first fruit of which was to
-hasten the advent of the modern aëroplane.
-
-A French novelist and aëronautic writer, G. de la Landelle, relates
-an amazing adventure in the art of soaring, which may have some
-foundation in fact, though savoring strongly of fiction. An experienced
-sailor, Captain Le Bris, having observed the albatross soaring without
-wing-beat, determined to imitate the fascinating flight of that
-limber-winged spirit of the sea. To such end he built the bird shown in
-Fig. 38, a ninety-pound albatross, with arched wings fifty feet across
-and articulated to the boat-like body. In this the brave aviator would
-stand upright, turn the wings and tail to maintain his balance, and
-steer grandly through the sky. Placing this long-winged creature across
-a cart driven by a peasant, he stood erect and headed against a breeze;
-the wings set low to prevent lifting till an opportune moment, and the
-bird held down to the car by a rope which the captain could quickly
-release. When the horse was a-trot, and the wind blowing freshly, Le
-Bris raised the front edges of the wings. Thereupon the albatross
-tugged upward, and the mooring rope was slipped, but accidentally
-whipped around the driver’s waist. The horse galloped away with the
-cart; the bird, with the exultant sailor on its back, soared 300 feet
-into the air, and incidentally carried up the peasant, dangling at
-the end of the rope and howling with fright. Noting the distress of
-his passenger, the kindly captain sailed close to earth, so that the
-peasant might disembark and run to his horse, meaning then to hie away
-for a long cruise in the clouds. But with this change of weight the
-vessel seemed not to navigate well; so she was brought skimming to
-land, with no mishap save a slight damage to the advancing wing, which
-broke as it touched the ground.
-
-[Illustration: FIG. 38.—LE BRIS’ AËROPLANE, 1855.]
-
-Having repaired the great bird’s wing, Captain Le Bris next made
-a launching from the arm of a derrick, 30 feet above the ground,
-overlooking a quarry 70 feet deep. The attendant swains stood
-open-mouthed, wondering whether this madman would overleap the clouds,
-or promptly butt out his brains on a jagged rock. When the wind blowing
-from the quarry seemed to float him in perfect poise, he tripped the
-suspension hook, and headed for the precipice on even keel. He was now
-happily launched, and keen for an aërial journey; but after passing
-the brink, he seemed to encounter an eddy which tilted his craft
-forward. The vessel dipped and rose; the captain plied his levers,
-turning now the tail, now the pinions. He crossed safely over the
-invisible breakers, and reached the quiet air of the quarry on level
-wing. But now his forward speed was lost, the great bird sank rapidly
-and crashed upon the rocky bed below. The wary seaman anticipating a
-bump, sprang upward to soften his fall; but a lever rebounding from the
-shock, hit one of his legs and broke it.
-
-Some twelve or thirteen years later, in 1867, Le Bris, aided by a
-public subscription at Brest, built a second albatross, with which
-he made a number of small flights, sometimes riding it himself, and
-sometimes replacing his weight by ballast. On one occasion the loaded
-bird, held by a light line, rose 150 feet and advanced against the
-wind. Suddenly the sailors holding the line observed it slacken, and
-saw with amazement the long-winged creature soar forward 600 feet, as
-stately and serene as its living prototype. Presently encountering a
-sheltered and quiet region of air before some rising ground, it settled
-softly to earth in perfect equipoise. But on a subsequent launching
-from the same favorable ground, the dumb creature pitched forward and
-plunged to the earth where it lay shattered and torn in a hopeless
-tangle. Le Bris looked on the wreck in despair, surveying sadly the
-remains of his once cherished bird; then sat upon the débris a long
-time, his head between his hands, his heart broken, his mind tortured
-with anguish. Impoverished, chagrined, derided, he now must abandon
-the albatross business. Five years later this intrepid sailor of sea
-and air was killed by some ruffians, in 1872, while a constable in his
-native place, and after a period of honorable service to the state in
-the Franco-Prussian War.
-
-The story is more romantic than instructive, for want of exact data.
-To give the experiments their proper value to others, fuller details
-of the mechanism should be furnished, and adequate measurements of the
-speed and direction of the aërial currents. At one time the sailing
-was even, at another, rough, though outwardly the conditions appeared
-the same. Apparently the successful flights occurred when the bird was
-launched to windward from rising ground, that is, when the current had
-an upward slant, to exert a propulsive effort. This species of soaring
-has been observed frequently in nature, and has been imitated both with
-models and with man-carrying gliders. Nevertheless Le Bris’ experiments
-were very remarkable for the time, and, if adequately reported, might
-have proved to be of much interest and value to aëronautical science.
-
-Another Frenchman alert to the glory of aërial motion was L. P.
-Mouillard, the poet-farmer of Algeria. From boyhood he studied the
-birds with unabated interest and pleasure. He would journey miles to
-attend the “morning prayer” of the starlings in the forest of Baba-Ali;
-noting, just before sunrise, how their melodies suddenly hushed, and
-the forest seemed to bound upward, and heaven filled with the music of
-innumerable wings. He would time the shadow of the high bird of passage
-riding the hurricane from continent to continent. He saw the tyrant
-eagle fold his wings in mid air and plunge a thousand feet in ferocious
-swoop after the swift-fleeing duck or rabbit. He loved to watch the
-great tawny vulture on the mountain top shake the dew from his vast
-plumes, straddle the morning wind, and all day long, with never a beat
-of those grand pinions, soar godlike through immensity, the marvel
-and delight of the nether world. When the electric wind of the desert,
-blowing from Central Africa, brought the big scavengers and noble birds
-of prey, he sat on the ground scrutinizing their majestic flight and
-planning to imitate it. He would lie in ambush where the silent-rowing
-owl darted at dusk through the timber, fierce and swift as the eagle;
-a dreadful thing, with its night piercing eyes, its big ears and beak,
-its horrid talons, its sudden shriek startling the forest with ominous
-echoes. No feature escaped him, and least of all an aërodynamic one.
-
-For thirty years he continued these studies. He would bring home
-the birds, lay them on their backs and mark their contour on paper,
-measure their projected area, weigh and compare them. He formulated
-curious conclusions about sailors and rowers, the functions of tail and
-quill feathers, weight and wing-spread, bulk, agglomeration of mass,
-resistance and velocity. He notes that only massive birds soar well,
-the broad-winged ones requiring a moderate wind, the narrow-winged ones
-requiring a gale, and sailing with perfect ease in a tempest; and he
-concludes that man may imitate both types. His book[24] is replete with
-charming anecdotes, observations and quaint theories, interesting alike
-to ornithology and aviation.
-
-But Mouillard did more than theorize; he built soaring machines and
-soared a little. His third and best glider, illustrated in Fig. 39, was
-a tailless monoplane made of curved agave sticks screwed to boards,
-and covered with muslin. The aviator, standing in the open space C,
-harnessed the plane on with straps looped round his legs and shoulders,
-and fastened to the points D D. His forearms, passing under straps,
-rested on the board, enabling him to tilt the whole by shifting his
-weight. In order to vary the dihedral angle between the wings, they
-were hinged together and actuated by rods running from the man’s feet
-to the ends of the boards, hardly as far out as the center of wind
-pressure, thus apparently stressing his legs like a wishbone.
-
-[Illustration: FIG. 39.—MOUILLARD’S AËROPLANE.]
-
-He now sent the home folks away from the farm, buckled on his wings and
-walked along the prairie road waiting for a breeze. The road was raised
-five feet above the plain and bordered by ditches ten feet wide. His
-wings felt light; he ran forward to test their lift, and he thought to
-amuse himself by jumping the ditch. The result is thus expressed in his
-own words:[25]
-
-  “So I took a good run across the road and jumped at the ditch.
-  But, oh, horrors; once across the ditch my feet did not come
-  down to earth; I was gliding on the air, and making vain
-  efforts to land; for my aëroplane had set out on a cruise. I
-  dangled only one foot from the soil, but, do what I would, I
-  could not reach it, and I was skimming along without the power
-  to stop. At last my feet touched the earth; I fell forward
-  on my hands; broke one of my wings, and all was over; but
-  goodness, how frightened I had been! I was saying to myself
-  that if even a light wind-gust occurred, it would toss me up
-  30 to 40 feet into the air, and then surely upset me backward,
-  so that I would fall on my back. This I knew perfectly, for I
-  understood the defects of my machine. I was poor, and I had not
-  been able to provide myself with a more complete aëroplane.
-  All’s well that ends well. I then measured the distance between
-  my toe marks, and found it to be 138 feet.
-
-  “Here is the rationale of the thing. In making my jump I
-  acquired a speed of 11 to 14 miles per hour, and just as I
-  crossed the ditch I must have met a puff of rising wind. It
-  probably was traveling some 8 to 11 miles per hour, and the
-  two speeds added together produced enough pressure to carry my
-  weight.”
-
-He repaired his wing and repeated the test a few days later. A violent
-wind gust came; picked him up from the earth, and whelmed him over. In
-his alarm he allowed his “wish-bone” to spread, and the wings to fold
-up like those of a butterfly at rest, pinching him between them like
-a nut in a nutcracker. One wonders whether the overwheeling vultures
-witnessed this gentleman’s flight with any sense of humor.
-
-After mature reflection, Mouillard concluded that he should give his
-aëroplane a rudder, and flex the wings, in order to insure adequate
-control. But here he halted, being a poor man unskilled in the art
-of construction. He had reached the limit of his endowments. He had
-observed faithfully and described charmingly the wonderful flights
-of various birds; but he must leave to his technical successors the
-pleasure of imitating or excelling those extraordinary maneuvers—leave
-them the pleasure, the sacrifice, the long years of toil and danger,
-accompanied perhaps by indiscriminate applause or derision.
-
-In the meantime another distinguished disciple of the birds was
-energetically at work in Germany. No less ardent than Le Bris, or
-Mouillard, Otto Lilienthal was far better equipped and circumstanced.
-He was a graduate of the Potsdam Technical School, and a student
-for three years in the Berlin Technical Academy. He was engaged in
-practical construction ten years in various machine shops at Berlin.
-After 1880 he operated a flourishing machine factory of his own. From
-boyhood he with his brother Gustavus had carefully studied the flight
-of birds, and had made numerous experiments in aviation. On moonlight
-nights in their little home place of Anclam, in Pomerania, the boys
-would run downhill, flapping their home-made wings, like Dædalus and
-Icarus, but with no other danger than discovery and teasing by their
-neighbors. At Potsdam and Berlin they continued to experiment and to
-construct wings of increasing size and power. Thus Otto Lilienthal
-reached early manhood thoroughly trained by his long courses in the
-technical schools and shops, brimming with well pondered ideas,
-strengthened by continuous observation and experiment, and in financial
-circumstances which permitted him to devote time and money to the
-unremunerative pursuit of aviation. To this may be added that his
-mature years were cast in a time when the allied sciences could aid
-him far more than they had aided his predecessors of the preceding
-generation.
-
-After careful research for the most efficient form of alar surface,
-Lilienthal resolved to imitate the birds. First he would build a pair
-of arched wings, and learn to coast down the atmosphere, balancing
-and steering like a stork in the gusty and treacherous current. He
-would thus acquire the pilot’s skill, and ascertain the towline power
-required to sustain a given weight. Then he would add a suitable
-propelling mechanism, test it cautiously, and acquire the mastery of
-dynamic flight. Incidentally, perhaps, he would learn to ride all over
-creation without motive power; for he was convinced that certain great
-birds soar without muscular effort, and that man could acquire this
-delightful art in favorable weather. To strengthen the plausibility
-of that doctrine, he announced his discovery that the general trend
-of the wind is three and a half degrees upward, a fact inexplicable
-and almost incredible to his illustrious confrère of the Smithsonian
-Institution.[26] Such was Lilienthal’s ample program; more, indeed,
-than he would live to accomplish, though possibly not beyond his power
-of achievement, if he could have lived to enjoy the hale long years of
-his illustrious countryman aëronaut, Count Von Zeppelin.
-
-In the year 1891 Lilienthal made his first series of trials in sailing
-flight. His glider was the bird-shaped apparatus shown in Plate XVI,
-made of willow wood covered with waxed sheeting. It weighed about 40
-pounds, and spread 107 square feet of surface. Taking this in his arms
-he first ran 24 feet along a raised board and jumped off, gliding
-through still air. Then, elevating the board to a height of six feet,
-he repeated the run, jump and glide, always landing very softly. Thus
-he became “king of the air in calm weather,” a title still creditably
-sustained by his numerous successors of the present day; for as yet no
-one “mounts the whirlwind and directs the storm.”
-
-Next he went to some little mounds in a field beyond Werder, and jumped
-from these, gradually lengthening his flights till he attained a range
-of nearly 80 feet. As he was now gliding in light winds, he found it
-necessary to add a vertical rudder, in order to preserve his balance
-easily, and keep his bow toward the direction of the wind. His complete
-apparatus was, therefore, a birdlike affair, with two rigid wings and
-a double tail for steering vertically and horizontally. He found also
-that he could fly longer and alight more softly when the wind was
-blowing—an obvious possibility.
-
-Encouraged by this experience Lilienthal explored the country about
-Berlin for sailing ground where he could make long glides, whatever
-the direction of the wind. Such a region he found near Rathenow, where
-the Rhinow hills, covered with grass and heather, slope gently upward
-from the flat plowland to a height of over 200 feet. This he thought
-an ideal coasting ground; for he felt the aërial currents very smooth,
-and he could always select clear land sloping ten to twenty degrees
-toward the wind. Here in the summer of 1893, with a new and improved
-glider, he made many flights, finally ranging from 200 to 300 yards,
-steering up and down, or to right and left at will; sometimes pausing
-in mid air, and several times returning to the starting point. This was
-more than coasting; for a mere coaster never maintains, nor returns
-to, his original level. It was a fair start at true soaring, the ideal
-locomotion. A glorious sport it was, sailing like an eagle high over
-the landscape and over the heads of the astonished spectators.
-
-The new machine resembled its predecessors in form and maneuver; but
-differed in dimensions. It was a birdlike craft with parabolically
-arched wings and a double tail. It measured 7 meters across, spread
-14 square meters of surface, weighed with the rider 200 pounds, and
-in calm air could sail down a slope of 9°, at a speed of 9 meters
-per second. This was very efficient sailing, the work of gravity
-being hardly two horse power. With the man lying prone, as eventually
-planned, the economy would be still greater.
-
-PLATE XVI.
-
-[Illustration: LILIENTHAL’S MONOPLANE GLIDER.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: LILIENTHAL’S BIPLANE GLIDER.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: PILCHER’S MONOPLANE GLIDER.]
-
-The craft was thought also to possess stability; and this it had, in a
-measure, about those two axes corresponding to the two rudders; but the
-control about the third axis, effected by dangling the legs to right
-or left, was extremely crude and primitive. It was in keeping with his
-adage: “to contrive is nothing; to construct is something; to operate
-is everything.” If he had contrived more intelligently, he would have
-operated more easily, and avoided those wild and dangerous dancings in
-space. A more scientific adage would read: “To design effectually is
-everything, to construct is routine, to operate is play.”
-
-The marvel is that Lilienthal, the observant, the technically trained,
-the practically skilled, should operate for three years, then patent,
-an aërial glider having two rudders, but lacking the third rudder,
-or torsional wing, now so commonly used throughout the world. But
-doubtless he contemplated a device for preserving the lateral balance
-without shifting his weight; for he acknowledged the economic advantage
-of lying prone on the machine, and stated that this might be done after
-some important improvements in the apparatus had been made.
-
-Having executed nearly two thousand flights with his monoplane,
-Lilienthal in 1895 built a two-surface glider. He found this still
-easier to control, and now thought he had sufficiently acquired the
-art of sailing to justify his undertaking the next and more difficult
-art of imitating the rowing flight of birds. He had constructed a
-ninety-pound engine, of two and a half horse power, to actuate the
-wings of his glider; but, before applying this motor, he went to the
-Rhinow Hills for a little further experience in sailing. Previously
-he had remained in the air twelve to fifteen seconds; but he wished to
-exceed this record.
-
-On the 9th of August, 1896, he made a long glide to prove the
-effectiveness of the horizontal rudder, and then wished to undertake
-a second flight of the greatest duration feasible. No intimation had
-he that this sail would prove disastrous. Giving the timepiece to his
-assistant, he set forth on a level course, but suddenly dipped forward
-and plunged headlong to earth through a height of fifty feet. He was
-dragged out from the débris with a broken spine, from which he died the
-following day.
-
-The machine on which the father of aërial gliding made his last flight
-is shown in Plate XVI. Of the hazardous nature of its construction Mr.
-Chanute thus writes: “The two surfaces were kept apart by two struts,
-or vertical posts, with a few guy wires, but the connecting joints were
-weak, and there was nothing like trussing. This eventually cost his
-most useful life. Two weeks before that distressing loss to science,
-Herr Wilhelm Kress, the distinguished and veteran aviator of Vienna,
-witnessed a number of glides by Lilienthal with his double-decked
-apparatus. He noticed that it was much wracked and wabbly, and wrote to
-me after the accident: ‘The connection of the wings and the steering
-arrangement were very bad and unreliable. I warned Herr Lilienthal very
-seriously. He promised me that he would soon put it in order, but I
-fear that he did not attend to it immediately.’”
-
-It will be observed that Lilienthal gave fair attention to the merits
-of both the monoplane and the biplane, the two familiar types in
-lively competition at the present hour. The first he found in Nature;
-the second he could have found in England, as the developments
-principally of Wenham and of Phillips. His example and prestige did
-much to promote the biplane; but he seems to have had no very decided
-preference for either. Though he found his biplane very satisfactory,
-he thought of returning to the monoplane.
-
-In April, 1896, he wrote:[27] “I am now engaged in constructing an
-apparatus in which the position of the wings can be changed during
-flight in such a way that the balancing is not effected by changing
-the position of the center of gravity of the body. In my opinion this
-means considerable progress, as it will increase the safety. This will
-probably cause me to give up again the double sailing surfaces, as it
-will do away with the necessity which led me to adopt them.” He thus
-seems to have studied the two types impartially, and to have invented a
-means for balancing the machine without shifting the center of mass.
-
-Lilienthal had given a powerful and permanent impulse to aviation,
-both by his writings and by his practical experience in the air. He
-first showed quantitatively the advantage of arched wings, by carefully
-derived tables of wind pressure; then he mounted the wings himself
-and taught the world, by bold and frequent flight, the art of aërial
-gravity sailing. The two remaining achievements, dynamic and soaring
-flight, he was to undertake as promptly as possible. If his life had
-been spared, no doubt he would have contributed much to the advancement
-of these arts, both by example and by direct effort; for he was in the
-prime of life, full of energy and daring, highly equipped, and ardently
-devoted to his favorite science. He began his studies in aviation at
-the age of thirteen and died at the age of forty-eight years.
-
-Among the admirable traits of the father of sailing flight must be
-mentioned his scientific liberality and _esprit de corps_. Though he
-patented his invention he did not conceal, or withhold, his discoveries
-when he could publish them properly. These discoveries were made at
-a great sacrifice of time and means, and must have appeared to him
-valuable trade secrets; yet he published all his scientific data, his
-theories, and observations; he encouraged his confrères in various
-countries to witness and emulate his experiments, to share intimately
-his laboriously developed knowledge of aviation, to join hands with
-him in hastening the advent of practical flight. Such is the _esprit
-de corps_ which has ever prevailed among truly scientific men, as
-distinguished from the mercenary and commercial; such are the unselfish
-investigators whom the world delights to honor, both for their genius
-and for their liberal contributions to the common and permanent
-possessions of humanity.
-
-Before his death Lilienthal had the pleasure of knowing that competent
-disciples were emulating him in doctrine and practice. One of the
-earliest and cleverest of these was Percy S. Pilcher, Assistant
-Lecturer in Naval Architecture and Marine Engineering at the University
-of Glasgow. In the summer of 1895 he built the glider shown in Plate
-XVI. This, like Lilienthal’s, was a double-tailed monoplane arched fore
-and aft; but, better than his for manual control, it was straight from
-tip to tip, like the designs of Henson, Penaud, and other predecessors.
-This improvement was introduced to prevent side gusts from rocking the
-craft so readily as they do the V-shaped gliders. His best sailer, the
-_Hawk_, shown in the figure, had wings curved one in twenty, about one
-third from their front edge.[28] Sometimes he sailed downhill; again
-he was towed or launched, like a kite, by means of a cord, running
-through five-fold multiplying gear, and drawn by running boys, or a
-horse. In both cases he controlled the machine to his own satisfaction,
-making in 1897 smooth downhill glides of 700 feet length, from an
-elevation of 70 feet.[29] He had also visited Lilienthal, but only
-after achieving success at home.
-
-Having acquired some skill in sailing, Mr. Pilcher began work on a
-power machine. This was to be propelled by a screw actuated by an
-oil engine, and was to be mounted on wheels backed by stiff springs.
-Having observed his speed of descent in gliding, he computed that
-two tow-line horse power would float him and his machine, weighing
-together 220 pounds. A like result was obtained when he was flown as
-a kite. He was, therefore, on the straight road to achieving human
-flight on a screw-propelled, wheel-mounted monoplane. If he had been
-more cautious he might have been the first person to achieve human
-flight in a practicable type of dynamic machine; for he seems to have
-equaled, if not excelled, his German master in aëroplane design. But
-like the master he provided inadequately for the structural strength
-of his glider, and braved too far the dangers of gusty weather. One
-stormy day, September 30, 1899, wishing to please several persons who
-had come a long distance to see him, he made two trial flights in a
-gentleman’s park near Rugby. The second of these proved fatal. The
-spectators heard a cracking noise, saw the tail break, and the whole
-craft plunge headlong to the ground. Poor Pilcher was mortally hurt and
-died thirty-four hours later, without ever regaining consciousness. He
-was then in his thirty-third year.
-
-Had this talented young Briton and his German tutor both lived, there
-would doubtless have been a pleasant race and rivalry between them;
-for the pupil was forming opinions and plans sufficiently divergent
-from those of his master and friend. He did not approve Lilienthal’s
-high wings and low center of gravity, nor his V-shape for lateral
-equilibrium, nor his flapping wing tips for propulsion, nor his method
-of launching the dynamic machine. Fortunately both published their
-ideas and experiments, leaving to their successors the task of judging
-the merits of their designs, and of adding any improvements that might
-still be required in order to achieve final success.
-
-Contemporary with Pilcher, Mr. Octave Chanute and Mr. A. M. Herring,
-in America, were emulating the work of Lilienthal. Mr. Chanute was an
-experienced civil engineer, who had previously written a history of
-aviation, and experimented with numerous flying models; Mr. Herring,
-his employee for the time, was a mechanical engineer who had assisted
-in Langley’s experiments, and previously had flown a Lilienthal glider,
-and had made researches in the science of mechanical flight. On June
-22, 1896, accompanied by two assistants, they went into camp among the
-sand dunes, on the southern shore of Lake Michigan, to study the art of
-navigating an aëroplane without artificial motive power. Mr. Chanute
-thought that the maintenance of equilibrium under all circumstances
-was at that time the most important problem of aviation; and that
-until automatic stability was secured, it would be premature and
-dangerous to apply a motor. He wished to evade, for he did not relish,
-Lilienthal’s way of balancing by shifting the body and kicking wildly
-at the stars. His main purpose, therefore, was to acquire the pilot’s
-science; but secondarily he would learn much about the architecture
-of gliders, the behavior of air currents, the elements of propulsion
-and sustentation.
-
-PLATE XVII.
-
-[Illustration: CHANUTE’S FIVE DECK GLIDER.]
-
-[Illustration: HERRING IN CHANUTE BIPLANE.]
-
-[Illustration: HERRING’S COMPRESSED-AIR BIPLANE.
-
-(Courtesy Carl Dientsbach.)]
-
-They made some flights with a Lilienthal monoplane; but, finding this
-unsafe and treacherous, they discarded it in favor of a multiple-wing
-glider designed by Chanute, which after many empirical modifications
-in the placement of the sustaining surfaces, assumed the form shown in
-Plate XVII. This glider resembled the Lilienthal biplane in having the
-surfaces vertically superposed, the rider below them, and the rudder in
-the rear; but it was a five-decker whose wings, on either side, could
-swerve fore and aft, so as to bring the center of lift always over the
-center of gravity, in order to prevent excessive rearing or plunging.
-This glider was found very tractable in a twenty-mile wind, and in a
-thirteen-mile breeze would sail down a slope of one in four.
-
-After further study, the five-decker was replaced by a three-decker;
-which presently was deprived of its obtrusive and unessential lower
-surface, thus assuming the familiar form shown in Plate XVII. As will
-be observed, this was a radically new and elegant design, consisting
-of two superposed arched surfaces held together by vertical posts and
-diagonal wires, like a Pratt truss. It was, in fact, the renowned
-“Chanute glider” which has been copied by so many succeeding designers
-of biplanes.
-
-The Chanute glider weighed 23 pounds, spread 135 square feet, and
-readily carried a total weight of 178 pounds at 23 miles an hour. It
-was provided, as shown, with side planes and a double rudder, and
-this latter was elastically connected to the main body to insure
-steadiness of flight, on the principle of the elastic wing margins used
-by D. S. Brown in 1874. This craft was found easy to manipulate in
-launching, sailing and landing, a two-inch shift of the pilot’s weight
-equivalencing a five-inch shift on the Lilienthal monoplane. It was
-steady at a speed of twenty to forty miles an hour through the air,
-even when the wind was blowing seventeen miles an hour overground. The
-angle of descent was 7.5° to 11°, depending on the speed and trend of
-the wind. The work of gravity expended in maintaining steady flight was
-at the rate of two horse power for the 178 pounds, a good showing with
-the rider vertical.
-
-Summer passed before Mr. Chanute could perfect the invention for
-automatic stability by means of swerving wings; but otherwise the
-gliding experiments were very satisfactory. The strong and simple
-biplane evolved during those few weeks of fruitful study, though not
-an original creation, having been foreshadowed theoretically and
-experimentally, in the work of Wenham,[30] Stringfellow, Lilienthal,
-Phillips, and Hargrave, was nevertheless an important contribution to
-the science of aviation, by reason of its strength and simplicity of
-design, its efficiency, its stability, and, best of all for that day,
-its record for good flights and safety. All who could appreciate it
-understood that the addition of a light motor would transform it to
-a dynamic flyer, navigable at least in mild weather. The most eager,
-perhaps, was Mr. Herring; for he had not only mastered this glider,
-but some years previously had flown successfully rubber-driven models
-very much resembling it in design. These two aviators, therefore, came
-to a parting of the ways, Chanute still pursuing automatic stability,
-Herring impatiently heading for dynamic flight by the shortest route
-available. Had they continued together on a practical course, they
-might, ere the close of the century, have anticipated at least the
-early flights of the French aviators, if they could have constructed or
-purchased an adequate motor.
-
-After some further development of the aërial glider to adapt it
-to power flight, Mr. Herring began the construction of a dynamic
-aëroplane. He had previously built very light steam and gasoline
-engines,[31] and deemed the latter best for a perfected flyer, though
-preferring steam or compressed air in a first experimental test.
-
-When seen by the present writer in October, 1898, at St. Joseph,
-Mich., Mr. Herring was about to launch himself in the compressed-air
-driven biplane shown in Plate XVII. It was essentially a powered
-Chanute-Herring glider, steadied by a double tail, and controlled by
-shift of the pilot’s weight, the tail being elastically attached.
-The writer then suggested that both a glider and a dynamic aëroplane
-should be controlled entirely by steering and balancing surfaces, on
-the principle set forth in his paper of 1893; and, in particular,
-indicated that the lateral balance should be controlled by changing the
-inclination of the wings on either side, while the double tail should
-be used to steer and steady the aëroplane sidewise and vertically; in
-other words, that a torque about each of the three rectangular axes of
-the machine should be secured from impactual pressure, thus obviating
-the need for shifting the pilot’s weight. Mr. Herring, while making no
-objection to this proposal, intimated that he had a device for insuring
-control without shifting the pilot’s weight, but believed the most
-important effort for the moment should be to make a short flight with
-the machine as it stood, for the purpose of enlisting capital, then
-to add the controlling devices at leisure. He expected to remove the
-wheels shown in the figure, hold the aëroplane against a stiff breeze
-from Lake Michigan, start the propellers, strike a soaring attitude,
-and fly forward for a few seconds against the wind.
-
-The successful accomplishment of such a flight covering an overland
-distance of seventy-three feet in eight or ten seconds, against a wind
-of thirty miles an hour, was reported in the Chicago _Evening News_,
-of November 17th of that year; but the present writer has not been
-able to ascertain the reporter’s name, or that of any other witness to
-the event, which, if true, is well worthy of verification and detailed
-record.
-
-In following the votaries of passive flight, as represented by
-Lilienthal and his school, we have overlooked the great man-carrying
-bird of Clément Ader, one of the most prominent and successful aviators
-of that active period. If the reports be true, Ader may justly claim to
-be the first person to navigate the air in a dynamic flying machine.
-However, it must be observed that his achievements did not at first
-arouse in France a great pitch of exultation and enthusiasm. There
-seemed at the time to be some skepticism as to the practicability of
-his device. But later cordial reparation was made by placing it on the
-Stand of Honor at the Aëronautical Salon, held in the Grand Palais, at
-Paris, in December, 1908.
-
-Clément Ader set out in life with the fixed determination to make
-a fortune, then to build a practical flying machine. Adopting the
-profession of electrical engineer, he quickly accumulated enough
-capital, as he thought, to realize his early ambition. He next visited
-Africa to study at close range the great soaring birds that Mouillard
-had described with so much admiration and vivacity. Going to Algeria
-he disguised himself as an Arab, and, with two Arab guides, journeyed
-to the interior where he watched the great soaring vultures, which
-he enticed with bits of meat to perform before him their marvelous
-maneuvers, wheeling in wide circles, and without wing beat, from earth
-to sky.
-
-After several years of study of the anatomy and flight of birds, Ader
-began, at the age of forty-two years, to construct an aëroplane. His
-first machine was a birdlike monoplane mounted on skids, or wheels,
-and driven by a 40-horse-power steam engine actuating a screw, placed
-forward. The total weight was 1,100 pounds, the spread 46 feet, the
-length 21 feet. The _Eole_, as he called it, received its first
-open-air test on the morning of October 9, 1890, in the grounds
-surrounding the Chateau d’Armainvilliers, near Gretz, a portion of the
-course being so prepared that the trace of the wheels would be visible.
-When everything was ready for the trial, Ader mounted the machine, in
-presence of a few friends, ran quickly over the ground, urged by the
-propeller thrust, then rose into the air and sailed 150 feet. Such is
-the report of the witnesses to what is claimed as the first flight of a
-human being in a power-driven flying machine.
-
-Subsequently this bold inventor built _Eole No. 2_, which, by special
-permission of the War Department, he tested on a prepared track, 2,400
-feet long, on the Satory Camp. Over this course he ran his machine
-several times, and on one occasion flew 300 feet; but on alighting
-broke one of the wings.
-
-Ader, now having spent one and a half million francs on his
-experiments, placed the _Eole_ on exhibition in order to raise money
-for their continuation. In this venture also he was successful,
-being presently subventioned by the French War Department to build an
-aëroplane for its use. His subsequent labors are concisely set forth in
-_Automobilia and Flight_ for February, 1909, as follows:
-
-  “Under these new conditions the workshop in the Rue Pajou was
-  abandoned for larger premises in the Rue Jasmin, where the
-  construction of the _Avion_ was commenced in May, 1892, all
-  persons engaged with the construction being under a military
-  vow of secrecy. The motor was built first, and tested before a
-  commission composed of army officers and some of the leading
-  technicians of France. It was found to develop 30 horse power
-  for a total weight of 32 kilogrammes; and even now, though
-  seventeen years old, is regarded as a _chef d’œuvre_. In the
-  spring of 1897 the _Avion_ was ready to make flights. Like its
-  predecessors it was modeled on the form of a bat; but, although
-  the wings could not be flapped, they could be folded, and
-  could be advanced or retarded horizontally.
-
-  “Everything appearing satisfactory, Ader informed the military
-  commission that he was ready to undergo tests; the committee
-  met at the workshops in the Rue Jasmin on August 18, 1897;
-  were pleased with the machine, and ordered flights to be made
-  immediately at Satory. It was not, however, until October 12th
-  that a flight was attempted on the carefully guarded military
-  ground, and in the presence of General Mesnier. The apparatus
-  covered a distance of 1,600 yards, and although it did not fly,
-  for this distance it is certain that on several occasions it
-  completely left the ground. Ader declared that according to
-  whether the wings were carried forward or to the rear, it was
-  the front or the rear wheels only which left the ground. The
-  pressure in the generator at this moment varied between 3 and 4
-  atmospheres. On increasing it to 6 or 7 atmospheres none of the
-  wheels touched.
-
-  “Satisfied with the results of the test, General Mesnier called
-  the commission together for further trials on the following
-  day, October 14, 1897. Unfortunately it was a rough, squally
-  morning, that would have prevented many a modern aviator from
-  bringing a machine into the open. But as the officers had been
-  brought together specially for this purpose, a flight was
-  attempted.
-
-  “‘After several revolutions of the propellers, and a few yards
-  covered at a moderate speed, we were off at a high rate of
-  travel,’ wrote Ader, who was at the wheel on this memorable
-  occasion. ‘The pressure was about 7 atmospheres. Almost
-  immediately the vibrations of the rear wheel ceased, and,
-  directly after, those of the front wheels were no longer felt,
-  showing that we had entirely left the ground. Unfortunately
-  the wind had increased in strength, and I had some difficulty
-  in keeping to the line that had been marked out. I increased
-  the pressure to 9 atmospheres, and immediately the speed
-  increased considerably, the vibrations ceased again, showing
-  that we had once more left the ground. Under the influence of
-  the wind the aëroplane had a constant tendency to drift to
-  the right, away from the circular track that had been marked
-  for it. Finally, with the wind broadside on, the machine was
-  in a rather dangerous position, for it was being still more
-  rapidly driven out of its course. I increased the pressure
-  still more and put the rudder hard over to the left, with the
-  result that for a few seconds the machine worked back towards
-  the track and still maintained itself in the air. But it was
-  impossible to struggle against the wind, and finding that the
-  machine was being carried towards some artillery sheds, and
-  somewhat unnerved by the speed at which the ground appeared to
-  be rushing past, I stopped the engine; there was a shock, and I
-  was on the ground.’
-
-  “Ader was uninjured, but his machine was rather badly smashed.
-  It had certainly flown, but with such difficulty in the face of
-  the wind that the army commission was evidently little inclined
-  to report favorably upon it. Several weeks passed without any
-  communication being received from the War Department; then it
-  became apparent to Ader that the Government had no longer faith
-  in his invention. This was proved early in the following year
-  by an official communication to the effect that no further
-  funds could be allotted to this work. Discouraged at the
-  abandonment after forty years’ labor and the expenditure of
-  about two million francs, Ader commenced the destruction of his
-  machines. The earlier ones were destroyed, but the _Avion_, the
-  one which had appeared before the army commission, was saved
-  and sent to the Museum of the Arts et Métiers in Paris.”
-
-The last aëroplane, or _Avion_, weighed 1,100 pounds, spread 270 square
-feet, and was driven by a 40-horse-power steam engine actuating twin
-screws projecting before the bird-shaped flyer. The engine weighed but
-7 pounds per horse power—quite a remarkable achievement for that day.
-
-In following the votaries of passive flight, as represented by
-Lilienthal and his school, we have overlooked the great dynamic
-aëroplane of Mr. Maxim, one of the most prominent aëroplane builders of
-that active period. Having in 1889 made elaborate experiments on the
-atmospheric resistance of sustaining surfaces, and on the thrust of
-screw propellers, he proceeded to build the gigantic aëroplane shown
-in Plate XVIII, the greatest flyer thus far known to history. It was a
-twin-screw multiplane mounted on a platform forty feet long by eight
-feet wide, and having four wheels running along a track eight feet
-wide and half a mile long. Above the rails of this track were guard
-rails to prevent the flyer from rising more than three inches during
-the tests. The whole machine weighed 3.5 tons, spread 5,500 square
-feet of surface, and, at a speed of 40 miles an hour, lifted more than
-a ton, in addition to the weight of the three men and 600 pounds of
-water. Its propelling plant comprised a naphtha tubular boiler, and a
-compound steam engine of 350 horse power actuating twin screws 17 feet
-10 inches in diameter which gave a thrust approximating 2,000 pounds.
-These screws were made of American yellow pine, covered with canvas and
-painted, then smoothly sandpapered to reduce the friction; for Maxim,
-like certain French aviators, erroneously imagined that a polished
-surface has less air friction than a dead even surface. The framework
-was composed of seamless steel tubing stayed with steel wire. The
-aëroplane was to be steered right and left by a rudder, and up and down
-by horizontal planes, one fore, another aft, and its lateral stability
-was to be secured by side planes set at a dihedral angle. A meritorious
-feature for that day were the superposed arched surfaces whose framing
-was smoothly covered below and above by skillfully stretched fabric,
-causing the air to flow evenly without wasteful eddies.
-
-PLATE XVIII.
-
-[Illustration: MAXIM’S AËROPLANE.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: LANGLEY’S LARGE AËROPLANE.
-
-(Courtesy Smithsonian Institution.)]
-
-Many runs along the track were made to test the working of this
-great apparatus before trusting it to launch forth in free flight.
-Dynamometers gave independently the thrust of the screws, and the lift
-of the wings on the front and rear axles. The ascensional planes for
-controlling the fore and aft equilibrium were tested during the run,
-as also the practical operation of the propelling plant. During the
-trials of 1893 the machine frequently lifted clear of the lower track,
-and flew forward resting against the guard rails above the wheels.
-Finally, on a gusty day, the lift against the upper track caused this
-to give way, whereupon the machine rose into the air with Mr. Maxim
-and his assistant, then toppled over on the soft earth, suffering
-some damage to its framework. Here the experiments were discontinued
-for lack of funds, having indeed demonstrated that a large weight
-can be carried in dynamic flight, but having proved little as to the
-feasibility of controlling an aëroplane in launching, in free flight,
-and in landing.
-
-Compared with the work of his contemporaries this achievement of Mr.
-Maxim was herculean, both in construction and expenditure, the cost
-being reported as nearly one hundred thousand dollars. It raised high
-hopes for aviation. It proved conclusively not only that a flying
-machine could be made to lift a pilot, but that it could carry hundreds
-of pounds additional weight. It still holds the world’s record for
-magnitude of machine and cargo. But it had two great defects; it was
-improperly balanced and it was inadequately powered; for, as Mr. Maxim
-says, “the quantity of water consumed was so large that the machine
-could not have remained in the air but a few minutes, even if I had had
-room to maneuver and learned the knack of balancing in the air.”[32]
-These defects, however, would soon be remedied by the work of others,
-and particularly by the costly experiments of the automobilists, who
-were rapidly developing a light gasoline motor suitable for aviation.
-
-The inventors thus far noticed had developed most of the important
-features of the present-day flying machines, but had not provided
-adequate mechanism for preserving a steady lateral balance. The present
-writer had proposed the combination of a double rudder and torsional
-wings to steer and control a flyer, and had published a paper setting
-forth its general principle and describing a specific device; but
-inventors had little need for a third rudder till they encountered
-the dangers of dynamic flight in gusty weather. The paper referred
-to was presented to the Third International Conference on Aërial
-Navigation, in August, 1893, under the title, _Stability of Aëroplanes
-and Flying Machines_, and was published with the proceedings of the
-conference.[33] It discusses mainly the question of automatic stability
-and steadiness; but recommends personal control during the experimental
-period. It concludes as follows:
-
-  “We have been considering the question of automatic stability,
-  in so far as it may be secured in the construction of the
-  craft itself,[34] apart from a pilot, or special equilibrating
-  devices. The application of the latter would give exercise
-  to an infinite amount of ingenuity, and would, perhaps, best
-  be left to the fancy of the individual inventor. One curious
-  design, however, occurs to me, which, since I have not seen it
-  described elsewhere, may be worth a moment’s notice.
-
-  “Suppose a Phillips’s machine (see Plate XIV) to be provided
-  with a double tail, and to have a vertical fin extending
-  longitudinally along its entire length, well above the
-  center of gravity. These would steady its flight and promote
-  stability. _Suppose also that its sustaining slats were
-  pivoted, so that a pilot could at pleasure change their
-  inclination on the right and left side independently. He could
-  then set the engine for a desired speed, sweep forward along
-  the earth with the sustainer slats horizontal, and at will
-  mount into the air, by giving the slats an upward inclination.
-  Once in the air he could raise or lower the machine by slightly
-  changing the angle of the slats; he could wheel to right or
-  left by giving one set of slats a little different slope from
-  the other; he could arrest all pitching, rocking and wheeling
-  by a slight counter movement of the sustainers._ It would be
-  necessary, of course, to preserve a rapid forward motion, for
-  it is a peculiarity of the compound aëroplane that, if it comes
-  to a standstill in the air, it will drop plumb down with a
-  frightful plunge until it acquires headway.”
-
-The succeeding paragraph disclosed a specific contrivance embodying
-the principle just given. This showed two levers rotating drum shafts
-for actuating wires adapted to change the impact angles of the wing
-surfaces. Accordingly this much of the mechanism of control, together
-with the broad device of the torsion wings, has been the common
-property of inventors since the publication of that paper. Furthermore,
-the combination of torsional wings and a double rudder, either fixed or
-movable, has been public property since that date.[35]
-
-Little was said about the manner of manipulating the double rudder and
-torsional wings; for the rules of manipulation would vary in different
-machines, depending upon structural design and external conditions.
-For example, if the proposed fin and vertical rudder were ample and
-suitably placed, the lateral balance could be controlled by merely
-twisting the wings, without touching the vertical rudder; but if the
-fin and rudder were not adequate, the lateral poise would be controlled
-by twisting the wings and working the vertical rudder conjunctively.
-A novice might prefer leaving the rudders fixed and controlling the
-poise in short flights by twisting the wings by means of a single lever
-having two independent movements, one to rotate the wings oppositely,
-the other to rotate them identically.
-
-The principle of control expressed in italics had been set forth also
-in a preceding paragraph. Having proposed means for securing both
-stability and steadiness about each of the three axes of an aëroplane,
-the text continued:
-
-  “These ends could probably be attained very well by mounting
-  two compound aëroplanes on a long backbone,[36] somewhat after
-  the manner of the Hargrave cellular kites, and adding a
-  compound rudder to the whole.” ... “_If the inclination of the
-  sustainers, front and back, could be altered independently,
-  it might be feasible for a pilot to preserve the equilibrium
-  of the machine even when its center of gravity was frequently
-  shifted, as by the moving of passengers to and fro._”[37]
-
-At that date, 1893, an inventor doubtless could have secured a broad
-claim on a mechanism embodying the torsion-wing-and-double-rudder
-mechanism of control. But in those days aviation was pursued largely
-as a liberal study by scientific men who wished to hasten the advent
-of practical flight, by presenting important physical measurements
-and principles which could be freely employed by all. Accordingly the
-three-rudder system of control seems not to have been claimed by an
-inventor much before the close of the nineteenth century. Since then it
-has been patented in one form or other by many practical aviators, some
-endeavoring to claim the whole broad contrivance, others claiming more
-restricted devices.
-
-The static principle of the torsion wing is a familiar one in
-elementary mechanics. It is this: a torque of given magnitude and
-direction has the same effect on a rigid body whatever its point of
-application. The longitudinal torque, or moment, may therefore be
-exerted by the wings, by suitable rudders, by forward planes, by any
-auxiliary planes, or fins, however placed or moved for the purpose.
-Accordingly there seems to be an unlimited variety of concrete
-patentable devices available to the inventor for securing impactual
-torque about the longitudinal axis, or either of the other two axes.
-But in planning such devices it is well to remember that the moment of
-a couple increases with its arm, so that in a wide aëroplane the wing
-tips may best furnish the torque; while in a high short-winged machine,
-vertical planes, fins, or rudders may give the desired longitudinal
-moment. Obviously such vertical guiding or controlling surfaces may be
-so placed as to tilt the machine toward the center of curvature of its
-path, at the same time opposing the centrifugal force, and exerting a
-torque about the vertical axis tending to steer the flyer along its
-path.[38]
-
-The principle of projectile stability is another consideration of
-some importance in aviation, or more generally in all submerged
-navigation, whether of air or water. A submerged body has projectile
-stability if its nose tends always to forerun its centroid, and follow
-a steady course. A dart is a good example; a fish, a torpedo. Thus if
-a torpedo-shaped homogeneous solid be hurled in any manner through a
-fluid, obliquely or even tail foremost, it promptly turns its nose to
-the front and proceeds steadily along an even course; but if the body
-has not true dynamical balance, it may oscillate or gyrate, or flit
-about in the most erratic manner.
-
-Projectile stability in a flyer, as in an arrow, may be attained by
-playing the centroid in or near the line of forward resistance, and
-well ahead of the side resistance. The reasons for this are manifest.
-If, however, this arrangement be neglected, a special damping, or
-controlling, device is required to preserve headlong and steady motion.
-In particular, the objections to placing the centroid too low were
-emphasized in the above quoted paper as follows:
-
-  “I have mentioned the advantage of placing the center of mass
-  below the center of surface; this has also its objections.
-  While the stability against inversion is increased, the
-  stability against rocking is sacrificed. The aëroplane so
-  constructed may not easily overturn; but it will sway to
-  and fro with a pendular motion. This, when lateral, is very
-  objectionable, when fore and aft it is fatal to uniform
-  progress, as we shall see in studying the longitudinal
-  stability of flying machines. We shall then see that the center
-  of mass cannot be lowered with impunity.”
-
-Of the various flyers and models thus far studied, some manifest fairly
-good, others very imperfect projectile stability. Many inventors have
-been more alert to the gravitational stability and safety of the
-parachute than to the kinetic stability and keen, direct flight of the
-arrow. Some of the most pretentious machines imitated the thistle down
-more nearly than the dart or swallow. But the exigencies of actual
-flight would easily rectify such imperfections of design.
-
-Tractional balance also is a property of some importance in fluid
-navigation. This requires that the line of propulsive thrust coincide
-with the line of fluid resistance. It is a property, however, that
-inventors readily apprehend, and usually provide for.
-
-In general a flyer is subject to four forces: weight, thrust, air
-pressure and inertia. When these balance about any axis the craft has
-equilibrium about that axis; when they balance about the three axes
-the craft is completely balanced, and preserves its orientation in
-flight. Devices for preserving this complete balance have already been
-described; as also provision for propulsion and sustentation, launching
-and landing safely.
-
-Thus at the close of the nineteenth century all the essential
-principles and contrivances of pioneer flight were worked out, except
-one—a suitable motor. This was the real problem of the ages. The rest
-was easy by comparison. A light enduring motor, if available to the
-old time inventors, would have brought dynamic flight centuries ago.
-That only could have baffled Da Vinci, Cayley, Henson, Wenham and the
-long line of pioneer aviators. Eventually, of course, steam engines had
-come, endowed with ample power; but costly to build and wasteful to
-operate. The light automobile engine appeared in the latter nineties;
-promptly thereafter followed the dynamic flyer, the snow-winged herald
-of the twentieth century.
-
-
-
-
-                              CHAPTER IX
-
-              AËROPLANES OF ADEQUATE STABILITY AND POWER
-
-
-The dawn of the twentieth century found several votaries contriving
-aëroplanes for one or more passengers. The epoch of models had
-virtually closed, bequeathing a rich heritage. The essential elements
-of aviation, barring the motor, had been clearly worked out. The age
-of practical flight was at hand. No further need to prove feasible
-the heavier than air; for that had been done repeatedly. Scientific
-design and patient trial, not invention and physical research, were now
-the chief demand. Further research would improve the aëroplane, but
-not bring it into practical operation. Capital, constructive skill,
-judgment in adapting principles and devices already known, energy,
-persistence, caution, imperturbability in danger and derision; these
-were requisites. Science had led the way, with uplifted torch; let the
-craftsmen follow her with kit and apron. The aëroplane was sufficiently
-invented; it now wanted, not fastidious novelty, but concrete and
-skillful design, careful construction, exercise in the open field.
-
-Of the group of aëroplanists in the beginning of the nineteenth century
-Mr. Hugo Mattullath, of New York, was one of the most original, daring
-and resourceful. He had been a successful inventor, manufacturer and
-business man, accustomed to large enterprises. In the latter nineties,
-deeming the time opportune for practical aviation, he determined to
-build a commercial flying machine. He would begin where Maxim had
-stopped. A larger and swifter craft appeared to him most desirable.
-In his judgment any clever mechanic could make a one-man flyer. “Take
-that for granted and waste no time on toys!” Professor Langley’s
-“aërodrome,” with every spare ounce filed away, should lift itself,
-of course. It might navigate a calm; possibly even a zephyr, if no
-one sneezed; but never could it carry passengers on schedule time. He
-therefore would jump the little flyers, and build at once a commercial
-aëroplane strong enough to defy the storm, powerful enough for regular
-traffic on a business scale. That meant a ship for numerous passengers,
-equipped to fly fifty miles an hour against the prevailing wind. A
-glorious project indeed; an enterprise suited to a gentleman of first
-rate ability.
-
-Mattullath’s aim was aërial transportation, not exhibition at county
-fairs and crowded carnivals. Regular interurban routes were projected,
-terminating in ample landing floors. Broad-winged aëroplanes, huge
-catamarans with shining hulls, sumptuously furnished in gold and
-crimson, should convey happy crews, in all seasons, from metropolis to
-metropolis. Six great engines and propellers to drive the ship, with
-abundant reserve power. Melodious strains of music rising incessantly,
-to soften the thunder of motors and the demoniacal howl of the wind.
-Then transcontinental voyages, outsailing the nimbus, how lovely to
-the anointed of fortune! Jocund savannas nestling by the sea, or in
-the bosom of orchid-crested hills, should welcome to earth the silken
-sojourners of the north migrating, gay-plumed and potent, to their
-winter homes in tropic paradise. All the isles of ocean, all the merry
-mountains, earth, sea and air, one shining empire, blissful and secure
-as Olympus. Chimborazo, girt with every clime, from torrid base to
-snowy peak should glow
-
-    With alabaster domes and silver spires,
-    And blazing terrace upon terrace high
-    Uplifted; here serene pavilions bright,
-    In avenues disposed; their towers begirt
-    With battlements that on their restless fronts
-    Bore stars—illumination of all gems!
-
-Such were his holiday fancies, seldom revealed, even to his associates.
-The public had no intimate part in his project. A few trusted
-engineers, eminent in their profession, and a few financiers, formed
-his advisory board. For two years he worked on the structural elements
-of the great sails, propellers, and framing of his ship. But unhappily
-when he was preparing to present his final plans to his council of
-engineers, before building the large vessel, he was brought suddenly to
-the close of his career.[39]
-
-Mattullath’s proposed air ship consisted of two parallel torpedo-shaped
-hulls sustained by superposed plane or slightly arched surfaces, and
-propelled by feathering-paddle disk wheels embedded in the planes;
-the engines, cargo and passengers to be placed within the hulls.[40]
-This arrangement would enhance the comfort of the passengers at high
-speeds, eliminate resistance, distribute the load on the framing,
-and increase the moment of inertia of the vessel, thereby rendering
-it less sensitive to side gusts. To improve the projectile stability
-and steadiness, the centroid was placed as high as practicable. Large
-steering planes were used fore and aft on both sides of the vessel,
-whose inclination could be changed independently, to turn the ship
-about its longitudinal or transverse axis. A vertical rear rudder
-steered to right or left, in conjunction with the side planes. All the
-posts were of double wedge shape; all the planes were canvassed above
-and below to shield the framing, after the style of Maxim. The hulls,
-the posts, the planes, all parts, were keenly sharpened to economize
-power. The ship was to run over its smooth launching field till it
-acquired a rising speed of forty to fifty miles an hour, then continue
-accelerating up to velocities sufficient for competition with passenger
-trains in all weather.
-
-While one may easily point out certain questionable features in
-Mattullath’s project, as for example, its odd propellers, one can not
-so easily estimate its true merits. The torsion wing device for lateral
-control and steering, which he claimed in his patent application,
-abandoned after his death, now constitutes a very important feature of
-every flying machine. His planes for fore and aft control, introduced
-by Maxim, are also in general use to-day. The principle of load
-distribution, which he greatly prized for diminishing stress and adding
-stability, has still to be evaluated by practical test in larger craft
-than any now in operation. The closed hull, for comfort and economy at
-high speed, is at present popular with many designers.
-
-One tentative assumption of Mattullath’s, made on the authority of
-Maxim and Langley, was that the friction of the air is a negligible
-part of the entire resistance encountered by the hull, framing and sail
-surfaces. Accepting their experimental conclusion, he designed a flyer
-so sharp and smooth in all its parts as practically to eliminate the
-pressural, or head resistance. With no skin friction, with scant hull
-and frame resistance, he could afford[41] to fly at a very slight
-angle, thus minimizing the drift, or wing resistance, while at the same
-time securing abundant lift by rapidity of flight. He thus arrived,
-by cold deduction from the data of those prominent experimentalists,
-at an aëroplane swift as the albatross, and wondrously economical of
-power. But his financiers were loath to gamble on that assumption. He
-therefore, at their suggestion, instigated systematic measurements
-of air friction on smooth surfaces, which demonstrated that in a
-sharp aëroplane flying at a very slight angle, the skin friction is
-nearly equal to all the other resistances combined. These results were
-obtained and published[42] some months after his death. They were
-unfavorable to his project, and to all projects for attaining high
-speed through the air by excessive sharpening of the vehicle.
-
-The first dynamic aëroplane of adequate stability and power to carry a
-man in prolonged flight, was that of Professor Langley. This machine
-was nearly a duplicate, on a four-fold scale, of the gasoline model
-previously described, which had flown many times with good inherent
-equilibrium. There was accordingly every reason to expect that,
-weighted and launched like the model, it would fly with the same poise
-and swiftness, even if left to govern itself. Having in addition
-a living pilot, provided with rudders for steering and balancing,
-together with adequate fuel for a long journey, it seemed to promise
-still better results than the model. But an unfortunate accident in the
-launching so crippled this carefully designed craft that it fell down
-helpless, without a chance to exhibit its powers of sustentation and
-balance, even for a moment, in normal flight.
-
-The first trial occurred on September 7, 1903, in the middle of the
-Potomac River at Widewater, Va. The aëroplane was placed on the same
-catapult, above the boat, that had previously started the models on
-their smooth and rapid maneuvers. The pilot took his seat, and started
-the 50-horse-power engine which ran the propellers without appreciable
-vibration. Tugs and launches were placed along the course where they
-might be of service. Photographers, on the water and along shore, were
-ready to furnish important pictorial records of the experiment. The
-aëroplane was released and sped along the track attaining sufficient
-headway for normal flight; but at the end of the rails it was jerked
-violently down at the front, and plunged headlong into the river,
-sinking beneath the waves. Buoyed up by its floats, it quickly rose to
-the surface, with its intrepid pilot uninjured, and with little damage
-to the structure.
-
-As revealed by an examination of the catapult and photographs, the
-guy post that strengthened the front pair of wings had caught in the
-launching ways, and bent so much that those wings lost all support. The
-aëroplane, therefore, had not been set free in the air, but had been
-wrenched and jerked downward. Thus the launching proved nothing of the
-propulsive or sailing powers of the machine.
-
-Those who understand the principles of aviation can judge the merit of
-Langley’s “aërodrome”[43] from its mechanical description. As shown in
-Plate XVIII, it was a tandem monoplane driven by twin screws amidships.
-The pilot seated in the little boat could control the poise and course
-by several devices; he could shift his weight longitudinally 4.5 feet,
-laterally 2.5 feet; he could elevate and depress the rear double
-rudder, which when untouched ensured steady longitudinal poise, on the
-principle introduced by Penaud; he could steer to right and left by
-turning about its vertical axis, the wind-vane rudder shown below and
-rearward of the boat. The lines of lift, propeller thrust and forward
-resistance passed through the centroid, or near it, thus providing
-for projectile and gravitational stability. In this feature Langley’s
-“aërodrome” far surpassed those of his immediate predecessors, whose
-machines, by reason of their low centroid, possessed the stability of a
-pendulum, rather than that of a dart, or swallow. These various devices
-combined should give the craft better control in free flight than that
-possessed by any of the models, which had flown successfully many times
-in moderate weather.
-
-If the projectile and steering qualities of Langley’s machine surpassed
-those of its predecessors, the propelling mechanism was a still
-greater advance in the art of aviation. The gasoline engine was a
-marvel of lightness, power, endurance and smoothness of running. It
-weighed, without accessories, 125 pounds, and developed 52.4 horse
-power in actual test at a speed of 930 revolutions a minute. With
-all accessories, including radiator, cooling water, pump, tanks,
-carburetor, spark coil and batteries, it weighed 200 pounds, or
-scarcely five pounds per horse power—a great achievement for that time.
-It could run many hours continuously under full load, consuming about
-one pound of gasoline per horse power per hour. Its five cylinders,
-arranged radially round a single crank shaft, were made of steel lined
-with cast iron, and measured 5 inches in diameter by 5.5 inches in
-stroke. Its running balance was excellent. By means of bevel gears it
-drove the twin screws at 700 revolutions per minute, giving a thrust
-of 480 pounds, the screws being very nearly true helices of unit pitch
-ratio and 30° width of blade, carefully formed of three radial arms
-covered with canvas.
-
-The whole machine weighed 830 pounds, including the pilot; spread 1,040
-square feet of wing surface; measured 48 feet from tip to tip, and 52
-feet from the point of its bowsprit to the end of its tail; soared at a
-speed of about 33 feet a second and a ten-degree angle of flight, the
-wings arching one in eighteen at one fourth the distance from their
-front edge. The double rudder, at the extreme rear, measured 95 square
-feet in each of its component surfaces.
-
-It is evident from these figures, very kindly furnished by Mr. Manly,
-the mechanical engineer in charge of the experiments, that such an
-aëroplane had every equipment needed for a steady flight of many hours
-in fair weather. A thrust of 490 pounds on well-designed surfaces
-should easily carry 500 pounds of gasoline in addition to the 830
-pounds regular weight of ship and pilot. This would enable the machine
-to fly practically all day without renewal of supplies. It appears,
-therefore, that Professor Langley had, in 1903, a dynamic aëroplane
-quite the peer, in many respects, of the best that were developed
-during the first decade of aviation, and that a mere accident, which
-should be expected in such complex experimentation, deprived him of
-the credit of the first man-flight on an adequately controlled and
-powered machine. Quite true, he lacked launching wheels; but how easy
-to add these, since they were proposed many times. He omitted the
-front steering plane, but had a rear one serving the same purpose. The
-worst that can be said is that he needed the equivalent of torsion
-wings for lateral control; but in moderate weather he could have flown
-successfully without them, as Farman, Delagrange, Paulhan[44] have so
-fully demonstrated. Besides, Langley had already tested the torsion
-wing device, and contemplated using it on his large machine.
-
-A second launching was attempted on the Potomac River near Washington,
-on December 8, 1903. This time the rear guy post was injured, crippling
-the rear wings, so that the aëroplane pitched up in front and plunged
-over backward into the water. After some repairs it was stowed away
-in the Smithsonian Institution, where its frame and engine are still
-intact, its wings having been injured in the wreck and discarded. The
-experiments were now abandoned for want of funds to continue them.
-
-Notwithstanding that Professor Langley had contributed much to the
-science of aërodynamics, by his elaborate researches, and had really
-developed a machine capable of sustained flight, if properly launched,
-he was subjected to unmitigated censure and ridicule; for he had
-incurred the enmity of various journalists and wiseacres, partly by
-his official secrecy, and partly by that natural reticence which
-avoids premature publicity in important scientific enterprises. This
-irresponsible criticism, combined with the cessation of work which
-should have brought success, profoundly grieved him, and doubtless
-hastened his death. He had, however, the satisfaction of knowing that
-a few competent specialists appreciated his labors, and would continue
-them to abundant fruition. A few days before his death he had the
-gratification of receiving, from the newly formed Aëro Club of America,
-the following communication acknowledging the value of his efforts to
-promote aërial travel.
-
-
-                RESOLUTIONS OF THE AËRO CLUB OF AMERICA
-
-                      _Adopted January 20, 1906._
-
-“_Whereas_, our esteemed colleague, Dr. S. P. Langley, Secretary of
-the Smithsonian Institution, met with an accident in launching his
-aërodrome, thereby missing a decisive test of the capabilities of this
-man-carrying machine, built after his models which flew successfully
-many times; and whereas, in that difficult experiment, he was entitled
-to fair judgment and distinguished consideration because of his
-important achievements in investigating the laws of dynamic flight, and
-in the construction of successful flying models; therefore be it
-
-“_Resolved_, That the Aëro Club of America, holding in high estimation
-the contributions of Dr. Langley to the science of aërial locomotion,
-hereby expresses to him its sincerest appreciation of his labors as a
-pioneer in this important and complex science; and
-
-“_Be it further resolved_, That a copy of these resolutions be sent to
-the Board of Regents of the Smithsonian Institution and to Dr. Langley.”
-
-This kindly message from America’s foremost aëronautic society brought
-a moment’s pleasure to the last hours of the illustrious scientist.
-“Professor Langley was on his deathbed when these resolutions were
-brought to his attention, and when asked what should be done with the
-communication, his pathetic answer was: ‘Publish it.’ To all who know
-his extreme aversion to publicity in any form, this reply indicates how
-keenly he felt the misrepresentation of the press.”[45]
-
-Professor Langley’s progress with the “aërodrome” was due largely to
-the skill, energy and devotion of his designer and superintendent of
-construction, Mr. Charles M. Manly. This talented young graduate in
-mechanical engineering, of Cornell University, in 1898, went directly
-from the class room to assume the chief burden of Langley’s researches
-in aërodynamics, and his practical experiments in mechanical flight,
-remaining till their termination in 1904. He was the confidential
-secretary and adviser to his chief in that whole enterprise. When
-in 1900 Dr. Langley stood baffled before the greatest obstacle in
-aviation, unable to find any manufacturer, in America or Europe, who
-could furnish a practical engine of the desired power, lightness and
-durability, Manly came to his rescue with a design which guaranteed
-success and which resulted in the wonderful gasoline motor built in the
-Smithsonian shops. Finally when the aëroplane was ready to be launched,
-it was Manly who bore the long weeks of trial in the malarial region of
-Widewater, harassed by accidents and foul weather, not to mention the
-merry agents of the press; and it was he who twice rode the ponderous
-aërodrome, shot forth in mid air at the imminent risk of his life.
-
-While Langley was building his great tandem monoplane, Wilbur and
-Orville Wright of Dayton, Ohio, were developing a biplane which was
-an improvement on the aërial glider of Chanute and Herring. This was
-to be their preliminary effort toward achieving continuous flight.
-Their first product, tried at Kitty Hawk, North Carolina, in the
-summer of 1900, is shown in Plate XIX. The chief points of departure
-from Chanute and Herring’s glider were (1) to place the rider prone
-on the lower surface, as first proposed and tried by Wenham, forty
-years’ previously; (2) to discard the vertical rudder; (3) to place
-the horizontal rudder forward, as done by Mattullath and Maxim; (4)
-to control the lateral balance by changing the impact angles of the
-wings, as recommended by the present writer in 1893. Of these four
-modifications the first was impractical for general use, though good
-for soaring and possibly racing; the second was unsatisfactory and
-later abandoned; the third was effective, and has been accepted by
-some aviators as an improvement, but rejected by others who prefer the
-rear[46] horizontal rudder; the fourth proved acceptable to them, as to
-various other inventors before and after them.
-
-With this glider they made a number of satisfactory flights. The front
-rudder and the torsional wings proved adequate to control the craft
-in sailing straight ahead down the Kill Devil sand hills, near Kitty
-Hawk, N. C. In this, as in all their machines to the present date, sled
-runners, fixed under the machine, as proposed by Ader and others, were
-used for launching and landing. With a surface of 165 square feet, they
-could glide down a slope of 9.5° at a speed of 25 to 30 miles an hour.
-This showed only a moderate efficiency, but it was a beginning.
-
-The glider used in the summer of 1901 was modeled after that of the
-previous year, but larger. It was 22 feet wide, 14 feet long, 6 feet
-high, spread 308 square feet, and weighed 108 pounds. With this a
-number of glides were made, of various lengths up to 400 feet. At a
-speed of 24 miles an hour gravity exerted on the aërial coaster 2½
-tow line horse power, showing an efficiency nearly equal to that of
-Pilcher’s glider of 1897.
-
-In camp with the Wright brothers in 1901 was Mr. Chanute, the leading
-aëronautic expert in America. They thus had the advantage of
-his long experience, both as a student of aviation and a practical
-experimenter. With them were also two other specialists, Mr. E. C.
-Huffaker, an experienced aëronautical investigator, who had worked
-successively with Langley and Chanute; and Dr. G. A. Spratt, who had
-made some important investigations on the value of curved surfaces and
-the travel of the center of pressure with the varying angles of flight.
-The numerous animated conferences with these gentlemen were instructive
-and profitable. When the season closed the brothers returned home and
-experimented on curved surfaces to improve the efficiency of their
-glider.
-
-PLATE XIX.
-
-[Illustration: FIRST WRIGHT GLIDER.]
-
-[Illustration: SECOND WRIGHT GLIDER.]
-
-The 1902 machine, shown in Plate XIX, had two main surfaces, measuring
-each 32 by 15 feet, and a front rudder measuring 15 square feet. The
-whole weight was 116 pounds. It will be noted that a vertical rudder
-was now employed. This was a reversion to the design of Chanute and
-Herring, but after some experience, the rudder was made adjustable,
-as in Henson’s aëroplane of 1842. Its surface was 12 square feet,
-but later reduced to six. With this machine they obtained between
-700 and 1,000 glides during the season. It showed greater efficiency
-than its predecessors, its normal angle of descent being estimated at
-seven degrees or less. This was some improvement over the efficiency
-of the Chanute-Herring glider, partly due, of course, to placing the
-rider flat, instead of allowing him the more comfortable erect posture
-adopted later.
-
-Whatever improvements of efficiency and strength had been made,
-these were of secondary importance compared with the provisions for
-projectile stability and manual control. Here at last, after ten
-years’ groping, was an actual glider with sufficiently high centroid
-to minimize the pendulum effect, and with three rudders to give
-impactual torque about the three axes. These simple provisions had
-been previously pointed out in aëronautic writing, and, in the latter
-nineties, had been embodied in Mattullath’s aëroplane, but not tested
-in the large machine, owing to his death. The wonder is that, of all
-the practical inventors of aëroplanes, Mr. Mattullath was the only
-one of that period fully to grasp and adopt these main ideas before
-starting to build a man-carrying machine. However, it must be added
-that he had previously made small flying models, which may have
-suggested the advantage of kinetic stability and the three-torque
-system of control. If Lilienthal and his disciples, who laid so much
-stress on gliding experience, had started like Mattullath with three
-torque-surfaces, they would have missed indeed those acrobatic and
-picturesque kickings at the sky, but they would have reached the
-desired goal with less danger, time and expense. They displayed more
-skill in riding a fractious glider than in designing a tractable
-one, by providing for impactual torque about each of three axes. Had
-they started with a good theory of dynamic control, they could have
-dispensed with coasting entirely, and commenced aviating with short
-runs over a smooth course followed by cautious leaps in the air, after
-the style of certain ingenious French aviators. However, the knack
-of balancing was finally acquired, and thus the glider was ready to
-receive the propelling mechanism.
-
-In 1903 a 16-horse-power engine and twin-screw propellers were applied
-to the navigable glider at Kitty Hawk, as shown in Plate XX. The power
-machine weighed 750 pounds, and was usually started by aid of a tow
-line and falling weight which helped the craft to acquire headway.
-After many trials and modifications, the first successful launchings,
-four in number, were made on December 17th. The first flight lasted
-12 seconds, the next two a little more, the fourth lasted 59 seconds,
-covering a distance of 852 feet over the ground in the face of a
-twenty-mile wind. To the superficial observer these performances did
-not seem a very remarkable advance on the flights of Ader, but they
-had in them greater promise and potency of practical flight. They were
-the first flutterings of a fledgling endowed with the chief essential
-organs of aërial locomotion—an awkward but healthy creature that had
-been evolving steadily for several generations. It would grow rapidly,
-and ere another half decade, increase the 59 seconds to so many minutes.
-
-PLATE XX.
-
-[Illustration: FIRST WRIGHT AËROPLANE (REAR).]
-
-[Illustration: FIRST WRIGHT AËROPLANE (SIDE).]
-
-The experiments were continued during the next two years with
-increasing success. During the season of 1904, on a field near Dayton,
-one hundred and five flights were made, some short, others covering the
-entire circuit of the field no fewer than four times, the two largest
-measuring each nearly three miles, each accomplished in about five
-minutes. Various improvements were made in the propelling and steering
-mechanism, and increased skill in maneuvering was gradually acquired.
-
-In 1905 the flights were resumed with a new machine embodying some
-changes dictated by experience, particularly in the method of control.
-Forty-nine landings were made involving seven breakages, but no
-personal injury. On September 26th a flight of eleven miles was
-achieved. This was followed, within the next nine days, by flights of
-twelve, fifteen, twenty-one and twenty-four miles, at a usual speed
-of 38 miles an hour. After this the field practice ceased for more
-than two years, and the machine was dismantled to preserve secret its
-mode of construction till the patents could be disposed of. As these
-performances and those preceding are of unusual interest, a fuller
-account is given in Appendix IV.
-
-The Wright brothers now had to assume in aviation the rôle of cautious
-business men. The gliding experiments had been a scientific recreation,
-and had been fairly well reported to engineers, except in those details
-to be covered by patent claims; but the details of the power machine
-were withheld, or sparingly disclosed. The brothers had sacrificed
-time and money. They were making aviation a profession. They must,
-therefore, be repaid. But if they exhibited too promptly their machine
-and aërodynamic data, they might jeopardize their financial interests
-by assisting or stimulating rival aviators. On the other hand, by
-procrastination and concealment they might, in various ways, forfeit
-priority and scientific credit. Chanute’s glider was already familiar
-in Europe, and it was estimated to have ample efficiency for successful
-flight with existent motors. Their own published experiments were
-being studied and repeated. They might, therefore, expect that, at any
-time, some rash or cunning fellow would bolt into the air and proclaim
-to all the world that their unpublished devices, if they possessed
-any novelty, were by no means necessary, as they fancied, to usher
-in actual dynamic flight. The aëroplane would thus appear to be the
-sudden outgrowth of fertile and mature conditions, rather than the
-product of uncommon originality. Scores of aviators would immediately
-spring into being—chauffeurs, mechanics, sporting gentlemen of every
-dye. Light motors being now available, any intelligent artisan could
-power a Hargrave kite, or Chanute glider, and soar aloft. Every odd
-craft, not too absurdly designed, would navigate, with some showing.
-Publicity and prize money would develop and perfect the various types
-with feverish haste. But in 1905 the Wright brothers apprehended no
-portentous or imminent invasion of the sky. The foreign bogie was five
-years behind, being unfamiliar with sand hill practice and the torsion
-wing. They would, therefore, chance the result of withholding their
-data and concealing their machine. It was a curious situation; Langley
-and Manly, who produced the first aëroplane endowed with all the
-essential powers of prolonged flight, were bound to official secrecy;
-the Wrights, who had a finished machine, tried and fairly ready for
-public exhibition, were hampered by trade secrecy. These silent leaders
-in aviation presented a gratifying contrast to the shouting fraternity
-who, in the daily press, announced impending marvels which never
-materialized.
-
-The same year, 1905, which crowned with most success the private
-flights of the Wright brothers, brought into unusual prominence
-the quarter century long experiments of Prof. J. J. Montgomery of
-Santa Clara College, Santa Clara, Cal. He had given much attention
-to the science of aviation, particularly to passive flight, and had
-constructed several successful gliders operated by himself or his
-friends. The most remarkable of these machines was a glider resembling
-in general appearance Langley’s tandem monoplane, but having means for
-changing the wing curvature during flight, thus varying the lift on
-such wing, and thereby enabling the operator to control the equilibrium
-and direction during his glides in the air.
-
-On April 29, 1905, a forty-five pound glider of this pattern bearing an
-intrepid parachute jumper, Daniel Maloney, was lifted from the college
-grounds by a hot-air balloon to an elevation of 4,000 feet, then cut
-loose. “In the course of the descent,” writes one of his pupils, “the
-most extraordinary and complex maneuvers were accomplished—spiral and
-circling turns being executed with an ease and grace almost beyond
-description, level travel accomplished with the wind and against it,
-figure-eight evolutions performed without difficulty, and hair-raising
-dives were terminated by abrupt checking of the movement by changing
-the angles of the wing surfaces. At times the speed, as estimated by
-eye-witnesses, was over sixty-eight miles an hour, and yet after a
-flight of approximately eight miles in twenty minutes the machine was
-brought to rest upon a previously designated spot, three-quarters of
-a mile from where the balloon had been released, so lightly that the
-aviator was not even jarred, despite the fact that he was compelled
-to land on his feet, not on a special alighting gear.” This daring
-performance amazed the world, and most of all, the specialists who all
-along knew such a feat to be practicable. As a further description
-of Professor Montgomery’s wonderful experiments may interest the
-reader, the following account, written by himself, is inserted from
-_Aëronautics_ for January, 1909:
-
-  “When I commenced practical demonstration in my work with
-  aëroplanes I had before me three points. First, equilibrium;
-  second, complete control; and third, long continued or
-  soaring flight. In starting I constructed and tested three
-  sets of models, each in advance of the other in regard to the
-  continuance of their soaring powers, but all equally perfect
-  as to equilibrium and control. These models were tested by
-  dropping them from a cable stretched between two mountain
-  tops, with various loads, adjustments and positions. And it
-  made no difference whether the models were dropped upside down
-  or in any other conceivable position, they always found their
-  equilibrium immediately and glided safely to earth.
-
-  “Then I constructed a large machine patterned after the
-  first model, and with the assistance of three cowboy friends
-  personally made a number of flights in the steep mountains near
-  San Juan (a hundred miles distant). In making these flights I
-  simply took the aëroplane and made a running jump. These tests
-  were discontinued after I put my foot in a squirrel hole, in
-  landing, and hurt my leg.
-
-PLATE XXI.
-
-[Illustration: MONTGOMERY’S AËROPLANE.]
-
-  “The following year I commenced the work on a larger scale, by
-  engaging aëronauts to ride my aëroplane dropped from balloons.
-  During this work I used five hot-air balloons and one gas
-  balloon, five or six aëroplanes, three riders—Maloney, Wilkie
-  and Defolco—and had sixteen applicants on my list and had a
-  training station to prepare any when I needed them.
-
-  “Exhibitions were given in Santa Cruz, San José, Santa Clara,
-  Oakland and Sacramento. The flights that were made, instead
-  of being haphazard affairs, were in the order of safety and
-  development. In the first flight of an aëronaut the aëroplane
-  was so arranged that the rider had little liberty of action,
-  consequently he could make only a limited flight. In some of
-  the first flights, the aëroplane did little more than settle in
-  the air. But as the rider gained experience in each successive
-  flight I changed the adjustments, giving him more liberty of
-  action, so he could obtain longer flights and more varied
-  movements in the flights. But in none of the flights did I
-  have the adjustments so that the riders had full liberty, as
-  I did not consider that they had the requisite knowledge and
-  experience necessary for their safety; and hence, none of my
-  aëroplanes were launched so arranged that the rider could make
-  adjustments necessary for a full flight.
-
-  “This line of action caused a good deal of trouble with
-  aëronauts or riders who had unbounded confidence and wanted to
-  make long flights after the first few trials, but I found it
-  necessary as they seemed slow in comprehending the important
-  elements and were too willing to take risks. To give them the
-  full knowledge in these matters I was formulating plans for a
-  large starting station on the Mount Hamilton Range from which
-  I could launch an aëroplane capable of carrying two, one of my
-  aëronauts and myself, so I could teach him by demonstration.
-  But the disasters consequent on the great earthquake,
-  completely stopped all my work on these lines. The flights that
-  were given were only the first of the series with aëroplanes
-  patterned after the first model. There were no aëroplanes
-  constructed according to the two other models, as I had not
-  given the full demonstration of the workings of the first,
-  though some remarkable and startling work was done. On one
-  occasion, Maloney in trying to make a very short turn during
-  rapid flight pressed very hard on the stirrup which gives a
-  screw shape to the wings and made a side somersault. The course
-  of the machine was very much like one turn of a corkscrew.
-  After this movement, the machine continued on its regular
-  course. And afterwards Wilkie, not to be outdone by Maloney,
-  told his friends he would do the same, and in a subsequent
-  flight, made two side somersaults, one in one direction and
-  the other in an opposite, then made a deep dive and a long
-  glide, and when about three hundred feet in the air, brought
-  the aëroplane to a sudden stop and settled to the earth. After
-  these antics, I decreased the extent of the possible change in
-  the form of wing surface so as to allow only straight sailing
-  or only long curves in turning.
-
-  “During my work I had a few carping critics that I silenced
-  by this standing offer: If they would deposit a thousand
-  dollars I would cover it on this proposition. I would fasten a
-  150-pound sack of sand in the rider’s seat, make the necessary
-  adjustments, and send up an aëroplane upside down with a
-  balloon, the aëroplane to be liberated by a time fuse. If the
-  aëroplane did not immediately right itself, make a flight, and
-  come safely to the ground, the money was theirs.
-
-  “Now a word in regard to the fatal accident.[47] The
-  circumstances are these: The ascension was given to entertain a
-  military company in which were many of Maloney’s friends, and
-  he had told them he would give the most sensational flight they
-  ever heard of. As the balloon was rising with the aëroplane,
-  a guy rope dropping switched around the right wing and broke
-  the tower that braced the two rear wings and which also gave
-  control over the tail. We shouted Maloney that the machine was
-  broken but he probably did not hear us, as he was at the same
-  time saying ‘Hurrah for Montgomery’s air ship,’ and as the
-  break was behind him, he may not have detected it. Now did he
-  know of the breakage or not, and if he knew of it did he take a
-  risk so as not to disappoint his friends? At all events, when
-  the machine started on its flight the rear wings commenced to
-  flap (thus indicating they were loose), the machine turned on
-  its back and settled a little faster than a parachute. When
-  we reached Maloney he was unconscious and lived only thirty
-  minutes. The only mark of any kind on him was a scratch from a
-  wire on the side of his neck. The six attending physicians were
-  puzzled at the cause of his death. This is remarkable for a
-  vertical descent of over 2,000 feet.”
-
-
-
-
-                               CHAPTER X
-
-                        ADVENT OF PUBLIC FLYING
-
-
-In 1903, Mr. Ernest Archdeacon stimulated by a conference with Mr.
-Chanute, at a meeting of the Aëro Club of France, founded a prize of
-3,000 francs to be awarded to the first person who should sail or
-fly 25 meters, with a maximum descent not exceeding one third of the
-range. As yet no one in either hemisphere had flown in a practical
-machine, but various aviators were industriously pluming their wings.
-Captain Ferber had been a follower of Lilienthal since 1898, and a
-pupil of Mr. Chanute since 1891. Dozens of votaries in France, not
-to mention other countries, had entered, or were about to enter, the
-aviation field. Archdeacon himself, Voisin, Blériot, Esnault-Pélterie,
-Vuia, Delagrange, Tatin, Cornu, Bazin, Levavasseur and many others,
-were stanch apostles of the heavier than air. Many of these were
-disciples of Lilienthal, but they were destined all to be distanced
-by an impetuous Hensonite, who could not realize the necessity for
-spending months, or years, cautiously coasting downhill to acquire the
-adroitness requisite to speed a flying chariot over the plain.
-
-In 1906, while many aviators in Europe were developing flyers, and
-cautiously testing them in various ways, by gliding above sand or
-water, or swinging from a high wire or traveling arm, Señor Alberto
-Santos-Dumont, of Brazil, brought forth in France the quaint and crude
-biplane shown in Plate XXII. Aërodynamically this was not a great
-improvement on the aëroplane of Sir George Cayley constructed 98 years
-earlier; but it had a petrol motor whose power and lightness would
-have astounded that talented pioneer in aviation. The motor was an
-eight-cylinder Antoinette, weighing 170 pounds and developing 50 horse
-power. The screw, formed of two aluminum blades, was of two meters
-diameter, one meter pitch, mounted on the engine shaft, and, at 1,500
-revolutions a minute, gave a thrust of 330 pounds. The total lifting
-surface of the aëroplane was 650 square feet, and the weight, including
-pilot, 645 pounds. This bird-shaped craft ran tail foremost through the
-air, having the screw at the rear, and the rider in a small basket just
-before the wings. By means of a pilot-wheel and lever, he could operate
-the “tail,” i. e., the front rudder, sidewise and vertically, thus
-steering the craft in two directions. The lateral balance was preserved
-automatically by means of the dihedral inclination of the wings, aided
-sometimes by the rider swaying his weight to right or left.
-
-After some days of preliminary adjustment and trial, Santos-Dumont was
-ready for a dash in his new aëromobile. On August 22d, 1906, he made
-a brief tentative flight, the first witnessed in Europe since Ader’s
-surreptitious experiment. On October 23d, he ran this strange machine
-swiftly over the ground and glided boldly into the air, flying above
-the excited spectators at a speed of 25 miles an hour, and covering
-a distance of 200 feet, thus gaining the Archdeacon cup. Again on
-November 12th, 1906, he made four flights, the last one covering 220
-meters in twenty-one seconds, thus gaining the prize of 1,500 francs
-offered by the Aëro Club of France for the first person who should fly
-100 meters. The demonstration was made before the general public and
-technical witnesses, including an official committee of the Aëro Club
-of France, who reported that the aëroplane preserved good balance and a
-true soaring speed independent of the acquired momentum.
-
-Intrinsically the achievements of November 12th were crude and
-primitive; but in moral effect they were very important. They marked
-the inception of public aëroplaning before the professional and lay
-world alike. There was no patent mechanism to conceal, no secret to
-withhold from rivals, such as had shrouded the work of more circumspect
-aviators in Europe and America. If Santos-Dumont was not the first to
-fly, he was the first aëroplane inventor to give his art to the world,
-and to inaugurate true public flying in presence of technical men, as
-he had initiated modern motor ballooning. His liberal enthusiasm and
-that of his colleagues, both aëroplanists and patrons, quickly made
-France the world’s foremost theater of aviation, at least for the
-moment. The contagion would of course spread swiftly, and involve the
-entire civilized world.
-
-Santos-Dumont’s unconventional dash into the air sounded the knell of
-Lilienthalism. This slow method served to pass time profitably in the
-nineties, while the gasoline motor was still developing. But with an
-_Antoinette_ in hand, what live man, particularly what live Frenchman,
-could tinker long years on the sand hills? Why not mount the craft
-on little wheels and take a cautious little run; then after some
-adjustment, make more runs followed by innocuous saltatory flights?
-This would be so easy, so fascinating, so instructive. How much better
-than to make two thousand preliminary jumps down the hill slope
-with the body dangling wildly to keep the balance, then to redesign
-the entire frame before an engine could be successfully applied!
-An _Antoinette_ motor, placed on a competently designed Henson
-aëroplane, would have obviated the whole Lilienthal school. However,
-they did noble and opportune work, while awaiting the growth of the
-gasoline engine. This school achieved success by a roundabout method
-because Henson’s method was not available till the present century,
-for want of a cheap, light motor. When that appeared Lilienthalism
-quickly subsided. In other words, Lilienthal’s method was a passing
-convenience, never a necessity. It could have been employed very
-profitably in Cayley’s time to develop the art of gliding and soaring;
-but in the time of Santos-Dumont and his colleagues, flying by Henson’s
-method would have burst upon the world by reason of its superior value
-and the allied progress, even if the Lilienthal school had never
-existed. This is illustrated by the fact that Santos-Dumont succeeded
-without aid from the sand-hill votaries.
-
-PLATE XXII.
-
-[Illustration: SANTOS-DUMONT’S BIPLANE.
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: SANTOS-DUMONT’S _DEMOISELLE_.
-
-(Courtesy A. J. Moisant.)]
-
-The next daring aëroplanist to arouse the world of aviation was Henri
-Farman, also a votary of the wheel-mounted flyer. He had been an adept
-motorist, therefore accustomed to brisk driving. In the summer of
-1907 he received from the Voisin brothers the aëroplane illustrated
-in Plate XXIII. With this he made a number of preliminary flights
-during the autumn, proving that his aëroplane had suitable stability
-and motive power. On October 26th, on the government drill grounds at
-Issy-les-Moulineaux he surpassed Santos-Dumont’s record, by flying
-771 meters. But this was to him of minor importance; he was preparing
-to win the Deutsch-Archdeacon prize of 50,000 francs offered for the
-first person who should fly one kilometer over a returning course.
-On January 12th, he convoked a committee of the Aëro Club of France
-to witness a trial on the morrow. Next morning at ten o’clock, the
-weather being calm and clear, his great machine ran a hundred yards
-across the course, then rose gracefully into the air, and sailed away
-for the 500-meter post. Here, making a wide curve, it rounded safely
-and returned, passing the home line in elegant flight, thus winning the
-grand prize.
-
-The machine with which Farman achieved his first success, and which
-broadly resembles his subsequent triumphal flyers, seems to be a cross
-between a Hargrave kite and a Chanute glider, having a Maxim horizontal
-steering plane in front. As shown in the figure it was mounted on
-four bicycle wheels; was steered up and down by the front plane, and
-sidewise by the box rudder seen in the rear. The rider seated between
-the large supporting surfaces, and in front of his engine, operated
-these rudders separately, by pushing or rotating a pilot wheel, and
-abetted the automatic lateral balance by swaying his body. The machine
-spread 559 square feet of sustaining surface, weighed 1,100 pounds
-and carried a 50-horse-power _Antoinette_ motor actuating a single
-two-blade aluminum propeller 6.9 feet in diameter by 3.6 feet pitch,
-directly connected to the engine shaft. The stability in mild weather
-was so great that Farman, during his first few weeks’ practice, made
-over 200 flights, measuring in length from 100 to 500 yards, without
-serious mishap. In gusty weather, however, his machine was defective
-in steadiness, and unsafe near the ground. This objection was remedied
-later by adding flexible wing margins for controlling the lateral
-balance.
-
-The age of prize flying was thus fairly ushered in by the feeble but
-very important public demonstrations of Santos-Dumont and Henri Farman.
-Other public flyers would quickly follow. Delagrange, Blériot, Curtiss
-would soon become international figures, not to mention numerous more
-recent aviators. They, were men of originality, skill and energy,
-who would shortly be in the front line contesting for world laurels,
-and winning them gloriously.
-
-PLATE XXIII.
-
-[Illustration: FARMAN BIPLANE, 1908.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: FARMAN BIPLANE, 1909.]
-
-[Illustration: HARMON IN FARMAN BIPLANE.]
-
-Leon Delagrange, the sculptor-inventor, who first had demonstrated
-the biplane, on March 30, 1907, aspired in 1908 to outfly Farman.
-He now practiced industriously on the military drill ground at
-Issy-les-Moulineaux, a large field which the Minister of War permitted
-the Aëro Club of France to use for such purpose. Here he and Farman,
-in friendly competition, flew day by day over gradually increasing
-courses. At times they were joined by other aviators, and thus the
-drill grounds at Issy became famous as an aviation school.
-
-Farman’s new rival made startling progress during those frequent trials
-of March, 1908. “Just imagine,” he says, “that within a week I was
-able to complete my education as an aviator.” On March 17th he made an
-official flight of 269.6 meters, thus winning a prize of 200 francs
-offered by the Aëro Club of France for a beginner who should fly over
-200 meters. Four days later he engaged in contest with Farman. Two
-poles were erected 500 meters apart to mark the points about which the
-men must race. The machines were brought forth from their sheds in
-the morning, gleaming dimly through a dense fog, and were given some
-preliminary trials. Then Farman made a flight of 2004.8 meters, going
-twice around the course in 3 minutes, 31 seconds. He thus trebled his
-grand prize flight of January. Presently Delagrange took wing and flew
-1,500 meters in 2.5 minutes. Having been beaten by Farman, he invited
-his successful rival to take a seat behind him, and the two sailed away
-close to the ground, covering a distance of 50 meters. This was the
-first trip ever made by two men in one flying machine. For the first
-time also two machines had flown in competition over a considerable
-course.
-
-Delagrange continued to pursue Farman for the championship. On April
-11th, he flew 2,500 meters, and would have exceeded Farman’s official
-record of 2,004 meters, had he not touched the ground. The next day
-he summoned the official committee of the Aëro Club of France to
-witness and time his performance. Poles were erected at the corners
-of a triangle 350, 200, 275 feet apart respectively. Around this
-course he flew nearly five times, covering a distance of 5,575 meters
-in 9¼ minutes. Of this range the last 3,925 meters were covered
-without touching the ground. Thus at last he had out-flown Farman and
-established a new official record, the total distance actually covered
-being about ten kilometers, or approximately six miles. This ended,
-at least temporarily, the friendly competition at Issy; for now the
-aviators separated, Farman going to Belgium, Delagrange to Italy.
-
-Delagrange’s fortune accompanied him abroad. On May 24th, he made some
-impressive demonstrations on the Place d’Armes at Rome in presence of
-the Minister of War and thirty thousand people. On May 27th, he flew
-before the King and Queen of Italy and many other court personages,
-remaining in the air nine and one half minutes, thus surpassing all
-previous European records for endurance and distance. But this was
-only preliminary. On the morning of May 30th, he came forth again on
-the Place d’Armes, a light breeze blowing. His machine rolled quickly
-over the ground, then circled gracefully ten times around in the air
-at a height of four to seven meters, covering an official distance of
-12.75 kilometers, and remaining aloft 15 minutes, 26 seconds. On June
-22d, at Milan, he flew before 15,000 people in the Place d’Armes,
-covering seventeen kilometers in 16 minutes, 30 seconds. Finally, on
-September 6th, at Issy-les-Moulineaux, he flew 29 minutes, 54 seconds,
-covering 14.8 miles, which proved his crowning effort for the year. As
-the two flights just mentioned surpassed all previous official ones
-in duration, it appears that Delagrange raised the world’s record
-four times within five months, increasing his own time from six and a
-half minutes in April to about thirty minutes in September, or nearly
-fivefold.
-
-In the meantime, Farman was making rapid progress, gathering prizes and
-achieving wide renown. On May 30th, at Ghent, Belgium, taking with him
-M. Archdeacon, he flew 1,241 meters at a height of seven meters. He
-thus established a new record with two people, and won the 1,200 franc
-wager made with Santos-Dumont and Archdeacon against M. Charron, who
-contended that a flying machine would not, within the year, carry two
-men weighing sixty kilograms each. On June 6th he flew 20 minutes, 20
-seconds, covering 19.7 kilometers, thus again increasing the world’s
-record, and winning the Armengaud prize of ten thousand francs for the
-first aviator to remain aloft fifteen minutes in France. On September
-29th and October 2d, at Chalons, he successively increased the world’s
-record, and achieved his best results for the year. The first of these
-trials lasted 42 minutes, covering 24.5 miles; the second lasted 44.5
-minutes, covering 25 miles. This last flight was forty times as long as
-the one of January, which gave him the grand prize of fifty thousand
-francs, and is a good index of the wonderful progress in aviation
-made in France during the year 1908. Between these two performances
-he, on September 30th, sailed from Chalons to Rheims, a distance of
-27 kilometers, in twenty minutes. This flight was made over trees
-and houses, sometimes at an elevation of 200 feet, and was the first
-town-to-town flight ever accomplished. The following day he won the 500
-franc prize for height, passing over balloons 82 feet from the ground.
-Such was the lively pace Farman set for the rest of the world.
-
-Mr. Curtiss drifted into the business of building and operating air
-ships and flying machines by frequent association with inventors, who
-came to his bicycle works at Hammondsport, N. Y., for assistance in the
-design and construction of aërial craft. He was particularly sought as
-a constructor of propelling mechanism, for he had special skill and
-experience in producing light gasoline engines. As a motor expert he
-was invited to the laboratory of Dr. Alexander Graham Bell, at Beinn
-Breagh, near Baddeck, Nova Scotia, in the summer of 1907. Dr. Bell had
-developed his wonderfully light, strong and stable tetrahedral kites
-to such an extent that he wished to convert them into “aërodromes” by
-applying light propelling mechanism. He accordingly invited two young
-Canadian engineers, F. W. Baldwin and J. A. D. McCurdy, to consult
-with him regarding the structural details of his proposed flyer,
-and contracted with Mr. Curtiss to supply the motive power. These
-gentlemen with Lieutenant T. Selfridge, a guest of Dr. Bell, developed
-so many independent ideas that Mrs. Bell suggested the advantage of
-forming themselves into a scientific organization, at the same time
-offering the capital required for experimentation. Acting on this
-advice and generous offer, they formed themselves into the now famous
-Aërial Experiment Association, whose object was the construction of a
-practical aëroplane, driven through the air by its own motive power,
-and carrying a man.
-
-PLATE XXIV.
-
-[Illustration: THE _RED WING_.]
-
-[Illustration: CURTISS BIPLANE.]
-
-[Illustration: CURTISS BIPLANE WITH PONTOONS.]
-
-After some preliminary downhill glides[48] and studies with a motorless
-aëroplane, the association, on March 12, 1908, brought forth their
-first dynamic machine, the _Red Wing_, shown in Plate XXIV, in order
-to speed it along the ice of Lake Keuka, near Curtiss’s factory; the
-purpose being, not to fly, but to test the effect of the vertical
-rudder. To the surprise of the twenty-five onlookers, the machine,
-after running two hundred feet along the ice, serenely rose into the
-air and flew 319 feet. “This,” says Dr. Bell, “was the first public
-exhibition of the flight of a heavier-than-air machine in America.”
-It is noteworthy also that this machine was completed and ready for
-trial in less than seven weeks from the time of starting. Its design,
-while embodying suggestions from each member of the association, was
-attributed chiefly to Lieutenant Selfridge, who took the leading part
-in evolving the plans, and who gave them his final approval, it being
-the intention of the association to offer each man a chance to produce
-a flying machine after his own notions, aided by the experience and
-liberal advice of his fellows.
-
-As the advantage of flying from the ice had been suggested some years
-before the death of Lilienthal, it seems remarkable that this method
-did not yield important results earlier in the development of aviation.
-A smooth ice field is such an ideal place for testing a dynamic
-aëroplane, that previous gliding experience would seem unnecessary,
-providing the machines were designed with a fair knowledge of the
-elementary principles of stability and control. Even glider practice
-could be effectively conducted over a smooth ice field after momentum
-had been acquired by aid of gravity, or a tow line. Having sufficient
-momentum the aviator could test his rudders cautiously without rising,
-then, after a little experience, make short glides in the air, and so
-be prepared to install the motor. Landing or falling on smooth ice at
-great horizontal speed, from a low elevation, is much less hurtful than
-tumbling on the ground, as every bold skater knows from experience.
-
-The aëroplane II, designed by Mr. Baldwin, aided by his associates
-and their combined experience, resembled that of Lieutenant Selfridge
-in the trussing of its body surfaces, but was mounted on wheels, and
-provided with torsional wing tips for lateral control. When tested, it
-was found easy to launch and land, besides responding very promptly to
-the three-rudder control. In the hands of Mr. Curtiss, on May 22d, this
-aëroplane, called the _White Wing_, flew 1,017 feet in 19 seconds, and
-landed smoothly on a plowed field. This at the time was the longest
-flight ever made by an aviator in his first trip on a heavier-than-air
-machine.
-
-It was now Mr. Curtiss’ turn to be captain of design and construction.
-Under his supervision aëroplane III, called the _June Bug_, was ushered
-forth, in the month of honeymoons. It differed from the two preceding
-in having a box tail; also in having a nainsook cover, instead of the
-red and white silk that characterized the _Red Wing_ and the _White
-Wing_.
-
-After some practice, this flyer behaved so well that it seemed
-competent to win the Scientific American Cup offered for a public
-flight of one kilometer straight away. Accordingly an official trial
-was arranged with a committee of the Aëro Club of America, for the
-fourth of July, 1908. It was the first official flight in the western
-hemisphere, and proved in every way most satisfactory. The machine
-flew 2,000 yards over an S-shaped course at a speed of 39 miles an
-hour, displayed admirable control, and had abundant motive power. The
-performance was an intimation and augury of the victorious flights to
-come the following year. As the Association now repaired to Dr. Bell’s
-summer home, the Hammondsport experiments terminated for the season.
-
-The year 1908 also brought to happy fruition the long and persistent
-experiments of Louis Blériot, the most illustrious pioneer and
-champion of the monoplane. Beginning in 1900, he had tried one type
-after another, of flying machine, till he became world renowned for
-his fertility of invention, his daring, his picturesque accidents and
-hairbreadth escapes. So long as he was not killed he was certain to
-make progress; for he had every endowment that ensures success. He
-possessed the energy of early manhood, having been born in 1872; he
-had the thorough technical training of the Central School of Arts and
-Manufactures, where he graduated in 1895; he possessed extraordinary
-talent for invention and constructional detail; he had the prowess,
-courage and coolness requisite for testing intractable and dangerous
-flyers; he was in the world’s most active center of aviation; he
-also had sufficient means. If he was late in achieving success, it
-was because he preferred to develop original ideas, and could not be
-content with merely copying his predecessors.
-
-Like many other novices in aviation, Blériot began by trying to build
-a machine with flapping wings that should fly like a bird. This was to
-be actuated by a carbonic acid motor. In 1904 he abandoned his first
-machine, of bird type, and turned to aëroplanes, beginning with a
-biplane of the Farman, or Voisin type. His second machine was built by
-Gabriel Voisin, one of the most experienced of the pioneer aëroplane
-manufacturers. This biplane, unprovided with an engine, was mounted
-on floats, towed along the Seine by a motor boat, and rose from the
-surface carrying Voisin as pilot. _Blériot III_, composed of elliptical
-cells, or sustaining surfaces, and powered with two _Antoinette_
-motors of 25 horse power each, was tested without success on Lake
-Enghien during the year 1905-6. _Blériot IV_ was made of quadrangular
-cells, and launched at Bagatelle in 1906, carrying a soldier, Peyret;
-but crashed to earth in its first trial. Finally in 1907, _Blériot
-V_, mounted by the inventor himself, rose into the air and flew
-successfully, but was lacking in stability. His sixth aëroplane was
-of the Langley type, provided with a 24-horse-power motor, then with
-a 50-horse-power _Antoinette_; but it was unstable fore and aft. One
-day it traversed 184 meters, then fell from a height of 25 meters and
-was shattered on the ground. His seventh was one of the swiftest yet
-constructed, attaining a speed of nearly 80 kilometers an hour, and, in
-two private trials, covering a distance of 500 meters. Thus seven years
-had slipped away, leaving Blériot still in the tentative period of his
-work. But now he was at the threshold of a career of brilliant success,
-which soon brought him the highest honors at home and throughout the
-world.
-
-After various minor flights in the spring and summer of 1908, Blériot,
-on October 31st of that eventful year in aviation, determined to
-attempt a cross country voyage, as Farman had done the day before. As
-will be remembered, Farman had flown from Chalons to Rheims, above
-trees and houses, a distance of nearly 17 miles, thus achieving the
-first town-to-town flight in history. Blériot would improve that record
-at once, by flying in a closed circuit embracing several villages.
-
-His renowned cross-country flight was directed from Toury to Artenay, a
-village nine miles distant. Mounting his aëroplane _VIII-ter_, at mid
-afternoon, in presence of a large gathering, Blériot followed the
-course shown in Fig. 40. In the neighborhood of Artenay he landed for a
-few minutes. After some slight repairs to his magneto, he reascended,
-turned about and headed for home. Half way on his return course he
-stopped again for a few minutes, at the Village of Santilly; then
-readily reascended and flew to the neighborhood of his starting point.
-He thus traveled about 17 miles in a closed circuit. This performance,
-with that of Farman the day before, inaugurated the period of aërial
-voyages in heavier-than-air machines. It appealed so powerfully to the
-sentiment of the community that a monument was erected at Toury to
-commemorate the glorious achievement.
-
-PLATE XXV.
-
-[Illustration: BLÉRIOT FLYING OVER TOURY-ARTENAY CIRCUIT.]
-
-[Illustration: BLÉRIOT MONOPLANE _NO. VIII_.]
-
-[Illustration: BLÉRIOT MONOPLANE _NO. IX_.]
-
-[Illustration: FIG. 40.—BLÉRIOT’S TOURY-ARTENAY AËROPLANE CIRCUIT,
-1908.]
-
-A fair view of the famous monoplane, in its renowned cross-country
-voyage, is presented in Plate XXV. It consisted of a single sustaining
-surface firmly attached to a long trussed spine mounted on three
-wheels, and carrying at its front end the gasoline motor and propeller,
-at its rear end two of the rudders, the third, or lateral, rudder
-being placed at the wing terminals. A part of the trussed frame was
-covered, to minimize the atmospheric resistance against the framing,
-pilot and engine. The vertical rudder at the rear turned the machine
-to right or left; the horizontal rear rudder controlled the elevation
-and pitching of the machine; the torsional wing tips controlled the
-lateral stability, and could be used to cant the aëroplane or check its
-listing, as in the Wright and Curtiss machines. The craft exhibited an
-easy poise in the air, and possessed good equilibrium, owing to its
-arrowlike structure and its three-rudder system of control. It was a
-strong rival of the biplanes previously noticed, and a herald of better
-things to come.
-
-In the meantime the Wright brothers had resumed their field practice.
-During the month of May, 1908, they tested their famous aëroplane of
-1905, provided with increased engine power, and carrying two passengers
-upright. A few brief flights were made at speeds of 41 to 44 miles an
-hour, showing that all the mechanism was adequate and effective. But on
-May 14th a false push on a lever, made by Wilbur Wright, brought the
-flyer to earth, wrecking it too badly to be repaired in the few days
-available for experimentation. These flights were but preliminary to
-the official trials set for the approaching summer; for the brothers
-had contracted to furnish one machine to the United States Signal
-Corps, another to a French syndicate.
-
-The Chief Signal Officer of the United States Army in December, 1907,
-had issued specifications, and invited bids, for a flying machine
-apparently far in advance of the art. The flyer was to carry two men
-aggregating 350 pounds, was to remain aloft one hour continuously, and
-was to maintain an average speed of 40 miles an hour in a cross-country
-flight to and fro, covering a distance of ten miles. The contractor
-must instruct two officers to operate the flyer. Furthermore the
-machine must be capable of flying 125 miles without stopping. The
-requirements seemed severe, even to those well versed in aviation.
-Nevertheless two bids were received; one from the Wright brothers for a
-biplane to cost $25,000, another from Mr. A. M. Herring for a biplane
-costing $20,000. Both bids were accepted for the summer of 1908; but
-only the Wright contract was eventually carried out.
-
-About the same time the Dayton inventors had sold their patent rights
-in France to a syndicate in that country. The contract specified
-a machine for two passengers, having a speed of 50 kilometers an
-hour, and a range of 125 miles. Furthermore, the inventors agreed to
-instruct three pupils to manage the aëroplane. The fulfillment of
-these two contracts occupied some months, but presented no formidable
-difficulties. Though neither of the brothers had ever flown an hour,
-and though both were comparatively unskilled as operators, they had
-such faith in their invention that they undertook to launch themselves
-publicly in untried machines, Wilbur Wright in France, Orville in
-America, at about the same time.
-
-Of these two tests, the one conducted by Orville Wright at Fort Myer,
-near Washington, was the most successful at first. After a few brief
-preliminary trips, he suddenly astonished the world by phenomenal
-flying. On the morning of September 9, 1908, he made a voyage above
-the drill ground lasting 57 minutes, 31 seconds, and again in the
-evening another flight lasting one hour and three minutes, this time
-before a throng of distinguished spectators. Immediately thereafter
-he took aboard Lieut. Frank P. Lahm for a flight of six minutes’
-duration. These records were improved day by day, and all things
-seemed propitious for the official tests of speed and endurance.
-But on September 17th, while sailing with Lieutenant Selfridge at a
-height of about 75 feet, a blade of the right-hand propeller struck
-and loosened a stay wire of the rear rudder. Instantly the wire coiled
-about the blade, snapping it across the middle. Thereupon the machine
-became difficult to manage, and plunged headlong to earth, throwing the
-men with their faces on the bare ground, fatally wounding Lieutenant
-Selfridge, and seriously injuring Mr. Wright. Lieutenant Selfridge did
-not recover consciousness, and died within three hours, from wounds
-on the forehead and concussion of the base of the brain. Mr. Wright
-suffered a fracture of the left thigh and of two ribs on the right
-side. The aëroplane was badly shattered in its framing, but the engine
-was practically intact. This accident terminated the tests for the
-season; but ere long a date was set for their resumption during the
-following year.
-
-PLATE XXVI.
-
-[Illustration: WRIGHT BIPLANE OF 1908.]
-
-[Illustration: STANDARD WRIGHT BIPLANE OF 1910.]
-
-[Illustration: WRIGHT RACING BIPLANE OF 1910.]
-
-Wilbur Wright began his demonstration for the French syndicate on the
-plain of Auvours, ten miles from Le Mans, France, on August 8,
-1908. For some weeks his flights were very brief, owing to the balky
-condition of his engine; but this difficulty was removed by the middle
-of September. After the accident to his brother he remained inactive
-for a few days; then, to reassure his supporters, he raised the world’s
-record by flying a distance of over 52 miles, remaining aloft 1 hour,
-31 minutes, 25 seconds. After this he continued at frequent intervals
-to make long flights, quite usually taking a passenger with him, and on
-several occasions a lady. His endurance, his altitude, his abandon and
-perfect control amazed and delighted Europe. Incidentally he won some
-valuable prizes, beating the French records for duration, distance and
-elevation. Once he rose to a height of 380 feet. On September 21st, he
-flew 42 miles in 1 hour and 31 minutes; on October 11th, he carried a
-passenger an hour and ten minutes; finally on the last day of the year
-he flew 77 miles in two hours and twenty minutes, thus winning the
-much coveted Michelin prize, of twenty thousand francs for the longest
-distance flown during the year. It was a triumphal close to the most
-progressive and eventful year in aviation—the first year of exhibition
-flying, the inaugural year of a noble art.
-
-Having completed the speed and distance tests at Le Mans by the close
-of the year 1908, Wilbur Wright went to Pau, in the South of France,
-for the winter practice with his three pupils, Count de Lambert, Paul
-Tissandier and Alfred Leblanc. Here on the vast trial grounds at Pont
-Long, six miles from Pau, he had a commodious hangar with a workshop
-on one side, and on the other, apartments for the aviator and his
-mechanics. He arrived with his pupils, on January 14th, and next day
-was joined by his brother and sister, who had followed him from Paris,
-Orville being now well recovered from his injuries received at Fort
-Myer. In a short time the machine was set up, and early in February
-began its regular service, having a pair of levers for the teacher and
-another pair for the passenger. The pupils quickly acquired the art of
-steering, being first allowed to control one lever, with Mr. Wright
-holding the other; then being entrusted to manage the whole machine,
-with their tutor as passenger; and finally becoming themselves teachers
-of the newly acquired art. Only a few hours’ practice was needed to
-attain proficiency, the whole time in the air aggregating hardly half a
-day for each pupil, though the lessons extended over many days.
-
-A pleasant feature of the sojourn at Pau and Le Mans was the number
-and character of the visitors, and the boundless enthusiasm displayed
-toward the new art. Tens of thousands of people from the neighboring
-places, and tourists from many parts of the earth assembled to see the
-flights; statesmen, military officers, scientific and parliamentary
-delegations, representatives of innumerable periodicals. Queen
-Margherita, having missed a flight on her first visit to Le Mans,
-came a second time, and remained three hours standing on the field,
-fascinated by the wonderful aërial equipage. The King of Spain, Alfonso
-XIII, who visited the aërodrome at Pau, on February 20th, manifested
-the keenest interest and delight in examining the aëroplane and seeing
-it fly; first with the pilot alone, then with an extra passenger. He
-took a seat in the machine beside Mr. Wright, discussed its working,
-and expressed his deep regret that reasons of state prevented him from
-making an ascension. A month later the King of England, who was at
-Biarritz, adjourned to Pau, where he remained to witness two unusually
-fine flights. He expressed the greatest pleasure in the performance,
-questioned the brothers about the details of the machine, and
-complimented them on their achievement.
-
-From Pau, Wilbur Wright went to Italy, about the end of March, to
-fulfill an engagement to give demonstrations and lessons in the use of
-the biplane. He was welcomed at Rome by the King of Italy, on April 2d,
-and later gave a public exhibition of flying, to aid the sufferers in
-the recent earthquake at Messina. His flights were attended with great
-enthusiasm, and his lessons in aviation were quickly mastered; his
-pupil, Lieutenant Calderara, soon making public flights alone. A rare
-sight it was, this modern winged chariot soaring above the ruins of
-that ancient campagna, bearing with it a moving-picture camera.
-
-By the end of April Mr. Wright had finished his task in Italy, and was
-journeying homeward with his sister and brother by way of London, where
-they enjoyed the hospitalities of the Aëronautical Society of Great
-Britain; and where, on May 3d, the brothers received the beautiful gold
-medal of that famous society, the oldest aëronautical organization in
-the world.
-
-The return to America was primarily for the purpose of completing
-the official tests at Fort Myer; but incidentally the brothers must
-find time to receive new honors and ovations. While in the shop at
-Dayton, working vigorously to complete a new aëroplane for the War
-Department, in the hope of finishing the demonstrations by June 28th,
-the limit of their allotted month, they were showered with attentions
-too numerous for their comfort. They must drop their tools in order to
-go to Washington to receive the gold medal of the Aëro Club of America
-from President Taft, at the White House, on June 10th. On June 17th
-they must witness an elaborate demonstration in their honor at Dayton,
-where they received a gold medal from the city, another from the State,
-and another from the Federal Government. Finally late in June, they
-arrived in Washington with the rehabilitated biplane, to make good
-their contract with the Signal Corps.
-
-The early tests of this aëroplane were not an unmixed triumph for the
-Wright brothers and their well-wishers. At first the machine failed to
-fly completely about the drill ground. It took the air with difficulty,
-and came to the earth on the first turn. Some lack of adjustment in the
-frame was suspected. The motor was accused of weakness. The launching
-weights[49] were too light. The brothers explained that a new flyer
-is like a new horse; the driver must learn his idiosyncrasies before
-attempting to show him off to advantage. They intimated also that
-they would be pleased to have the great throng of prominent people,
-who flocked daily to the drill ground, kept away until their flying
-instrument was properly tuned for public performances. They discouraged
-superfluous attentions. The big legislators who ventured audaciously
-to peep into the sacred shed containing the marvelous machine, were
-hailed by the military guard, and unceremoniously marched across the
-line among the plain people. It was a dreadful shock to these mighty
-signors, and many a fat lawmaker cursed audibly, vowing never to vote
-a cent for flying squadrons. But still they haunted the drill ground
-daily, despite the long journey and the late dinner; for they were
-fascinated by the untold and unconjecturable possibilities of the new
-art.
-
-June 28th came quickly, obliging the patient aviators to beg another
-extension of time. They were granted thirty days longer, which seemed
-to them more than necessary; but in this judgment they were mistaken.
-One accident after another delayed the consummation of their official
-task of flying one hour above the field, then five miles across country
-and return. Finally, on July 27th, Orville Wright, who was making all
-the flights, took with him Lieut. Frank P. Lahm, and sailed gloriously
-for one hour, twelve minutes and forty seconds, before ten thousand
-delighted spectators. It was an ideal summer evening, and all the
-maneuvers were performed with excellent poise, security and grace. A
-new world’s record was established. Now all the vast throng from the
-President and his cabinet to the simplest laborer, appreciating the
-achievement as a triumph for America and for humanity, burst forth into
-prolonged acclamation and applause.
-
-The cross-country flight was next in order. The course from Fort
-Myer to Alexandria lay over scattered forests and a deep valley. The
-flight seemed a difficult and hazardous enterprise; but the brothers,
-confiding in their machine, seemed to have little apprehension of
-failure or peril. Indeed, they seemed most concerned about the bonus
-to be secured by flying at an average rate exceeding the contract
-speed of 40 miles an hour; for each additional mile an hour would pay
-them $2,500 above the normal price of the aëroplane. They accordingly
-declined to fly in any but very calm weather, no matter how vast the
-gathering of visitors, or how illustrious. They wished, of course, to
-expedite the final and crucial test; but they could not always have
-ideal conditions, and would not take undue chances. On the evening
-after the endurance test the engine balked, owing to the clogging of a
-rubber pipe from the gasoline tank. Dusk came on, and the disappointed
-crowd went home to a late dinner. The Secretary of War, who was
-present, very kindly granted a third extension of time, covering the
-rest of the month. Next evening it was a trifle breezy. Wilbur Wright
-announced that the flight could be made, but that the bonus would
-be less than on a still evening; he would therefore wait for calmer
-weather. Twelve thousand people were turned away disappointed. There
-was muttering among the impatient and warm of blood. It was remarked
-that the War Department could easily drop these procrastinated
-experiments and buy a practical aëroplane in the open market for
-$5,000. But the discommoded officers good-naturedly allowed the thrifty
-sons of Dayton to have their way in striving for a large bonus, beyond
-the normal price of $25,000.
-
-On the following evening the weather was clear and fairly still. All
-was in readiness for the flight to Alexandria and return. Orville
-Wright, taking with him Lieut. B. D. Foulois, circled the drill ground
-on easy wing, then sailed directly across country for the captive
-balloon at Shuter’s Hill. In a few moments they vanished beyond the
-forest, and for a while even the most optimistic were doubtful of their
-safety. At length they reappeared sailing homeward at very great speed.
-The machine proudly circled the drill ground amid thunders of applause,
-and landed softly at the lower end, beyond the shed.
-
-The multitude hastened to congratulate the aviators on their marvelous
-performance. For everybody it was a scientific and national triumph;
-for Wilbur Wright it was something more. With pencil and pad he quickly
-computed the bonus, surrounded by a wall of reporters. “Wise old
-Wilbur,” remarked one, “he knows the worth of coin in a crude republic.
-While Fame blows her trumpet he counts the solid gain.” The figures
-showed an average speed of 42.6 miles, making the bonus $5,000. The
-voyage was one of the finest ever executed up to that date; it was
-a glorious termination to a long and troublesome, but epoch-making
-demonstration. Now there remained only the task of instructing two
-officers to fly, and this was leisurely accomplished by Wilbur Wright
-in October.
-
-As shown in Plate XXVI the Wright aëroplane used at Fort Myer in
-September, 1908, was a twin screw biplane mounted on skids and having
-the three-rudder system of control. The rear rudder turned the machine
-right or left, the front rudder raised or lowered it, the warping of
-the wings controlled the lateral poise. The turning right or left
-could be effected on level wing; but the inventors canted the machine
-sidewise, to obviate skidding, or sidewise gliding of the craft, due
-to centrifugal force. These three-rudder movements were performed by
-three separate levers actuating suitable mechanism; but they could be
-performed easily by a single lever having three separate movements, as
-preferred by some designers. The aëroplane in launching ran along a
-monorail, accelerated by a towrope passing over pulleys, and attached
-to a falling weight comprising nearly a ton of iron. The dimensions of
-the various parts are given as follows by Major George O. Squier,[50]
-the officer in charge of the experiments:
-
-  “The aëroplane has two superposed main surfaces 6 feet apart
-  with a spread of 40 feet, and a distance of 6½ feet from front
-  to rear. The area of this double supporting surface is about
-  500 square feet. A horizontal rudder of two superposed plane
-  surfaces about 15 feet long and 3 feet wide is placed in front
-  of the main surfaces. Behind the main planes is a vertical
-  rudder formed of two surfaces trussed together about 5½ feet
-  long and one foot wide. The motor, which was designed by the
-  Wright brothers, has four cylinders and is water cooled. It
-  develops about 25 horse power at 1,400 r. p. m. There are two
-  wooden propellers 8½ feet in diameter which are designed to run
-  at about 400 r. p. m. The machine is supported on two runners
-  and weighs about 800 pounds.”
-
-On the whole the demonstrations at Fort Myer in 1909 did not greatly
-enhance the prestige of aviation. They were attended by too many delays
-and accidents, and too much waiting for ideal weather. As a consequence
-the guardians of the national purse were not clamoring for an aërial
-flotilla. Some few, no doubt, understood that the aëroplane could
-brave more than a zephyr with safety; but the general public accepted
-the demonstrations at their face value. The unthinking multitude did
-not realize that with sufficient incentive, such as war presents,
-the Wright brothers could repeat those brilliant flights, of the end
-of July, under more severe weather conditions. Fortunately, events
-were transpiring elsewhere which vastly increased the popular fame
-and valuation of the new art. This refers more particularly to those
-startling achievements in aviation abroad which were largely stimulated
-by competition and prizes.
-
-After the Fort Myer flights the Wright brothers separated, Orville
-going to Germany to represent their interests and give demonstrations;
-Wilbur exhibiting at the Hudson-Fulton celebration in New York, and
-teaching the Signal Corps officers to manipulate the newly purchased
-government aëroplane. As usual, both achieved distinction in their new
-fields. At Potsdam, on October 2d, Orville Wright, after a ten-minute
-flight with Crown Prince Frederic William, ascended alone, mounting
-steadily in circles for fifteen minutes, and reaching an elevation
-roughly estimated at 500 meters, after which he descended safely in
-five minutes. On September 18th, he made a new record at Berlin by
-carrying a passenger, Captain Englehardt, for 1 hour, 35 minutes and 47
-seconds. Wilbur Wright, on September 9th, flew from Governor’s Island,
-in New York harbor, to and around the Statue of Liberty, then returned
-to the point of departure. On October 4th, starting from the same
-point, he flew over the waters of New York Bay and above the Hudson
-River to a point opposite Grant’s Tomb, then returned to Governor’s
-Island, covering a distance of about 19½ miles in 33½ minutes. The
-trip upward was made at an elevation of about 200 feet, through a
-stratum disturbed by vortices rising from the steamer smokestacks, and
-eddies caused by the northeast wind blowing over the tall buildings.
-The return was made at a level of 50 feet on the Jersey side of the
-river where the air was less turbulent. He intended later in the day
-to make a long flight, but, owing to the bursting of a cylinder head,
-he stopped his demonstrations and returned to Washington to finish
-his instruction of the Signal Corps officers. This was easy routine,
-and it afforded opportunity to try the effect of transferring one of
-the forward steering planes to the rear and applying it there as a
-fixed horizontal tail, as used by Voisin, Curtiss and others. The new
-arrangement was reported to increase the longitudinal steadiness of the
-aëroplane, and was used in subsequent Wright aëroplanes.
-
-The brothers now ceased public flying for a while, to attend to the
-business of manufacturing and selling their craft. They formed an
-American company, enlarged their facilities for constructing machines,
-procured grounds for training operators, and prepared generally to
-fill orders both for aëroplanes and for public exhibitions. Not the
-least of their labor was to defend their patent claims, which they
-wished to be interpreted so broadly as practically to exclude all
-flyers whose lateral poise is controlled by changing the angle of
-incidence of the wings, or of lateral stabilizing planes. This was
-not an easy undertaking, since the torsion wing was a well-known
-device, having been described many times in public print, and having
-figured in earlier patents and experiments in various countries. To
-add to the difficulty, their patent claims apply specifically to the
-warping of normally flat sustaining surfaces, the warping of arched
-wings having been patented by Prof. J. J. Montgomery, whose invention
-antedates theirs.[51] However, if they produced no novel and radical
-invention in aviation, they, like Santos-Dumont in aëronautics, were
-first to achieve some measure of practical success, by applying a light
-automobile engine to a familiar machine in which former inventions
-and ideas were skillfully employed. On this ground of practical
-success they strove for an interpretation broad enough to establish
-a monopoly covering even Montgomery’s rights, which apparently they
-were infringing. But when to this end they applied for a preliminary
-injunction restraining Curtiss from using his system of control, and
-Paulhan from using Farman’s system, they were unable to convince the
-court of the justice of their petition, and the injunction suit was
-vacated.
-
-
-
-
-                              CHAPTER XI
-
-                     STRENUOUS COMPETITIVE FLYING
-
-
-The cardinal allurements in aviation for 1909 were the prize offered
-for the first flight across the English Channel, and the prizes to be
-won at the world’s first aviation meet, scheduled for the last week
-in August of that year, at Rheims, France. The desire to win these
-honors stimulated to livelier effort the most noted designers and
-operators of aëroplanes, all of whose machines were represented at the
-great tournament. It also brought into sudden prominence several new
-aviators. Young men, little versed in the science or literature of
-flight, took to wing, and in a few days found themselves world-famous.
-Aërial chauffeurs, skillful and daring, delighted vast throngs of
-people, kept the cables warm with news, and incidentally filled their
-purses with money. Thus the trade of aëroplane jockey was one of the
-interesting products of this eventful year.
-
-The first half of the aviation season of 1909 brought forth many
-improvements which seemed to augur well for the public demonstrations
-to follow. Hubert Latham, with the swallowlike _Antoinette_ monoplane,
-designed by Levavasseur, the inventor of the _Antoinette_ motor, began
-soaring grandly in the sky and into fame. Paul Tissandier, on May 20th
-at Pau, established a new French record by flying 1 hour and 2 minutes.
-The Voisin brothers were perfecting in detail their boxlike aëroplanes,
-noted for inherent stability, and destined to achieve further renown
-during the summer, under the dexterous hand of intrepid young Paulhan.
-This new and daring young aviator, after a few practice flights, began
-making world records. On July 15th, he flew 1 hour, 7 minutes and
-19 seconds. On July 18th he made a new world’s record for altitude,
-driving his Voisin aloft 150 meters at Douai. Impatient Roger Sommer,
-rejecting his own make of biplane, purchased a machine from Farman,
-and after a little practice, broke the world’s record for distance on
-August 7th, by flying at Chalons, 2 hours, 27 minutes, 15 seconds. Many
-others were advancing in skill, and would erelong achieve excellent
-results. Most strenuous of all, perhaps, were Curtiss and Blériot, the
-champions of high speed, respectively in the biplane and monoplane, and
-Farman, the winner of large prizes.
-
-In the latter part of April, Henri Farman tested a new biplane of
-his own design and manufacture, which proved very satisfactory. It
-resembled his former craft, but was provided with small balancing
-planes hinged to the rear margins of the wings near their tips.
-This machine, furthermore, was provided with both landing skids and
-wheels, the latter yielding to any unusual stress by means of elastic
-connections, so that the skids took up the shock. With this improved
-biplane, Farman beat his former records by flying continuously 1 hour,
-23 minutes, at Chalons, on July 19th. Four days later he made a new
-cross-country record by flying from the Chalons parade ground to Suppe,
-about forty miles, in 1 hour and 5 minutes. These flights were gently
-suggestive of what might be expected at Rheims the following month.
-
-During the opening period of the 1909 aëroplane season, Glenn H.
-Curtiss brought forth a new biplane, designed for the Aëronautic
-Society of New York, with the coöperation of his new partner, Mr. A.
-M. Herring, and began active practice for various prizes at home and
-abroad. After some brief trials at Hammondsport, N. Y., he shipped his
-aëroplane to Morris Park, in order to participate in the Aëronautic
-Society’s first flight exhibition of the year. On June 26th he flew,
-but without official witness, far enough to win one of the $250
-prizes offered to the Aëro Club of America by its president, Mr.
-Cortlandt Field Bishop, for the first four persons who should fly one
-kilometer. He now wished to make an official flight for this prize
-and also for the Scientific American trophy, a beautiful engraved
-silver cup—which he had won a year previously for the first public
-flight of one kilometer, made in America, but which now should go to
-the person making the longest official flight of the year 1909, not
-under 25 kilometers. But the Morris Park race track proved unsuitable
-for such contest, being too restricted. He therefore took his biplane
-to Mineola, Long Island, where he could practice on a wide plain, and
-possibly make some new records. Here a triangular course 1.3 miles long
-was staked off, and some short trial flights were made. Then Mr. C. M.
-Manly, who was official timekeeper for the Aëro Club of America, was
-notified that a trial for the prize would be made.
-
-The demonstrations near Mineola were most successful, and proved the
-beginning of a brilliant summer for Mr. Curtiss. On July 17th he won in
-quick succession both of the prizes mentioned above. The trial for the
-smaller prize began at 5.15 in the morning and lasted but 2½ minutes,
-followed 6 minutes later by the start for the coveted cup. In both
-cases the machine took the air with ease and grace, after a 200-foot
-run over the rough marsh land. In the cup trial the first twelve
-turns, aggregating 25 kilometers, were accomplished in 33½ minutes,
-but the machine continued for seven more rounds, and finally landed
-in excellent form, just 52½ minutes after it had crossed the starting
-line. The actual measured distance flown was 24.7 miles, but the true
-distance traversed by the machine was probably 30 miles, making the
-time speed between 30 and 40 miles per hour. This was slow, indeed, but
-the control was satisfactory. Those who wished for high speed would
-find it in the new aëroplane which Mr. Curtiss would presently take to
-Rheims for the speed contest, in which he was to fly as sole champion
-of the United States.
-
-The type of machine used by Mr. Curtiss in 1909 was a natural outgrowth
-of his previous ones, but very much perfected in power and finish. It
-was a biplane mounted on a three-wheeled chassis, two wheels under the
-main body and one well to the front, so as to prevent toppling forward.
-It was propelled by a single screw at the rear, directly connected to
-a water-cooled motor of the Curtiss make. Its flight was controlled
-by three rudders exerting torque respectively about the three axes of
-the aëroplane, supplemented by two fixed keels, a vertical one in the
-front and a horizontal one in the rear. Of the three rudders mentioned,
-one in the rear turned the craft right and left, like a boat, one in
-the front raised or lowered her, while the third or lateral rudder,
-consisting of small horizontally pivoted planes between the wing-ends,
-and turning oppositely to each other, controlled the lateral poise.
-These lateral rudders, or winglets, used by Curtiss, Farman and others,
-are commonly called _ailerons_.
-
-PLATE XXVII.
-
-[Illustration: _BLÉRIOT XI_ WITH MOISANT AVIATOR ON MEXICAN BORDER.]
-
-(Courtesy A. J. Moisant.)
-
-[Illustration: _BLÉRIOT XII._
-
-(Courtesy E. L. Jones.)]
-
-Louis Blériot with his two new machines, his _No. XI_ at Douay and his
-_No. XII_ at Issy-les-Moulineaux, practiced nearly every fine day in
-June and July, making fast progress in the art, and achieving some
-notable records. By warping the wings he could keep his balance better
-than in former years, and dare more severe weather. On June 12th, he
-made a straightaway flight of 820 feet in his _No. XII_, taking as
-passengers A. Santos-Dumont and A. Fournier, the entire weight being
-1,232 pounds. This was the first flight of three passengers in an
-aëroplane. On June 25th, despite a strong wind, he circled in his _No.
-XII_ eleven times about the parade ground at Issy-les-Moulineaux in 15½
-minutes, maintaining excellent stability. Next day he made 30 circuits
-in 36 minutes, 55⅗ seconds, stopping finally because of spark failure
-due to excess of oil. On July 4th, at the aëronautic meet at the Juvisy
-Aërodrome, for sufferers from the earthquake in the south of France,
-he flew in his _No. XI_ for 50 minutes, 8 seconds, at a height of 50
-to 80 feet, finally stopping because of feed trouble in his engine.
-This flight was his second up to that date. On July 13th, he made a
-new cross-country record by an early morning flight in his _No. XI_
-from Etampes to within eight miles of Orleans, stopping some minutes
-en route, to show the practicability of his monoplane. Thirty-five
-minutes after landing, his machine was taken apart and shipped back to
-his factory at Neuilly, near Paris. After this record he received gold
-medals from the Aëro Club of Great Britain and the Aëro Club of France.
-He was also awarded the _Prix de Voyage_ of 14,000 francs, of which he
-himself received 5,000 as pilot, 4,000 as constructor, while 3,000 went
-to the motor manufacturer and 2,000 to the propeller designer.
-
-The monoplanes _No. XI_ and _No. XII_ represented Blériot’s most
-successful types. They bore a family resemblance to his preceding
-machines, but had a more vigorous lateral control due to warpage of
-their main surfaces instead of the wing-tips, as of old. Both were
-provided with a single-screw propeller in front, and both were mounted
-on three-wheeled chassis with shock absorbers. The larger machine, or
-_No. XII_, had a wing surface of 337 square feet; the smaller a surface
-of 151 square feet. The latter, on its historic cross-Channel trip,
-carried a three-cylinder air-cooled Anzani engine.
-
-Hubert Latham, in his beautiful _Antoinette_ monoplane, began to
-achieve distinction for himself and his admirably designed long-tailed
-flyer early in the spring, and, ere midsummer, was one of the favorite
-idols of the thronged aërodromes. He preferred a lofty course; he
-cut through the sky with the precision and grace of a winged-spear;
-he fascinated the spectators by the steadiness of his sweep. The
-French reporters declare they saw him roll and light cigarettes in
-full flight. Not only did he delight the artist, but he surprised the
-official measurer. Toward the end of May he established a new monoplane
-record by a flight lasting 37 minutes and 3 seconds. On the 5th of
-June he flew continuously 1 hour, 7 minutes and 37 seconds, at a speed
-of 45 miles an hour. This was done in a wind and heavy rain which
-drenched and blinded him, finally inducing him to come down. On June
-7th he carried a passenger, something new for a monoplane. In July he
-increased the altitude record by flying 450 feet high. Next day he
-flew across country from Arras to Douai, 12½ miles, in 20 minutes.
-Very reasonably, therefore, he announced, his intention of sailing for
-England above the waters of the turbulent strait.
-
-The _Antoinette_ monoplane resembled, at a distance, a long-winged
-fish with its head cut off and replaced by a screw-propeller. It had a
-skifflike body with the screw in front, followed by the _Antoinette_
-engine, then by the pilot’s seat, the tail part carrying fixed
-horizontal and vertical fins and movable horizontal and vertical
-rudders. These rudders together with _ailerons_, or warping wings,
-controlled the poise in flight. The body was mounted on a light chassis
-having cushioned wheels, and a landing skid for absorbing shocks. The
-engine employed no carburetor, and was cooled by water which turned
-to steam in the engine jackets, condensed in tubes on the side of the
-prow, then was pumped back to the jackets.
-
-PLATE XXVIII.
-
-[Illustration: _ANTOINETTE_ MONOPLANE OF 1909.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: _ANTOINETTE_ MONOPLANE OF 1910.]
-
-The cross-Channel prize, above mentioned, was a cash sum of one
-thousand pounds, offered by the _London Daily Mail_ for the first
-successful flight from France to England. Many would fain have it,
-though the voyage seemed dangerous, if not foolhardy. Of the various
-aviators who coveted the prize, Latham and Blériot were the most
-strenuous in competing for it. The bold boy tried first.
-
-Housing his aëroplane on the high cliff facing the Channel near Calais,
-Latham looked toward England, impatiently waiting for placid weather,
-and a chance to soar. The venture was hazardous. By some it was deemed
-rash, owing to the uncertainty of having to alight upon the water, if
-the motor should fail. But the brave youth was less alarmed than the
-old aviators, who had no intention of competing with him. So, with a
-boy’s confidence, he brought forth his huge-winged _Antoinette_, on
-July 19th, skimmed along the ground, soared grandly above the high
-cliffs, and sped over the waters at a great elevation, as usual in his
-aërial voyages.
-
-Latham’s flight was magnificent, but brief. Owing to spark failure
-and the stoppage of his motor six miles from the French shore, he
-settled promptly, but skillfully, down upon the sea. When found by
-the accompanying torpedo boat destroyer, detailed to follow him from
-Calais, he was seated on the aëroplane, serenely smoking, buoyed up by
-the great hollow wings. He was quickly brought to shore, undaunted and
-eager for another trial; but in the rescue his frail flyer was roughly
-handled and very much wrecked.
-
-Louis Blériot now hurried to Calais eager to attempt the cross-Channel
-flight. Placing his little monoplane, _No. XI_, in a tent on a farm
-near Calais, he waited an opportune moment to sail. On Sunday, July
-25th, he was routed from bed very early by his friend, Alfred LeBlanc,
-and taken forth all reluctant to the field, for preliminary practice
-before sunrise; for the weather was favorable and he should sail as
-soon as the sun arose. Though suffering from a foot burned in a recent
-accident, he discarded his crutches and mounted his winged machine with
-eager courage, remarking: “If I cannot walk I will show the world that
-I can fly.” For some minutes he circled about the ground where, even
-at that early hour, many scores of people were assembling. All was now
-in readiness; the flyer was in excellent trim, the pilot in buoyant
-spirits, and the torpedo boat destroyer, _Escopette_, well out at sea
-to escort her swift aërial charge as well as might be.
-
-The moment of departure had come. Blériot, buttoned in his
-close-fitting suit and hood, sat on his white-winged machine, headed
-for the cliff, and surrounded by a group of well-wishers. At 4.35 the
-light-wheeled craft with propeller whirring, sped along the ground,
-rose gracefully in the air and shot bravely over the precipice, with
-the hustling aviator on its back. The admiring spectators were wild
-with excitement and joy. But there was one sad group in Calais that
-morning. Latham and his watchers, who had been waiting for better
-weather, rose in time to see his rival on the wing, but too late for
-pursuit, as the wind had suddenly risen. The unwary boy remained
-behind, weeping with disappointment.
-
-Blériot was now soaring high over the sea, faring toward Dover without
-a guide or a compass. For some time he could observe the _Escopette_
-following him, her great column of smoke obscuring the new risen sun.
-Presently both shores vanished, and for ten minutes he could descry
-neither land nor signal of any kind. He was sailing over the sea at
-forty miles an hour and drifting with the air he knew not whither; but
-he allowed his fiery steed to follow its instinct, as a bewildered
-horseman does sometimes. Along the horizon now appeared the white
-cliffs of the English shore. He was headed not for Dover but for
-Deal, carried adrift by the southwest wind. Three boats crossing his
-course seemed plying for some port on his left, and hailed him with
-lively greeting. He could not well inquire the way, but he followed
-the general course of the vessels, soaring high aloft. At length he
-saw a man on the cliff violently waving the tricolor, and strenuously
-shouting: “Bravo! Bravo!” He plunged in the direction of the signaler,
-whom he knew to be his friend M. Montaine. On nearing the earth he was
-caught in a violent turmoil of air and whirled about. Wishing to land
-at once, he stopped his power sixty feet aloft, and swooped abruptly
-down with an awakening thud upon the old English soil, sleeping in the
-peaceful sunlight of a Sabbath morning.[52]
-
-Blériot’s landing was the greatest jolt to British insularity since the
-birth of steam navigation. Nevertheless it was welcomed with unfeigned
-delight as emphasizing the triumph of a new art which enriches all
-people. Shortly afterward was erected on the spot a monument in white
-granite having the plan and size of the renowned _No. XI_ monoplane.
-
-Sportsmanlike, Latham wired his congratulations to Blériot, expressing
-the hope to follow ere long. Two days later he flew across the Channel
-to within one mile of the English coast, where he had to land in the
-water again because of motor failure. This time he struck the sea
-violently and suffered a broken nose. His goggles were shattered and
-cut his face.
-
-The big competitive flyers of the world now turned toward Betheny
-Plain near Rheims, where the first International Aviation Meet was to
-be held August 22-29, 1909. Here was a place to make record flights,
-to win rich prizes, and to achieve great distinction. A well-designed
-aërodrome had been prepared for the occasion. In the midst of a broad
-plain was marked by means of high poles, or pylons, a rectangular
-course, measuring roughly one by two miles, or more exactly, 1,500 by
-3,500 meters. At one end was the judges stand, the grand stand, the
-café and the aëroplane sheds. The numerous cash prizes offered for
-speed, for distance, for endurance, for altitude, etc., totaled in
-value nearly forty thousand dollars. But the most coveted prize of
-all was the James Gordon Bennett Aviation Cup, together with $5,000
-cash, the winner of which should have the honor of placing the next
-international contest in his own country. This should be awarded to the
-aviator having the best speed over a two-round, or 20-kilometer course.
-The next most desired prize was a cash sum of $10,000 for the longest
-flight. A special charm of the tournament was that each fortunate
-entrant should meet the distinguished aviators from all localities, and
-should fly in presence of a world-gathering. Aëroplanes of all the most
-successful types were there, numbering together thirty-eight machines.
-
-The first day of the great aviation week, Sunday, August 22d, was
-devoted to elimination trials to determine which aviators should
-represent France in the race for the Bennett trophy. Of the seventeen
-entrants in these trials the three who should cover two rounds of
-the course in the shortest time should be selected as champions, the
-next six, in order of speed, to act as reserve pilots. But owing to
-the severe weather of that day, only six of the seventeen entrants
-succeeded in flying well enough to be admitted in either capacity.
-Of these six the cup champions were: Blériot, Lefebvre, Lambert and
-Latham; the reserve champions being in order, Tissandier, Paulhan and
-Sommer. These men won their places by bold flying in rough conditions;
-for rain had fallen heavily during the previous night, and the wind
-was still blowing in swift and gusty current over the sodden field.
-Indeed, the weather seemed anything but propitious at the opening of
-that great experimental tournament, on the success of which should be
-based the estimates and forecast of so many subsequent meets. Swift
-clouds overhead, and black flags displayed on high masts, indicated
-that flying would be impossible. A passing storm raged at five o’clock
-in the afternoon. But toward evening the face of Nature brightened,
-and with it the hopes of the aviationists. The weather at last became
-ideal. Nearly all the aëroplanes came forth, and at six o’clock no
-fewer than seven were on the wing at one time. Some of them were
-doing most startling feats. Lefebvre would make a threatening swoop
-at the grand stand, then circle swiftly away. Blériot, in a moment of
-unsteadiness, charged a wheat stack with his swift monoplane, damaging
-his sharp-bladed propeller. Count de Lambert sailed under Paul
-Tissandier, heedless of the aërial wake beneath. The crowds applauded
-and cheered every novel and bold maneuver. The closing hour with its
-sunny calm atmosphere and its vivacious well-pleased populace, presaged
-greater joys for the morrow. Sir Henry Norman, who was present,
-declared that those events marked the birth of a new epoch in human
-development.
-
-Monday, the second day of the meet, dawned fair and calm, with
-promise of settled weather. It was the last qualifying day for
-the ten-thousand-dollar long-distance prize, the Grand Prix de la
-Champagne. No one who had not flown a reasonable space on, or before
-Monday, could take part in the trials for that coveted honor on
-Wednesday, Thursday and Friday. The aviators were about early, and many
-had qualified before evening. Several of the pilots tried for speed
-records. Blériot, with an 80-horse-power monoplane, made one round of
-the course in 8 minutes, 42⅖ seconds. Curtiss, in his 60-horse-power
-biplane, lowered the time to 8 minutes, 35⅗ seconds. This was an
-achievement of the greatest concern, since Curtiss stood alone, as
-champion of America, against the more experienced flyers of Europe.
-He thought of nothing, engaged in nothing, except the speed trials,
-for in these he hoped to win, with his 60-horse flyer, even against
-renowned Blériot, in his 80-horse machine. Other interesting events
-were designed solely to entertain or amuse the people. Lefebvre again
-furnished merriment by sweeping over and under, and around Paulhan, who
-was flying at an elevation of 25 feet. M. Kapferer had navigated from
-Meaux, in the dirigible _Colonel Renard_, and sailed about the grounds,
-with fine effect.
-
-Tuesday should have brought ideal conditions and performances; for it
-was the day set for the visit of M. Falliéres, President of France.
-But the morning was dark, with ominous clouds gathering over the
-aërodrome, and black flags streaming in the strong wind. When the
-President arrived, though the clock told four, no flying had yet begun.
-He examined the machines, held an informal reception, and at five took
-his box in the grand stand. Presently Bunau-Varilla in his Voisin
-biplane, rocking in the fifteen-mile wind, flew past, waving his hat to
-the distinguished spectators. After him came dauntless young Paulhan
-who also passed the President, shortly before the latter, with his
-party, returned to the railway station. He flew at an elevation of 300
-to 500 feet, his Voisin heaving and lurching in the tumultuous wind,
-like a boat on the breakers. He had no lateral stabilizing plane, so
-he let his box kite rock. The people were appalled, but what cared he
-for wind gusts, so far from earth? Let the craft roll and pitch; he
-was not uneasy. On the return lap he raced and beat a railway train.
-These were but inklings of what he would do with increased experience.
-Latham followed presently on his long swift monoplane, to the delight
-of all who love the graceful in mechanism and motion. Ere long he
-was chased and overhauled by Blériot, in his cross-Channel flyer.
-This was exciting, but Blériot produced still greater enthusiasm by
-beating the speed record, lowering it to 8 minutes, 4⅖ seconds, for
-one round of the 10-kilometer (6.21 mile) course. The day was ended,
-and the spectators were charmed again by the spectacular evolutions
-of Lefebvre, who cavorted in the air before the grand stand, cutting
-impressive curves and figure “8’s.”
-
-Wednesday morning, the fourth of the meet, was heavy with black clouds,
-which presaged unfavorable weather. The winds were light, but still
-nothing transpired till late in the afternoon to break the monotony
-of waiting. During this long interval the crowd could amuse itself
-with gossip, refreshments and music, and with an occasional flight of
-lesser moment. About four o’clock Paulhan set forth in a six-mile wind
-to try for the Grand Prix de la Champagne. His lumbering Voisin had
-a speed of hardly more than thirty miles an hour, but it was driven
-by a very reliable 50-horse Gnome 7-cylinder motor, whose body spins
-round a fixed crank, carrying the propeller with it. No one at first
-expected a very long flight. The wind rose, sometimes exceeding 20
-miles an hour, tossing the young pilot terribly, and once throwing
-him so far within the course that he must turn a complete circle in
-order to round the corner post, or pylon. But he kept right on, so
-long as there remained a drop of fuel. He first broke Wilbur Wright’s
-best record, by 23 minutes, then Sommer’s recent record, by 6 minutes,
-finally landing, at half past six o’clock, with a new world’s record
-of 82 miles in 2 hours, 43 minutes and 24⅘ seconds. The people were
-frantic with excitement; they clapped their hands and waved thousands
-of handkerchiefs; they rent the air with tremendous applause as he
-was borne toward the grand stand on the shoulders of his clamorous
-comrades. Others at the same time had been flying with varied fortune.
-During Paulhan’s long demonstration, Fournier had encountered a
-miniature whirlwind, turned over in the air, at a great height, and
-crashed sidewise to the ground, with some injury to his nose, and with
-much damage to the wings and tail of his machine. Latham, wishing to
-lower his circuit time, flew thrice around the course, but without
-improvement. During his flight, a splendid rainbow appeared, which
-together with the _Antoinette_ dragon fly soaring high aloft with
-Latham on its back, produced an impressive spectacle.
-
-Thursday morning brought fine weather and the promise of an eventful
-day. As a consequence serious efforts were made to excel all previous
-records, particularly for speed, duration and distance. In the forenoon
-Latham flew 43.5 miles in the _Antoinette XIII_. In the afternoon Count
-de Lambert, in his Wright biplane, flew 72 miles. Blériot entertained
-the throng by carrying Delagrange as passenger; but while sailing near
-the ground he encountered some dragoons, turned sidewise to avoid
-striking them, and plunged into a fence, breaking his propeller. But
-the great sensation of the day was Latham’s afternoon flight for the
-Grand Prix, in his _Antoinette No. 29_. Starting with plenty of fuel
-and favorable weather, he rose to a high level and flew till his supply
-was exhausted, at times encountering rough winds and for a while
-plowing through a rainstorm. It was the banner flight of the week thus
-far; for it surpassed all other long ones in distance and speed, though
-not equaling Paulhan’s in endurance. His total range, when compelled
-to alight through exhaustion of fuel, was 95.88 miles, in 2 hours,
-18 minutes, 9⅗ seconds. This showed an average speed of 41.63 miles
-an hour for the whole distance, while the speed for his first round
-was 44.65 miles an hour. For this great achievement he could thank
-his 50-horse, 8-cylinder _Antoinette_ motor, one of the lightest in
-existence, for that power.
-
-Friday, August 27th, was the last day allotted for the distance, or
-Grand Prix contest. After the wonderful new records of Paulhan and
-Latham, people were marveling what might happen on the final day. Many
-assumed, of course, that Latham’s record of 96 miles would remain
-unsurpassed. At four-thirty, Latham started on another long flight, in
-his _Antoinette_ monoplane _No. 13_, followed presently by Farman and
-Sommer in Farman biplanes; these flying six to twelve feet from the
-ground, with gallant Latham soaring aloft nearly three hundred feet in
-his swift long-winged fish, and occasionally gaining a lap on them.
-Sommer stopped after three rounds, because of motor trouble. Latham’s
-fuel gave out after a voyage of 68.35 miles, and he glided to earth.
-Farman continued to plod along on his slow, low-wandering craft, with
-little attention. Others were in the air, with biplanes and monoplanes,
-entertaining the populace—Blériot, Curtiss, Delagrange, Tissandier,
-Bunau-Varilla—these had the applause. Presently the spectators
-remembered that ground-skimming Farman had been a very long time on the
-wing. He now became the center of rapt attention. Slowly he distanced
-Paulhan’s great world’s record of Wednesday; slowly he distanced
-Latham’s greater world’s record of Thursday; but still he plodded away.
-The sun sank on his flight; darkness came on the field, so that he
-vanished from view at the far end of the course. At the close of the
-nineteenth round he landed in the dark before the grand stand, limp
-and exhausted, having journeyed 3¼ hours and traversed 118.06 miles.
-For the second time he had won a $10,000 prize; nineteen months ago by
-flying 1 kilometer, to-day by flying 190 kilometers. A searchlight was
-thrown upon him. He was pulled from his machine and carried upon the
-shoulders of his friends, receiving a prolonged and tremendous ovation.
-
-The seventh morning of the tournament, Saturday, August 28th,
-came with a beaming smile, promising good flights and a pleasant
-termination of the glorious cup contest for the highest speed in two
-rounds of the 10-kilometer course. The air was calm, mild and hazy
-above the Betheny plain. The flyers were in fine mood for great
-achievements. The thronging groups of well-dressed men and women
-awaited further startling events, with varied animation and constant
-chatter. The day was well diversified with interesting flights; but,
-of course, not with long ones. The chief interest centered in the
-leading cup-champions—solitary Yankee Curtiss and great Blériot with
-his 80-horse monoplane, supported, if need be, by his allies in the
-contest, Lefebvre and Latham.
-
-Curtiss, shortly after ten o’clock, made a preliminary trial, lowering
-his best anterior time. With this he was so pleased that he prepared
-immediately for the one official flight allowed in that contest. He
-filled his small gasoline tank, replenished his radiator, signed a
-legal paper certifying this to be his trial for the cup, and at once
-took wing, circling before the grand stand, then crossing the line at
-full speed. The biplane pitched perceptibly at its unusual gait, but
-turned the corner in easy curves, completing the first round in 7.57⅖,
-the second in 7.53⅕; the total time being 15 minutes, 50⅗ seconds, and
-showing an average speed of 47.04 miles an hour.
-
-About noon Blériot came forth with his 80-horse monoplane _No. 22_,
-which was expected to eclipse the Curtiss biplane, but in reality
-proved exasperatingly slow. At two o’clock he tried another propeller,
-with little encouragement. An hour later he tried again with a
-four-blade propeller, but descended before completing the round. After
-tinkering for an hour, aided by several mechanics, he flew to his shed,
-shortly before five o’clock. As no start was allowed after five-thirty,
-he hastened zealously and started his official flight at five-ten. The
-mighty monoplane cut the air at terrific speed, without pitching, or
-rolling, and finished the first round in 7.47⅘, or 5⅔ seconds less
-than Curtiss’ best lap. The overjoyed French throng rent the air with
-frantic bravos! Curtiss and Mr. Bishop were silent, appreciating the
-skill of that fiery antagonist, with his monster engine. As the steady
-birdlike craft turned the last pylon, and swept homeward in magnificent
-career, the timers called out the seconds. The throng listened with
-abated breath and then with alarm. Blériot had lost speed in the
-second round. When he crossed the line his total time was 5⅗ seconds
-greater than that of his only rival. The conqueror of the Channel, the
-champion of France, was defeated and the international trophy must go
-to America, won by a taciturn, calculating Yankee, never before seen in
-Europe, and hardly known to fame.
-
-Other official flights for the cup during the day were made by Latham
-and Lefebvre for France, and by Mr. Cockburn, champion for England,
-the latter bird-man sailing into a stack of wheat in the middle of
-his first round, then wheeling to earth. Incidentally Henri Farman
-established a new world’s three-man duration distance and speed record
-by carrying two passengers ten kilometers in 10 minutes 39 seconds.
-Thus ended the chief day of the tournament, leaving the contestants in
-the following order of speed: Curtiss, Blériot, Latham, Lefebvre.
-
-Of the other leading prizes, that for the fastest single round was
-taken by Blériot; that for the fastest three-round flight was won by
-Curtiss on Sunday, with a record of 23 minutes, 29 seconds for the
-thirty kilometers; the Altitude Prize was won by Latham, who attained
-an elevation of 508.5 feet; the Prix des Mecaniciens was won by
-Bunau-Varilla in a flight of 100 kilometers; the Prix des Aëronats
-was won, on Sunday, by the large dirigible, the _Colonel Renard_,
-in a voyage of 50 kilometers, or 31.06 miles, at an average speed of
-24.9 miles an hour. Along with the chief prizes, many smaller ones of
-considerable value were awarded, thus summing up the total of $37,000.
-
-The small band of men who organized the first international aviation
-meet, with the Marquis de Polignac as president, and the great wine
-merchants of the Champagne district as their supporters, were now
-elated and triumphant. They had undertaken a novel and costly sporting
-enterprise, regarded by many as hazardous, or rash, even though
-sanctioned by the Aëro Club of France. For an enormous attendance
-would be required to meet the expense of preparations and prize money.
-It was doubtful whether the few available aviators could draw large
-crowds to Betheny for a week, even in ideal weather, and there was risk
-of sending the critical populace away displeased if abundant flights
-were not made. The whole event might prove a painful fiasco, if rains
-and high winds should predominate; for were not aviators notoriously
-reluctant to fly in rough weather? Vain apprehensions, ignoring the
-reckless and intrepid daring of the Gallic sportsmen! Nothing short of
-a week’s continual tempest could have kept them down.
-
-The great tournament was a triumph, not only to the courageous
-promoters, but also to the aviators, the manufacturers, the whole of
-mankind. It astonished both actors and spectators. It marked a new
-epoch in the art of aëroplaning. It inaugurated a magical and wholly
-novel kind of recreation and public amusement that should be demanded
-at once in all civilized countries. It eradicated, in a measure, the
-inveterate notion that the aëroplane is essentially a fair-weather
-machine. With a cheap instrument capable of flying scores of miles
-in rain and wind, what applications might not come, of the greatest
-import to the world?
-
-The fashion set at Rheims was imitated in other cities. Before the
-close of the year 1909, aviation meets were scheduled for Brescia in
-Italy, Berlin, Juvisy, near Paris, Blackpool and Doncaster, England.
-The succeeding year was to have more such events than the really
-capable aviators could attend. In both hemispheres, sums in cash,
-equaling or exceeding those at Rheims, would be offered by many
-prominent communities, eager to witness such novel and thrilling
-entertainment as only dexterous aviators could furnish. But it would be
-learned also that considerable financial risk attends an aviation meet,
-unless good judgment mark the choice of site, season, pilots and the
-executive agencies. Several of the meets following the one at Rheims
-succeeded neither in defraying expenses nor in furnishing competent
-aviators to repay the trouble of holding the tournament. The meets
-held in England were practically failures. A most interesting flight,
-however, was performed by Latham in a wind of 25 to 35 miles an hour.
-This itself was a very impressive achievement. The Brescia meeting was
-remarkable for the turbulence of its aërial currents and for Rougier’s
-record high flight of 645 feet.
-
-The two most wonderful flights in the autumn of 1909 were those of
-Count de Lambert and Farman. During a meet at the Juvisy aërodrome,
-Lambert, on October 18th, after circling the ground a few times on a
-Wright biplane, attaining a height of 450 feet, started for Paris,
-steadily ascending in the direction of the Eiffel Tower. Circling this
-at an altitude of about 1,300 feet, he returned to Juvisy at 5.30
-P.M., having journeyed 30 miles over that dangerous route, in about
-50 minutes. This indicated that lofty flying might enable one to
-pass safely over a city, even with an unreliable motor, since, if the
-propeller stopped, a glide of many thousands of feet could be made, to
-choose a landing. Farman’s flight was less spectacular, but quite as
-marvelous. On November 4th, while competing for the Michelin trophy
-for the longest distance traversed in 1909, he flew continuously for
-4 hours, 6 minutes, 25 seconds, voyaging in that time 144 miles, at
-an average speed of 35.06 miles an hour. This proved to be the record
-distance-and-endurance flight for the year. Other men spoke of sailing
-all day in a machine carrying ample gasoline, but failed to make good
-their words.
-
-PLATE XXIX.
-
-[Illustration: ESNAULT-PELTERIE MONOPLANE, EARLY PATTERN.
-
-(Courtesy W. J. Hammer.)]
-
-[Illustration: ESNAULT-PELTERIE MONOPLANE OF 1910.]
-
-Unheralded, but quite astonishing, were the flights of Santos-Dumont
-in September, 1909. Though conspicuous as a pioneer in aviation, he
-for a while had been absorbed in other affairs, and had not kept pace
-with his brother aëroplanists in France, since his bold and brief
-dashes into the air in the early days of the art. During the season of
-1909, however, he developed a surprisingly small and simple monoplane,
-spreading 102 square feet of wing surface, and weighing in complete
-running order, 259 pounds. It was driven by a Darrac motor, mounted
-above the main surface, carrying the propeller directly on its shaft,
-and having radiator tubes along the inner surface of the main plane.
-Its triangular trussed frame was wheel-mounted, and tapered rapidly
-to the rear, terminating in horizontal and vertical rudders. With
-this tiniest flyer he sailed across country from St. Cyr to Buc, 4¾
-miles, in five minutes, at the unprecedented speed of 55 miles an
-hour, repeating the performance several times, according to report. He
-also left the ground after a run of 60 feet, in an unofficial trial.
-Characteristically, he presented to the public the scale drawings of
-his machine, with all rights to its use.
-
-A very original type of monoplane was developed by Robert
-Esnault-Pélterie, who began experimenting in 1903. As shown in Plate
-XXIX, its body frame was covered to reduce air-resistance, and was
-provided with ample keel surface to promote directness and steadiness
-of flight. The weight was borne on two wheels in tandem, aided by
-wheels at the wing tips to preserve the lateral balance when the
-machine was resting. When under way the lateral poise was controlled by
-wing warping; the motion about the other two axes being controlled by a
-horizontal and a vertical rudder, the latter being “compensated,” that
-is, having its axis near the center of side pressure, when in action.
-An air-cooled motor of 30 to 35 horse power with a direct mounted
-four-blade screw formed the propulsion plant. Though the “R. E. P.”
-aëroplane, as it was commonly called, did not achieve great distinction
-at first, due, perhaps, to the inventor’s being over original, and
-making all its parts himself, instead of buying some high-class engine
-and propeller, as other successful aëroplanists had done, still his
-machine was greatly admired by technicians for its excellent finish and
-the fastidious, thorough and patient manner in which its young inventor
-labored to make it perfect, both in design and construction. It was
-regarded as a future record breaker, which, indeed, it was destined to
-become on further improvement.
-
-Although little was accomplished in building aëroplanes in other
-countries than America and France, up to the beginning of 1909, that
-year witnessed some good flights in homemade machines in Germany,
-England and Canada. In November, 1909, Herr Grade, in Germany, made
-a flight of 55 minutes in his monoplane. Mr. S. F. Cody, who
-constructed a biplane for the British army, flew over forty miles
-across country on September 8th, high above trees and buildings,
-remaining on the wing for 63 minutes. The machine spanned 52 feet,
-weighed with the pilot, nearly a ton, and was controlled by front
-and rear vertical rudders and two lateral rudders, well in front, so
-geared that if worked oppositely the machine listed, while if worked
-identically it rose or fell. In Canada Dr. Alexander Graham Bell and
-his associates continued the experiments, already described, begun
-in 1908 by the Aërial Experiment Association. In 1909 their fourth
-machine, the _Silver Dart_, flew many times round a course on the
-frozen lake, Bras d’Or, traversing, all told, about 1,000 miles in 100
-flights.
-
-PLATE XXX.
-
-[Illustration: GRADE MONOPLANE.
-
-(Courtesy E. L. Jones.)]
-
-[Illustration: CODY BIPLANE.]
-
-The last months of this strenuous year, 1909, and of the first decade
-of dynamic flight, closed without further startling developments. True,
-some records were made, but they merely pleased, not perturbed the
-world, now accustomed to marvels. Be it recorded, however, that, with a
-Voisin biplane, Paulhan, on November 1st, flew 96 miles in 2 hours, 20
-minutes, and on November 20th flew 1,960 feet high in a Farman biplane;
-on December 9th, Maurice Farman, mounted on his own type of biplane,
-rode through the icy atmosphere from Buc to Chartres, a distance of 40
-kilometers, in 50 minutes, the longest town-to-town flight up to that
-date; and on December 31st he flew from Chartres to Orleans, a distance
-of 41.6 miles, in forty-six minutes. But several fine achievements
-which the world anticipated for that year remained unattempted. The
-great prize flight of 183 miles from London to Manchester was still
-untried, though several machines and pilots seemed equal to the voyage,
-and $50,000 would be awarded by Lord Northcliffe to the brave aviator
-who should accomplish that journey in not more than three stages and
-within a period of twenty-four hours. Neither had anyone yet flown
-to an elevation of one kilometer. These tasks were left over as
-allurements for the succeeding year.
-
-
-
-
-                              CHAPTER XII
-
-                            FORCING THE ART
-
-
-The decade that inaugurated dynamic man-flight had closed without fully
-demonstrating the capabilities of such aëroplanes as had been so far
-developed. No considerable altitude record had as yet been achieved. No
-very long cross-country flight had yet been attempted, though for many
-months the New York _World_ had offered $10,000 for the first aërial
-voyage from Albany to New York, and the London _Daily Mail_ had long
-offered $50,000 for a flight from London to Manchester. The uses of the
-aëroplane for scouting by land and sea had not been tested, much less
-its probable value in aggressive warfare. Such experiments were for
-the immediate future, as also the development of specialized types of
-machines for racing, for climbing, for burden bearing, for distance,
-for endurance, for landing on water, for rising from water, for
-protection of passengers from severe weather. To air men and spectators
-alike the future of the art promised to be quite as captivating as the
-past.
-
-The first startling achievements to usher in the new decade were the
-great altitude flights. New world records followed in rapid succession
-all through the year 1910, with marked persistence and wonderful
-progress. Levels that had been regarded as the peculiar region of motor
-balloons were passed one after another, until the aviators vanished
-beyond the clouds, their limbs palsied with cold, and their aëroplane
-wings whitened with frost. Though the greatest prizes were not offered
-for this species of flight, and frequently none at all, it had an
-abiding fascination for both the flyers and the public. At the same
-time it proved to be as safe as it was theatrical and popular.
-
-The starter in this exciting race for cloudland was Hubert Latham,
-already the official holder of the world’s altitude record. At Bouy,
-on January 7th, in presence of official witnesses, he rose in his
-_Antoinette_ monoplane, describing a great upward spiral till his
-barometer recorded 1,050 meters; then returned to earth with like ease
-and precision, landing softly near his hangar, before his assistants,
-transported with enthusiasm. He had touched the goal of Gallic
-ambition, having driven his aëroplane to the height of one kilometer.
-
-Latham’s tenure of the world’s altitude record quickly passed to
-his doughty rival, Louis Paulhan. At Los Angeles, on the twelfth of
-January, Paulhan, mounted on a Farman biplane, ascended 4,165 feet, as
-against Latham’s record of 3,444 feet. This was a great step upward,
-due not only to Paulhan’s prowess and dexterity, but also to the
-science and constructive skill of the less spectacular gentlemen in the
-designing room, workshop and laboratory.
-
-Latham strove again for the world’s altitude record and gained it on
-July 7th at the second Rheims tournament, by driving his _Antoinette_
-to a height of 4,541 feet.[53] But again his victory was soon eclipsed;
-for two days later, Walter Brookins at Atlantic City ascended 6,175
-feet in a Wright biplane. An American was thus the first to fly above
-one mile, as a Frenchman had been first to pass the 1-kilometer limit.
-The 2-kilometer and 2-mile elevations were exceeded before the close of
-the year, as shown by the following table, which also manifests a fair
-distribution of honors among various nations and types of machines:
-
-  --------+------------+------------+---------------+------------
-    Feet  |  Aviator   |  Aëroplane |     Place     |   Date
-  --------+------------+------------+---------------+------------
-    3,445 | Latham     | Antoinette | Betheny Plain | January 7
-    4,165 | Paulhan    | Farman     | Los Angeles   | January 12
-    4,541 | Latham     | Antoinette | Rheims        | July 7
-    6,175 | Brookins   | Wright     | Atlantic City | July 9
-    6,604 | Drexel     | Blériot    | Lanark, Sc.   | August 11
-    8,271 | Morane     | Blériot    | Havre, France | September 3
-    8,406 | Chavez     | Blériot    | Issy          | September 8
-    9,104 | Wijnmalen  | Farman     | Mourmelon     | October 1
-    9,714 | Johnstone  | Wright     | Belmont Park  | October 31
-   10,499 | Leganeaux  | Blériot    | Pau           | December 9
-   11,474 | [54]Hoxsey | Wright     | Los Angeles   | December 26
-  --------+------------+------------+---------------+------------
-
-Such lofty flights have proved a severe test of both the aëroplane and
-the pilot. In the lighter atmosphere the engine must turn the propeller
-at higher speed to secure the same thrust, and the aëroplane must sail
-faster to support the same weight as at the lower levels. Thus more
-power is required on high, though the explosive medium, being less
-dense, is less capable of exerting power. The driver has, therefore, to
-jockey his machine with assiduous care and alertness, at a time when he
-is least fitted for exertion, owing to fatigue, cold, and it may be,
-physical discomfort due to the great change of atmospheric pressure.
-But still, both aëroplane and pilot are capable of ascending well above
-any levels thus far attained.
-
-After the triumphant altitude flights of 1910 the aëronautical
-skeptics could no longer contend that the aëroplane was useless in
-transportation and warfare, because of its inability to fly above
-high land or the usual range of the guns of battleships and coast
-fortifications. Most of the important mountain passes lie below 10,000
-feet. The safe elevation for motor balloons menaced by terrene guns is
-taken to be much less than two miles, and in military practice they
-usually operate below the one-mile level. The aëroplanes, therefore,
-may not only cross mountain ranges, but may also scrutinize, or
-grievously molest, land forces, marine squadrons and perhaps even the
-great gaseous cruisers of the atmosphere, which they can far outspeed,
-and may even destroy.
-
-The increase in speed of flight during 1910 was also quite remarkable.
-The official record by which Mr. Curtiss won the Bennett Aviation
-Contest at Rheims, in 1909, showed a speed of 47.04 miles an hour.
-Still higher velocities, ranging from 50 to 60 miles an hour, were
-reported later in that season from England and France. In 1910,
-however, at the Rheims aviation meet, Morane, with a Blériot monoplane,
-covered the 20-kilometer course in 12 minutes 45.2 seconds, or at an
-average speed of 66.2 miles an hour, showing a gain of forty per cent
-on Mr. Curtiss’s speed of the preceding year. Still better was achieved
-at the international tournament held at Belmont Park in 1910. Le Blanc
-in a 100-horse Blériot monoplane, especially designed for speed,
-covered nineteen laps of the 5-kilometer course at an average rate of
-61 miles an hour, and his fastest lap at the rate of 71.68 miles an
-hour, thus exceeding Curtiss’s speed of the previous year by fifty per
-cent. Other spurts during the latter part of 1910 were reported to have
-attained nearly 80 miles an hour over a closed circuit, though perhaps
-not a level one. The best results were achieved with machines having
-high power engines, small surfaces and slight forward resistance.
-
-The advance in long-distance flying in 1910 more than kept pace with
-the progress in speed. The best achievement at the close of the
-preceding year had been Farman’s flight of 144 miles at an average rate
-of 35.06 miles an hour in a closed circuit. At the Rheims aviation meet
-in 1910, Jan Olieslaegers, in a Blériot monoplane, driven by a Gnome
-engine, covered 244 miles in a rectangular course, at an average speed
-of 48.31 miles an hour. At Buc, on the 28th of October, an aviator of
-three months’ practice, Maurice Tabuteau, in a Maurice Farman biplane,
-driven by a Rénault engine, flew over a closed circuit, covering 288.8
-miles at an average speed of 47.9 miles an hour. At Pau on December
-21st, M. G. Leganeaux, in a Blériot monoplane, flew for the Michelin
-Cup, covering 516 kilometers or 320.6 miles in six hours and one
-minute, or at an average speed of 53¼ miles an hour—a splendid showing.
-Finally, at Buc, on December 30th, Tabuteau, flying for the annual
-Michelin prize, covered 362.66 miles in a Maurice Farman biplane with
-an 8-cylinder 60-horse Rénault motor. The average speed in this very
-long flight was 47.3 miles an hour, or practically the rate by which
-Curtiss won the international contest of the preceding year. Of course
-a considerably better showing of both distance and velocity could have
-been made on a longer course.
-
-The world records for cross-country flying and for endurance and load
-illustrate both the increasing perfection of the machine and of the
-pilot’s skill and confidence. At Los Angeles, on January 19th, Mr. and
-Mrs. Paulhan, in a Farman biplane, flew together 21 miles overland from
-the aviation field to Redondo and Hermosa Beach and return. On January
-31st Van der Born made a world’s duration record with a passenger on
-a Farman biplane, flying 1 hour 48 minutes 50 seconds. On March 5th,
-Henri Farman, who had previously twice broken the world’s duration
-record for a pilot with two passengers, set a new and astonishing
-pace at Mourmelon, by carrying Mr. Hevardson and Madame Frank in
-easy flight for 62.5 minutes on his new biplane. In France, on April
-3d, Emile Dubonnet on his _Tellier_ monoplane flew from Juvisy to La
-Ferte-Saint Aubin, a distance of 109 kilometers or 70 miles in 1 hour
-and 50 minutes, thus winning the ten-thousand-franc prize offered
-by _La Nature_ for the first straightaway flight of 100 kilometers
-to be effected in less than two hours, over a previously indicated
-course. This fine record voyage was achieved in a machine never before
-thoroughly tried. At Chalons-sur-Marne, on April 8th, Daniel Kinet,
-a Belgian, mounted with a passenger on a Farman biplane driven by
-a 50-horse Gnome engine, broke the world’s record for duration and
-distance for two persons by flying round a closed circuit 2 hours 19¼
-minutes, covering a distance of 152 kilometers, or 94 miles. On April
-17th, H. Farman, with a passenger in his biplane, voyaged from Etampes
-to Orleans, 28 miles. Next day, Paulhan, mounting the same machine,
-flew 108 miles, and the following day 42 miles. This tour established a
-new cross-country record for total distance, for single stage distance
-with one passenger, and for duration and single stage distance with two
-passengers. During the same month Farman made a new record for four
-passengers by carrying three gentlemen for 1 hour and 4 minutes on his
-new biplane, spreading 47.6 feet. On June 9th, two French officers,
-Lieutenant Fequant piloting and Captain Marconnet observing, flew
-on a Farman biplane from Bouy to Vincennes, 145 kilometers, in two
-hours and a half, thus breaking the world’s cross-country distance and
-duration record for a pilot with a passenger. On June 13th, Charles K.
-Hamilton, in a Curtiss biplane, flew from New York to Philadelphia, a
-distance of 86 miles in 103 minutes, and returned the same day, thus
-completing 172 miles in one day. This was an exhibition flight made for
-_The New York Times_ and the _Philadelphia Ledger_, for a sum reported
-to be $10,000. It was a sequel to Glenn H. Curtiss’s memorable flight
-on June 5th, down the Hudson River from Albany to New York, for the New
-York _World’s_ $10,000 prize. Hamilton’s average speed was 50 miles
-an hour going and 51 miles returning. On August 29th, at Lille, Louis
-Bréguet is reported to have carried with him on a biplane of his make,
-five passengers, who, together with the gasoline, weighed 921 pounds.
-It may be added that the Bréguet biplane of that date was advertised
-and guaranteed to carry a cargo, or extra load, of 250 kilograms. It
-thus appears that by 1910 the aëroplane had grown powerful enough for
-an aërial cab service, and that it could carry sufficient explosive
-gelatine to derange a battleship.
-
-The contest for cross-country records continued unabated all that
-memorable year. During the first three days of September, Jean
-Bielovucic, a youth of twenty-one, mounted on a new type of Voisin
-biplane, with but a few days’ practice, flew from Paris to Bordeaux,
-covering 540 kilometers, or 336 miles, in four stages, comprising
-altogether 6¼ hours on the wing. In spite of severe weather, at times,
-he beat the regular express train and established a new world’s record
-for cross-country straightaway distance flying with stops. On August
-17th, Alfred Le Blanc, finished a six-stage tour round a hexagonal
-circuit northeast of Paris, with the finish at Issy, near Paris,
-covering a total distance of 785 kilometers, or 440 miles, in 12
-hours 56.4 seconds effective time. On September 7th, Weyman flew with
-a passenger from Paris to Clermont near the Puy de Dome, covering
-205 miles in one day, while trying for the Michelin prize of 100,000
-francs, for a flight to the Puy de Dome inside of six hours. On
-December 18th, Thomas Sopwith, competing for the longest flight across
-the Channel and into Belgium, on a British-built aëroplane, flew from
-the Isle of Sheppy across the Channel, and landed at Beaumont, Belgium,
-covering a distance of 174 miles in 3.5 hours. At Buc, on November
-27th, Laurens, in a 60-horse R. E. P. monoplane, flew with his wife 53
-miles at an average speed of nearly 50 miles an hour. On December 22d,
-Lieutenant Cammerman, a French army officer, won the L. Weiller prize
-by flying across country with a passenger, 147 miles in 4 hours and 2
-minutes.
-
-These are but a few of the records which serve to illustrate the
-progress in cross-country flying during that year of strenuous and
-world-wide popular demonstrations. But the bare numerical statement of
-facts can give no conception of the delight and exultation aroused in
-millions of souls who witnessed or learned of these marvelous human
-achievements. They were the advancing triumph of a proud and fortunate
-generation, happy in realizing one of the fondest dreams of the ages.
-Often during one of these cross-country flights the aëroplane was
-accompanied by a swift railway train whose passengers were delirious
-with enthusiasm. The entire route was thronged with people assembled
-from afar. It was a general holiday for all the fortunate cities and
-villages along the way. Mills and factories blew their whistles and
-forgot the serious business of life, homes were deserted, schools
-were dismissed; the whole population for the time congregated in
-the open; bearded mechanics in their aprons, bare-armed housewives
-holding their children aloft, girls and boys with wondering eyes, all
-shouting, waving banners, throwing up hats, and hailing with tumultuous
-demonstration that strange and huge-winged creature gliding from
-horizon to horizon with the steadiness, precision and directness of a
-mighty projectile. But beyond stating the records of this season of
-aërial wonders, only a passing notice can be given to some of the more
-conspicuous events.
-
-The most famous overland voyages of the season 1910 began with the
-race for the London _Daily Mail_ prize of $50,000, offered by Lord
-Northcliffe for the first person who should fly from London to
-Manchester, 183 miles within twenty-four hours, with not more than
-two stops. An Englishman, Claude Grahame-White, comparatively new in
-the pilot’s art, was first to undertake that difficult and perilous
-adventure. Starting from London, without competitor, on April 24th, he
-flew in his Farman biplane, from London to Rugby, thence to Hademore,
-about halfway to Manchester, landing at a quarter past nine o’clock
-at night, after a four-hour trip, and hoping to reach Manchester next
-day. But during the night his aëroplane, which was left in the open,
-was damaged by the wind, thus necessitating repairs and a new start. On
-April 27th, while he was strenuously mending and adjusting his biplane
-for a new start, Louis Paulhan, who the day previously had arrived from
-France with a Farman biplane to enter the contest, was also vigorously
-setting up and adjusting his machine.
-
-At half past five in the afternoon, Paulhan suddenly set out for
-Manchester. Mr. White, who was much fatigued and expecting to start on
-the morrow at dawn, after much-needed rest, learned toward six o’clock
-that his rival was on the wing, and hurriedly sailed from London,
-hoping by skill and good chance to overtake the flying Frenchman.
-The race was now the most exciting event in the world. The first
-flyers of France and England were competing for the greatest prize
-yet offered in the history of aviation, competing in a most modern
-and extraordinary race, attended with abundant danger and hardship.
-The contestants were evenly matched in mechanism and capability, but
-the Frenchman had gotten the march on the unwary Englishman. Paulhan
-followed the Northwestern Railway, at times outracing the special
-pilot train carrying his mechanics and supplies. At ten minutes after
-eight o’clock, he landed at Lichfield, having covered 115 miles. Mr.
-White had landed five minutes before eight near Roade, after flying
-fifty-nine miles.
-
-Next morning, Paulhan sailed away at a quarter past four. Mr. White,
-hoping to overtake him, had started at dead of night and covered
-twenty miles before Paulhan had started. It was a heroic effort, but
-unavailing. At twelve minutes after five, Mr. White landed at Hademore,
-having completed two thirds of the entire journey. Twenty-five minutes
-later Paulhan landed on the outskirts of Manchester, greeted by a
-thousand persons. He had covered the whole distance in 4.2 hours, and
-had fulfilled all the essential conditions for winning the great prize.
-
-The next world-famous aëroplane voyage was that of Glenn H. Curtiss for
-the New York _World’s_ prize of $10,000 for the first aërial journey
-from Albany to New York, allowing two stops. Aviators had been yearning
-for this prize since the previous year, but had been too timidly shying
-at the dangers of the route. After most careful preparations for this
-voyage, Curtiss, bearing a letter from the Mayor of Albany to the
-Mayor of New York, sailed away at seven o’clock on Sunday morning, May
-29th, accompanied by a New York Central special train, bearing his wife
-and a few friends and newspaper men. He landed an hour for supplies
-and adjustment at Camelot, 41 miles down the river, and thence flew to
-Spuyten Duyvil, at the northern extremity of New York, having completed
-the required distance, 128 miles, in 2 hours and 32 minutes, or at the
-rate of 50.52 miles per hour along the course. An hour later, he flew
-down the river to New York Harbor and landed on Governor’s Island,
-where he received a becoming ovation.
-
-Perhaps the most exciting incident of the voyage to Mr. Curtiss was his
-transit of the Storm King Mountain. As he was flying through the narrow
-gap at this place he caught the down-rolling air on one side more
-than on the other, and dropped very suddenly sidewise 30 or 40 feet.
-By shifting his front control, he quickly gained headway and promptly
-righted his machine.
-
-Commenting on Mr. Curtiss’s average speed of 50 miles an hour and his
-rugged course, _Aëronautics_ makes comparison between his voyage and
-Paulhan’s great prize flight as follows:
-
-  “Paulhan took 4 hours 12 minutes elapsed time to cover 183
-  miles when he won the _London Mail’s_ $50,000 and made it in
-  two stages of 117 and 66 miles each. The 117 miles were covered
-  in 2.39, a rate of nearly 44 miles per hour. A night’s sleep
-  intervened and the remaining 66 miles were covered in 1.23, a
-  rate of nearly 48 miles per hour. The average for the above
-  was 44.37 miles per hour. Paulhan could have landed at almost
-  any time and started again, whereas Curtiss could not have
-  started if he had had to land in the water, and for the whole
-  distance there was scarcely a suitable space for landing on the
-  ground, as for nearly the entire way rocky, wooded hills with
-  precipitous sides line the river.”
-
-The most audacious and marvelous aëronautic exploit of the year was the
-flight of George Chavez across the Alps from Brig to Domodossola, in
-his attempt to win the prize of 70,000 francs offered by the Italian
-Aviation Society for the first aëroplane flight from Brig to Milan, a
-distance of 75 miles. From the nine volunteers for this contest who
-presented themselves to the committee in charge, five competitors
-were selected, and these for several days made tentative efforts to
-scale the lofty pass, but were baffled by the wind or fog. Finally at
-one-thirty, on September 23d, the conditions being favorable, Chavez
-rose, from Briegen-Berg, in his white-winged Blériot, spiraled upward
-1,000 meters, circling around the vast amphitheater of the mountains,
-and in nineteen minutes appeared in magnificent career well above the
-Simplon Pass, probably 7,000 feet above the sea, whence he glided
-grandly down the Italian slope, parrying the rude cross winds and
-finally reaching Domodossola, where the enthusiasm was at its climax.
-Here he expected to land on a level spot to replenish his supplies,
-thence proceed over the easy remaining two thirds of his journey. But
-though the perilous pass had been crossed so successfully, disaster
-appeared in the valley when least expected. As the aëroplane was
-gliding thirty feet high over the level tract chosen for landing, it
-met a sudden gust, its wings collapsed, and it fell crashing to earth,
-pinioning its brave pilot under the débris.
-
-Poor Chavez suffered severe wounds about the face and head, had both
-legs broken, and for some moments lay unconscious. But he was soon
-revived by his friends and taken to a hospital, where he died four
-days later. Thus ended the career of a brave and most promising youth
-of twenty-three. He had taken his pilot’s license only in February,
-1910, yet had established a new world’s record on September 8th, by
-driving his Blériot to an elevation of 8,406 feet. He was of Peruvian
-parentage and born in Paris.
-
-The exact nature of the accident was never ascertained, but it was
-surmised that the sudden starting of his engine preparatory to landing
-overstressed some part of the structure already fatigued from hard
-usage. However this be, the committee recognized that Chavez had with
-excellent skill covered all the really difficult and dangerous part
-of this journey. Accordingly they very generously waived the exact
-letter of the rules, and awarded him one half the prize, though he had
-completed but one third of the journey.
-
-Quite as dangerous, spectacular and brilliant as the flight across
-the Alps, though less arduous, was Hubert Latham’s aërial voyage over
-Baltimore. On previous occasions cross-city flights had been made,
-but never one of such length or one executed under such exacting
-conditions. At various times aviators had flown above Paris, Rome,
-Berlin, etc. On October 14th Mr. White had flown across Washington,
-landing on a narrow street between the White House and War Department;
-on October 15th Leganeaux had flown above Paris with a passenger; but
-these were short flights over an uncharted course. Latham’s voyage
-was unique; for he had to follow a long and a prescribed course over
-the business section and closely built residence portion of the city.
-This great exploit was an exhibition flight made on the invitation
-of the _Baltimore Sun_ for a sum of $5,000. It was to be made at the
-time of the Baltimore aviation tournament at Halethorpe, Md., and was
-calculated to be seen by half a million people; for the whole city was
-to be notified and would cease its usual activities to witness the rare
-and hazardous demonstration.
-
-The voyage was triumphant and glorious in every feature. Starting from
-the aviation ground, seven miles south of Baltimore, about noon on
-November 7th, Latham drove his beautiful _Antoinette_ about the field
-in an ascending spiral, like some imperial bird taking its bearings;
-then, chart in hand, deliberately sailed away over his elaborately
-prescribed journey. This was a figure 8 course with its bottom at the
-aviation field and its center at the _Sun_ Building in the heart of
-Baltimore, the whole length being 22 miles. As the long-winged bird
-in majestic poise, with the intrepid rider on its back, approached
-in the distance, soaring 1,000 feet above the gleaming waters of the
-Chesapeake, the great bell of the City Hall sounded a mighty peal, and
-the whole populace responded in tumultuous chorus; whistles, bells and
-a myriad voices mingling their heartiest welcome to the bravest of
-aviators. With arrowlike speed and directness he rounded the center of
-the course at the _Sun_ Building, then looped the vast northern half of
-the city, flying a thousand to three thousand feet high, more easily
-to parry the surging eddies of the northwest wind; rounded again the
-center of his course and then returned to the aviation field, where he
-landed with infinite coolness before the excited throng of applauding
-spectators, whose acclaim was all too feeble to express their mingled
-wonder, admiration and delight. The voyage lasted forty-two minutes and
-fulfilled perfectly every minute requirement, including a short circle
-and salutation before the home of Mr. Ross Winans, an invalid gentleman
-who had solicited this unique favor, and rewarded it with a gift of
-$500. It was the climax of the aviation week at Baltimore.
-
-Among the many brilliant flights of that memorable year of strenuous
-piloting will long be remembered the voyage of the Hon. C. S. Rolls to
-Calais and return without landing, and that of Mr. Sopwith, already
-recounted; the splendid flight of Mr. Clifford B. Harmon in his Farman
-biplane from Mineola, Long Island, to a small rounded island before
-his house on the Connecticut shore, for the trophy offered by _Country
-Life_ to the first person who should fly across Long Island Sound;
-Henri Farman’s flight of December 18th, for the Michelin long-distance
-prize, covering 288 miles, and establishing a new endurance record of
-8 hours 23 minutes; Mlle. Helene Dutrieu’s flight of December 21st,
-for the Coupe Femina, covering 103¾ miles in 2 hours and 35 minutes
-in a Farman biplane. Interesting, too, were the first attempt to fly
-from Paris to Brussels with a passenger, when Mahieu and Manihé on
-starting were brought to bay by a vicious dog which violently attacked
-the propeller and was cut in two; and when Loridan and Fay landed on a
-tree, from which they descended by a ladder. After this followed the
-glorious voyage of Henri Wijnmalen, the youthful and many-sided Dutch
-sport, for the prize of 150,000 francs offered by the Automobile Club
-of France for the quickest aëroplane trip not exceeding 36 hours, with
-a passenger from Paris to Brussels and return. This voyage of some
-320 miles was valiantly accomplished by Wijnmalen and his companion
-Dufour, in a day and a half, of 13.2 effective hours, and in weather
-for the most part windy or tempestuous. Finally to the foregoing list
-of splendid achievements must be added the glorious voyage of John
-Moisant, who in August flew with a passenger, by compass, from Paris to
-London, though he had never been over the route before and had only
-just learned to use an aëroplane.
-
-The International Aviation Tournament of 1910, held at Belmont Park,
-Long Island, October 22d to 31st, was the most prominent and eventful
-meet of the year, and the second of its kind in history, as the
-meeting of the preceding year at Rheims was the first. The present
-meet was conducted by the Aëro Corporation, Limited, of New York,
-under the auspices and official sanction of the Aëro Club of America,
-representing the Federation Aëronautique Internationale.
-
-This tournament was the annual aërial Olympic contest of the world, and
-should have been indicative not only of the aviator’s skill, but also
-of the state of national progress in the science and art of aëroplane
-construction. Unfortunately, however, for the prestige of the most
-deserving nations, the rules of the International Aëronautic Federation
-did not confine the contestants to the use of home-built machines, to
-prevent the glory of winning the international contest from passing to
-the nation which merely furnished the operator, a person who might be
-an illiterate jockey, and representative of a country wholly devoid of
-science. As luck decided, however, the highest honor in 1910 was won by
-a first-class French machine driven by a first-class English aviator.
-
-In some respects the raw material and working elements of this meet
-were most satisfactory. The site is near the wealthiest and most
-populous center in America. The grounds are spacious and level,
-and provided with all the equipment of a great race course; the
-transportation facilities by carriage and by rail from the heart of
-New York are adequate to every requirement. The personnel of the
-meet comprised the most experienced and most devoted members of the
-Aëro Club of America, the oldest and strongest aëronautical body in
-the western world, and the only one representing the International
-Aëronautic Federation. It is true the season was late and the weather
-would probably be cold and tempestuous; the management was burdened by
-a costly license, whether just or unjust, imposed upon it as the price
-of immunity from patent litigation; the remaining time, after the final
-placement of the meet, was all too short for the myriad preparations
-to be made. But whatever the obstacles, physical or financial, the
-personnel was paramount, and naturally made the huge tournament a
-glorious triumph. It was the cardinal sporting event of the year.
-
-The status of aviation was well represented in both pilots and
-machines. Twenty-seven aviators were entered on the program, many of
-them world famous. Of these Alfred Le Blanc, Hubert Latham, Emile
-Aubrun were the formidable champions of France in the contest for the
-James Gordon Bennett aviation trophy; Claude Grahame-White, James
-Radley, A. Ogilvie represented England; while Walter Brookins, J. A.
-Drexel, Charles K. Hamilton were enlisted as defenders of the coveted
-cup and of American prestige. All told, the aviators brought with them
-nearly two-score machines, ranging in capacity from 30 to 100 horse
-power. Of these about half were monoplanes and half biplanes, for the
-most part of French and American manufacture.
-
-The prizes and remuneration awarded to the contestants were on a
-scale proportionate to their skill and number. All told the winnings
-aggregated more than $60,000. Further appropriations were made to
-cover the expenses of the aviators, and a further sum equal to about
-forty per cent of the winnings was paid for immunity from prosecution
-for possible infringement of an unlitigated patent. Considering the
-immense expenditures for buildings, for policing and other incidentals
-of the meet, it may be readily inferred that there was an ample
-deficit, and that the air men as a whole were much better rewarded
-than some of the sportsmen who gave so much time and labor to the
-organization of the tournament.
-
-A conspicuous feature of the meet was the display of hardiness and
-skill of several of the aviators in facing the cold and tempestuous
-weather. This was particularly characteristic of Latham in his
-_Antoinette_ monoplane, and of Ralph Johnstone and Arch Hoxsey in
-Wright biplanes. On October 27th Latham flew round the regular course
-for an hour when it was nearly impossible to turn the pylons against
-the fierce wind, while Johnstone and Hoxsey performed lofty altitude
-flights in a powerful gale which carried them backward, sometimes at
-the rate of 40 miles an hour. As a consequence they landed in the
-open country, remained overnight and returned next day. Johnstone was
-carried backward to Holtsville, 55 miles east of the aviation grounds,
-and Hoxsey was blown to Brentwood, 25 miles away, both landing at dusk
-in open fields, and both having attained great elevations: Hoxsey,
-6,903 feet; Johnstone, 8,471 feet.
-
-An interesting novelty of the aviation week, at least to Americans,
-were the erratic Demoiselle monoplanes, invented by Santos-Dumont and
-piloted by Garros and Audemars. These aëroplanes were notable as having
-the pilot under the sustaining plane, and the engine above with its
-direct mounted propeller. The lateral stability was enhanced by a low
-placement of the center of mass, and by a slight dihedral inclination
-of the wings. Furthermore, as there was not much leverage or surface in
-the rear double rudder, the flight was more stable than steady, like
-that of a propelled parachute. In fact, the little monoplanes pitched,
-rocked, and fluttered about so like huge butterflies as to provoke
-constant merriment. They gave a faint suggestion of how ludicrous
-aëroplane clowns could be made by one who has genius for such things.
-
-Barring the stormy voyages above mentioned, the most memorable events
-of the tournament were the Gordon Bennett speed contest, the Statue of
-Liberty race and Johnstone’s great altitude flight. Of the numerous
-other performances little need be said, except that they contributed
-to the general success of an elaborate and most interesting program.
-They served the daily need of a costly tournament; they delighted vast
-throngs of spectators whose admission fees helped to promote the aërial
-sport; but they did not of themselves have more than local interest, or
-constitute an advance in the records of first-class achievement.
-
-The chief race of the meet, the James Gordon Bennett speed contest,
-was scheduled for Saturday, October 29th. The prize of $5,000 and the
-coveted cup were to be awarded to the pilot who should make the best
-average speed in 20 laps over a 5-kilometer course, aggregating 100
-kilometers, or 62.14 miles. The winner should have the distinguished
-honor of taking to his own country the next annual contest for the
-precious speed prize.
-
-Grahame-White, England’s foremost aviator and strongest hope in
-the contest, brought forth his untried 100-horse Blériot in the
-calmest part of the day, and took wing a quarter before nine. He
-flew with steady poise and swift, well-sustained speed, completing
-the 100-kilometer distance in 1 hour 1 minute and 4.7 seconds, at an
-average speed of 61 miles an hour.
-
-Le Blanc, the most likely winner of all, sailed at nine o’clock. He was
-mounted on a 100-horse Blériot with nearly flat wings, the swiftest
-monoplane of French manufacture. He was the boldest, sturdiest and
-most dexterous pilot in a nation of renowned aviators, the winner of
-unnumbered trophies, the “Vainquer de l’Est.” He now flew at unwonted
-speed, establishing new world records at every round of the course. It
-seemed evident to the timers that only an accident to this impetuous
-Frenchman could retrieve the glory of England and save that of America.
-Suddenly the accident came. In the last lap, when victory seemed
-assured, the gasoline failed; the monoplane shot downward, knocked off
-a telegraph pole, and, with broken frame and engine, fell crashing
-to earth, entangling the brave aviator. Le Blanc was cut and bruised
-about the forehead, and was taken to the hospital to be bandaged,
-not seriously injured but in a towering rage, suspecting that some
-trickery had given him a shortage of fuel. He had lost the day, though
-his average speed for the whole flight was 67 miles an hour as against
-Grahame-White’s speed of 61 miles.
-
-No well-tried machine was available to defend the American prestige.
-Curtiss had constructed a new monoplane designed for speed, but though
-he had brought the cup to America, he was not chosen as one of its
-three defenders. The little Wright biplane of 61 horse power had
-flown a few minutes with great velocity, and was looked to with some
-confidence. Mounted by Walter Brookins, it set out with tremendous
-speed, but had only well started when the cylinders began to miss fire.
-Brookins turned toward the infield to land, struck the ground with
-terrific shock and tumbled violently on the field beside his broken
-machine. He, too, was taken to the hospital for treatment, but was not
-seriously injured.
-
-It was now granted that Grahame-White would be the ultimate winner.
-Other aviators attempted to defeat him, but lacked either the necessary
-speed or endurance. The cup was accordingly taken from the nations
-that had done the most to develop the practical art of aëroplaning. Of
-these two nations, the one most deserving of victory, by virtue of its
-more careful preparation, was defeated by an extraordinary mishap, when
-victory was at hand; the other failed perhaps for want of preparation
-rather than from lack of manipulative or constructive skill.
-
-Of the various highly coveted stakes the largest in monetary value was
-known as the Thomas F. Ryan Statue of Liberty Prize. This was a cash
-sum of $10,000, to be awarded to the properly qualified contestant who
-should fly from the aviation ground to and around the Statue of Liberty
-in New York Harbor, and return in the shortest time, the airline
-distance being 16 miles each way. The prize was founded by Mr. Thomas
-F. Ryan, whose son, Allan A. Ryan, was Chairman of the Committee on
-Arrangements of the tournament, and who though suffering with pain and
-ill-health, labored so indefatigably to insure the success of the event
-so germain to the aëronautical prestige of his country.
-
-The Statue of Liberty race occurred on Sunday afternoon, October 30th,
-beginning just after three o’clock. Count De Lesseps in a 50-horse
-Blériot monoplane led the race, followed three minutes later by
-Grahame-White. They passed toward the southwest in perfect poise and
-vanished beyond the horizon unchallenged by an American contestant;
-for Moisant, the American champion, had shortly before injured his
-racing monoplane, and the other American racing machines had been
-damaged the week before, or had not yet been fully tested. But with
-admirable enterprise, Moisant telephoned Le Blanc, in New York, who
-was not racing because of the accident to his 100-horse Blériot the
-day previously, and offered the Frenchman $10,000 for his 50-horse
-Blériot monoplane. The sale was effected in time for the race that
-day. But for all that the enterprise seemed futile; for as Moisant
-was preparing to start, the others were returning, Grahame-White well
-in the lead, having overtaken De Lesseps. As these two aviators were
-receiving the applause of innumerable spectators and the felicitations
-of their friends, audacious Moisant, the impetuous soldier of fortune,
-and hero of the famous flight by compass from Paris to London, started
-toward the declining sun, just after four o’clock. He was determined
-to win by superior skill and daring. His prudent competitors had
-followed a circuitous southern route interspersed with landing places;
-but he flew like a maniac straight over the church spires and crowded
-buildings of Brooklyn, guided to his goal by a compass, rounded the
-Statue of Liberty at a great altitude and plunged homeward with all
-possible speed and directness. The megaphone announced his progress,
-which indicated some hope of victory so little expected and so much
-desired by the vast throng that stood gazing toward the western sun.
-In headlong career the swooping monoplane shot by the judges’ stand,
-circled and softly landed on the field, triumphant by 43 seconds
-over the 100-horse Blériot of Grahame-White. As the intrepid aviator
-approached the vast and delighted throng of spectators to acknowledge
-its noisy and tumultuous ovation, he was met by the chiefs of the
-tournament, draped in an American flag, and paraded before the grand
-stand, “which shook in its effort to do honor to the little air
-conqueror.” Ultimately, however, the prize was awarded to Count
-De Lesseps, because Moisant had failed to qualify properly, and
-Grahame-White had fouled the initial pylon.
-
-The final day of the tournament was made memorable by Johnstone’s
-altitude flight. The best previous record was that of Wijnmalen to an
-elevation of 9,104 feet, made at Mourmelon, France. Johnstone ascended
-on a small Wright machine with powerful propellers adapted to rapid
-climbing, determined not only to surpass Wijnmalen but to exceed,
-if possible, the ten-thousand-foot level, and win the special prize
-offered for such achievement. He actually rose to the great elevation
-of 9,714 feet, but could not develop power enough to continue upward.
-On his descent he fully exhausted his fuel at 3,000 feet, and thence
-glided to earth, landing softly, 1 hour and 43 minutes from the time of
-starting.
-
-Thus the greatest tournament of the year terminated with fine new
-laurels for the science and art of aviation; for the spectacular
-pilots and for the unseen men behind them—the scientific men in the
-laboratories, the designing rooms and the workshops. New standards had
-been established in speed, in altitude, in prowess and daring. In these
-elements, the spectators could hardly ask for a better exhibition. What
-is it to the onlooker to have an aëroplane go higher than the cumuli,
-since at that level a thousand feet makes no perceptible difference?
-What more could he wish in dexterity of manipulation and audacity in
-braving the elements? One thing more, doubtless, and that is, security
-and precision of flight in stormy weather. When these improvements
-shall have been effected much will have been added to both the sportive
-interest and practical utility of the aëroplane.
-
-The most businesslike and crucial flying contest of the year was the
-famous “Circuit de l’Est,” organized by the Paris _Matin_. It was a
-competitive voyage over an irregular hexagonal course, lying generally
-northeast of Paris, and having its vertices at various cities to the
-east and north of the national capital. The main prize offered by
-the _Matin_ was one hundred thousand francs for the first air man to
-complete the entire course, doing the first side of the hexagon on
-August 7th, and the succeeding sides in regular order on successive
-odd days of the month, the place and hour of starting each stage
-being assigned in advance. Various subsidiary prizes aggregating
-nearly a hundred thousand francs more, were available for meritorious
-performances at the various stages and stopping-places along the
-route. But there were also penalizations for those contestants who
-failed to start on schedule time and observe the rules of the course.
-
-[Illustration: FIG. 41.—MAP OF THE “CIRCUIT DE L’EST.”]
-
-The race began at Issy, near Paris, on August 7th, with eight aviators
-on the wing—Le Blanc, Aubrun, Leganeaux, Mamet, Lindpainter, Weyman. It
-terminated August 17th, headed by Alfred Le Blanc on his Blériot, and
-followed by Emile Aubrun on a Blériot, then by Weyman on a Farman, all
-three driven by Gnome engines actuating Chauvière propellers. Le Blanc
-completed the tour of six stages, covering an air-line distance of 488
-miles, in 12 hours’ effective flying, or at the average rate of 40.6
-miles per hour.
-
-This long tour on schedule time over a rough and varied country in
-face of fog, wind and rain, was a most severe trial of the prowess and
-endurance of the brave pilots who had the hardiness and pertinacity
-to complete the voyage. Needless to add that it created unbounded
-enthusiasm among millions of people who witnessed the event, or read of
-it, and that the clocklike precision of the “grand raid” inspired new
-confidence in the practicability of the aëroplane.
-
-A particularly impressive feature of the event was that many of its
-participants, the aviators, government officers, and members of the
-controlling committee, assembled at Issy and other posts of duty,
-not by rail, but by aëroplane, sailing across country from many
-directions and from great distances. This matter-of-fact procedure led
-many persons to believe that the period of mere demonstrations had
-approached its close, and that the epoch of practical utility was at
-hand; that after marveling so much at the aëroplane, with mingled faith
-and skepticism, people would next calmly turn it to practical use.
-
-Though the progress in designing and constructing aëroplanes in 1910
-did not keep pace with the wonderful advance in new records, still the
-inventors and manufacturers continued industriously to perfect the
-details of their best standard machines, and in a few instances to
-make radical innovations. The perfection in details of construction
-manifested itself in the public performance of aëroplanes, particularly
-in their greater reliability and their increased capabilities. The
-radical innovations were mainly experimental, and not generally
-exhibited, though none the less important for all that. Chief of these
-perhaps were the hydro-aëroplane developments of Fabre in France, and
-of Mr. Glenn H. Curtiss in America, which enabled the aviator to launch
-into the air directly from the water and to alight safely on the water,
-thus virtually adding a new and very important domain to the empire of
-dynamic flight.
-
-Curtiss, in 1909, succeeded in landing his aëroplane safely on the
-water of Lake Keuka, first with sheet iron cylindrical floats under
-each wing, and a simple float well to the front of his protruding
-chassis, then with a hydroplane surface to the front as being more
-effective than the float. But when he attempted to glide up from the
-lake with this arrangement, he could not entirely clear the surface,
-though his aëroplane under the powerful thrust of her aërial screw,
-very nearly lifted from the water. Then he planned to use hydroplane
-floats, of hollow wing form, and of such size that they would buoy up
-the machine when at rest, and during motion would skim over the water
-like a skipping stone, till the biplane should acquire sufficient speed
-to rise by the dynamic reaction of the air. In the successful execution
-of this plan, however, he was anticipated by Fabre, who made the first
-successful flight from the water, on March 28th, 1910, at Martigues,
-France. But the Frenchman was not left to bear the palm alone. Early in
-the year 1911, Mr. Curtiss rose and landed successfully on the water at
-San Diego Bay, Cal., by means of a single float like a flatboat placed
-centrally under his biplane, seconded by small auxiliary floats at the
-wing ends. A full account of these valuable contributions to aviation
-is given in Appendix V.
-
-PLATE XXXI.
-
-[Illustration: FABRE HYDRO-AËROPLANE.
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: PAULHAN HYDRO-AËROPLANE.
-
-_Photo E. Levick, N. Y._]
-
-[Illustration: MOISANT METAL MONOPLANE.
-
-(Courtesy A. J. Moisant.)]
-
-As shown in Plate XXXI, Fabre’s hydro-aëroplane was substantially a
-monoplane mounted on three richochet floats. It was propelled by a
-screw at the rear, and controlled in flight by the usual three-torque
-system, in this case consisting of horizontal rudders in front,
-vertical rudders front and rear, and suitable mechanism for twisting
-the wings. The floats were hollow to give them static buoyancy; they
-were curved fore and aft like wings, to give them dynamic lift, both in
-water and in air; they were elastically constructed with thin veneer
-bottoms and flexibly attached to the framing, so as to endure the
-severe buffeting, at high speeds, against the uneven water surface;
-they were capable of landing the machine safely on a sandy beach or
-meadow, as well as on the water. Indeed, a plan was conceived for
-rising and alighting on land and water indifferently.
-
-[Illustration: FIG. 42.—DIAGRAM OF CURTISS HYDRO-AËROPLANE.
-(_Scientific American._)]
-
-The first machine weighed in flight 950 pounds and spread 280 square
-feet of surface, giving a loading of 3.4 pounds per square foot. It was
-driven by a 50-horse Gnome engine actuating a Chauvière propeller 7.5
-feet in diameter. In the trials of March 28th, the machine cleared the
-water at a speed of 34 miles per hour, and flew about one-third of a
-mile, at an elevation of two to three yards; then at the will of the
-operator it alighted softly on the water.
-
-The structural design of the Fabre monoplane was novel and unique, not
-to say radical. The wing framing consisted of a single Fabre trussed
-beam with ribs attached like the quills of a bird, over which was
-stretched the light sailcloth cover, then laced to the beam. The girder
-itself was formed of two ash planks eight inches wide by one-fourth
-inch thick trussed together by flat steel plates zigzagging trelliswise
-between them. As all parts of the beam cut the air edgewise it offered
-very little resistance, while at the same time being very strong. The
-ribs being attached only at one end allowed the sailcloth to be quickly
-slipped on and off for washing and proper care.
-
-The characteristic features of Fabre’s wing construction were adopted
-by Paulhan in his novel and picturesque biplane shown in Plate
-XXXI. Trussed beams were used for all parts requiring considerable
-stiffness, the longitudinal ones being covered with fabric to reduce
-the resistance. The wings whose solid ribs were fastened only at their
-front ends were quite elastic, a quality conducive to stability, as
-long taught by writers[55] on aviation. In addition to the front
-rudder, there was at the rear a horizontal rudder with a vertical one
-just before it. To reduce the air resistance further the pilot and
-passenger were to sit tandem in a torpedo-shaped car with the 50-horse
-Gnome engine and fuel tank back of them. Beneath the longitudinal
-girders were two Farman skids flanked with the usual wheels,
-elastically connected. The machine, besides flying well, was readily
-demountable. The wings could be quickly removed, thus allowing the
-biplane to enter a door fifteen feet wide. The entire machine could be
-packed in a case 15½ feet long by 3¼ feet square, the whole case cubing
-less than six solid yards. Hundreds of them, therefore, could be stowed
-away in an ocean cruiser.
-
-The flying quality of adequately designed flexible aëroplanes is well
-illustrated by the swallowlike monoplane shown in Fig. 43. This airy
-creation of the distinguished Austrian engineer, Igo Etrich, came into
-public prominence in the spring of 1910, though it had been developing
-privately for half a decade or more. On May 14th, near Vienna, it
-carried pilot Illner 84 kilometers in 80 minutes, at an elevation of
-300 meters, thus surpassing all previous Austrian records for distance,
-duration and altitude. Its successor, _Etrich IV_, had wing tips still
-more turned up, and possessed such stability that during the meet at
-Johannisthal in October, Illner circled the pylons with his hands off
-the warping levers. At times he wheeled round curves of only ten meters
-radius, the whole machine tilted at an alarming angle, yet maintaining
-its poise with the natural ease and grace of a soaring albatross.
-
-The prominent feature of Etrich’s monoplane was the elastic
-construction of its wings and tail. Across the rigid main bars of each
-wing were fastened numerous ribs with bamboo terminals, thus making
-the rear margin and tip of the wing flexible. Similarly the tail, or
-horizontal rudder, was framed of bamboo. Hence the pilot, by use of
-control wires, could flex both the wing margins and the tail up and
-down at will, to steer the machine, or he could let go the controls and
-allow the distorted surfaces to spring into their normal positions,
-and the machine to pursue the even tenor of its way. Moreover, the
-gusts and whirls in the air, on striking the elastic rear margins of
-the tail and wings, exert a propulsive effort. Thus could be utilized
-the wind’s energy of turbulence, as indicated by the present writer
-in 1893, in a paper on “Windgusts and Their Relation to Flight,”
-published in the _Proceedings of the International Conference on Aërial
-Navigation_ of that year. In passing it may be remarked that many other
-aëroplane designers, notably Bréguet, have emulated Mr. Etrich, though
-unconsciously perhaps, in providing elastic ribs, hinges or pivots to
-permit the rear parts of the wings and tails of their machines to yield
-freely to intentional or unusual impulses, and then spring back to
-their normal positions.
-
-[Illustration: FIG. 43.—THE ETRICH MONOPLANE OF 1910.]
-
-The carefully elaborated monoplane of Robert Esnault-Pélterie, which
-had been steadily improving for eight years, had now attained great
-perfection of finish, and merited prominence in actual flight. As shown
-in Plate XXIX, it had a general resemblance to the _Antoinette_, though
-differing throughout in its manifold details. The stream-line body was
-of steel tubing, braced with wire, and tightly covered with smooth
-fabric to reduce resistance. A five-cylinder R. E. P. motor in front
-connected directly with the two-blade propeller. The pilot sat between
-the wings with the passenger before him at the center of gravity, both
-having control levers when desired for instruction. The wings could be
-warped and the rudders, at the end of ample empennage planes, occupied
-the extreme rear as shown. An elastically cushioned skid between the
-two freely turning wheels served to absorb the shock of hard landing,
-though usually not touching the ground. The R. E. P. monoplane of 1910
-was a very graceful, swift and strong machine, of marked efficiency.
-
-As always happens in the many-minded development of a complex
-invention, the general exhibition and use of the aëroplane led toward
-uniformity of design. This became particularly noticeable during the
-world-wide demonstrations of 1909 and 1910. Whatever predilection the
-inventor might have for his own devices, he would rather cast them
-aside than lose at the tournament and in the market. Without a monopoly
-of the flying art, he could ill afford to retain too affectionately
-his own second-rate device in competition with a rival having a more
-effective one. Accordingly there was a judicious and general adoption
-of those devices which had proved best in practice, from whatever lowly
-intellect they had emanated. Thus there was a marked tendency to the
-general use of starting wheels, landing skids, large warping surfaces,
-and, in racing machines, to the stream line concentration of the load,
-and the severe elimination of resistance.
-
-A few examples will illustrate this tendency to choose the most
-practical devices from the world’s general stock. The Wright brothers,
-who, following Maxim, had been ardent votaries of the forward
-horizontal rudder, discarded this in 1910 for the elastic rear
-horizontal rudder introduced by Etrich. At the same time they abandoned
-the antiquated catapult introduced by Langley, and adopted the
-combination of wheels and skids introduced by Farman. In their racing
-machine they no longer placed the aviator beside his engine, presenting
-a broad front to the wind, but, like Curtiss and foreign designers,
-they placed the driver and power plant in line, to diminish the
-atmospheric resistance. These manifold and timely improvements indicate
-clearly the advantages to mankind of an “open door” in a crescent art.
-
-But if the Wrights adopted the most successful devices of their
-neighbors, these in turn were not slow to reciprocate that policy.
-There was ample recognition of the merit of the combination of warping
-sustainers and double rudder proposed by scientific men before the
-advent of power aëroplanes, and so admirably employed by the Wrights
-and Prof. Montgomery in their early coasting flights. The warping wing
-was quite generally used on monoplanes in 1910; not to mention the
-_ailerons_, which frequently were an adaptation of the same principle.
-
-As further illustrations, it may be noted that Voisin brothers adopted
-the Farman _ailerons_ and abandoned the cellular type of sustaining
-surface introduced by Hargrave, finding the vertical surfaces strongly
-frictional and unnecessary for lateral equilibrium, in presence of
-the _ailerons_. They also abandoned the forward horizontal rudder,
-seeing that it could very well be omitted. On the other hand, it must
-be observed that the Farmans, Sommer and Curtiss still retained the
-combined fore and aft rudder. Curtiss and Farman also tried their hands
-at monoplane construction, though without abandoning the biplane. The
-most famous monoplanists, however, held firmly to their first love.
-In this they were emulated by many new designers, Nieuport, Hanriot,
-Déperdussin, etc. These show a marked tendency to employ smoothly
-covered hulls shaped after the fish or torpedo.
-
-To drive the little aëroplanes so far developed, especially the
-racers, there was a general preference for a single-screw propeller
-mounted directly on the engine shaft, though doubtless for machines
-weighing many tons a multiplicity of such propellers would be used.
-Theoretically the advantage of twin screws was conceded, but in
-practice they were employed by very few constructors. The Chauvière
-wooden propeller was the favorite in France, and was approved by
-the constructors of propellers elsewhere, at least in its general
-features. The Voisin firm, indeed, still adhered to the metal
-propeller, and occasionally some experimentalist employed the more
-venerable French screw consisting of radial sticks covered with fabric.
-But the great records in the sporting world were achieved with solid
-wooden propellers.
-
-A special chapter would be required to describe the various motors,
-even cursorily. Their relative values, however, may be summarized in
-the following brief words by Réné Gasnier, in the _Aërophile_ for
-November, 1910:
-
-  “Last year we had but few light types; this year there is no
-  dearth of them, and at their head stands that admirable motor
-  _Gnome_, which has enabled aviators to accomplish all their
-  fine performances. At first many persons had no confidence in
-  the future of the rotatory motor. One must bow to the facts;
-  on considering the nature of this motor it is seen to be of
-  an admirable simplicity. It is evidently the typical aviation
-  motor, and an approach toward the veritable rotatory motor
-  which later will be the turbine. Numerous motors of four to
-  eight cylinders are very well spoken of, but none attain the
-  lightness of the _Gnome_. Among the air-cooled motors the
-  _Esnault-Pélterie_ is remarkable for the series of trials it
-  has endured, and among water-cooled motors we may cite the
-  splendid performance of the _Antoinette_—2,100 kilometers in
-  one week at the Bordeaux meeting. This would be quite a good
-  run even in an automobile. It is noticeable that the aëroplane
-  motor tends distinctly to differentiate itself from its senior,
-  the automobile motor, and assume a type absolutely adapted
-  to its special work. In addition to the greatest possible
-  lightness, a demand now arises for a slight consumption of
-  fuel, and a range of speed which is indispensable for landing.
-  It is dangerous to descend rapidly with the motor at full
-  speed; on the other hand, in cutting off the ignition to glide
-  down, one risks not being able to restart the motor, if need
-  be, while if the motor relax sufficiently the descent takes
-  place in perfect security. It suffices to speed up at the right
-  moment.”
-
-The practical utility of aviation began now to be questioned. The
-aëroplane had passed the primary epoch of experimental development
-and was becoming a standard article of manufacture representing a
-considerable industry. But what was it all worth? Aviators had flown
-faster than the eagle, higher than the clouds, farther than the common
-distance from metropolis to metropolis. Schools were licensing new
-pilots from day to day. But what career had these before them, and what
-essential function in the affairs of humanity could they perform? Some,
-indeed, might fit themselves for aërial service in warfare, some for
-the pleasant profession of amusing and entertaining mankind; but in the
-serious business of life, what important rôle could the air men hope
-to play? This was the pertinent inquiry, and it was largely a question
-of the reliability and economy of the aëroplane. Improvement in these
-two elements might therefore receive attentive consideration in the
-immediate future.
-
-The reliability of the aëroplane depends partly on its environment,
-partly on its plan and structure, partly on the skill of its pilot.
-The pilot’s skill had been admirably developed in the tournaments and
-public exhibitions. The aërodynamic design conducive to stability and
-steadiness, the structural design conducive to maximum strength and
-resiliency, uniformly proportioned to the stress and work of each
-part of the complex machine; and above all the design of the motor,
-to ensure it against a thousand foibles—all these could be improved
-by the patient methods of theoretical and experimental science.
-The environment could, of course, be chosen. At first only the most
-favorable regions need be attempted for regular transportation, regions
-of level plain and farm land, or of lake and river surrounded by
-country not too rough and precipitous.
-
-The general cost of the aëroplane to mankind depends on its plan and
-structure, on the methods of manufacture, on the material running
-expense; but its particular cost to the passenger is determined largely
-by the cupidity or business acumen of those who furnish the machine
-and those who operate it. Naturally when the world first awoke in
-the morning of practical sporting aviation, with a sudden and strong
-relish for flying, the prices would be fabulous, not to say ridiculous.
-During that hour no commercial transportation could be contemplated.
-But without monopoly the prices must quickly abate; for neither the
-manufacture nor manipulation of the aëroplane demand rare ability or
-training. The cost of manufacture would promptly be diminished by means
-of specialized tools and operatives, immediately upon the assurance
-of large and continuous orders. The cost of pilotage would become
-insignificant when a single chauffeur could take a dozen passengers on
-one aëroplane.
-
-So much for the human and external elements in the cost of aviation.
-The inherent and material cost of the aëroplane could also be reduced,
-though perhaps less readily. It was unlikely that the machine would
-be built of much cheaper materials, or made much lighter per pound of
-cargo. Nor were such improvements of so much importance since they
-would affect only the first cost of the flyer. But an increase of
-aërodynamic efficiency in the propeller and aëroplane proper, together
-with increased thermodynamic efficiency in the motor, would materially
-lower the current cost of transportation at any given speed. These
-improvements would require careful research in the laboratory and
-patient trial in the workshop and field. The refinement and perfection
-of the aëroplane might therefore be looked for in those communities
-where men have sufficient foresight, enterprise and liberality to endow
-research, and to encourage the science and the art of aviation to
-supplement each other.
-
-
-
-
-                               PART III
-
-                        AËRONAUTIC METEOROLOGY
-
-
-
-
-                             CHAPTER XIII
-
-                    GENERAL PROPERTIES OF FREE AIR
-
-
-For aëronautic uses the atmosphere may be regarded as a mixture of two
-substances, dry air and water. The first remains always in the gaseous
-state; the second shifts erratically through all possible states. Rain
-drops freeze or evaporate; sleet, snow, and hail evaporate or melt;
-the aqueous vapor condenses or congeals. Thus the world is wrapped in
-a dual sea, one part naturally serene, the other capricious, protean,
-and turbulent. Dry air, indeed, is a composite of many gases of vast
-concern in chemistry and biology; but in relation to aëronautics it
-is practically a single permanent gas. This placid element and its
-inconstant mate, so curiously mingled, constitute the medium whose flux
-and vicissitudes the aërial sailor has duly to learn before he can
-navigate with skill or safety.[56]
-
-But these aërial oceans, the moist and dry, are of very different
-depth. They commingle only in the lower levels of the atmosphere, whose
-qualities vary accordingly, both physical and transportational. While
-the dry air may reach up to more than a hundred miles, substantial
-enough to singe a meteorite, the sea of aqueous vapor is bounded
-practically by the shallow region of the visible clouds. Beyond the
-feather-like cirri, which just overtop the loftiest mountain peaks,
-there is scant, if any, moisture. Never rain, nor cloud is there, nor
-tempest nor any great perturbation. Beyond the highest excursions of
-the cirri, at an elevation of some ten miles, stretches the deep ocean
-of eternal sunshine, of equable and nearly constant temperature. Into
-that zone of perpetual serenity no tumult of the nether atmosphere
-can penetrate; against the floor of the isothermal layer the cyclonic
-currents spread and dissipate. The upper air has, of course, a
-considerable drift, like a majestic river or stream of the sea, but
-never turmoil or tempest disturbs its stately march.
-
-In some respects, therefore, that lofty ocean is an ideal one for swift
-transportation. But at present it is beyond the range of any navigable
-craft of human invention. Occasionally, indeed, a gauzy balloon from
-the hand of some inquisitive weather sage penetrates a little way into
-the exalted deep next the cosmic void, bearing its delicate recorders
-of heat and pressure; but it wanders alone in a silent and vast
-solitude outcubing all the habitable space allotted to bird, beast
-and fish; then at last sinks down to deliver the story of its strange
-voyage in that lifeless outer sphere. Volcanic and celestial dust may
-flourish there, tingeing the twilight with rosy flush, but no biologic
-forms from the teeming underworld may find refuge or sustenance. It is
-the unconquered domain of who knows what meteoric craft of the future,
-sweeping the globe from continent to continent, with now unimaginable
-celerity, grace and precision.
-
-Incidentally and aside from its aëronautic interest, the composition
-of the atmosphere may be presented in fuller detail, showing the
-wide variations from level to level, and the manifold complexity of
-the fluid we daily breathe, not to mention the myriads of motes and
-germs inhabiting every inch of it. The gaseous components and their
-distribution are well exhibited in the following table,[57] which
-represents an average condition:
-
-                                TABLE I
-
-         _Percentage Distribution of Gases in the Atmosphere_
-
-  Key:  HT = Height in Kilometers.
-         A = Argon.
-         N = Nitrogen.
-        WV = Water Vapor.
-         O = Oxygen.
-        CD = Carbon Dioxide.
-        HY = Hydrogen.
-        HE = Helium.
-        TP = Total Pressure in Millimeters.
-  ----+--------------------------------------------------+--------
-      |                      GASES.             |
-   HT +------+-------+------+------+------+-------+------+   TP
-      |   A  |   N   |  WV  |   O  |  CD  |   HY  |  HE  |
-  ----+------+-------+------+------+------+-------+------+--------
-  150 |      |       |      |      |      | 99.73 | 0.27 |  0.0043
-  140 |      |       |      |      |      | 99.70 | 0.30 |  0.0048
-  130 |      |  0.02 |      |      |      | 99.64 | 0.34 |  0.0054
-  120 |      |  0.10 |      |      |      | 99.52 | 0.38 |  0.0060
-  110 |      |  0.40 |      | 0.02 |      | 99.16 | 0.42 |  0.0067
-  100 |      |  1.63 |      | 0.07 |      | 97.84 | 0.46 |  0.0076
-   90 |      |  6.57 |      | 0.32 |      | 92.62 | 0.49 |  0.0090
-   80 |      | 22.70 |      | 1.38 |      | 75.47 | 0.45 |  0.0123
-   70 | 0.02 | 53.73 |      | 4.0  |      | 41.95 | 0.27 |  0.0248
-   60 | 0.04 | 78.16 |      | 7.32 |      | 14.33 | 0.15 |  0.0810
-   50 | 0.08 | 86.16 |      |10.01 |      |  3.72 | 0.03 |  0.466
-   40 | 0.16 | 86.51 |      |12.45 |      |  0.88 |      |  1.65
-   30 | 0.22 | 84.48 |      |15.10 |      |  0.20 |      |  8.04
-   20 | 0.55 | 81.34 |      |18.05 | 0.01 |  0.05 |      | 39.6
-   15 | 0.74 | 79.56 |      |19.66 | 0.02 |  0.02 |      | 88.2
-   11 | 0.94 | 78.02 | 0.01 |20.99 | 0.03 |  0.01 |      |168
-    5 | 0.94 | 77.89 | 0.18 |20.95 | 0.03 |  0.01 |      |405
-    0 | 0.93 | 77.08 | 1.20 |20.75 | 0.03 |  0.01 |      |760
-  ----+------+-------+------+------+------+-------+------+--------
-
-Fixing attention first upon the gases other than water, it will be
-at once observed from the table that these gases show a very uniform
-mixture in the moist and turbulent region, while farther aloft the
-lighter of them tend to predominate in relative proportion. This
-uniformity of composition at the lower levels, which accords with
-experience, is due to the constant circulation and turmoil in that
-region. But for this constant agitation, the uniformity of mixture
-could not last. If the atmosphere were perpetually at rest throughout,
-or moving only in horizontal flow, each constituent gas would assume
-the same status and distribution as if the others were absent. Each,
-therefore, obeying Dalton’s law of diffusion, would form an atmosphere
-of itself, independent of the others, and unaffected in density by
-them. Such a condition is assumed for the higher levels. The percentage
-distribution in the higher levels is calculated from the known
-elasticity and density of the gases, assumed as resting in perpetual
-calm at a constant temperature of .55° C. beyond eleven kilometers, or
-above the highest ascent of man, and, furthermore, as having at the
-earth’s surface 1.2 per cent moisture and a temperature of 11° C.
-
-But only in the quiescent outersphere can that dynamic gradation be
-established or perpetuated. Below this lofty region is the sea of
-water vapor, mingled intimately with the dry air, and churned with
-it, yet not sharing its uniformity of distribution. Why this rapid
-diminution of moisture with elevation, as shown in the table? Because
-throughout the moist region the temperature falls rapidly—about 6° C.
-per kilometer ascent above the earth—thus chilling and precipitating
-the vapor, whose pressural resistance to liquefaction diminishes with
-waning temperature. The explanation is obvious; but why does it not
-apply as well to the other elements of the atmosphere: why do not the
-other gases present liquefy with falling temperature as well as the
-water vapor, which is merely water in the gaseous state? The question
-cannot be answered very profoundly, but an essential condition of
-liquefaction of any gas can be stated in learned phraseology, after the
-preliminary exposition of certain general properties of matter.
-
-We may first set forth those general physical properties, then apply
-them to answering the above question. Every known substance may exist
-in either of three states, the solid, liquid or gaseous. For every
-substance there is a critical temperature above which it can exist
-only as a gas, and cannot be liquefied by any pressure, but below
-which a suitable pressure will cause liquefaction. Below its critical
-temperature a gas is called a vapor, above it a permanent gas. Now in
-the free atmosphere some of the gases are never below their critical
-temperatures and, therefore, cannot be liquefied by any pressure,
-without special cooling; others are sometimes below their critical
-temperatures and are then capable of liquefaction by sufficient
-pressure, which however is not always found in free space, but can be
-supplied by a compression pump; one other gas, that is water vapor,
-is always below its critical temperature in the free atmosphere, and
-therefore may always be turned into water by sufficient pressure at its
-actual atmospheric temperature. Such sufficient pressure in the water
-vapor actually occurs from time to time in all parts of the atmosphere
-from the earth’s surface to the highest cirrus region, but more
-frequently in the nimbus levels, a mile or two above the earth. Thus
-at all parts of the lower atmosphere liquefaction of aqueous vapor is
-sometimes observed, either as mist or rain, snow or ice particles, and
-on the earth as dew or frost. In order to illustrate the above ideas
-by numerical citation, the accompanying table is given, showing the
-critical temperature and pressure of the chief gaseous constituents of
-the atmosphere.
-
-                               TABLE II
-
- _Critical Temperature and Corresponding Pressure of Liquefaction for
-            the Chief Constituent Gases of the Atmosphere._
-
-  --------------+-------------+-------------
-                |   Critical  |   Critical
-    Substance   | Temperature |   Pressure
-                |      C.     | Atmospheres.
-  --------------+-------------+-------------
-  Dry Air       |    -140     |     39
-  Nitrogen      |    -146     |     34
-  Oxygen        |    -118     |     50
-  Carbonic Acid |    - 31     |     75
-  Argon         |    -120     |     51
-  Hydrogen      |    -242     |     20
-  Ammonia       |     130     |    115
-  Water         |    +365     |    200
-  --------------+-------------+-------------
-
-A glance at this table shows that for the pressures and temperatures
-prevailing in our atmosphere most of the constituents are permanent
-gases. The conspicuous exception is water which, when in the gaseous
-state, always exists as a vapor, and never as a permanent gas, since
-it never even approaches the critical temperature. Fortunately for all
-life on earth the aqueous vapor condenses at very ordinary temperatures
-and pressures, else there would be no rainfall for irrigation and
-drinking. Fortunately also the other gases do not so precipitate, else
-the world might be flooded with liquid nitrogen and oxygen, entailing
-who knows what disastrous consequences.
-
-After this digression on the composition of the atmosphere, we may
-henceforth regard the aërial ocean as a mixture of two substances,
-dry air and water; the first, a permanent gas; the second, a
-variable element, existing at times in either the solid, liquid, or
-vaporous state. For the sake of convenience we may first study the
-dry atmosphere, then the moist. The dynamic properties of the dry
-atmosphere may in large measure be deduced by an application of two
-well-established laws of physics. These will be taken in order.
-
-By careful investigation it has been proved that throughout a
-considerable range of pressure and temperature the permanent gases
-very approximately obey the following law; the volume of a permanent
-gas varies directly as its absolute temperature and inversely as its
-pressure. In other words the product of its pressure and volume equals
-the absolute temperature multiplied by a numerical constant. This may
-be expressed algebraically by the following formula:
-
-                          _PV_ = _RT_     (1)
-
-in which _P_ is the pressure and _V_ the volume of a given portion of
-gas at the absolute temperature _T_, and _R_ is a numerical constant
-for the gas in question.
-
-The value of _R_ in the foregoing equation has been determined
-experimentally for the component gases of the atmosphere, and for dry
-air as a whole. For dry air, which, under such conditions as surround
-the aëronaut, may be treated as a single uniform gas, the equation
-applied to one kilogram gives R = _PoVo/To_ = 29.27, where _Po_, _Vo_,
-_To_, are respectively the pressure, volume and temperature, in the
-metric system, of the one kilogram of air under standard conditions;
-i. e., _Po_ = 10,330 kilograms per square meter, being the normal
-atmospheric pressure; _Vo_ = 1/1.293 cubic meter, being the volume of
-one kilogram of dry air at normal pressure and freezing temperature;
-_To_ = 273° C., being the absolute temperature of freezing. In passing,
-be it said that the absolute temperature is that measured from the
-absolute zero, which on the Centigrade scale is 273° below freezing, on
-the Fahrenheit, 460.6° below freezing.
-
-The second law referred to follows directly from the principle of the
-permanence of mass. It is a general observation in physics that a given
-portion of matter is of constant mass, however its pressure, volume,
-temperature and other conditions may vary. In particular, the mass of a
-given portion of matter always equals the product of its mean density
-and volume, since density is defined as the amount of mass in the unit
-volume. Expressing this physical law, or relation algebraically, gives
-ρ_V_ = mass = ρ_o_, _Vo_, in which ρ, _V_, are the general symbols
-for the density and volume of the given portion of matter under any
-condition, while ρ_o_, _Vo_, are the specific values of ρ and _V_
-observed for some one state and circumstance of the substance in
-question. In particular, if the mass of air be unity, we may write:
-
-                             ρ_V_ = 1     (2)
-
-This relation, together with that expressed in equation (1), will
-enable us to deduce many of the properties of dry air and of a dry
-atmosphere.
-
-First let us observe from equation (1) the effect, in turn, of keeping
-constant one of the quantities _P_, _V_, _T_, while the other two vary.
-The equation shows that if the temperature of a gas is kept constant
-the volume is inversely proportional to the temperature. This is called
-the law of Boyle and Mariotte from its two independent discoverers,
-of whom Boyle seems to have been the first. As an example of Boyle’s
-law, if any empty glass, or diving bell, be inverted over water,
-then submerged deeper and deeper, the air within it will shrink with
-increase of pressure, its volume becoming one half when the pressure is
-doubled, one third when the pressure is trebled, etc. In particular, if
-the pressure changes by one unit, the corresponding change of volume
-is 1/_P_ part of that volume. For example, if a captive balloon is
-anchored in air at constant temperature, while the barometric pressure
-changes from 30.0 inches to 30.1 inches, the volume of the balloon
-will contract 1/300 part of itself.
-
-Again equation (1) shows that if the pressure of a gas is kept
-constant, the volume is proportional to the absolute temperature. This
-is the law of Charles and Gay Lussac, so called from its discoverers,
-of whom Charles is thought to have been the first. As an example of
-this law, if a captive thin rubber balloon is heated, or cooled, its
-volume will vary directly as its absolute temperature. In particular,
-if the temperature is changed one degree, the volume changes 1/_T_
-part of itself. For example, if the temperature of a balloon in air of
-constant barometric pressure is heated from 300° C. to 301° C., its
-volume will expand 1/300 part of itself. Historically, be it said, this
-law of Charles and the law of Boyle were discovered separately, then
-combined, giving equation (1).
-
-Still a third, though not independent relation may be read from
-equation (1), thus: when the volume of a gas is kept constant, the
-pressure is proportional to the absolute temperature. In particular, if
-the temperature is changed one degree, the pressure varies accordingly
-by 1/_T_ part of itself. For example, if an air tank or gas tank, in a
-room at 500° F., changes one degree in temperature, its pressure will
-change 1/500 part.
-
-With minute detail these three conclusions from the general equation
-(1) have been set forth and illustrated, because of their practical
-importance. Other valuable results may be obtained by similar
-reasoning. Thus equation (2) may be read; the volume of a unit mass of
-any substance is the reciprocal of its density. Hence, if in the three
-foregoing conclusions, the reciprocal of the density is everywhere
-written for the volume, three new relations will be obtained which
-are of frequent practical use. Two of them may be expressed in the
-following important law; the density of a gas varies directly as its
-pressure and inversely as its temperature. Useful applications of this
-law in aëronautics suggest themselves at once.
-
-By means of the various foregoing equations, the value of either one
-of the four quantities _P_, _V_, _T_, ρ, representing respectively
-the pressure, volume, absolute temperature, and the density, may be
-obtained in terms of any two of the others. If then any two of the
-quantities is observed, the others can be at once computed. If, for
-example, the pressure and temperature of dry air be observed at any
-point, its density can be computed from the formulæ, also its volume
-per kilogram weight, and thence its volume for any other weight. It is
-important therefore to be able to measure satisfactorily at least two
-of the four quantities. In usual studies of the atmosphere the pressure
-and temperature are observed directly. The method and instruments
-employed for that purpose are too well known to require description
-here.
-
-In some speculations the pressure and temperature of the atmosphere
-are assumed, and certain interesting conclusions drawn. For instance,
-if the temperature is assumed constant throughout a dry atmosphere,
-the fluid will obey Boyle’s law, and it can be easily shown that the
-height of such a medium is the same whether it comprise much gas or
-little.[58] Again assuming the temperature and pressure constant, the
-height of the normal homogeneous atmosphere can be computed by dividing
-the pressure per square unit by its weight per cubic unit. In this way
-the height of the normal homogeneous atmosphere has been found to be
-about five miles. But these are hypothetical cases, of purely theoretic
-interest. In practice the temperature may, on the average, be assumed
-to decrease 6° C. for each kilometer of ascent, and the pressures may
-then be computed for various elevations by use of Boyle’s law, as done
-for Table I.
-
-This leads us to a study of the gaseous properties of moist air. By
-moist air is meant a mixture of dry air and aqueous vapor in the form
-of an invisible elastic gas. The definition does not comprise air
-containing visible steam, or mist, or cloud, but clear moist air such
-as one ordinarily breathes. The study of this mixture may be preceded
-by a brief account of the gaseous properties of the vapor alone.
-
-If water in sufficiently small quantity be introduced in a vacuum
-bottle at any ordinary temperature, it will promptly evaporate,
-forming an invisible gas known as aqueous vapor, filling the bottle
-and exerting a uniform pressure on its walls, except for the minute
-difference at top and bottom due to gravity. The vapor weighs 0.622 as
-much as dry air having the same volume, temperature and pressure, or
-quite accurately ⅝ as much. It obeys all the laws given above for
-ordinary gases and dry air. But it has one singularity; at ordinary
-atmospheric temperatures, it cannot be indefinitely compressed
-without condensing to a liquid. In this respect it differs from the
-chief components of the atmosphere, which at ordinary temperatures
-can endure indefinite pressure without liquefaction. The ammonia and
-carbon dioxide in the air can, it is true, be condensed by pressure at
-their usual temperatures, but not by such pressures as occur in the
-free atmosphere, thus still leaving aqueous vapor the one singular
-constituent.
-
-Reverting to the behavior of the water in the assumed vacuum
-bottle at fixed temperature, it may be observed that the pressure
-of the invisible vapor is directly proportional to the amount of
-liquid evaporated. In other words, for any fixed temperature the
-vapor pressure is directly proportional to its density. When this
-density reaches a certain definite amount, dependent solely upon the
-temperature, no further evaporation will occur, unless some of the
-vapor condenses. The pressure of saturation for that temperature has
-been reached, and any attempt to increase the pressure, by diminishing
-the volume of the vapor, will cause liquefaction at constant
-temperature.
-
-If, however, the space is not saturated, the mass of vapor present may
-be expressed as a percentage of the amount required for saturation at
-that temperature. This percentage is called the relative humidity. Thus
-if the relative humidity is seventy per cent, the actual mass of water
-vapor present at the observed temperature is seventy per cent of the
-maximum that can exist in the given space, at the given temperature. In
-other words, the relative humidity is the ratio of the actual to the
-possible humidity at a given temperature.
-
-In like manner, for any given vapor pressure there is a definite
-saturation temperature, known as the dew-point. If with constant
-pressure the vapor is given various temperatures higher than the
-dew-point, it will remain gaseous and invisible; but if it falls in
-temperature to the dew-point, liquefaction occurs, and drops of water
-appear on the inner wall of the vessel. Further cooling will entail
-still further liquefaction and reduction of pressure; for the lower
-the temperature the less the possible mass and pressure of saturation.
-But for all temperatures, down to freezing and considerably below,
-some vapor exists, and obeys the same laws as at higher temperatures.
-When, however, saturation occurs below freezing, the vapor may be
-precipitated as snow instead of water. This is a familiar phenomenon
-in the free atmosphere.
-
-The actual mass of water vapor present in a cubic unit of space
-is sometimes called the absolute humidity. A formula giving the
-absolute humidity _f_, in kilograms per cubic meter, for any observed
-temperature _t_, and vapor pressure _e_, may be written as follows:
-
-                 _f_ = 0.00106 _e_ / (1 + 0.00367 _t_)
-
-in which _e_ is the vapor pressure in millimeters of mercury, and _t_
-is the common Centigrade reading. As an illustration of the actual
-values of the pressure, temperature and density of saturated water
-vapor, for various conditions, the following table is presented:
-
-
-                               TABLE III
-
-    _Temperature, Pressure and Density of Aqueous Vapor, in Metric
-                              Measures._
-
-  -------------+--------------+-----------------
-  Temperature, | Pressure,    | Density Kilos.
-  Centigrade.  | Millimeters. | per cubic meter.
-  -------------+--------------+-----------------
-      -25      |      0.61    |     .557
-      -20      |      0.94    |     .892
-      -15      |      1.44    |    1.395
-      -10      |      2.15    |    2.154
-      - 5      |      3.16    |    3.244
-        0      |      4.57    |    4.835
-      + 5      |      6.51    |    6.761
-       10      |      9.14    |    9.329
-       15      |     12.67    |   12.712
-       20      |     17.36    |   17.117
-       25      |     23.52    |   22.795
-       30      |     31.51    |   30.036
-       35      |     41.78    |   39.183
-       40      |     54.87    |
-       45      |     71.36    |
-  -------------+--------------+-----------------
-
-Now by Dalton’s law, each gas or vapor in a mixture of several behaves
-as if it were alone. Thus if the foregoing experiment be conducted in
-a bottle containing various gases chemically inert to water, the same
-mass of water will be evaporated, and exert the same uniform pressure,
-in addition to those exerted by the gases. Now the density of each
-gas or vapor present, will equal its mass divided by its volume, and
-the density of the mixture will equal the total mass divided by the
-volume. Furthermore, it is well known that aqueous vapor is less dense
-than dry air at the same temperature and pressure. From this it is at
-once evident that moist air, which is merely a mixture of dry air and
-aqueous vapor, must be lighter than dry air at the same temperature and
-pressure. This is true whether the two fluids compared be in closed
-vessels or in the free atmosphere.
-
-Accordingly in all precise dealing with the free air, whether involving
-its buoyancy, its resistance, its energy or any other mass function,
-its density as affected by the humidity must be taken into account.
-This can be computed from the observed pressure, temperature and
-relative humidity as revealed by well known instruments, the barometer,
-thermometer and hygrometer. Thus from the observed temperature and
-relative humidity, the mass of vapor present per cubic meter is read
-from Table III, the reader, of course, multiplying the given tabulated
-mass by the observed percentage of humidity. To this aqueous mass must
-be added the mass of dry air present. Then the total mass per cubic
-meter is the density.
-
-Various formulæ are available for computing the density of moist
-air from the readings of the three instruments mentioned above.
-Also, tables have been worked out giving the density without further
-calculation. Moreover, the density of free air may be directly
-measured, accurately enough for most purposes, by means of a
-densimeter. A simple formula for finding the density of moist air is
-as follows:
-
-                        ρ = 0.465(_b − e_)/_T_
-
-in which _b_, _e_, are the pressures in millimeters mercury
-respectively of the moist air and its vapor, as revealed by the
-barometer and hygrometer.
-
-In practice no great error will be made in assuming the relative
-humidity to be fifty per cent. For the moisture content never exceeds
-five per cent of the mass of the moist air, and hence in assuming a
-fifty per cent relative humidity, when there is actually a maximum
-or minimum humidity, the greatest possible error in estimating the
-moisture content is 2.5 per cent of the mass of moist air. Now if 2.5
-per cent of a mass of air be assumed to be aqueous vapor when all is
-really dry air, or conversely if 2.5 per cent of the whole mass be
-assumed as dry air when it is really aqueous vapor, an error of much
-less than 2.5 per cent is made in estimating the true density. No error
-at all would ensue if both air and vapor were of the same density; but
-since one is ⅝ as heavy as the other, the possible error is ⅜ of
-2.5 per cent, or 0.6 per cent. This is a negligible quantity in all
-mechanical considerations, except where great accuracy is required.
-
-When any gas changes density or volume it also changes temperature,
-unless there be transfer of heat between it and its environment. When
-change of volume occurs without such transfer of heat the expansion,
-or contraction, is called “adiabatic;” when it occurs at constant
-temperature, the expansion is called “isothermal,” the temperature
-being kept uniform by suitable transfer of heat; when it occurs at
-constant pressure it is called “isopiestic.” In either case work may
-be done by the enlarging gas, if it press against a moving piston,
-or yielding envelope of some kind; and conversely work may be spent
-on the gas in compressing it either isothermally, adiabatically or
-isopiestically.
-
-If, for example, a balloon rises rapidly its contents will expand
-adiabatically, pushing the envelope out in all directions against the
-static pressure of the embracing atmosphere. Thus it will do work and
-rapidly cool. But if it rapidly sinks, it will contract adiabatically
-and grow warm, owing to the work done by the surrounding air in
-compressing it. A like thing occurs when a great volume of air rises
-or sinks quickly in the free atmosphere. In this case the change of
-temperature is about 6° C. for each kilometer change of level, so long
-as the air remains unsaturated. A familiar example of this effect in
-Nature is manifested when an uprushing column of moist air chills, and
-precipitates moisture, forming a cloud toward its top. Thus a lone
-thundercloud in a clear sky may mark the upper part of such a column,
-or upward vortex in the air. And contrarywise, a descending column may
-absorb its visible moisture, causing it to become clear aqueous vapor,
-and thus vanish from view.
-
-
-
-
-                              CHAPTER XIV
-
-               GENERAL DISTRIBUTION OF HEAT AND PRESSURE
-
-
-Having thus briefly examined the composition and certain gaseous
-properties of free air, both dry and moist, we may now study the
-atmosphere as a whole. We wish particularly to know of its distribution
-of temperature and pressure; of its general and permanent circulation;
-of its great periodic currents; of its vertical movements, and its
-minor local winds with their pulsations of velocity and direction.
-Fortunately much information is available, due both to governmental
-and private research, though this was collected more for purposes of
-meteorology than of aërial locomotion. Of late, however, attention has
-been given to the aëronautic study of the atmosphere, which will, it is
-hoped, prove valuable to the aërial navigator.
-
-The movements of the atmosphere are due mainly to the sun’s heat and
-to the rotation of the earth. The earth’s internal heat and the moon’s
-attraction are other minor agencies, but these may be neglected by
-comparison. The earth’s rotation also would be ineffectual in modifying
-the aërial movements, except for the coöperation of the sun. Without
-his influence the atmosphere, always stagnant, would simply rotate with
-the globe, at constant angular velocity and uniformly graded density at
-various levels. This evenness of density for any level is broken by the
-solar radiation increasing the temperature and moisture, otherwise the
-air would remain practically at a standstill.
-
-Though the moisture by its lesser density causes some lightening of
-the air at fixed temperature, this at most is hardly one per cent, as
-already shown, and on the average is much less. Its effect, therefore,
-is equivalent to less than that caused by a rise of temperature of
-three degrees. But if precipitation occurs, an enormous amount of
-stored sunshine, or latent heat, is liberated and applied to warming
-the associated air. Thus each pound of vapor condensed may, by the
-release of its thermal store, heat more than a ton of air one degree
-in temperature, or more than half a ton of air two degrees, etc.
-The actual number of pounds of air at constant pressure, raised one
-degree Centigrade by the condensation of one pound of vapor at various
-temperatures, is given in the following table:
-
-                               TABLE IV
-
-  --------------------------------+-------+-------+-------
-  Temperature of condensation     |    0° |   25° |   50°
-  Pounds of air heated one degree | 2550  | 2480  | 2407
-  --------------------------------+-------+-------+-------
-
-The sun then is father of the wind. By uneven heating of the atmosphere
-it disturbs the uniform density gradation that would otherwise exist.
-Thus abnormal pressures are generated which disturb the repose of the
-aërial sea, causing the fluid to flow from regions of excessive to
-regions of defective pressure. Hence the study of insolation[59] and
-temperature distribution is fundamental to the science of the winds.
-
-Without detailed study, we may note the aggregate insolation received
-by the earth, at various latitudes, and its general effect on
-terrestrial temperature. The sun emits a nearly constant stream of
-radiation, from year to year, which plays continuously upon the earth
-as a whole, with an intensity which varies but slightly from month to
-month, due to the slightly varying distances of the earth from the
-sun. Owing to the sun’s seasonal wandering across the equator, the
-insolation at any latitude varies considerably month by month, and
-the polar regions receive much more light than if no such wandering
-occurred. The total yearly insolation for every 5° of latitude is shown
-in the following table from Hann, in which the unit is the amount that
-the earth would receive in one day at the time of the equinox, if the
-sun were at its mean distance from the earth:
-
-                                TABLE V
-
-                    _Annual Amounts of Insolation_
-
-  -----------+---------+------------
-   Latitude. | Thermal | Difference.
-             | Days.   |
-  -----------+---------+------------
-       0°    |  350.3  |
-       5°    |  349.1  |    1.2
-      10°    |  345.5  |    3.6
-      15°    |  339.4  |    6.1
-      20°    |  331.2  |    8.2
-      25°    |  320.5  |   10.7
-      30°    |  307.9  |   12.6
-      35°    |  293.2  |   14.7
-      40°    |  276.8  |   16.4
-      45°    |  258.7  |   18.1
-      50°    |  239.6  |   19.1
-      55°    |  219.4  |   20.2
-      60°    |  199.2  |   20.2
-      65°    |  180.2  |   19.0
-      70°    |  166.2  |   14.0
-      75°    |  156.5  |    9.7
-      80°    |  150.2  |    6.3
-      85°    |  146.5  |    3.7
-      90°    |  145.4  |    1.1
-  -----------+---------+------------
-
-From this it appears that the equator receives nearly 2.5 times as much
-heat yearly as the poles. Since, moreover, the equator enjoys nearly
-constant insolation, while the polar regions suffer great variations of
-heat, with the varying altitude of the sun, the equatorial atmosphere
-is both much hotter and more equable than the poles, and high latitudes
-generally. Thus at the equator the frost level stands constantly
-at 18,000 feet, while in the middle latitudes it varies greatly in
-height from season to season. If, for example, a circle be drawn to
-represent the earth, and above it a line to indicate the mean altitude
-of the frost level in July, the frost line starting at the equator
-at an elevation of 18,000 feet will decline north and south, finally
-touching the earth well toward the frigid zones. The levels for other
-temperatures, above and below freezing, are similarly inclined downward
-from the equator to north and south. Obviously these isothermal
-levels vary with the varying season, and at any fixed time differ on
-different longitudes. On the plane of any given latitude the frost
-line varies much less in altitude, and so for the other isothermals.
-This is particularly true at the poles and equator, and everywhere at
-considerable altitude. If one voyaged around the earth at the equator
-at an elevation of 5,000 feet, he should find the average temperature
-about 65° F. In the temperate zone, following a line of latitude
-at the same height, he should have a lower temperature, but still
-comparatively equable. The average annual temperature of the earth’s
-entire surface is about 60° F.
-
-In practical meteorology the temperature is observed at many points
-simultaneously over a wide stretch of the earth’s surface. These
-are then plotted on a weather chart, and through all points of like
-temperature are drawn lines known as isothermals. These lines not only
-map the earth’s surface into regions of equal temperature, but they
-also show the direction of fall or rise of temperature, and its space
-rate of change. This rate is called the “temperature gradient,” and
-when estimated straight across from isothermal to isothermal, that is
-in the direction of liveliest change of temperature, it is the maximum
-gradient. Such a map is very useful in forecasting the weather. It is
-but a particular instance of the more general map conceived by the
-physicist, exhibiting the thermal condition of the entire atmosphere by
-means of a series of equal temperature surfaces one above the other.
-Here, of course, the temperature gradient at any point is the space
-rate of change of temperature in any direction, being zero along the
-isothermal surface and greatest normal to it.
-
-The vertical temperature gradient is of particular interest, since
-it determines the condition of fluid equilibrium at any point in the
-atmosphere when the level surfaces are isothermal. If, for example, a
-balanced balloon or portion of air, on starting upward from any level,
-cools faster than the environing stagnant air, it will become more
-dense, and cease to ascend, in which case the atmospheric equilibrium
-is stable. Again, if the ascending gas or air cools more slowly than
-the surrounding medium, it will become less dense, and so continue
-to ascend, in which case the atmospheric equilibrium at the point
-is unstable. Thirdly, if the rate of cooling be identical for the
-ascending gas and its surrounding medium, the equilibrium is neutral,
-and the motion will be stopped by friction but unaffected by change
-of buoyancy, since no such change can occur. Of these three states of
-equilibrium, the stable is dominant above the cirrus level, while below
-that level each state may be found, at various times, prevailing at
-random in all parts of the world, but more generally the stable and
-neutral states. When the unstable condition occurs at any locality and
-any level, it is usually followed ere long by a commotion or upheaval
-in the atmosphere, until the temperature gradient alters to the neutral
-or stable.
-
-Many observations have been made to determine the variation of
-temperature along the verticle in various places and in different
-seasons. From the temperature records obtained in 722 balloon
-ascensions near Paris, France, the mean fall of temperature per 1000
-feet up to 20,000 feet was found to be 2°.4 in winter, 2°.8 in spring,
-2°.6 in summer, 2°.5 in autumn and 2°.6 for the year. Near Berlin 3°.1
-for the year was found from 75 balloon ascensions, the rate being
-nearly the same for the halves of the year. Fig. 44 gives the average
-of 52 winter and 65 summer temperature gradients, taken at about 8 A.M.
-by means of sounding balloons sent up at Munich, Strassburg, Trappe and
-Uccle. It will be noted that in both summer and winter the temperature
-falls rapidly with increase of elevation, up to ten or eleven
-kilometers, but above twelve remains nearly constant for all altitudes.
-The difference in temperature summer and winter is interesting, also in
-its gradual diminution with altitude. Another striking feature is the
-inversion of gradient shown at twelve kilometers elevation, where the
-temperature ceases to diminish, and may even increase with altitude.
-This region is known as the upper inversion level of the atmosphere, as
-distinguished from other levels at or below three kilometers height,
-known as lower inversions, where the temperature gradient is sometimes
-reversed, though not so illustrated in the diagram.
-
-Thus the atmosphere divides into three marked layers. The lower
-layer, three kilometers deep, is the region of turbulence and storm,
-the home of heavy rain clouds, lightning, wind gusts and irregular
-temperatures. The middle layer, some seven kilometers thick, bounded
-top and bottom by the upper and lower inversion levels, is a clear
-region of steady-falling temperature, for the most part frigid—a region
-of far reaching and rapid winds, sweeping eastwardly, except near the
-equator, and bearing on their backs the frosty cirrus clouds. The upper
-layer reaching from the cirri to the cosmic void, is always cloudless
-and very frigid, with temperature nearly constant, or maybe slightly
-increasing with elevation.
-
-[Illustration: FIG. 44.—SUMMER AND WINTER AVERAGE VERTICAL TEMPERATURE
-GRADIENTS.]
-
-A striking peculiarity of these three regions is that the lower and
-middle layers may freely intermingle with each other, but never with
-the upper, or isothermal layer. Owing to its constant temperature, the
-upper layer floats on its neighbor like oil on water.[60] If a mass of
-dry air were forced up into it from below, with the natural cooling due
-to adiabatic expansion, such mass would be denser than the surrounding
-medium, and hence would promptly sink back to its initial position.
-Thus whatever turmoil may vex the middle or lower region, it can at
-most upheave the floor of the isothermal layer, leaving inviolate the
-crystal depths of the empyrean.
-
-We may now turn to the distribution of barometric pressure in
-the atmosphere and the effect of its variation. In general, the
-distribution is not very uniform, but it can be graphically pictured by
-drawing a series of surfaces connecting all points of equal pressure.
-These are called isobaric surfaces. In a stagnant uniformly heated
-atmosphere, for example, these surfaces would lie one above the other
-parallel to the ocean face; but where turmoil exists, and irregular
-temperature distribution, the isobaric surfaces are bent into hills
-and hollows of varied form. These surfaces not only map the aërial sea
-into regions of equal pressure, but they also show the direction of
-fall or rise of pressure, and its space rate of change. This rate is
-called the “pressure gradient.” When estimated straight across from
-surface to surface, that is, in the direction of the liveliest change
-of pressure, it is the maximum pressure gradient. Along this normal
-direction the air tends to flow with an acceleration proportional to
-the gradient. The velocity thus acquired by any portion of air in
-being pushed along the line of falling pressure, combined with its
-velocity due to other causes, gives its true velocity. A most important
-consideration, therefore, in a scientific study of the wind is the
-pressure distribution.
-
-In practical meteorology, observations of the barometric pressure are
-made simultaneously at many points on the earth’s surface, and the
-readings then plotted on a map, after “reduction to sea level.” This
-reduction is made by adding to each barometric reading the weight of a
-column of air between the barometer level and the sea level, according
-to tables prepared for this purpose. Lines called “isobars”[61] are
-then drawn, at regular intervals, through all points of like sea-level
-pressure, the indicated change of pressure between consecutive isobars
-on the U. S. weather map being usually one-tenth of an inch of mercury.
-These exhibit at once, over the entire field of observation, the
-horizontal pressure gradient reduced to sea level, and commonly called
-the “barometric gradient.” In meteorology, the pressure normal to the
-isobar is called the gradient, and is expressed in millimeters of
-mercury per degree of a great circle. On the same weather chart are
-mapped the isothermal lines and wind directions for all the stations
-of the weather service. From these data and the reported moisture
-conditions, the meteorologist forecasts the probable weather some hours
-or days in advance.
-
-No perfectly comprehensive formula can be given for the barometric
-pressure at any place and altitude, but certain general laws may be
-observed. Where, for example, the speed of the air is increased along
-any level of an air stream, the pressure is lessened, and conversely.
-Thus, if the wind blows squarely against the front of an isolated
-house, the speed will be greatly checked at the center front, and
-accelerated at both sides and over the roof, thereby increasing the
-apparent barometric pressure on the front, and lessening it on the
-sides and over the top. A similar effect may be observed when the air
-flows round the hull and framing of air craft.
-
-Again, if the atmosphere over any locality is heated appreciably more
-than its environment, the heated column tends to expand upward and
-overflow aloft in all directions toward the cooler neighborhood, thus
-lessening the pressure throughout the heated column, and increasing
-the pressure throughout the environing atmosphere laterally. When this
-effect is marked the plotted isobars often form a series of closed
-curves about the heated region, manifesting a pressure gradient at the
-lower levels in all directions toward the heated area. This grouping of
-the isobars exhibits the familiar low pressure area of the weather map.
-On the other hand, if any locality be cooled appreciably more than its
-environment, the cooled column sinks, so that the surrounding warmer
-air aloft flows in over it, thereby increasing the pressure over the
-cooled area, and diminishing it throughout the environment. The isobars
-may then form a series of closed curves about the cooled region, with a
-pressure gradient along the higher levels in all directions away from
-the cooled area. Of course, if heat were the only agency disturbing
-the earth’s barometric pressure, there should be a parallelism between
-the heat and pressure gradients; but, as already noted, the speed
-or momentum of the aërial currents is also a substantial agency in
-modifying the pressure lines.
-
-It is well to remember that, while the base of a warm column of air
-may, due to the overflow aloft, have less pressure than the base of
-the cool environing column which receives the overflow, the high part
-of the column may have greater pressure than the equally high part of
-the cool. For if the columns be initially of the same temperature and
-pressure, heating one of them uplifts its levels of given pressure
-above those of its neighbor. When the overflow begins, a partial
-equalization of pressure levels occurs, but not a complete one so long
-as the flow has any head.
-
-An interesting hygrometric feature of these highs and lows may here
-be observed in passing. As already explained, when a column of air
-ascends it cools by expansion, and tends to precipitate its water
-content as cloud or rain; and conversely, when the air sinks it heats
-by compression, thus acquiring greater moisture capacity and tending
-to clarify. As a consequence, the areas of low pressure and a rising
-atmosphere are usually marked by clouds and rainfall, while the areas
-of high pressure and falling atmosphere are marked by clear, or
-clearing weather. In the low, damp areas, then, the air feels heavy
-while it is really light; in the high and dry area the air feels light,
-while it is really dense, and most favorable to air men for carrying
-heavy loads in their balloons or flyers. Similarly when air flows over
-a mountain range the ascending stream precipitates moisture, due to
-cooling by expansion, while the descending stream, on the other side,
-comes down hot and dry, due to compression.
-
-A characteristic mechanical feature of the high and low pressure areas
-is the closed circulation between them, involving practically the whole
-atmosphere below the isothermal layer. If we conceive the entire globe
-spotted with high and low areas, we may picture the air surging upward
-in the lows, flowing outward under the isothermal layer, descending in
-the highs, then flowing outward along the earth’s surface toward the
-lows in a continuous cycle. Thus, chiefly is maintained the vast and
-multifold circulation of the atmosphere over the entire world.
-
-In general the motion is of a vortical nature, by which is meant that
-the masses of air as they flow along stream suffer more or less change
-of orientation in space, the rotation at times being so slight as to
-be undetectable, and again so marked as to excite wonder, as in the
-whirlwind. Many of these atmospheric vortices, even though varying
-in diameter from a few yards to hundreds of miles, resemble in their
-behavior the gyrating column of water in a common circular basin
-emptying through an orifice at its bottom. If the water is very still
-when the drain opens, the column descends with imperceptible, if any,
-rotation; but if the column has an initial whirl, or angular velocity,
-this is magnified as the water approaches the axis of the vortex,
-the tendency of the mass being to preserve its angular momentum, or
-fly wheel property. A like action obtains in the great atmospheric
-vortices, though here the motion far from the axis may seem like a
-straight-blowing wind, rather than part of a vast whirl covering
-thousands of square miles.
-
-But even if all the air started directly for the axis of the ascending
-column, like still water in a basin, it would promptly acquire vortex
-motion, because it flows on the surface of a rotating sphere. The
-deflection so produced is evidently greatest at the poles, and for
-other places equals the polar value multiplied by the sine of the
-latitude. The effect is similar to what occurs when a basin, rotating
-about a vertical axis and carrying water with the same angular
-velocity, is opened at the bottom. In this case the water at once
-begins to gyrate within the basin, as the particles move toward its
-axis.
-
-With these preliminary generalities we may proceed to study the more
-prominent movements in the atmosphere.
-
-
-
-
-                              CHAPTER XV
-
-                     PERMANENT AND PERIODIC WINDS
-
-
-The winds of the world are commonly classified as the permanent, the
-periodic and the nonperiodic, according to their genesis and character.
-Their chief features may be briefly outlined.
-
-The most conspicuous and important aërial current on the globe is
-the permanent double vortex playing between the equator and the
-poles. The heated air of the equatorial belt, uplifted by expansion,
-overflows beneath the isothermal layer toward the north and south,
-thereby increasing the pressure in the higher latitudes sufficiently
-to generate a surface inflow along the earth, and thus maintaining a
-perpetual closed circulation which is felt all over the globe. The
-main features of this motion have been determined mathematically by
-Ferrel,[62] and summarized as follows:
-
-  “In the preceding part of this chapter it has been shown that,
-  if all parts of the atmosphere had the same temperature, there
-  would be a complete calm over all parts of the earth’s surface.
-  But that, in consequence of the difference of temperature
-  between the equatorial and polar regions of the globe, and
-  the consequent temperature gradient, there arise pressure
-  gradients and forces which give rise to and maintain a vertical
-  circulation of the atmosphere, with a motion of the air of
-  the upper strata of the atmosphere from the equator toward
-  the poles, and a counter current in the lower part from the
-  poles toward the equator, as represented by the arrows in the
-  following figure, and that this of course requires a gradual
-  settling down of the air from the higher to the lower strata in
-  the middle and higher latitudes and the reverse in the lower
-  latitudes. It has also been shown that in case the earth had
-  no rotation on its axis, this would be exclusively a vertical
-  circulation in the planes of the meridians without any east or
-  west components of motion in any part; but that, in consequence
-  of the deflecting forces arising from the earth’s rotation, the
-  atmosphere at the earth’s surface has also an east component
-  of motion in the middle and higher latitudes, and the reverse
-  in the lower latitudes, and that the velocities of the east
-  components increase with increase of elevation, so that at
-  great altitudes they become very much greater than those
-  at the earth’s surface; while those of the west components
-  decrease with increase of altitude up to a certain altitude,
-  where they vanish and change signs and become east velocities,
-  now increasing with increase of altitude to the top of the
-  atmosphere.
-
-  “It has been further shown that the deflecting forces arising
-  from the east components of motion of each hemisphere from the
-  earth’s surface to the top of the atmosphere, in the middle
-  and higher latitudes and of the upper part of the atmosphere
-  in the lower latitudes, drives the atmosphere from the polar
-  regions toward the equator, while those arising from the west
-  components of motion in the lower part of the atmosphere in
-  the lower latitudes, having a contrary effect, but small in
-  comparison with the other on account of the weakness of these
-  forces near the equator, tend to drive the air a little from
-  the equator toward the poles. There is, therefore, a depression
-  of the isobaric surfaces at all altitudes in the polar
-  regions, especially in the southern hemisphere, a much smaller
-  depression in the equatorial regions, and a bulging up of the
-  isobaric surfaces in the vicinity of the parallel of 30° in
-  the lower part of the atmosphere, the maximum being nearer the
-  equator as the altitude increases, as represented in Fig. 45,
-  but at high altitudes there is a minimum of barometric pressure
-  at the poles and a maximum at the equator.
-
-[Illustration: FIG. 45.—GENERAL CIRCULATION OF THE ATMOSPHERE.]
-
-  “In the accompanying figure the solid arrows in the interior
-  part represent the resultant motions of the winds (longer
-  arrows indicating greater velocities), in case of an earth
-  with a homogeneous surface over both hemispheres, in which
-  the motions would be symmetrical in both and the same at all
-  longitudes, and the equatorial and tropical calm belts would
-  be situated at equal distances from each pole. The dotted
-  arrows indicate the strong, almost eastern motion of the air
-  at all latitudes at some high altitude, as that of the cirrus
-  clouds.
-
-  “The outline of the outer part of the figure represents an
-  isobaric surface high up where the bulging up near the parallel
-  of 30° disappears and the maximum pressure at the same altitude
-  is transferred to the equator. For lower altitudes the isobaric
-  surfaces have a bulging up at the parallel of 30°, and a slight
-  depression at and near the equator. The arrows in this part
-  represent the polar and equatorial components of motion, the
-  former above and the latter below, except near the earth’s
-  surface on the polar sides of the tropical calm-belts, where
-  there is a polar component of motion arising from the air’s
-  being pressed out from under the belt of high pressure. This,
-  perhaps, does not extend beyond the polar circles, beyond
-  which there can be little motion in any direction, except from
-  abnormal disturbances.
-
-  “For reasons given in §103, the actual mean position of the
-  equatorial and tropical calm-belts are not precisely as here
-  represented, but are all a little displaced toward the north
-  pole, and the polar depression of the isobaric surfaces is
-  greater in the southern than in the northern hemisphere.”
-
-The conclusions from this approximate analysis are in the main
-supported by observation, except as modified by the heterogeneity
-of the earth’s surface. The sea-level distribution of barometric
-pressure between the equator and poles, as found by Ross’ long series
-of measurements, manifests a variation of about one inch of mercury,
-with maxima at about 30° of latitude, north and south, as required
-by Ferrel’s theory. As a further cause of the depression toward the
-poles, may be mentioned the greater speed of the permanent east wind
-with the consequent centrifugal lift in the atmosphere.
-
-As to the general easterly direction of the winds at middle and
-higher latitudes, that is well known from observation of the motion
-of clouds and of the air near the earth. At the cirrus level the
-velocity in those latitudes is almost exactly eastward. But the flow
-in longitude, illustrated by the outer arrows in Fig. 45, has not
-been fully determined by observation. Moreover, as Ferrel himself
-showed, the unequal heating of continents and oceans sets up gradients
-in longitude, especially in the northern hemisphere, thus adding
-considerable disturbance to the general circulation. To this agency
-must be added also the latitudinal shifting of insolation, due to the
-annual march of the sun across the equator, entailing an oscillatory
-seasonal shift of the hot belt, and therefore of the twin-hemispheric
-cycle of the atmosphere.
-
-Some currents of the general and permanent circulation are sufficiently
-prominent to have special names, such as the _trade-winds_, the
-_antitrade-winds_, the _prevailing westerlies_, and, in the lower
-latitudes, the _calm belts_, where the flow is exceptionally feeble.
-All these currents have been known to sailors since early times, and
-have been of considerable importance in marine navigation. Eventually,
-perhaps, they may be of like importance in aërial navigation.
-
-The trade-winds are mild tropical surface currents of remarkably steady
-speed and direction. Springing from the high-pressure belts in either
-hemisphere, at about latitude 30°, they blow toward the equator with
-increasing westerly trend. As shown in charts 46 and 47 for midwinter
-and midsummer, the trade winds cover a large portion of the tropical
-zones in both oceans, and shift slightly in latitude with the sun.
-They are separated at the heat equator by the equatorial calm belts, or
-doldrums, and are bounded north and south respectively by the calms of
-Cancer and of Capricorn. Particularly interesting are the trade-winds
-blowing from Spain to the West Indies, which favored Columbus on his
-westward voyage, and which certain adventurous Germans have proposed
-using to duplicate that memorable voyage, in air ships.
-
-[Illustration: FIG. 46.—NORMAL WIND DIRECTION AND VELOCITY FOR JANUARY
-AND FEBRUARY. (KÖPPEN.)]
-
-The antitrade-winds, or counter trades, are lofty winds blowing over
-and contrary to the trade winds. As some doubt regarding the direction
-of these counter trades had existed, an expedition was sent in 1905, by
-two distinguished meteorologists, Teisserenc de Bort of France, and A.
-Lawrence Rotch of America, to explore the atmosphere above the tropical
-Atlantic. Mr. Rotch has summarized their measurements and conclusions
-as follows:[63]
-
-  “Pilot balloons, dispatched from the island of Teneriffe and
-  St. Vincent, were observed with theodolites at the ends of a
-  base-line, and in this way the heights at which the balloons
-  changed direction could be ascertained. Later the balloons
-  were sent up from the yacht itself, which steamed after them,
-  measurements being made of their angular elevation. The
-  observations which are plotted in Fig. 46 prove conclusively
-  the existence of the upper counter-trade. The courses of
-  the balloons are represented as if projected upon the
-  surface of the sea and show that the northeast trade-wind
-  extended only to the height of 3,200 or 4,000 meters, and
-  then gradually turned into a southerly current which, higher
-  up, came from the southwest. The width of the dotted band
-  represents approximately the varying velocity of the trade and
-  counter-trade. Similar proofs of the northwest trade-wind,
-  south of the equator were obtained by the same expedition
-  during the following year, but the above suffices to show that
-  it would be possible for an aëronaut in the ordinary balloon
-  to start from the African coast, or from some of the islands
-  in the trade-wind region, and, after drifting towards the
-  southwest, to rise a few miles into the current, which would
-  carry the balloon north and eventually northeast back to land.
-  Nevertheless, it does happen in certain atmospheric situations
-  over the tropical north Atlantic that the winds from the
-  general northwesterly direction prevail up to great heights
-  without any evidence of the return-trade. Near the equator the
-  winds are easterly up to the greatest heights which have been
-  attained.”
-
-[Illustration: FIG. 47.—NORMAL WIND DIRECTION AND VELOCITY FOR JULY AND
-AUGUST. (KÖPPEN.)]
-
-[Illustration: FIG. 48.—TRADE AND COUNTER TRADE-WINDS.]
-
-The prevailing westerlies are high-latitude surface winds of the
-permanent circulation. In the southern hemisphere they are particularly
-strong and steady owing to the comparatively unbroken stretch of
-ocean. In the north also they are strong and persistent, but variable
-in direction because of disturbances by local winds due to unequal
-heating of tracts of land and sea. These features are well illustrated
-in charts 47 and 48. Of particular interest in aëronautics is the
-prevailing wind blowing from the United States to Europe, which has
-been considered a suitable current for transoceanic balloon voyages.[64]
-
-The periodic winds are those whose gradient alternates annually or
-daily, due to annual or daily fluctuations of temperature on sloping
-or on heterogeneous parts of the globe. The annually fluctuating winds
-due to alternate heating and cooling of continents, or large land
-areas, bear the general name of monsoon. Among diurnal winds the most
-prominent are the land-and-sea breezes, and the mountain-and-valley
-breezes. Both kinds are practically available in aëronautics; the
-monsoons for long-distance travel, the diurnal winds for local use.
-
-The general motive cause is the same for all periodic winds. When any
-portion of the earth’s surface is periodically more heated above its
-normal temperature, or average for the year, than the neighboring
-region, the resulting abnormal temperature gradient causes a periodic
-surface wind tending toward the excessively heated place, and a counter
-wind above. That is, the cooler and heavier column of air sinking and
-uplifting the lighter, results in a lowering of the common center of
-gravity of the two columns of air, and thus furnishes the driving
-power of the wind. For example, an island or a peninsula may be
-considerably hotter by day and cooler by night than the surrounding
-water; a continent may be much hotter in summer and much colder in
-winter than the bordering ocean. Thus during the hot period a moist
-wind blows landward; during the cold period a dry wind blows seaward.
-If the land has vast and lofty slopes the uprush of air during the hot
-period and the downrush during the cool period may be very powerful.
-The currents so produced by the aggregate of local agencies, including
-the deviation caused by the earth’s rotation, combine with the general
-circulation of the atmosphere to form the actual wind of the place.
-Thus the periodic current may conspire with the general circulation,
-or oppose it; may intensify, weaken or obliterate it; may overmaster,
-reverse or mask it completely.
-
-Of the various continental monsoons of the globe the most powerful
-spring from the annual flux and reflux of the atmosphere over the vast
-declivities and table-lands of Asia. Here the conditions are especially
-favorable. As the sun approaches Cancer, the burning deserts and high
-plateaus, combining their force with the draft on the mountain sides,
-generate a continental uprush that sucks in all the aërial currents of
-the surrounding seas, hurling them aloft to the isothermal layer whence
-they radiate as the four winds of heaven; for here at this season the
-planetary circulation is disrupted, obliterated or reversed, appearing
-merely as a perturbation of the monsoon at its height. In India the
-force is particularly effective. Along the north the Himalayas stretch
-1,300 miles in latitude, with an average height of 18,000 feet and
-with sunburned areas on either side. North of this range are the lofty
-plateaus of Thibet and Cashmere, south of it the desert of Gobi and
-the borders of the Indian Ocean. Over this watery tract from beyond the
-equatorial line, from the isles of Oceanica and from the wintry plains
-of Australia, the air flows in with accumulated strength, sweeping the
-Bay of Bengal and the Arabian Sea in a continuous gale bearing up the
-mountain slopes incredible floods of water. Over the Arabian Sea in
-summer the gale is so steady and swift that no ordinary ship can force
-a passage from Bombay to the Gulf of Aden. Above the Bay of Bengal the
-moist south winds, converging between the coast and headlands, pour
-cloud laden up the Himalayan slopes, precipitating their whole vapor
-in prodigious torrents seldom seen elsewhere. Khasia at this season
-sustains a Noachian deluge, the rain at times falling nearly a yard
-deep in one day and night.[65] Quite appropriately, therefore, the
-summer monsoon over India, especially its component southwest wind from
-the Arabian Sea, and southerly wind from the Bengal Bay and farther
-east, is called the wet monsoon.
-
-The winter monsoon of Asia, is the reverse of the summer one, both
-in direction of gradient and in physical character. It is a cold
-flood of air pouring from the frigid table-lands and wintry depths
-of the desert, down the mountains and valleys in continual overflow
-on all sides of the continent, and then far out over the sea, where
-it reascends to complete its long cycle. In its descent all moisture
-vanishes by heating, and no intensive temperature gradient occurs, as
-in summer, to accelerate its gently modulated tide. In India the winds
-from Cashmere and Thibet pour down the Himalayas toward the Arabian Sea
-a clear current of air which unites with the trade-wind, increasing
-its force, and forming the moderate winter monsoon of that region, or
-as it is commonly called, from its lack of moisture, the dry monsoon.
-
-The kinematic character, and the extent of both summer and winter
-currents, are well portrayed in charts 47 and 48 for all the south and
-southeast of Asia. Across the islands of Japan, it will be observed,
-the winds blow in opposite directions summer and winter. In Siberia
-the monsoon winds trend along her great rivers and valleys, generally
-northward in the winter and the reverse in the summer, combining in
-both seasons with the prevailing westerlies, due to the rotation of the
-earth.
-
-All the other continents have their monsoons, though less powerful
-than those of Asia. In the great desert of Sahara, for example, there
-is an ascending hot current in the summer, causing a strong indraught
-from the Atlantic and the Mediterranean; but this is far less intense
-than if its action were fortified by lofty slopes and table-lands. In
-winter when the Sahara cools to nearly the oceanic temperature, little
-monsoon effect is perceptible, and the general circulation continues
-unperturbed. In Australia the monsoon influence is still feebler,
-owing to the limited extent of the country and to the general lowness
-and flatness of the land. Over parts of South America, the annual
-ebb and flow of the atmosphere is considerable, particularly along
-the northeastern coast, and in the whole Amazon Valley, whose aërial
-currents in general conspire with the trade-winds, strengthening them
-materially in the southern summer, though it is less in winter when the
-continental temperature more nearly approximates that of the ocean. The
-monsoons of North America have been described in some detail by Ferrel
-as follows:
-
-  “On the continent of North America we have monsoon influences
-  similar to those of Asia, but not nearly so strong, because
-  the extent of the continent, and consequently the annual range
-  of temperature, are not so great. They are, for the most part,
-  not sufficiently strong to completely overcome and reverse the
-  current of the general circulation of the atmosphere, and so
-  to produce a real monsoon, but they cause great differences
-  between the prevailing directions of the winter and summer
-  winds.
-
-  “In the summer the whole interior of the continent becomes
-  heated up to a temperature much above that of the oceans on the
-  same latitudes on each side—indeed, above that of the Gulf of
-  Mexico and the Pacific Ocean on its southern and southwestern
-  borders. The consequence is that the air over the interior of
-  the continent becomes more rare than over the oceans, rises
-  up and flows out in all directions above while the barometric
-  pressure is diminished, and the air from all sides, from the
-  Atlantic on the east to Pacific Ocean on the west, the Gulf of
-  Mexico on the south, and the polar sea on the north, flows in
-  below to supply its place. On the east the tendency to flow in
-  is not strong enough to counteract the general easterly motion
-  of the air at the earth’s surface in the middle latitudes, and
-  to cause a westerly current, but it simply retards the general
-  easterly current and gives rise to a greater prevalence of
-  easterly winds along the Atlantic sea-coast during the summer
-  season....
-
-  “In winter the thermal conditions over the continent are
-  reversed. The interior of the continent is now the coldest
-  part, and it is especially colder than the surrounding oceans
-  at that season. It has also very high plateaus and mountain
-  ranges. The air, therefore, of the lower strata, and especially
-  those next the earth’s surface, now tends to flow out in all
-  directions to the warmer oceans and the Gulf of Mexico, and
-  especially to run down the long slope of plateau from the
-  Rocky Mountains into the Mississippi Valley. The effect over
-  the whole of the United States east of the Rocky Mountains
-  is to cause the winds, which otherwise would be westerly and
-  southwesterly, to become generally northwesterly winds, instead
-  of southerly and southwesterly ones, as in summer. There is not
-  a complete monsoon effect, but simply a great change between
-  summer and winter in the prevailing directions of the winds. In
-  Texas, however, and farther east along the northern border of
-  the Gulf, the effect is somewhat that of a complete monsoon. In
-  New England and farther south in the Eastern States the monsoon
-  effect is to cause the prevailing winds to be from some point
-  north of west, instead of south of west as in summer.
-
-  “In summer, Central America and Mexico have a much higher
-  temperature than that of the adjacent tropical sea on the
-  southwest, and having high mountain ranges and elevated
-  plateaus, there is consequently a strong tendency to draw in
-  air from the southwest at this season, which not only entirely
-  counteracts the regular trade-winds of these latitudes, but
-  even reverses them and causes southwest winds. The effect is to
-  cause in midsummer a large area here, extending far westward,
-  of calms and irregular and light winds, mostly southwesterly
-  ones, and an apparent widening of the equatorial calm-belt at
-  this season so as to make its northern limit reach up, along
-  the coast, nearly to the parallel of 20°. The effect is similar
-  to that in the Atlantic west of the Gulf of Guinea and Liberia,
-  except that it here appears to be some greater, and causes
-  a true monsoon effect, since during the winter the regular
-  northeasterly trade-winds prevail, but strengthened by the
-  reverse thermal conditions of the winter season. On the eastern
-  side, and over the western end of the Gulf of Mexico, there is
-  a somewhat regular monsoon effect, the prevailing winds being
-  easterly, or blowing toward the land, during the summer, and
-  the reverse in winter.
-
-  “Along the west coast of North America in the middle latitudes
-  there is a strong monsoon influence; for the interior of the
-  continent becomes heated in summer to a much higher temperature
-  than that of the southwesterly ocean, and hence a strong
-  current is drawn in from this direction, at right angles to
-  the general trend of the coast which, combining with the
-  general southwesterly winds of these latitudes in the general
-  circulation of the atmosphere, causes the strong and steady
-  westerly and southwesterly winds of this region during the
-  summer. Farther north, up toward Alaska, the summer monsoon
-  effect is combined with the current caused by the deflection
-  of the continent as well as the general easterly current of
-  high latitudes, so that the winds here are generally southerly,
-  but still have somewhat of a monsoon character, being southerly
-  and southwesterly in summer and easterly and southeasterly
-  during the winter.
-
-  “Along the northern coast of America, as along that of Siberia,
-  the monsoon tendency is to draw the air from the colder land
-  to the warmer ocean in winter, and the reverse in summer; and
-  these effects, combined with the general easterly motion of
-  the atmosphere in these latitudes, gives rise to prevailing
-  southwesterly winds in winter and northwesterly ones in summer.
-  The winter monsoon influence, however, is small here—much
-  more so than in Siberia, for the ocean contains so many large
-  islands that it has rather a continental than an oceanic winter
-  temperature; and besides, it has not the influence of a warm
-  current—such as the continuation of a part of the Gulf Stream
-  along the northern coast of Europe and Asia.”
-
-Similar to the monsoons in essential nature are the diurnal winds of
-seacoast and mountain side. They begin with the heating of the land
-in the morning, attain their maximum intensity about mid afternoon,
-or during the hottest of the day, and finally are reversed at night.
-Besides being so much briefer than monsoons, they are also in general
-feebler and less extensive. They may be quite noticeable on calm
-days, especially in clear weather and in hot climates; but usually
-they are masked or entirely overwhelmed where other marked currents
-occur—currents due either to the general circulation or monsoons, or
-other powerful disturbing agencies.
-
-In land-and-sea breezes, which usually extend not far inland, there is
-a surface inflow of sea air during the forenoon and early afternoon,
-balanced by an outflow of warm air above, rising from the heated soil.
-After sundown this is reversed, the chilled air from inland pouring
-out to sea, while overhead the warmer sea air is forced landward at a
-higher level. These currents are strongest where the diurnal range of
-temperature is greatest and where the local topography is of suitable
-configuration. Particularly favorable are steeply declining shores,
-narrow bays and inlets, girded by mountains or lofty hills. During
-the day heated air ascends such declivities with alacrity, like smoke
-through an inclined flue, while at night, when cooled by radiation
-and contact with the soil, it rushes torrentlike down the valleys and
-hillsides, passing out to sea, often in sudden squalls that embarrass,
-or endanger, small sailing craft. Circulatory currents like the above
-have sometimes been used by aëronauts to carry them out to sea and back
-again to land at a different level.
-
-In like manner the mountain-and-valley winds may be used by the
-skillful aëronaut. It is well known that these flow up the courses of
-rivers, cañons and land slopes generally by day, but at night reverse
-their course and pour down again with considerable force. For this
-reason experienced hunters place their camp fires below tent in a
-sloping valley. The strength of the breeze depends, of course, upon
-the daily range of temperature, and the steepness and expanse of the
-slope. Such winds are deftly used by the masters of soaring flight, the
-great robber and scavenger birds, and no doubt may be used by men in
-motorless aëroplanes, to gain elevation, and journey great distances
-without expenditure of energy.
-
-
-
-
-                              CHAPTER XVI
-
-                   CYCLONES, TORNADOES, WATERSPOUTS
-
-
-Besides the periodic winds so far treated, there are prominent aërial
-movements having no regular course or season. These are the nonperiodic
-winds which so exercise or perplex the weather forecaster and those who
-confide in him. In general such winds are of a temporary character,
-arising from an unstable condition of the air in some locality, or
-from unequal heating, either of which causes may generate, or briefly
-sustain, an updraught, with its attendant gyration. Owing to the
-whirling character of such ascending currents, they have received
-various significant names, such as cyclone, tornado, whirlwind; the
-three terms applying to vortices in decreasing order of magnitude. Each
-in turn may be treated briefly.
-
-The cyclone is a temporary large gyratory wind. It may last a few hours
-or a few days. It may measure fifty to a hundred miles across, or it
-may measure more than a thousand miles. On the weather map it is in
-general marked by a group of closed isobars, showing a considerable
-pressure gradient toward a small internal area where the pressure is
-a minimum. To an observer looking about the earth’s surface and lower
-levels of the atmosphere, the cyclone appears merely as an ordinary
-wind, accompanied perhaps by rain or snow. It is not a swiftly rotating
-narrow column, or cone of air, like a tornado or whirlwind, full of
-gyrating dust and débris.
-
-The motive power of a cyclone, though in general due to the buoyancy
-of heated air, may spring from more than one set of conditions. Notice
-has already been taken of vortices due to a hot column of air at lower
-barometric pressure than its lateral environment. Take another case.
-If a dry atmosphere is of uniform temperature and pressure at various
-levels, but has a vertical temperature gradient a little greater than
-the normal cooling of an ascending gas, a portion of air started upward
-in any casual way becomes warmer than its lateral environment, and
-hence continues to rise until the unstable condition due to abnormal
-temperature gradient ceases. Again, while the surface stratum is in
-stable equilibrium, it may happen that the second mile of air is
-abnormally hot, and the third mile abnormally cold, and thus a vortex
-may occur in mid air, without disturbing the face of the earth.
-
-Whatever be the initial atmospheric condition causing the vertical
-uprush, the nature of the resulting circulation is in general that of
-the cyclone, illustrated, in part, by the whirling vortex of water in
-a basin. As the current ascends, an indraught occurs in all the lower
-regions of air, and an outflow in all directions above, sometimes
-at the height of a mile or two, again in all the region next to the
-isothermal layer. As the earth has at all places above the equator
-a component of rotation about the vertical line, it follows that in
-northern latitudes all the air flowing toward the vortex is in a whirl
-opposite in motion to the hands of a watch lying face upward, and all
-the outflowing air above has a like angular motion, but gradually
-diminishing until it is reversed. At the lower portion of the vortex
-the air whirls inward and upward with increasing velocity, while
-above, it whirls outward and upward, with waning velocity, thus moving
-in a double-spiral path shaped like a cord wound on an hourglass. In
-the constricted part, or neutral plane of the vortex, the air moves
-neither outward nor inward, but spirals straight upward. To match the
-upflow, and complete the closed circulation, there must be a downflow
-on the exterior of the cyclone, and since the whirl is reversed
-in direction, this outer mass of downflowing reverse-whirling air
-embracing the cyclone is called the anticyclone.
-
-Between the inner and outer vortex the air is comparatively calm and
-the pressure is a maximum, with steepest gradient toward the center
-of the cyclone. Also the air is calm just at the axis of the vortex,
-while for some distance away its speed increases as the radius of its
-whirl, so that the central mass rotates practically as a solid column,
-thus still further lowering the pressure near the axis. This solidly
-rotating central column of air is sometimes called the core of the
-vortex.
-
-High above the center of the cyclone, where perhaps the air is sucked
-downward, clarified by compression, then whirled outward, the sky is
-usually clear, or thinly fogged, while without this central patch are
-heavy clouds. The obscure or clear central part is called the “eye[66]
-of the storm.” Through this the cirrus clouds may sometimes be seen
-high above, either stationary or radiating away, if the vortex extends
-so high. Sailors on the deck of a vessel passing through a cyclone have
-often noticed the eye of the storm overhead, perhaps ten or twelve
-degrees in diameter, and with special clearness in the tropics. To the
-white, feathery cirrus clouds, scurrying away radially from the top of
-the vortex, they have given the name “plumes of the storm,” or “mares’
-tails.” In sailing their vessel through the center of a cyclone, they
-have observed the circulatory motion of the winds and clouds, and
-frequently have found the deck covered or surrounded with cyclone
-sweepings, such as land and water birds, insects, butterflies, etc.,
-brought into the quiet core of the vortex from the incurving winds
-beyond. Further details of the motion in a cyclone vortex are given as
-follows by Ferrel, §178:
-
-  “In Fig. 49 is given a graphic representation of the resultant
-  motions and of the barometric pressures for both the surface
-  of the earth and for some level high up in the atmosphere and
-  above the neutral plane, where the motions in the vertical
-  circulation are outward from the center. The solid circles
-  represent isobars at the earth’s surface and the solid arrows
-  the directions, and in some measure, by their different
-  lengths, the relative velocities of the wind. The heavy circle
-  represents the circle of greatest barometric pressure at the
-  earth’s surface, say 765 mm., while the pressure of the outer
-  border is 760 mm., and the dividing line between the cyclone
-  and the anticyclonic gyrations. Within this limit the pressure
-  diminishes to the center, and the gyrations are cyclonic, and
-  the direction of the resultant of motion inclines in toward the
-  center, but beyond that limit the gyrations are anticyclonic,
-  and the direction of resultant motion inclines toward the outer
-  border of these gyrations. The heavy dotted circle represents
-  the circle of maximum pressure at some high level, and is much
-  nearer the center than that at the earth’s surface. It is
-  also the dividing line between the cyclonic and anticyclonic
-  gyrations at that level. The dotted arrows indicate the
-  directions and in some measure the relative velocities, of the
-  wind at this level. The arrows in the cyclonic part represent
-  the direction of the wind as declining outward, because the
-  plane here considered is supposed to be above the neutral
-  plane, where the radial component of motion is outward, but
-  for any level below the neutral plane the inclination is still
-  inward. The arrows are shorter above in the cyclonic part and
-  longer in the anticyclonic part than they are at the earth’s
-  surface, since the cyclonic gyratory velocities decrease and
-  the anticyclonic increase with increase of altitude.
-
-[Illustration: FIG. 49.—VELOCITY DIAGRAM IN HORIZONTAL SECTION OF A
-CYCLONE.]
-
-  “The upper part of the figure is a representation of a vertical
-  section of the air, very much exaggerated in altitude, in
-  which the solid curved line represents a section of an isobaric
-  surface near the earth’s surface, say of 740 mm. barometric
-  pressure. The lowest part corresponds with the center of the
-  cyclone and the highest part with the heavy circle in the
-  lower part of the figure, and the steepest gradients with the
-  longest solid arrows, since the greater the gyratory velocities
-  at the earth’s surface the greater the gradients, though they
-  are not strictly proportional. The second dotted curved line
-  from the top represents a section of the isobaric surface of
-  high altitudes, in which the highest parts correspond with
-  the heavy dotted circle below, since the highest pressure at
-  all altitudes is very nearly where the cyclonic gyrations
-  vanish and change to the anti-cyclonic. The depression here
-  is smaller because the cyclonic area is smaller, and the
-  gyratory velocities less, than at the earth’s surface. The
-  upper dotted line belongs to an isobaric surface still higher,
-  where the gyrations are supposed to be all anti-cyclonic, and
-  here, consequently, the greatest pressure is in the center, as
-  indicated by the curved line.
-
-  “As the interior of the whole cyclonic system is warmer
-  than the exterior, and consequently the air less dense, the
-  distances between the isobaric surfaces are necessarily greater
-  in the interior than the exterior part, and so, however much
-  the isobaric surface at or near the earth’s surface may be
-  depressed by the cyclone gyration there, at a considerable
-  altitude, if the temperature difference is great enough, it
-  must become convex instead of concave.
-
-  “The track of any given particle of air in a cyclone, resulting
-  from the vertical and gyratory circulation, is that of a
-  large converging and ascending spiral in the lower part, but
-  of a diverging and ascending spiral in the upper strata of
-  the atmosphere, and the nearer the earth’s surface the more
-  nearly horizontal is the motion, since the vertical component
-  gradually decreases and vanishes at the surface.
-
-  “The whole energy of the system by which the inertia of the
-  air and the frictional resistance are overcome and the motions
-  maintained, is in the greater interior temperature and the
-  temperature gradients, by which the circulation is maintained.
-  This being kept up, the deflections and gyrations are merely
-  the result of the modifying influence of the earth’s rotation,
-  which is not a real force, since it does not give rise to
-  kinetic energy, but merely to changes of direction.
-
-  “It must be borne in mind that the preceding is a
-  representation of the motions and pressures of a cyclone
-  resulting from perfectly regular conditions, in an atmosphere
-  otherwise undisturbed, and having a uniform temperature,
-  except so far as it is affected by the temperature disturbance
-  arising from the cyclonic conditions. Accordingly results so
-  regular are not to be found in Nature, but generally only rough
-  approximations to them.
-
-  “Since the wind inclines less and less toward the center of the
-  cyclone below the neutral plane and declines from the center
-  above it, the upper currents above this plane in a cyclone are
-  always from a direction, in the northern hemisphere, a little
-  to the right of that of the lower currents, when not affected
-  by abnormal circumstances.”
-
-Observation of cyclones in Nature very well confirms the leading
-features set forth on theoretical grounds. If the vortex pass centrally
-over an observatory there is noted first a high barometer and calm air,
-attended perhaps by scurrying cirrus clouds; next a rapidly falling
-pressure and increasing wind, with dark clouds and precipitation,
-commonly accompanied by thunder and lightning; then the hushing of
-the storm to a dead calm, and low barometer and thinning or clearing
-of the clouds overhead; then a rising barometer with renewed winds in
-the reverse direction, and finally subsiding winds, rising barometer
-and clearing weather. These phenomena are the more definitely presented
-if the whirl is strong while its travel along the earth is slow. But
-owing to their progressive easterly motions, cyclones in the north have
-their moist hot southern masses elevated, chilled and precipitated
-on their eastern fronts and beyond, while their rear experiences the
-opposite action and is called the clearing side. Conversely in the
-tropics the westerly moving cyclones have cloudy and wet rears, because
-the easterly drift on high carries the precipitating masses toward the
-rear. The general hygrometric appearance of a centrally passing cyclone
-in middle latitude is thus described by Ferrel, §207:
-
-  “In the regular progression of a cyclone in the middle
-  latitudes somewhat centrally over a place, the cloud and rain
-  area of the front part, extending far toward the east, first
-  passes over, occupying a half-day, or a day and more, and
-  then the front part of the ring of dense cloud with a heavy
-  shower of rainfall. After this there are indications of a
-  clearing up, and even the sun may break through the cloud for
-  an hour or two; but presently there is an apparent gathering
-  and thickening of the cloud and a second shower. This is at
-  the time of the passage of the rear side of the ring of denser
-  cloud. After this there is the final clearing up.”
-
-Except for special conditions, cyclones are never stationary, but drift
-along with the general march of the atmosphere, like dimpling eddies in
-a stately flowing river. In general, therefore, their trend is westward
-in lower latitudes, eastward in middle and higher latitudes, with a
-pace slow or swift according to the prevailing current. Notably also
-they have a poleward trend. Thus, if the path extends from tropic to
-temperate clime, it is frequently concave toward the east and sensibly
-parabolic in form. This is markedly true of those swift-whirling, small
-cyclones called hurricanes,[67] and particularly those vigorous ones
-blowing past the West Indies and the Philippines, and those that vex
-the Indian Ocean.
-
-As to the speed of travel of cyclones, that may be judged, at least for
-northern latitudes, from the accompanying table, taken from Loomis,[68]
-and showing the average monthly rate of progression in miles per hour,
-of cyclone centers over the United States, the Atlantic Ocean and
-Europe. In general, beyond the tropics tall cyclones travel faster than
-short ones, owing to the faster drift of the higher strata.
-
-  ----------+----------+--------------+---------
-            |          |   Atlantic   |
-            |  United  | Ocean Middle | Europe.
-    Month.  |  States. |  Latitudes.  |
-  ----------+----------+--------------+---------
-  January   |   33.8   |    17.4      |  17.4
-  February  |   34.2   |    19.5      |  18.0
-  March     |   31.5   |    19.7      |  17.5
-  April     |   27.5   |    19.4      |  16.2
-  May       |   25.5   |    16.6      |  14.7
-  June      |   24.4   |    17.5      |  15.8
-  July      |   24.6   |    15.8      |  14.2
-  August    |   22.6   |    16.3      |  14.0
-  September |   24.7   |    17.2      |  17.3
-  October   |   27.6   |    18.7      |  19.0
-  November  |   29.9   |    20.0      |  18.6
-  December  |   33.4   |    18.3      |  17.9
-  ----------+----------+--------------+---------
-    Year    |   28.4   |    18.0      |  16.7
-  ----------+----------+--------------+---------
-
-To find the actual speed of the wind at a place, of course, the linear
-velocities of whirl and of translation must be combined; or, vice
-versa, if one of these be known it can be graphically subtracted from
-the observed wind velocity to find the other. This combination of two
-wind components to find their resultant, or, vice versa, can easily be
-done by laying off on paper, arrows of suitable length and direction
-to represent the two known velocities, placing the head of one arrow
-to the tail of the other, then completing the triangle, and taking its
-third side to represent the required wind velocity, in magnitude and
-direction. Obviously if the cyclone moves eastward, whirling oppositely
-to the hands of a watch, the swiftest wind is on its right side,
-which consequently is known as the dangerous side. In the northern
-hemisphere, therefore, the rule for dodging a great whirlwind is to run
-north, if that be practicable.
-
-Stationary cyclones occur under favorable conditions. At least that
-name has been applied to columns of hot air streaming up from a fixed
-base, more or less circular. Every island in the ocean generates such
-a vortex on a clear, hot summer day, since its temperature far exceeds
-that of the surrounding water. All day long this uprush continues
-whatever be the humidity. And if the soil slopes upward steeply, the
-vortex is so much the stronger, particularly if the island be in a calm
-region. Above such a tract the gulls and vultures, and possibly even
-man, might soar all day without motive power. This condition and its
-interesting possibility deserve investigation.
-
-Cyclones may occur at any season, but in general they are most abundant
-when the greatest temperature disturbances occur. The relative
-frequency of tropical cyclones for various localities and for the
-twelve months of the year is seen in the following table[69]:
-
-       _The Yearly Periods of Cyclone Frequency in Several Seas_
-
-  ------------+---------+---------+----------+----------+-------+-------
-              | Arabian | Bay of  | S. Indian|   Java   | China |
-              |   Sea.  | Bengal. |  Ocean.  |   Sea.   |  Sea. |Havana.
-  ------------+---------+---------+----------+----------+-------+-------
-  No. of years|   234   |   139   |     40   |    --    |   85  |   363
-  No. of      |         |         |          |          |       |
-    cyclones  |    70   |   115   |     53   |    12    |  214  |   355
-              |         |         |Piddington|Piddington|
-   Authority. |Chambers.|Blanford.|Thom and  |and       |Schuck.| Poey.
-              |         |         |Reid.     |Thom.     |       |
-  ------------+---------+---------+----------+----------+-------+-------
-  Jan         |    6    |   2     |    17    |    25    |    2  |    1
-  Feb         |    4    |   0     |    25    |    42    |    0  |    2
-  Mar         |    3    |   2     |    19    |     8    |    2  |    3
-  April       |   13    |   8     |    15    |     8    |    2  |    3
-  May         |   18    |  16     |     7    |     0    |    5  |    1
-  June        |   29    |   9     |     0    |     0    |    5  |    3
-  July        |    3    |   3     |     0    |     0    |   10  |   12
-  Aug         |    3    |   4     |     0    |     0    |   19  |   27
-  Sept        |    4    |   5     |     2    |     0    |   27  |   23
-  Oct         |    6    |  27     |     2    |     0    |   16  |   17
-  Nov         |   14    |  16     |     7    |     0    |    8  |    5
-  Dec         |    3    |   8     |     6    |    17    |    3  |    2
-  ------------+---------+---------+----------+----------+-------+-------
-
-The tornado is a slender cyclone or hurricane. It is usually but a
-few yards or rods in diameter, and seldom exceeds one mile across its
-active column, whereas a cyclone may cover an area of any size from
-fifty to one or two thousand miles in diameter. Moreover, the cyclone
-requires for its inception an extensive pressure gradient marked by
-closed isobars, and once generated may last several days. A tornado per
-contra may spring into action where the lateral pressure is uniform,
-spend its force in a few moments, and leave a uniform barometric field
-in its wake. In shape the tornado is usually of greater height than
-width. The cyclone is far-flung laterally, but in height may not exceed
-the narrow tornado, since both must terminate beneath the isothermal
-layer, and commonly do not extend so high. Both vortices are caused
-by the ascensional force of hot air. In both the air spirals in and
-upward at the bottom, out and upward at the top, constantly cooling
-by expansion, and finally descends on the outside to complete the
-closed circulation. In general the tornado is the more violent and
-destructive, though limited to a brief and narrow path. More aptly,
-perhaps, the tornado may be called a slender hurricane of brief
-duration; both of them being small cyclones, or aërial vortices, of
-minor size and concentrated intensity. The relation of the tornado and
-cyclone has been defined as follows, by Professor Moore:
-
-  “The cyclone is a horizontally revolving disk of air of
-  probably 1,000 miles in diameter, while the tornado is a
-  revolving mass of air of only about 1,000 yards in diameter,
-  and is simply an incident of the cyclone, nearly always
-  occurring in its southeast quadrant. The cyclone may cause
-  moderate or high winds through a vast expanse of territory,
-  while the tornado, with a vortical motion almost unmeasurable,
-  always leaves a trail of destruction in an area infinitesimal
-  in comparison with the area covered by the cyclone.”
-
-Two initial conditions seem essential to the genesis of a substantial
-tornado. In the first place, the atmosphere of its immediate locality
-must have appreciable gyration. Of course, in all extra equatorial
-regions the air has some incipient whirl due to the earth’s rotation,
-and this whirl is magnified as the fluid is sucked into the vortex. But
-the magnification may be slight owing to the brief lateral displacement
-of the air feeding the tornado. If, however, the fluid be drawn from a
-considerable distance, and have from local conditions some additional
-whirl superadded to that due to the earth’s rotation, the gyratory
-flow in the medium near the vortical axis may be very swift. On the
-other hand, the additional whirl, due to local conditions, may tend
-to neutralize that due to the earth’s component, thereby leaving a
-very feeble gyration, if any. But in general the rotation of tornadoes
-is observed to be in the direction of the earth’s component; to the
-left north of the equator, to the right south of it. This observation
-is doubtless the more striking because when the accidental local spin
-conspires with the permanent terrestrial one, the resultant whirl
-is intensified, while in the opposite case it is so enfeebled as to
-attract scant, if any attention.
-
-In the second place, the genesis of a tornado requires unstable
-equilibrium in the local atmosphere. This instability, as in cyclones,
-may arise from abnormal temperature gradation. Thus, if along any
-vertical the temperature falls more than six degrees Centigrade for one
-thousand meters ascent, a mass of air started upward will continue to
-rise, since it cools less rapidly than the environing medium. In this
-way there will ensue a continuous uprush of air so long as the unstable
-state endures; and the action may be very vigorous if a large stratum
-of air is greatly heated before it disrupts into the cold upper layers.
-In general, the loftier the tornado the more violent it is, just as
-the taller flue generates the stronger draft with the same temperature
-gradient.
-
-Dynamically, the tornado may be treated as a rotating pillar of air
-in which each mass of fluid fairly retains its angular momentum. This
-means that for any mass of the whirling air the radius of its path,
-multiplied by its circular speed, remains a constant product; in
-other words, the velocity of whirl varies inversely as the radius.
-Accordingly, the circular velocity is exceedingly rapid where the
-radius is very small. Now, when any mass runs round a circle its
-centrifugal force is known to be directly as the square of the speed of
-its centroid and inversely as the radius. But by the above assumption
-the speed itself is inversely as the radius. Hence, the centrifugal
-force varies inversely as the cube of the radius of the inflowing
-mass of air. This centrifugal force, acting on the inner layers of
-air of the rotating column, must be supported by the pressure against
-them exerted by the outer layers as they pass inward. Thus there is a
-strong barometric gradient from the remote still air toward the swiftly
-whirling parts of the vortex.
-
-It follows from the above argument that inside a tornado the barometric
-pressure may be much below the normal; and it is easy to see that if
-a barometer, starting from some point on the tornado base, be moved
-vertically upward it must show a declining pressure, but if moved
-upward and outward it may be made to show a constant pressure all the
-way to the upper portion of the vortex. The instrument would thus
-travel along an isobaric, bell-shaped surface opening upward. On a
-series, therefore, of concentric circles on the base of a tornado,
-we may erect a family of coaxial bell-shaped surfaces to mark the
-points of equal pressure, and thus map out the isobars of the vortex.
-Inside these coaxial surfaces reaching to earth, others of still
-lower pressure may be drawn tapering downward to a rounded point and
-terminating at various places on the axis. In an actual tornado one of
-these infinitely numerous funnel-shaped isobaric surfaces may become
-distinctly outlined and visible, if the air has sufficient moisture to
-start precipitation when it reaches a surface of suitably low pressure.
-This quite usually occurs in Nature, the funnel sometimes reaching to
-earth, sometimes only part way, according to the pressure at which
-precipitation begins, this pressure depending, of course, on the
-percentage of humidity of the uprushing air.
-
-The form of the funnel-like cloud ere it reaches the earth is
-interesting. Being an isobaric surface, it would support in static
-equilibrium a free particle resting on it and sharing its rotatory
-motion. The lower rounded part of the funnel is parabolic, the upper
-outer part hyperbolic; the two together delineating the well-known
-Rankine double vortex of hydrodynamics. Students of hydrostatics know
-that when a glass of water is spun round its axis at a fixed velocity,
-the dimple observed is of parabolic form, and if frozen will sustain
-in repose a small shot resting on its surface and whirling with it.
-Similarly the lower part of the funnel is parabolic because in it the
-air rotates, as one solid body, while the broader part of the funnel is
-hyperbolic because in it the air has a speed inversely proportional to
-its radius of motion.
-
-If everywhere in a tornado the circular velocity of the inflowing air
-were inversely proportional to the radius, as above assumed, the speed
-near the axis would be indefinitely great. This cannot be admitted.
-Practically, the inflow ceases when the centrifugal force of the
-gyrating stratum equals the pressure urging it toward the axis. Within
-this stratum is a column of air rotating everywhere with constant
-angular velocity about the vortical axis, and thus having quite calm
-air at its center. Outside this solidly rotating core the air spirals
-radially inward and upward. Some idea of the stream lines in such
-spiral flow may be obtained from Fig. 50 if a rapid circular motion be
-added to the inward and upward velocity represented by the arrows.
-
-In the foregoing discussion no account of friction was taken. Near the
-earth’s surface this dampens the whirl and centrifugal force, so that
-the air flows more directly into the vortex, while farther aloft the
-centrifugal force near the axis so effectually checks the inflow as
-to allow the central core of air to rush up nearly unimpeded, as in
-a walled flue, taking its draught mostly from the lower part. As a
-consequence, the upward speed of the heated air in the tornado tube may
-be enormous, supporting in its stream objects of considerable mass.
-
-[Illustration: FIG. 50.—FUNNEL-LIKE CLOUD SOMETIMES OBSERVED IN A
-TORNADO.]
-
-The true horizontal speed anywhere in a tornado is compounded of the
-velocities of gyration and of translation, as in the cyclone. Hence the
-advancing side may be considerably the swifter and more destructive,
-particularly more destructive since the impact of air increases as
-the square of the velocity. If the vortex were stationary it would
-be equally dangerous on all sides, standing erect and symmetrical;
-but it drifts with the whole mass of air, sometimes quite swiftly and
-often with varying speed of travel at different levels; thus, in its
-slenderest forms, appearing bent and not infrequently twisted, as
-it advances writhing serpentlike through the sky. Furthermore, the
-intensity of whirl may fluctuate momentarily, with consequent shifting
-of the isobaric surface, including that one whose form is visible
-by reason of incipient condensation; and thus the funnel-like misty
-tongue appears to dart earthward as a foggy downshoot from the cloud
-above, whereas its parts are really rushing upward at all times very
-swiftly, whether visible or not. This agile protrusion of the nimbus,
-now a tongue, now a dark and mighty tower, is the strenuous part of
-the storm, the abominated “twister” which the Kansan farmer sedulously
-shuns, or peeps at from a hole in the ground. Unwelcome, indeed, are
-its visitations, when, with mickle and multitudinous roar, it claps
-his house in sudden darkness, hurls it aloft and sows its sacred relics
-over all the adjoining township, “that with the hurly-burly hell itself
-awakes.”
-
-Theory, as well as experience, accredits the tornado with vast energy
-and power. For, suppose a surface stratum of air one mile in area
-and one thousand feet thick to increase in absolute temperature one
-per cent, thus uplifting the superincumbent atmosphere ten feet. The
-total energy stored in this way equals the weight lifted multiplied by
-its upward displacement. The weight is a ton per square foot and the
-displacement is ten feet; hence the stored energy is ten-foot tons per
-square foot of the heated tract, or about 280,000,000 foot tons for
-the square mile of heated air. This is equivalent to the work of one
-million horses for over a quarter of an hour. A goodly percentage of
-this stored work may be converted into kinetic energy in the active
-part of the dry tornado. It is the energy of a vast reservoir suddenly
-gushing through a tall penstock. It is a colossal upward cataract, an
-aërial Niagara, a Johnstown flood suddenly liberated and quickly spent.
-
-A vortex of that description possesses enormous devastating power, for
-it is endowed with four destructive elements: rapid onset for razing,
-violent spin for distorting, swift uprush for lifting, low pressure for
-disrupting. These four grim powers may operate at once and in accord.
-When, for example, they assault a house, the horizontal blasts push and
-wrench it on the foundation, the cellar air suddenly expanding puffs it
-aloft, the internal air bursts its walls or windows, the uprush carries
-its members on high and scatters them wantonly to the four winds.
-These powers are abundantly attested by authentic reports from many
-localities.
-
-When the tornado appears as a misty column it is familiarly called
-a “waterspout,” particularly if it appears over a sea or lake. As
-already explained, the visible and cloudy portion of the column is
-due to condensation of the aqueous vapor in the air, as it rushes
-expanding and cooling into the low pressure part of the vortex. From
-the lashed and rippling sea surface, where it upcones into the base of
-the spout, some water is carried aloft as spray mingling with the mist
-of the chilled vapor, but not necessarily in very large proportion,
-and never rising in solid body to the cloud, as popularly supposed. On
-the contrary, waterspouts, however massive and formidable looking, are
-very tenuous, and may occur on land or water indifferently. Doubtless
-they are better defined, more regular and more familiar over water,
-and hence their name; but essentially they are vapor spouts, though
-mingled at times with dust or spray. Owing to rapid precipitation of
-the uprushing aqueous vapor, there may be heavy rainfall on all sides
-of the waterspout, so that at sea it may be difficult for the observer
-to ascertain how much of the downpour is salt water and how much is
-fresh. On land the downpour is sometimes mingled with débris, and even
-with live fish and frogs caught up from neighboring bodies Of water.
-Copious hail also may fall with the rain, if the vortex be a lofty one.
-
-[Illustration: FIG. 51.—VERTICAL SECTION OF THE ST. LOUIS, MO., TORNADO
-OF MAY 27, 1896, SHOWING THE VORTEX TUBES IN A THEORETICAL, TRUNCATED,
-DUMBBELL-SHAPED VORTEX.]
-
-[Illustration: FIG. 52.—HORIZONTAL SECTION OF ST. LOUIS TORNADO OF MAY
-27, 1896.]
-
-The following description and analysis of a representative spout is due
-to Professor Bigelow of the U. S. Weather Bureau:[70]
-
-  “The tornado may be illustrated by the St. Louis storm of May
-  27, 1896. It is a truncated dumbbell vortex out off at the
-  ground on the plane where the inflowing angle is about 30°.
-  This vortex is much smaller than the hurricane, although of
-  the same type. It is about 1,200 meters high and about 2,000
-  meters in diameter on the surface. The vortex tubes are shown
-  in Figs. 51 and 52. In these figures can be seen the vortex
-  tubes, geometrically spaced, through each of which the same
-  amount of air rises. The rotating velocity is greatest about
-  300 meters above the ground, but the dimensions are such as to
-  produce enormous velocities in the lower levels. The radius in
-  the outer tube is taken to be 960 meters, and the inner tube
-  55 meters. The radial inward velocity on the outer tube is—8
-  meters per second; on the outer tube the tangential velocity
-  is 13 meters per second, and on the inner 224 meters per
-  second; on the outer tube the vertical velocity is 0.27, and
-  on the inner tube it is 80 meters per second. On the outer
-  tube the total velocity is 15 meters per second, and on the
-  inner tube 270 meters per second. The volume of air ascending
-  in each tube is 774,500 cubic meters per second. On account
-  of the distortion of the theoretical vortex, due to the
-  cutting of the lower portion by the truncated plane, and to the
-  progressive motion of the whole system that constitutes the
-  tornado, there is difficulty in computing the pressure to fit
-  these observed velocities and radii.
-
-  “Tornadoes occur in the southern and southeastern quadrants of
-  areas of low pressure, along the borders of the cold and the
-  warm masses which entered into the structure of the cyclone.
-  When a cold mass is superposed upon a warm mass, as was the
-  case at St. Louis, a tornado will occur if the difference in
-  specific gravity be sufficient to inaugurate a violent mixing,
-  and the rotation be about a vertical axis, instead of about a
-  horizontal axis, as in the case of thunderstorms.”
-
-[Illustration: FIG. 53.—VERTICAL SECTION OF SHORT TORNADO.]
-
-The size and form of waterspouts alter greatly with the state of the
-atmosphere. As Ferrel observes, they may vary “from that of a cloud
-brought down over a large area of the earth’s surface in a tornado
-where the air is nearly saturated with vapor and the general base of
-the clouds very low, somewhat as represented in Fig. 53, to that which
-occurs when the air is very dry, and when the tornadic action is barely
-able to bring the cloud down from a great height into a slender spout
-of small diameter, somewhat as represented in Fig. 54. Horner says that
-their diameters range from 2 to 200 feet, and their heights from 30
-to 1,500 feet. Dr. Reye states that their diameters on land, at base,
-are sometimes more than 1,000 feet. Oersted puts the usual height of
-waterspouts from 1,500 feet to 2,000 feet, but states that in some rare
-cases they cannot be much less than 5,000 or 6,000 feet. On the 14th of
-August, 1847, Professor Loomis observed a waterspout on Lake Erie, the
-height of which, by a rough estimate, was a half mile, and the diameter
-about 10 rods at the base and 20 rods above.
-
-“Judge Williams, in speaking of the tornado of Lee’s Summit, where he
-saw it, says: ‘It seemed to be about the size of a man’s body where it
-touched the clouds above, and then tapered down to the size of a mere
-rod.’”
-
-[Illustration: FIG. 54.—VERTICAL SECTION OF A TALL TORNADO.]
-
-When the tornado vortex is so tall and strong as to carry raindrops up
-to freezing strata it is commonly known as a hailstorm. The congealing
-occurs usually in those isobaric surfaces which dip down in the center
-of the vortex, but reach only part way to the earth. As indicated
-in Fig. 55, the clear aqueous vapor near the earth is condensed to
-cloud on crossing an isobaric surface of sufficiently low pressure
-and temperature; then it proceeds as mingled cloud and rain till it
-crosses the freezing isobar into the region of snow and hail formation;
-thence finally curves outwardly to stiller air and descends as a cloud
-of mingled vapor, rain and frozen parts. Of this frozen shower one
-part may come to earth as hail or rain, the snow and sleet melting on
-the way; while another part may be redrawn into the swift uprush, and
-carried aloft till its frozen drops, or pellets, have grown so large by
-accretion as to plunge to earth by sheer bulk, even though they must
-traverse a furious ascending wind. A good illustration from Nature of
-this cycle in the center of a hailstorm is presented in the following
-by Mr. John Wise, America’s adventurous pioneer balloonist:
-
-  “This storm originated over the town of Carlisle, Pa., on
-  the 17th of June, 1843. I entered it just as it was forming.
-  The nucleus cloud was just spreading out as I entered the
-  vortex unsuspectingly. I was hurled into it so quickly that I
-  had no opportunity of viewing the surroundings outside, and
-  must therefore confine this relation to its internal action.
-  On entering it the motions of the air swung the balloon to
-  and fro and around in a circle, and a dismal, howling noise
-  accompanied the unpleasant and sickening motion, and in a
-  few minutes thereafter was heard the falling of heavy rain
-  below, resembling in sound a cataract. The color of the cloud
-  internally was of a milky hue, somewhat like a dense body
-  of steam in the open air, and the cold was so sharp that my
-  beard became bushy with hoar frost. As there were no electric
-  explosions in this storm during my incarceration, it might
-  have been borne comfortably enough but for the seasickness
-  occasioned by the agitated air-storm. Still, I could hear
-  and see, and even smell, everything close by and around.
-  Little pellets of snow (with an icy nucleus when broken) were
-  pattering profusely around me in promiscuous and confused
-  disorder, and slight blasts of wind seemed occasionally to
-  penetrate this cloud laterally, notwithstanding there was an
-  upmoving column of wind all the while. This upmoving stream
-  would carry the balloon up to a point in the upper clouds,
-  where its force was expended by the outspreading of its
-  vapor, whence the balloon would be thrown outward, fall down
-  some distance, then be drawn into the vortex, again be carried
-  upward to perform the same revolution, until I had gone through
-  the cold furnace seven or eight times; and all this time the
-  smell of sulphur, or what is now termed ozone, was perceptible,
-  and I was sweating profusely from some cause unknown to me,
-  unless it was from undue excitement. The last time of descent
-  in this cloud brought the balloon through its base, where,
-  instead of pellets of snow, there was encountered a drenching
-  rain, with which I came into a clear field, and the storm
-  passed on.”
-
-As might be expected the hailstones vary much in form, size and
-quantity. If by chance any stones become slightly flattened they ride
-level in the ascending current, and hence by aggelation grow most
-rapidly on the periphery which is a line of diminished pressure. At
-times they are more or less oval, and again they appear as fragments of
-considerable masses of ice, broken perhaps by collision in the violent
-parts of the tornado tube. Their great variety in shape and bulk may be
-appreciated from the following extracts taken from the records of the
-Signal Service:
-
-[Illustration: FIG. 55.—VERTICAL SECTION OF A HAIL TORNADO.]
-
-In _Professional Paper of the Signal Service No. 4_, describing the
-tornadoes of May 29th and 30th, 1879, in Kansas, Nebraska, Missouri,
-and Iowa, this passage occurs relative to a tornado at Delphos, Mo.:
-
-  “On the farm of Mr. Peter Bock, in the adjoining township of
-  Fountain, about 4 miles W. of the storm’s centre, and during
-  the hailstorm that preceded the tornado, masses of ice fell as
-  large as a man’s head, breaking in pieces as they struck the
-  earth. One measured 13 inches in circumference, another 15, and
-  a hole made by one that fell near the place of Mr. J. H. Kams
-  measured 7 inches across one way and 8 the other. This immense
-  fragment of aërial ice broke into small pieces, so that its
-  exact size could not be determined.”
-
-The following description is given of the tornado that visited Lincoln
-County, Neb., at that time:
-
-“At first the hailstones were about the size of marbles, but they
-rapidly increased in diameter until they were as large as hens’ eggs
-and very uniform in shape. After the precipitation had continued about
-fifteen minutes, the wind ceased and the small hail nearly stopped,
-when there commenced to fall perpendicularly large bodies of frozen
-snow and ice, some round and smooth and as large as a pint bowl, others
-inclined to be flat, with scalloped edges, and others resembled rough
-sea-shells. One of the latter, after being exposed an hour to the sun,
-measured fourteen inches in circumference.”
-
-The following was reported by the Signal Service observer at Fort
-Elliott, Tex., 1888:
-
-  “A thunder-storm began at 4.10 P.M. and ended at 7.40 P.M.,
-  moving from southwest to northwest. Hail began at 5.18 P.M.
-  and ended at 5.26 P.M., the hailstones being spheroidal in
-  shape and about two inches in diameter; formation, solid snow.
-  The ‘break’ (hills) at the foot of the plains several miles
-  northwest of station were absolutely white with hailstones for
-  three hours after the storm. This was observed by everybody
-  at the station; on the morning of the 26th I walked down to
-  the Sweetwater Creek, three fourths of a mile distant, and saw
-  great banks of hailstones which had been washed down during the
-  night. The bottoms along the Sweetwater were literally covered
-  with banks of hailstones from six to eight feet in depth. It
-  was estimated that there was enough hail to cover ten acres to
-  a depth of six feet. The hailstones killed five horses which
-  were out on the prairie on a ranch six miles north of station.
-  The Sweetwater Creek was higher than ever known before, the
-  freshet destroying nearly the entire post garden. The high
-  water is supposed to have been caused by a ‘cloud-burst’ at
-  or near the foot of the plains, where the Sweetwater has its
-  source; there was only 0.36 inch of rainfall at the station. On
-  Sunday, May 27th, hailstones were collected on the banks of the
-  Sweetwater, which had been washed down and lay in drifts 6 feet
-  deep, actual measurement by the observer.”
-
-When, after imprisonment and long sustention in a powerful tornadic
-vortex, the accumulated rain or hail finally breaks through and pours
-down to earth, in solid cataract, the phenomenon is commonly called
-a cloud-burst. The foregoing example is a partial illustration.
-The following is quoted from Espy, describing a cloud-burst near
-Hollidaysburg, Penn., in which the water seems to have poured down
-nearly in a solid stream:
-
-  “On examining the northern side of this ridge, large masses
-  of gravel and rocks and trees and earth, to the number of 22,
-  were found lying at the base on the plain below, having been
-  washed down from the side of the ridge by running water. The
-  places from which these masses started could easily be seen
-  from the base, being only about 30 yards up the side. On going
-  to the head of these washes they were found to be nearly round
-  basins from 1 to 6 feet deep, without any drains leading into
-  them from above. The old leaves of last year’s growth, and
-  other light materials, were lying undisturbed above, within an
-  inch of the rim of these basins, which were generally cut down
-  nearly perpendicularly on the upper side, and washed out clean
-  on the lower. The greater part of these basins were nearly of
-  the same diameter, about 20 feet, and the trees that stood in
-  their places were all washed out. Those below the basin were
-  generally standing, and showed by the leaves and grass drifted
-  on their upper side how high the water was in running down the
-  side of the ridge; on some it was as high as three feet. It
-  probably, however, dashed up on the trees above its general
-  level.”
-
-Dry whirlwinds of moderate size, but sometimes of considerable
-violence, frequently occur in clear weather when the percentage of
-humidity is small and when the vertical temperature gradient is
-unusually pronounced. In this case there may be strong agitation of
-the air, rendered visible at the earth’s surface by light débris on
-land, or boiling of the water at sea; but the main body of the tube is
-invisible and free from mist except high up where precipitation begins,
-capped by a growing patch of white cloud in a clear sky, and which
-may gradually broaden and condense sufficiently to cause a shower of
-rain. On land the dry whirlwind may be delineated as a tall column, by
-whirling dust or sand. In this case, if the gyration is violent, the
-central core may appear clean and clear owing to the centrifugal force
-which keeps the grains out where they are balanced by the pressure of
-the inrushing air. In such vortices the sand spout may appear to be
-hollow as in the case of waterspouts whose interior cores are free
-from cloud or condensed vapor. On the other hand, myriads of mild
-transparent whirlwinds unmarked, except by down or humanly invisible
-dust, or dim aërial refractions, may frisk and play in the boundless
-sky unnoticed by the blunt eyes of men, yet constantly engaged in
-generating or marshaling the clouds and in buoying upward the ponderous
-eagles, the vultures and the whole brood of passive flyers whom we
-have not yet learned to emulate. Thus when we remember that an upward
-trend of air of scarcely one yard per second, and too feeble to support
-a falling hair, is yet sufficient to carry the condor and albatross
-without wing beat, it seems important to explore these minor vortices
-and to ascertain their availability and practical usefulness for human
-soaring.
-
-
-
-
-                             CHAPTER XVII
-
-                       THUNDERSTORMS, WIND GUSTS
-
-
-Still another interesting kind of aërial disturbance is the familiar
-heat thunderstorm. This is not synonymous with those electrified
-tornadoes and cyclones which are accompanied by thunder and lightning,
-sometimes of great violence. Most tornadoes are thunderstorms, but
-not vice versa. The thunderstorm is not essentially a vortex, but
-rather a wind squall marked by sudden changes of temperature and
-pressure, bearing with it massive clouds fraught with rain, or hail,
-and disruptive electric charges flashing frequently to earth, or
-from point to point in the sky. Its approach is usually announced by
-rumbling thunder and heavy black clouds along the horizon. Its duration
-is brief, varying from a few minutes to an hour or two. Further
-characteristics are thus expressed by Moore:
-
-  “On land, thunderstorms occur most frequently at specific hours
-  of the day or night, such as 3 to 5 in the afternoon or 9 to 10
-  in the evening and sometimes even at 2 or 3 A.M., but no such
-  diurnal period is observed in midocean. The phenomena usually
-  occur in a pretty regular order of succession. After several
-  hours of fair weather, with gentle winds, there comes a calm;
-  the cumulus clouds grow larger, the lower stratum of clouds is
-  seen to be moving rapidly; gusts of wind start up with clouds
-  of dust, rain is seen to be falling at a distance; the movement
-  of rain and dust shows that the wind is blowing out from this
-  rain cloud near the ground no matter which way the rainy region
-  is advancing; a few large drops fall from slight clouds and
-  then suddenly the heavy rain begins. Lightning that may have
-  occurred during the preceding few minutes becomes more frequent
-  and more severe as the rain increases. After the maximum
-  severity of rain and wind, the lightning also diminishes or
-  entirely ceases, and we are soon able to say that the storm has
-  passed by. If we watch its retreat from us in the afternoon
-  we shall see the rear of a great cumulus on which the sun is
-  shining, but through whose dark-blue curtain of cloud and rain
-  nothing save occasional lightning is visible. After the storm
-  has passed, the lower atmosphere soon becomes appreciably
-  cooler and drier, the sky is nearly clear of clouds, and the
-  wind has shifted to some other point of the compass than that
-  which prevailed before the storm.”
-
-The genesis of thunderstorms is varied and manifold. In one simple
-type, a large tract of heated air in the unstable state and with a high
-percentage of humidity swells upward at the center, the ascending moist
-air forming, at the precipitation altitude, a growing cloud which may
-become very broad, dark and bulky, drifting along over the earth with
-the prevailing current. Eventually rain begins to form, or may be hail
-or snow, if the heated column reaches to a great height. The falling
-shower cools the air from the cloud down to the earth, increasing its
-density and materially weighting it with the descending liquid or
-solid particles. The showery column then sinks, especially along its
-inner part where it is maturest, thus causing an outrush of cool air
-along the earth, the immediate forerunner and herald of the rain. This
-outrushing current pushes upward the environing clear moist air, thus
-forming new margins of massive cumuli around the older nimbus widening
-within, showering, cooling and sinking. Thus the rain area is broadened
-and propagated, sometimes with nearly equal speed in all directions,
-but generally fastest in the direction of the most unstable condition,
-or of the then prevailing drift of the atmosphere. Indeed, the forward
-cloud ranks may far outspeed the wind, seeming by their imperious
-bluster and gigantic gloom to commandeer new recruits, as if by magic,
-out of the clear sky. Before this solemn mustering and turbulent front
-of the storm the black vapors suddenly startled into visible shape,
-rush buoyantly upward in ragged shreds, like smoke from unseen fires,
-and quickly blend with the general array of compact cloud expanding
-across the sky. Again, several thunderstorms, merged like a mountain
-range in solid phalanx, may sweep abreast over a continent, with long
-horizontal[71] roll, ever rising in front and upheaving the sultry
-air, thus replenishing perpetually the ponderous cumuli which form
-the vanguard of this far-flung and titanic march of the clouds. Such
-a storm is usually powerful and persistent, commonly enduring until
-the sun’s decline and the shades of night have cooled the lower air,
-and thus allayed the commotion by enfeebling the forces that favor its
-progress.
-
-The speed of rise of the air beneath the base of the thunderhead is
-a question of some interest in aëronautics. If the ascent be so much
-as a foot or two per second, one may expect the vultures to prefer
-soaring beneath the thundercloud during its formative period. Here
-also the aëroplanist might attempt a record flight, if the cloud were
-high enough to be out of his way. But if he ventured to penetrate the
-base of the thunderhead, he might find the turmoil too irregular and
-strenuous for his comfort.
-
-Of like interest is the long aërial swell that leads the advancing
-storm. When will aviators make this the theater of their adventurous
-frolic, careering playfully before the brow of the tempest and the
-harmless rage of the lightning, gay-winged heralds of the coming
-tumult, sailing perhaps with slackened motive power, yet swift and
-secure as the storm-riding petrels at sea?
-
-Besides the winds and aërial currents commonly studied by
-meteorologists, are the minor disturbances which affect more
-particularly the wayfarers of the sky, whether birds or men. The
-atmosphere quite usually is vexed with invisible turmoils; most
-sensible, indeed, over rough territory, but conspicuous also above
-the smooth terrene, and at all elevations from earth to the highest
-cloudland. Before sunrise, and generally in weather uniformly overcast,
-these miscellaneous and nondescript movements of the air are least
-active, for any given speed of the general drift of the atmosphere;
-but when the sun shines and the soil is nonuniformly heated, the
-disturbances become most pronounced. A whole troop of playful zephyrs
-rise and set with the sun, in addition to the diurnal winds already
-studied. Over the dusty plain they reveal their presence and shape
-in those coiling columns that constitute the safety vents of the
-atmosphere, and obviate the disruptive violence of the uprush that
-would occur should a considerable region of surface air become
-excessively heated. Over the city, particularly in winter, the local
-turmoils of the atmospheric surf are revealed in the play of a thousand
-smoky columns, and better still, when it snows, by the incessant
-swell and veering of the flaky flood whose surges and eddies bewilder
-the vision by their complexity. Over the water the clouds of fog
-and steaming vapor are the best index of the local zephyrs, where,
-it must be remembered, the rising and veering of the vapor wreaths
-accompany like motions in the atmosphere. Over the forest, field and
-meadow the interminable wandering of thistle down and gauzy shreds of
-vegetation, now fast, now slow, now high aloft, then sheer earthward,
-indicate what erratic and perpetual motions prevail throughout the open
-country even on the stillest days. In the deep bosom of the atmosphere,
-the parallel ranks of the cirri all across the sky mark the crests
-of undulations quite as regular and tumultuous as the billows of a
-wind-swept sea; while the fierce seething and upsurging of the separate
-cumuli manifest the operation of vortices of prodigious energy. These
-visible billows and whirlwinds suggest an infinitude of transparent
-ones hardly less powerful, at the various levels unmarked by clouds.
-For wherever two streams of abnormally graded densities neighbor each
-other, a readjustment may occur agitating the entire region with a host
-of pulsations, squalls, cataracts and fountains which the bird and
-navigator must parry with proportionate care and skill.
-
-And it is because of the amazing resistance of these wandering zephyrs,
-waves and eddies that they demand the attention of aëronauts; nay,
-more, it is because of the substantial labor they can perform when
-adroitly encountered and duly employed. For the simplest elements of
-aërodynamic science make clear that a rising zephyr hardly strong
-enough to support a falling leaf is adequate to sustain the heaviest
-soaring birds and aëroplanes gliding swiftly through it. In fact, the
-sailors of fast air ships feel a heavy impulse and distinct shock in
-plowing those mild cross winds which, to the fixed observer, seem not
-like blasts, but rather as gentle swells or harmless currents. These,
-therefore, have been made the subject of investigation by various
-students of aëronautics.
-
-The first incentive to the instrumental study of the fluctuations
-of the wind in speed and direction seems to have been the hope to
-furnish a quantitative basis for various theories of soaring flight.
-Pénaud,[72] in 1875, had explained this phenomenon by postulating
-an upward current. Lord Rayleigh,[73] in 1883, had made the more
-general assumption of a wind having either a variable speed or a
-variable direction as a necessary and sufficient condition for such
-flight. Marey,[74] in 1889, and Langley,[75] in 1893, gave elementary
-qualitative explanations of soaring in a horizontal wind of variable
-velocity, though neither adduced concrete data to prove that the feat
-could be performed in an actual wind. Each and all of those theories
-may be sound enough in the abstract, but to show that they represent
-realities of art or Nature they should be applied to a concrete
-instance of soaring of a machine or a bird of known resistance, in a
-wind of known variability.
-
-To such end the writer in 1892 devised an anemograph for recording
-simultaneously the speed of the wind and its horizontal and vertical
-components of direction, while Dr. Langley devised a very light and
-delicate cup anemometer for recording the variations of wind speed in
-a horizontal plane, but not the changes of direction. Both instruments
-were set up in January, 1893, and both investigations were published
-with the _Proceedings of the International Conference on Aërial
-Navigation_ of that year; but neither investigation was pushed far
-enough to prove conclusively the possibility of a particular bird
-or model soaring in the particular wind recorded. The two together
-did, however, reveal quite astonishing fluctuations of the wind in
-both speed and direction, results that have since received ample
-exemplification in the more extended records of other observers.
-
-[Illustration: FIG. 56.—UNIVERSAL ANEMOGRAPH. (The vanes are high above
-the point indicated by the break in the vertical pipe.)]
-
-Fig. 56 shows the recording anemometer for speed and double direction
-constructed by the writer in 1892. A large weather vane was firmly
-strapped to a vertical pipe which turned freely on ball bearings and,
-by means of a small crank actuating a chronograph pencil, recorded its
-fluctuations on a long sheet of paper winding on the drum from a roll
-behind. On top of the pipe and about fifteen feet from the ground,
-was mounted a carefully balanced horizontal vane, from which a fine
-steel wire ran down the axis of the pipe to a fixed pulley, thence
-to a second recording pencil. A third pencil recorded the beats of a
-pendulum, thus standardizing the speed of the paper. A fourth pencil,
-not shown, was designed to record the turns of an anemometer mounted
-near the top of the pipe. The records of the wind speed thus secured
-are omitted for lack of standardization, as the experiments were
-prematurely terminated.
-
-[Illustration: FIG. 57.—RECORDS OF WIND VARIATION IN HORIZONTAL AND
-VERTICAL DIRECTION.]
-
-Typical records of the wind direction are shown in Fig. 57 in which
-the circles represent the paths swept by the wind-vane cranks that
-operated the corresponding pencils. Both vanes, as shown by their
-diagrams, veered quite frequently ten degrees in a short interval of
-time, and not seldom twenty to thirty degrees. Frequently, also, it was
-observed, in scanning the various records, that a rise or lull in the
-wind speed was accompanied by a corresponding variation in direction;
-but the observations were not sufficiently numerous and extended to
-establish this phenomenon as a general occurrence. But as it can be
-shown theoretically that a horizontal stream of air of constant cross
-section and uniform velocity at each section, can not greatly fluctuate
-in velocity from point to point, without more pronounced changes of
-density than the barometer records, it naturally follows that the
-stream must broaden where the air speed lags, and narrow where it
-accelerates; in other words, it follows that there must be some change
-in direction. The records were taken in the middle of a clear open
-space of two hundred acres at Notre Dame University on a sunless day in
-January, 1893, when the temperature was 24° F., and the wind eight to
-twelve miles per hour. Their application to the theory of soaring need
-not be considered here.
-
-Further studies of the wind pulsations were made by use of a toy
-balloon attached to a long thread. The first trials are thus recounted
-in the paper above cited:
-
-  “After some preliminary tests from the top of the Physical
-  Laboratory of the Johns Hopkins University, during the Easter
-  vacation of 1893, I ascended the Washington Monument at
-  Baltimore, where I paid out the exploring line at a height
-  of 200 feet. The wind was blowing toward the southeast at
-  the speed of 25 to 35 miles per hour, and the sky, which had
-  remained clear till 3 o’clock, was rapidly darkening, with
-  indications of approaching rain. The balloon, when let forth,
-  immediately fell to a depth of 30 or 40 feet, being caught
-  in the eddy of the monument, then presently encountering
-  the unbiased current, sailed in it toward the southeast,
-  approximately level with the spool end of the thread. After
-  the balloon had drawn out 100 feet of thread I checked it to
-  observe the behavior of this much of the exploring line. The
-  balloon rose and fell with the tossing of the wind, but did
-  not flutter like a flag, as it would do if formed of irregular
-  outline. Neither did the thread flutter, nor do I believe there
-  is ever a tendency in a line greatly to flutter in a current
-  as does a flag or sail. Presently I paid out 300 feet of the
-  exploring line, whereupon the waves in the thread became quite
-  remarkable. The thread then, as a rule, was never approximately
-  straight. Sometimes it was blown into the form of a helix of
-  enormous pitch; at other times into the form of a wavy figure
-  lying nearly in a single vertical plane; and again, the entire
-  exploring line should veer through an angle of 40° to 60°,
-  either vertically or horizontally. The balloon, of course,
-  seldom remained quiet for more than a few seconds at a time,
-  but tossed about on the great billows like a ship in a storm.
-  Quite usually the billows could be seen running along the
-  line from the spool to the balloon, and, as a rule, several
-  different billows occupied the string at one time.
-
-  “The observations just delineated, however curious they may
-  be, afford no adequate conception of the behavior of the air
-  currents over an open plane, nor at a great height above the
-  earth, because the Washington Monument at Baltimore stands but
-  100 feet above the surrounding buildings, which undoubtedly
-  send disturbances to a greater height than 200 feet. To
-  supplement these explorations, therefore, I determined to
-  have them repeated from the top of the Washington Monument at
-  Washington and the Eiffel Tower at Paris.”
-
-Some months later in the year, the experiment was repeated at the top
-of the Washington Monument in Washington, at a height of five hundred
-feet. The balloon, with a stone attached, was paid out from the north
-window of the monument till it reached the ground. Then the stone was
-removed by an assistant who drew the balloon well away from the huge
-eddy of the great shaft, and let it fly toward the east, drawing the
-thread after it like a mariner’s log in the wake of a ship. When six
-hundred feet of the thread had been let out, it was observed to veer in
-all directions under the varying surges of the wind. These variations
-seemed larger than could be expected from the wake of the shaft alone
-near its summit, where it measures about thirty feet in thickness.
-
-Such qualitative observations, though interesting and suggestive,
-are not wholly satisfactory. The same may be said of the study of
-air currents by aid of smoke from tall chimneys. The eddy about such
-columns may extend to a considerable height above them, and the wake
-is farreaching. The experiments would therefore best be made from high
-open-work towers above plane country or a broad sheet of water.
-
-A better method perhaps would be to liberate a pilot balloon, or
-discharge a bomb giving a bright compact cloud, and to trace its path
-by means of two cameras, as it floats from point to point in the
-aërial current. The instruments, if suitably stationed, would give the
-continuous space history of the floating object; that is, its actual
-path and the speed at each part thereof, or, in other words, the
-magnitude and direction of the velocity at each point. But, of course,
-this method would not reveal the wind’s history at any given fixed
-point, as recorded by the anemograph above described.
-
-[Illustration: FIG. 58.—RECORDS OF WIND SPEED OBTAINED BY LANGLEY.]
-
-Fig. 58 is a typical wind-speed record obtained by Langley in January,
-1893, by means of a very light cup anemometer mounted eleven feet
-above the north tower of the Smithsonian Institution, and 153 feet
-from the ground. The abscissæ represent time in minutes, the ordinates
-wind speed in miles per hour. The records were taken in cloudy weather
-and in a south-southeast wind. Other records were taken during the
-month of February, showing like deviations from the mean, though at
-times more pronounced; for Dr. Langley noted that “the higher the
-absolute velocity of the wind, the greater the relative fluctuations
-which occur in it.”
-
-It will be observed from this record that, when the average speed was
-about twelve miles an hour, the extreme fluctuation was rarely one
-third greater or less than that, and on the average varied hardly
-one sixth. It must be further added that the air on approaching the
-anemometer had traversed a mile of the lower residential section of
-the city, then crossed the body of the Smithsonian building, which
-itself is half as high as the tower. It should be expected, therefore,
-that this wind was, other things equal, naturally more turbulent than
-if flowing in from a level plain. This surmise is justified by the
-more extensive records of wind speeds shown in meteorological records
-taken respectively in clear and in obstructed places. On the other
-hand, even in level places where no obstruction is visible for several
-miles, the wind, though it may be steady at one time, can at another
-time be gustier than that shown in Langley’s record, according to the
-state of the weather; for the gusts are not all due to neighboring
-obstacles, but may be transmitted from afar, even from the depths of
-the atmosphere.
-
-Assuming the wind speed at any instant to vary by one sixth of the
-mean, its impactual pressure will then vary by thirty-six per cent of
-the pressure of the mean wind, remembering that the pressure varies as
-the square of the speed. This fluctuation of the impactual pressure
-tallies fairly well with that found by Professor Marvin at the top of
-Mount Washington, in 1890, by means of a pressure plate.[76] He found
-the variation to be approximately thirty-five per cent of the mean
-pressure. Professor Hazen, however, reports but little variation in
-the wind speed in the free atmosphere well above the earth. In several
-balloon ascensions he suspended from the basket a lead weight by means
-of a cord to which was looped the thread of a toy balloon. He found
-that the little balloon sometimes moved ahead if the weight sometimes
-followed it, but that in general the relative motion was very feeble,
-thus indicating that the fluctuations of the velocity in the depth of
-the atmosphere at those times were very slight.[77] However this be for
-such distances from the earth and its protuberances, the fluctuations
-of wind speed found at meteorological stations sufficiently resemble
-those reported by Dr. Langley. As corroborative evidence, the reader
-may be referred to the wind records published in the _Interim Report_
-for 1909, of the British Advisory Committee for Aëronautics.
-
-Without the material evidence of commotion in the atmosphere, a
-moment’s reflection will make clear that such turmoil must exist, even
-over a vast, smooth plain, especially in bright weather, and more
-particularly over bare ground in dry weather. For it is well known
-that clear, dry air transmits radiation with very slight absorption,
-when the sun is well toward the zenith, and hence that the temperature
-in the depth of the atmosphere is but little changed from moment
-to moment, due to the passage of sunlight. At the earth’s surface,
-however, the air by contact with heating or cooling soil may change
-temperature rapidly. The direct sunlight falling perpendicularly upon
-a perfectly absorbent material transmits nearly two calories of heat
-per minute to each square centimeter of the receiving surface. It
-would, therefore, under favorable circumstances, elevate by nearly
-two degrees C. per minute a layer of water one centimeter deep, or
-a layer of air something over a hundred feet thick, if all the heat
-falling on the assumed surface were communicated to the neighboring air
-stratum. In practice, a large percentage of the incident sunlight is
-reflected and radiated by the soil, into sidereal space without heating
-the air. But every one per cent of it caught up by the air in contact
-with the earth is sufficient to heat a layer roughly one foot thick
-one degree per minute. Hence, unless the heated air streamed upward
-continually, the layer next the earth would quickly be raised to a
-very abnormal temperature, which would result in a violent uprush. The
-gradual ascension of the surface air may take place in large or small
-columns, or in both kinds at once. In either case, the composition of
-the ascensional motion with the general movement of the wind due to
-barometric gradient must cause gustiness and marked irregularity of
-speed and direction.
-
-Various causes have been assigned for the gustiness of the winds.
-Ferrel and many other writers assume that the air, especially near
-the earth, is full of small vortices rotating about axes of various
-inclination. These whirls, on passing squarely across a weather vane,
-cause it to point one way for a moment, then presently the opposite
-way, while if they cross obliquely they cause a like sudden veering of
-the vane, but less extensive.
-
-Helmholtz has proved that in the atmosphere strata of different
-densities come at regular intervals to be contiguous one above
-the other, and thus to beget conditions favorable to the formation
-of aërial waves, sometimes so large as to set the lower regions of
-air into violent commotion and thereby generate the so-called gusty
-weather. He has summarized as follows some of the important conclusions
-of his dynamic analysis.[78]
-
-“As soon as a lighter fluid lies above a denser one with well-defined
-boundary, then evidently the conditions exist at this boundary for
-the origin and regular propagation of waves, such as we are familiar
-with on the surface of water. This case of waves, as ordinarily
-observed on the boundary surfaces between water and air, is only to be
-distinguished from the system of waves that may exist between different
-strata of air, in that in the former the difference of density of the
-two fluids is much greater than in the latter case. It appeared to me
-of interest to investigate what other differences result from this in
-the phenomena of air waves and water waves.
-
-“It appears to me not doubtful that such systems of waves occur with
-remarkable frequency at the bounding surfaces of strata of air of
-different densities, even although in most cases they remain invisible
-to us. Evidently we see them only when the lower stratum is so nearly
-saturated with aqueous vapor that the summit of the wave, within which
-the pressure is less, begins to form a haze. Then there appear streaky,
-parallel trains of clouds of very different breadths, occasionally
-stretching over the broad surface of the sky in regular patterns.
-Moreover, it seems to me probable that this, which we thus observe
-under special conditions that have rather the character of exceptional
-cases, is present in innumerable other cases when we do not see it.
-
-“The calculations performed by me show, further, that for the observed
-velocities of the wind there may be formed in the atmosphere not only
-small waves, but also those whose wave lengths are many kilometers
-which, when they approach the earth’s surface to within an altitude
-of one or several kilometers, set the lower strata of air into
-violent motion and must bring about the so-called gusty weather. The
-peculiarity of such weather (as I look at it) consists in this, that
-gusts of wind often accompanied by rain are repeated at the same place,
-many times a day, at nearly equal intervals and nearly uniform order of
-succession.”
-
-Commandant Le Clement de Saint-Marcq has drawn some interesting
-conclusions from the hypothesis that an ordinary wind consists of a
-uniform current on which is superposed periodic motions in the wind’s
-main direction and also at right angles thereto. But he has not
-established his hypothesis by adequate observations. He assumes the
-pulsations to be simple harmonic motions, which of course they would be
-if they were plane compressional waves; but at the same time he shows
-that the fluctuations are too large to be compressional waves, with the
-concurrent slight variations of the barometric pressure.
-
-It is still a question whether the pulsations of the natural wind be
-harmonic. If so, the speed records should be sine curves, and the to
-and fro acceleration of any mass of moving air should be variable for
-any given pulsation. But the few records available show in many parts a
-constant acceleration of the wind speed throughout a particular swell
-or lull of velocity, indicating that the pulsations are not generally
-simple harmonic ones.
-
-In scanning the wind-speed records published by Langley, so many
-instances of uniform wind acceleration are noticed that one naturally
-inquires whether the rate of gain of velocity be sufficient to sustain
-in soaring flight an aëroplane or bird held to the wind solely by
-its inertia, as Langley believed to be possible. The total forward
-resistance of a well-formed aërial glider, or bird, may be taken as
-one eighth of its weight; hence, if poised stationary in its normal
-attitude of flight, it will just be sustained by a direct head wind
-having a horizontal acceleration of one eighth that of gravity, or
-four feet per second. Now, the most favorable parts of the record here
-shown (Fig. 58) exhibit nowhere an acceleration so great as four feet
-per second, and on the average far less than that, as may be proved
-by sealing the diagram. Hence, the wind here recorded was wholly
-inadequate to support by its pulsative force either bird or man. But
-as this record is a fair representative of all those published by Dr.
-Langley, it follows that such pulsations can at best merely aid in
-soaring when happily and adroitly encountered; but that they cannot
-fully sustain soaring at any level, much less during ascensional flight
-to great altitudes, or migrational flight to vast distances. It still
-remains, therefore, to ascertain what kind of aërial currents are
-adequate to sustain those marvelous feats of soaring on passive pinions
-which for ages have been the delight and wonder of all keen observers,
-and which are of such enduring interest to mankind. This investigation,
-however, appertains more particularly to the science of applied
-aërodynamics.
-
-
-
-
-                              APPENDICES
-
-
-
-
-                              APPENDIX I
-
-                    STRESS IN A VACUUM BALLOON[79]
-
-                            _By A. F. Zahm_
-
-
-As inventors frequently propose the construction of a vacuum balloon,
-to secure buoyancy without the use of gas, it may be desirable to
-estimate the strength of material required to resist crushing, say in a
-spherical balloon.
-
-The unit stress in the wall of a thin, hollow, spherical balloon
-subject to uniform hydrostatic pressure, which is prevented from
-buckling, is given by equating the total stress on a diametral section
-of the shell to the total hydrostatic pressure across a diametral
-section of the sphere, thus:
-
-                           2π_rtS_ = π_pr^2_
-
-in which _S_ may be the stress in pounds per square inch, _p_ the
-resultant hydrostatic pressure in pounds per square inch, _r_ the
-radius of the sphere, _t_ the wall thickness.
-
-The greatest allowable mass of the shell is found by equating it to the
-mass of the displaced air, thus:
-
-                   4π_r_^2_t_ς_{1} = 4π_r_^3ς_{2}/3
-
-in which ς_{1} is the density of the wall material, ς_{2} the density
-of the atmosphere outside.
-
-Now, assuming _p_ = 15, ς_{1}/ς_{2} = 6,000, for steel and air, the
-equations give:
-
-        _S_ = 3_p_ς_{1}/2ς_{2} = 45 × 6,000/2 = 135,000 pounds
-
-per square inch as the stress in a steel vacuum balloon.
-
-For aluminum ς_{1} is less, but the permissible value of _S_ is also
-less in about the same proportion.
-
-The last equation shows that for a given material and atmospheric
-environment, the stress in the shell or wall of the spherical balloon
-is independent of the radius of the surface. It is also well known
-that the stress is less for the sphere than for any other surface.
-Hence, no surface can be constructed in which _S_ will be less than
-3_p_ς_{1}/2ς_{2}. The argument is easily seen to apply to a partial
-vacuum balloon, since a balloon of one nth vacuum will float a cover of
-but one nth the mass and strength.
-
-The above result was obtained on the assumption that the shell was
-prevented from buckling. As a matter of fact, it would buckle long
-before the crushing stress could be attained. We must conclude,
-therefore, that while a vacuum balloon has alluring features, the
-materials of engineering are not strong enough to favor such a
-structure. Perhaps it is nearer the truth to say that such a project is
-visionary, with the materials now available.
-
-                   •       •       •       •       •
-
-A like argument applies to the balloon reservoir in which it has
-been proposed to compress the surplus gas taken from a balloon hull
-on expansion of its contents by change of level or temperature. If a
-given mass of gas obeying Boyle’s law be pumped into a receiver of
-given shape and mass, the resultant stress in the receiver wall will be
-independent of the size. Hence the material of the proposed reservoir,
-if expanded to the size of the hull itself, will weigh the same, and
-suffer the same increment of unit stress, for a given mass increment of
-gas. Hence, instead of pumping the above-mentioned gas surplus from the
-hull into the reservoir, this latter may be discarded and its mass of
-material spread over the hull itself. This argument applies only if the
-shapes of hull and reservoir be equally effective, as, for example, if
-both be cylindrical.
-
-
-
-
-                              APPENDIX II
-
-                AËRONAUTIC LETTERS OF BENJAMIN FRANKLIN
-
-
-                                                PASSY, Aug. 30, 1783.
-
-On Wednesday, the 27th instant, the new aërostatic Experiment, invented
-by Messrs. Montgolfier of Annonay, was repeated by M. Charles,
-Professor of experimental Philosophy at Paris.
-
-A hollow Globe 12 feet Diameter was formed of what is called in England
-Oiled Silk, here Taffetas gommé, the Silk being impregnated with a
-Solution of Gum elastic in Linseed Oil, as he said. The Parts were
-sewed together while wet with the Gum, and some of it was afterwards
-passed over the Seam, to render it as tight as possible.
-
-It was afterwards filled with inflammable Air that is produced by
-pouring Oil of Vitriol upon Filings of Iron, when it was found to have
-a tendency upwards so strong as to be capable of lifting a Weight of 39
-Pounds, exclusive of its own Weight which was 25 lbs and the Weight of
-the Air contain’d.
-
-It was brought early in the morning to the Champ de Mars, a Field in
-which Reviews are sometimes made, lying between the military School and
-the River. There it was held down by a Cord till 5 in the afternoon,
-when it was to let loose. Care was taken before the Hour to replace
-what Portion had been lost, of the inflammable Air, or of its Force, by
-injecting more.
-
-It is supposed that not less than 50,000 People were assembled to see
-the Experiment, The Champ de Mars being surrounded by multitudes, and
-vast Numbers on the opposite Side of the River.
-
-At 5 O’clock Notice was given to the Spectators by the Firing of two
-Cannon, that the Cord was about to be cut. And presently the Globe was
-seen to rise, and that as fast as a Body of 12 feet Diameter, with a
-force only of 39 Pounds, could be suppos’d to remove the resisting Air
-out of its Way. There was some Wind, but not very strong. A little
-Rain had wet it, so that it shone, and made an agreeable appearance.
-It diminished in Apparent Magnitude as it rose, till it enter’d the
-Clouds, when it seem’d to me scarce bigger than an Orange, and soon
-after became invisible, the Clouds concealing it.
-
-The multitude separated, all well satisfied and delighted with the
-Success of the Experiment, and amusing one another with discourses of
-the various uses it may possibly be apply’d to, among which many were
-very extravagant. But possibly it may pave the Way to some Discoveries
-in Natural Philosophy of which at present we have no conception.
-
-A Note secur’d from the Weather had been affix’d to the Globe,
-signifying the Time & Place of its Departure, and praying those who
-might happen to find it, to send an account of its state to certain
-Persons at Paris. No News was learned of it till the next Day, when
-information was received that it fell a little after 6 o’clock, at
-Gonesse, a Place about four Leagues Distance, and that it was rent
-open, and some say had ice in it. It is suppos’d to have burst by the
-Elasticity of the contain’d Air when no longer compress’d by so heavy
-an Atmosphere.
-
-One of 38 feet Diameter is preparing by Mr. Montgolfier himself, at the
-Expence of the Academy, which is to go up in a few days. I am told it
-is constructed of Linen & Paper, and is to be filled with different
-Air, not yet made public, but cheaper than that produc’d by the Oil of
-Vitriol, of which 200 Paris Pints were consum’d in filling the other.
-
-It is said that for some Days after its being fill’d the Ball was found
-to lose an eighth Part of its Force of Levity in 24 Hours; Whether this
-was from Imperfection in the Tightness of the Ball, or a Change in the
-Nature of the Air, Experiments may easily discover....
-
-M. Montgolfier’s Air to fill the Globe has hitherto been kept secret;
-some suppose it to be only common Air heated by passing thro’ the Flame
-of burning Straw, and thereby extreamly rarefied. If so, its Levity
-will soon be deminish’d by Condensation, when it comes into the cooler
-Region above....
-
-P. S. I just now learned that some observers say, the Ball was 150
-Seconds in rising, from the cutting of the Cord till hid in the Clouds;
-that its height was then about 500 Toises, but, being moved out of
-the Perpendicular by the Wind, it had made a Slant so as to form a
-Triangle, whose base on the Earth was about 200 Toises. It is said the
-Country People who saw it fall were frightened, conceiv’d from its
-bounding a little, when it touched the Ground, that there was some
-living Animal in it, and attack’d with Stones and Knives, so that it
-was much mangled; but it is now brought to Town and will be repair’d.
-
-The great one of M. Montgolfier is to go up, as is said, from
-Versailles, in about 8 or 10 days. It is not a Globe but of a different
-Form, more convenient for penetrating the Air.
-
-It contains 50,000 cubic Feet, and is supposed to have Force of Levity
-equal to 1,500 pounds weight. A Philosopher here, M. Pilâtre du Rozier,
-has seriously apply’d to the Academy for leave to go up with it, in
-order to make some experiments. He was complimented on his Zeal and
-Courage for the Promotion of Science, but advis’d to wait till the
-management of these Balls was made by Experience more certain & safe.
-They say the filling of it in Montgolfier’s Way will not cost more
-than half a Crown. One is talk’d of to be 110 feet Diameter. Several
-gentlemen have ordered small ones to be made for their Amusement.
-One has ordered four of 15 feet Diameter each; I know not with what
-Purpose; but such is the present Enthusiasm for promoting and improving
-this Discovery, that probably we shall soon make considerable Progress
-in the art of constructing and using the Machines.
-
-Among the Pleasanteries Conversation produces on this subject, some
-suppose Flying to be now invented, and that since Men may be supported
-in the Air, nothing is wanted but some light handy instrument to give
-and direct Motion. Some think Progressive Motion on the Earth may
-be advanc’d by it, and that a Running Footman or a Horse slung and
-suspended under such a Globe so as to have no more of Weight pressing
-the Earth with their Feet, then Perhaps 8 or 10 pounds, might with a
-fair Wind run in a straight Line across Countries as fast as that Wind,
-and over Hedges, Ditches & even Waters. It has been even fancied that
-in time People will keep such Globes anchored in the Air, to which by
-Pullies they may draw up Game to be preserved in the Cool & Water to be
-frozen when Ice is wanted. And that to get Money, it will be contriv’d
-to give People an extensive View of the Country, by running them up in
-an Elbow Chair a Mile high for a Guinea, &c., &c.
-
-                                                         B. FRANKLIN.
-
-
-                                               PASSY, Nov. 22d, 1783.
-
-... Enclosed is a copy of the Proces verbal taken of the Experiment
-yesterday in the Garden of the Queen’s Palace la Muette, where the
-Dauphin now resides, which being near my House I was present. This
-Paper was drawn up hastily, and may in some Places appear to you
-obscure; therefore I shall add a few explanatory Observations.
-
-This Balloon was larger than that which went up from Versailles and
-carried the Sheep, &c. Its bottom was open, and in the middle of the
-Opening was fixed a kind of Basket Grate, in which Faggots and Sheaves
-of Straw were burnt. The Air rarefied in passing thro’ this Flame rose
-in the Balloon, swell’d out its sides, and Fill’d it.
-
-The Persons who were plac’d in the Gallery made of Wicker, and attached
-to the Outside near the Bottom, had each of them a Port thro’ which
-they could pass Sheaves of Straw into the Grate to keep up the Flame,
-& thereby keep the Balloon full. When it went over our Heads, we could
-see the Fire which was very considerable. As the Flame slackens, the
-rarefied Air cools and condenses, the Bulk of the Balloon diminishes
-and it begins to descend. If those in the Gallery see it likely to
-descend in an improper Place, they can by throwing on more Straw, &
-renewing the Flame, make it rise again, and the Wind carries it farther.
-
-One of these courageous Philosophers, the Marquis d’Arlandes, did me
-the honour to call upon me in the Evening after the Experiment, with
-Mr. Montgolfier, the very ingenious Inventor. I was happy to see him
-safe. He informed me that they lit gently, without the least Shock, and
-the Balloon was very little damaged.
-
-This method of filling the Balloon with hot Air is cheap and
-expeditious, and it is supposed may be sufficient for certain
-purposes, such as elevating an Engineer to take a view of an Enemy’s
-Army, Works, &c., conveying Intelligence into, or out of a besieged
-Town, giving Signals to distant places, or the like.
-
-The other method of filling a Balloon with permanently elastic
-inflammable Air, and then closing it is a tedious Operation, and
-very expensive; Yet we are to have one of that kind sent up in a few
-days. It is a Globe of 26 feet diameter. The Gores that compose it
-are red and white Silk, so that it makes a beautiful appearance. A
-very handsome triumphal Car will be suspended to it, in which Messrs.
-Roberts, two Brothers, very ingenious Men, who have made it in concert
-with Mr. Charles, propose to go up. There is room in this Car for a
-little Table to be placed between them, on which they can write and
-keep their journal, that is, take Notes of everything they observe, the
-State of their Thermometer, Barometer, Hygrometer, &c., which they will
-have more leisure to do than the others, having no fire to take care
-of. They say they have a contrivance which will enable them to descend
-at Pleasure. I know not what it is. But the Expence of this machine,
-Filling included, will exceed, it is said, 10,000 Livres.
-
-This Balloon of only 26 feet diameter, being filled with Air ten times
-lighter than common Air, will carry up a greater Weight than the other,
-which tho’ vastly bigger, was filled with an Air that could scarcely be
-more than twice as light. Thus the great Bulk of one of these Machines,
-with the short duration of its Power, & the great Expence of filling
-the other will prevent the Inventions being of so much Use as some may
-expect, till Chemistry can invent a cheaper light Air producible with
-more Expedition.
-
-But the Emulation between the two Parties running high, the Improvement
-in the Construction and Management of the Balloons had already made
-a rapid Progress; and one cannot say how far it may go. A few Months
-since the idea of Witches riding thro’ the Air upon a Broomstick, and
-that of Philosophers upon a Bag of Smoke, would have appeared equally
-impossible and ridiculous.
-
-These Machines must always be subject to be driven by the Winds.
-Perhaps Mechanic Art may find easy means to give them progressive
-Motion in a Calm, and to slant them a little in the Wind.
-
-I am sorry this Experiment is totally neglected in England, where
-mechanic Genius is so strong. I wish I could see the same Emulation
-between the two Nations as I see between the two Parties here. Your
-Philosophy seems to be too bashful. In this Country we are not so
-much afraid of being laught at. If we do a foolish thing, we are the
-first to laugh at it ourselves, and are almost as much pleased with
-a Bon Mot or a Chanson, that ridicules well the Disappointment of a
-Project, as we might have been with its Success. It does not seem to me
-a good reason to decline prosecuting a new Experiment which apparently
-increases the power of a Man over Matter, till we can see to what use
-that power can be applied. When we have learnt to manage it, we may
-hope some time or other to find Uses for it, as men have done for
-Magnetism and Electricity, of which the first Experiments were mere
-Matters of Amusement.
-
-This Experience is by no means a trifling one. It may be attended with
-important Consequences that no one can foresee. We should not suffer
-Pride to prevent our progress in Science.
-
-Beings of a Rank and Nature far superior to ours have not disdained
-to amuse themselves with making and launching Balloons, otherwise we
-should never have enjoyed the Light of those glorious objects that rule
-our Day & Night, nor have had the Pleasure of riding round the Sun
-ourselves upon the Balloon we now inhabit.
-
-                                                         B. FRANKLIN.
-
-                                                 PASSY, Dec. 1, 1783.
-
-In mine of yesterday I promised to give you an account of Messrs.
-Charles & Roberts’ Experiment, which was to have been made this Day,
-and at which I intended to be present. Being a little indispos’d, &
-the Air cool, and the Ground damp, I declin’d going into the Garden
-of the Tuilleries where the Balloon was plac’d, not knowing how long
-I might be oblig’d to wait there before it was ready to depart; and
-chose to stay in my Carriage near the Statue of Louis XV, from whence I
-could well see it rise, & have an extensive View of the Region of Air
-thro’ which, as the Wind sat, it was likely to pass. The Morning was
-foggy, but about one o’clock the Air became tolerably clear; to the
-great satisfaction of spectators, who were infinite. Notice having been
-given of the intended Experiment several days before in the Papers,
-so that all Paris was out, either about the Tuilleries, on the Quays
-& Bridges, in the Fields, the Streets, at the Windows, or on the Tops
-of Houses, besides the inhabitants of all the Towns & Villages of the
-Environs. Never before was a philosophical Experiment so magnificently
-attended. Some Guns were fired to give Notice that the departure of
-the great Balloon was near, and a small one was discharg’d which went
-to an amazing height, there being but little Wind to make it deviate
-from its perpendicular Course, and at length the Sight of it was lost.
-Means were used, I am told, to prevent the great Balloon’s rising so
-high as might endanger its Bursting. Several Bags of Sand were taken
-on board before the Cord that held it down was cut, and the whole
-Weight being then too much to be lifted, such a Quantity was discharg’d
-as to permit its Rising slowly. Thus it would sooner arrive at that
-Region where it would be in equilibrio with the surrounding Air, and
-by discharging more Sand afterwards, it might go higher if desired.
-Between One & Two o’Clock, all Eyes were gratified with seeing it
-rise majestically from among the Trees and ascend gradually above the
-Buildings, a most beautiful Spectacle! When it was about 200 feet high,
-the brave Adventurers held out and wav’d a little white Pennant, on
-both sides their Car, to salute the Spectators, who return’d loud Claps
-of Applause. The Wind was very little, so that the Object, tho’ moving
-to the Northward, continued long in View; and it was a great while
-before the admiring People began to disperse. The persons embark’d
-were Mr. Charles, Professor of Experimental Philosophy, & zealous
-Promotor of that Science; and one of the Messieurs Robert, the very
-ingenious Constructors of the Machine. When it arrived at its height,
-which I suppose might be 3 or 400 Toises, it appeared to have only
-horizontal Motion. I had a Pocket Glass, with which I follow’d it,
-till I lost Sight first of the Men, then of the Car, and when I last
-saw the Balloon, it appear’d no bigger than a Walnut. I write this at
-7 in the evening. What became of them is not yet known here. I hope
-they descended by Day-light, so as to see and avoid falling among
-Trees or on Houses, and that the Experience was completed without any
-mischievous Accident, which the Novelty of it & the want of Experience
-might well occasion. I am the more anxious for the Event, because I am
-not well informed of the Means provided for letting themselves gently
-down, and the Loss of these very ingenious Men would not only be a
-Discouragement to the Progress of the Art, but be a sensible Loss to
-Science and Society.
-
-Tuesday Morning, December 2,—I am reliev’d from my Anxiety by hearing
-that the Adventurers descended well near l’Isle Adam, before Sunset.
-This Place is near 7 Leagues from Paris. Had the Wind blown fresh, they
-might have gone much farther.
-
-P.S. Tuesday Evening ... I hear farther that the Travellers had perfect
-Command of the Carriage, descending as they pleas’d by letting some of
-the inflammable Air escape, and rising again by discharging some Sand;
-that they descended over a Field so low as to talk with Labourers in
-passing and mounted again to pass a Hill. The little Balloon falling at
-Vincennes shows that mounting higher it met with a Current of Air in a
-contrary Direction; an Observation that may be of use to future aërial
-Voyagers.
-
-                                                         B. FRANKLIN.
-
-
-
-
-                             APPENDIX III
-
-                SUCCESSFUL MILITARY DIRIGIBLE BALLOONS
-
-                                FRANCE
-
-
-                      _The Clément-Bayard II_[80]
-
-The _Clément-Bayard II_ may be classed among the airships usually
-called “flexible.” The shape of its hull is preserved not by any rigid
-framing, but by internal gas pressure maintained by ballonets fed by
-ventilating fans. Moreover, the suspension which binds envelope and car
-together as one solid is composed wholly of flexible elements, without
-any rigid intermediary structure.
-
-The general plan, then, of the craft comprises three prominent
-features, well marked and distinct in character:
-
-(_a_) The fish-shaped envelope with major section well forward, a form
-favorable to both speed and stability.
-
-(_b_) The trussed girderlike car whose length allows the load to be
-distributed over the hull, thus preserving its nicety of outline.
-The most minute and technical and mechanical details were studied
-for eighteen months by M. Clément and his devoted collaborator, the
-engineer Sabathier. The girder car, as will be seen presently, is
-particularly well designed to serve as car, sustainer and stiffener. No
-stabilizing device is attached to the envelope; all are fixed to the
-car, on which is mounted also the complete propulsion plant.
-
-(_c_) The suspension which binds the buoyant envelope to the car serves
-no other purpose. Note also the ingenious arrangement of two motors
-and two propellers, forming two independent systems, yet unitable
-under certain conditions. The placement of the propellers, rudders and
-stabilizing surfaces well above the bottom of the car, insures them
-against dangerous contact on landing, or while maneuvering near the
-ground.
-
-The envelope is of rubberized Continental cloth. Its volume is 7,000
-cubic meters, length 76.5 meters and major diameter 13.22 meters, or
-an elongation of 5.76 diameters. Inside the gas envelope is an air bag
-of 2,200 cubic meters. It is divided into two compartments, _Q_ and
-_Q´_, which can be filled with air together or separately through the
-air duct, _Q_, joined to a blower, _P_, run by the two motors, or by
-hand when so desired. The balloon proper comprises two gas valves, _R_.
-Each compartment of the ballonet has one air valve, _S_. The valves of
-the type Clément-Bayard-Chauvière are automatic. Their construction is
-so perfect that for the first time in France, at least on a balloon of
-so large bulk, the blower runs continuously in constant communication
-with the ballonet, the pressure in the envelope remaining invariable,
-due to the regular play of the valves, which yield at the pressure for
-which they are set. They may also be Worked by hand from the pilot’s
-bridge in case of emergency. The envelope has on its upper side three
-ripping seams, one in the middle, the others toward either end. These
-rip panels can be worked together or separately, and permit the rapid
-deflation of the balloon.
-
-The long car is attached to the hull by hempen duck feet fastened to
-a bolt rope running along the envelope below the equator; these duck
-feet terminate below in steel suspension cables fixed to the car. Below
-the principal bolt rope are others to which are fastened the duck
-feet of the oblique cords, which assure the perfect solidarity of the
-envelope and car. The steel cable sustainers have an ingenious patented
-regulating windlass. The girder car consists of a latticed girder,
-built of steel tubes united with cast-iron joints and steel-tie wires.
-Its whole length is 45 meters, of which 14.5 meters constitute the car
-proper. It is divided into segments which are easily demountable, thus
-rendering it easily transportable by truck or railway. The forward
-segment, _A_, tapers toward the front to a sharp point and is of
-triangular cross-section. The mid segment, _B_, constituting the car,
-has a quadrangular section of variable size. The rear segment, _D_, is
-of triangular section, diminishing progressively toward the rear, which
-rises to a sort of tail supporting the empennage and the direction
-rudders. The entire girder car when resting on the ground is supported
-by two pneumatic shock absorbers, _U_, _U_, projecting from its floor.
-
-The car proper comprises three parts: in front, the motor and machine
-room, 2.5 meters wide; in the middle, the elevated bridge, _N_, for
-the pilot and his aide; in the rear, the passenger cabin, 8 meters
-long, 1.3 meters wide and 2 meters high for the observers and wireless
-telegraphy plant. The two reservoirs of essence, _M_, _m_, are placed
-above the passenger about the center of pressure. The blower _P_, for
-the ballonets, and the guide ropes _T_, are placed above the pilot’s
-bridge.
-
-In the motor room are symmetrically arranged two Bayard-Clément
-engines, _G G_, separated enough to allow free passage between them.
-Each motor is elastically supported to obviate vibrations, and connects
-with the transmission shaft by a variable speed gear. The engines
-can be run separately or together by a connecting sprocket chain, and
-develop 100 to 130 horse-power each. The cooling of each motor is
-effected by an aluminum radiator, _L L_, of large surface.
-
-The Chauvière propellers, _K K_, six feet in diameter, are driven by
-shafting and gear wheels at a normal speed of 250 rotations per minute.
-A special recording device serves to show their thrust at each instant,
-as also the torque of the motors.
-
-The pilot, standing on the bridge where he enjoys a clear view, has
-immediate charge of the vessel’s movements. Before him are the various
-controls which he must operate, and the divers indicators which he must
-consult. These are the direction wheel, the manometers, the aneroid
-and registering barometers, the clinometer, the blower control to
-regulate the amount and distribution of pressure, the elevating-rudder
-wheel, the spark control, the ripping cord, the release string of the
-guide-rope, and the system of transmitting orders to the mechanicians
-whereby he can control the engines and the blowers which furnish air to
-the radiator and ballonet.
-
-The direction and poise of the vessel in flight are controlled by the
-rudders and empennage at the rear, and its altitude from minute to
-minute is governed by the elevating biplane _E´_, of 30 square meters
-above the car in the mid region of the vessel.
-
-
-                           The _Patrie_[81]
-
-The _Patrie_, the third of its type, was first operated in 1906. The
-gas bag of the first balloon was built by Surcouf at Billancourt,
-Paris. The mechanical part was built at the Lebaudy Sugar Refinery.
-Since then the gas bags have been built at the Lebaudy balloon shed at
-Moisson, near Paris, under the direction of their aëronaut, Juchmes.
-The gas bag of the _Patrie_ was 197 feet long with a maximum diameter
-of 33 feet, 9 inches, situated about 2/5 of the length from the front;
-volume 111,250 cubic feet; length approximately six diameters. This
-relation, together with the cigar shape, is in accordance with the
-plans of Colonel Renard’s dirigible, built and operated in France in
-1884; the same general shape and proportions being found in the Ville
-de Paris.
-
-The first Lebaudy was pointed at the rear, which is generally admitted
-to be the proper shape for the least resistance, but to maintain
-stability it was found necessary to put a horizontal and vertical plane
-there, so that it had to be made an ellipsoid of revolution to give
-attachment for these planes.
-
-The ballonet for air had a capacity of 22,958 cubic feet or about 1/5
-of the total volume. This is calculated to permit reaching a height of
-about one mile and to be able to return to the earth, keeping the gas
-bag always rigid. To descend from a height of one mile, gas would be
-released by the valve, then air pumped into the ballonet to keep the
-gas bag rigid, these two operations being carried on alternately. On
-reaching the ground from the height of one mile, the air would be at
-the middle of the lower part of the gas bag and would not entirely fill
-the ballonet. To prevent the air from rolling from one end to the other
-when the air ship pitches, thus producing instability, the ballonet
-was divided into three compartments by impermeable cloth partitions.
-Numerous small holes were pierced in these partitions, through which
-the air finally reached the two end compartments.
-
-In September, 1907, the _Patrie_ was enlarged by 17,660 cubic feet
-by the addition of a cylindrical section at the maximum diameter,
-increasing the length but not the maximum diameter.
-
-_The Gas Bag._—The gas bag is cut in panels; the material is a rubber
-cloth made by the Continental Tire Company at Hanover, Germany. It
-consists of four layers arranged as follows:
-
-                                                          Weight oz. per
-                                                           square yard.
-  _a._ Outer layer of cotton cloth covered with lead chromate  2.5
-  _b._ Layer of vulcanized rubber                              2.5
-  _c._ Layer of cotton cloth                                   2.5
-  _d._ Inner layer of vulcanized rubber                        2.21
-                                                             ------
-        Total weight                                           9.71
-
-A strip of this cloth one foot wide tears at a tension of about 934
-pounds. A pressure of about one inch of water can be maintained in the
-gas bag without danger. The lead chromate on the outside is to prevent
-the entrance of the actinic rays of the sun, which would cause the
-rubber to deteriorate. The heavy layer of rubber is to prevent the
-leaking of the gas. The inner layer of rubber is merely to prevent
-deterioration of the cloth by impurities in the gas. This material
-has the warp of the two layers of cotton cloth running in the same
-direction and is called straight thread. The material in the ballonet
-weighs only about 7¾ ounces per square yard, and has a strength of
-about 336 pounds per running foot. When the _Patrie_ was enlarged in
-September, 1907, the specifications of the material allowed a maximum
-weight of 10 ounces per square yard, a minimum strength of 907 pounds
-per running foot, and a loss of 5.1 cubic inches of hydrogen per square
-yard in twenty-four hours at a pressure of 1.18 inches of water. Bands
-of cloth are pasted over the seams inside and out with a solution of
-rubber to prevent leaking through the stitches.
-
-_Suspension._—One of the characteristics of the _Patrie_ is the “short”
-suspension. The weight of the car is distributed over only about 70
-feet of the length of the gas bag. To do this, an elliptical-shaped
-frame of nickel-steel tubes is attached to the bottom of the gas
-bag; steel cables run from this down to the car. A small hemp net
-is attached to the gas bag by means of short wooden cross-pieces,
-or toggles, which are let into holes in a strong canvas band which
-is sewed directly on the gas bag. The metal frame, or platform, is
-attached to this net by means of toggles, so that it can be quickly
-removed in dismounting the air ship for transportation. The frame can
-also be taken apart, 28 steel cables about 0.2 inches in diameter run
-from the frame down to the car, and are arranged in triangles. Due
-to the impossibility of deforming a triangle, rigidity is maintained
-between the car and gas bag.
-
-The objection to the “short” suspension of the _Patrie_ is the
-deformation of the gas bag. A distinct curve can be seen in the middle.
-
-_The Car._—The car is made of nickel-steel tubes (12 per cent nickel).
-This metal gives the greatest strength for minimum weight. The car is
-boat-shaped, about 16 feet long, about 5 feet wide and 2½ feet high.
-About 11 feet separate the car from the gas bag. To prevent any chance
-of the fire from the engine communicating with the hydrogen, the steel
-framework under the gas bag is covered with a noncombustible material.
-
-The pilot stands at the front of the car, the engine is in the
-middle, the engineer at the rear. Provision is made for mounting a
-telephotographic apparatus, and for a 100-candle-power acetylene
-searchlight. A strong pyramidal structure of steel is built under the
-car, pointing downward. In landing the point comes to the ground first
-and this protects the car, and especially the propellers, from being
-damaged. The car is covered to reduce air resistance. It is so low,
-however, that part of the equipment and most of the bodies of those
-inside are exposed, so that the total resistance of the car is large.
-
-_The Motor._—The first Lebaudy had a 40-horse-power Daimler-Mercedes
-benzine motor. The _Patrie_ was driven by a 60 to 70-horse-power
-4-cylinder Panhard and Levassor benzine motor, making 1,000 r. p. m.
-
-_The Propellers._—There are two steel propellers 8½ feet in diameter
-(two blades each) placed at each side of the engine, this giving the
-shortest and most economical transmission. To avoid any tendency to
-twist the car, the propellers turn in opposite directions. They are
-“high speed,” making 1,000 to 1,200 r. p. m.
-
-The gasoline tank is placed under the car inside the pyramidal frame.
-The gasoline is forced up to the motor by air compression. The exhaust
-is under the rear of the car pointing down and is covered with a metal
-gauze to prevent flames coming out. The fan which drives the air into
-the ballonet is run by the motor, but a dynamo is also provided so
-that the fan can always be kept running even if the motor stops. This
-is very essential as the pressure must be maintained inside the gas
-bag so that the latter will remain rigid and keep its form. There are
-five valves in all, part automatic and part both automatic and also
-controlled from the car with cords. The valves in the ballonet open
-automatically at less pressure than the gas valves, so that when the
-gas expands all the air is driven out of the ballonet before there is
-any loss of gas. The ballonet valves open at a pressure of about O.78
-inches of water, the gas valves at about 2 inches.
-
-_Stability._—Vertical stability is maintained by means of fixed
-horizontal planes. One having a surface of 150 square feet is attached
-at the rear of the gas bag and due to its distance from the center of
-gravity is very efficient. The elliptical frame attached under the gas
-bag has an area of 1,055 square feet, but due to its proximity to the
-center of gravity, has little effect on the stability. Just behind
-the elliptical frame is an arrangement similar to the feathering of
-an arrow. It consists of a horizontal plane of 150 square feet, and a
-vertical plane of 113 square feet. To maintain horizontal stability,
-that is, to enable the air ship to move forward in a straight line
-without veering to the sides, fixed vertical planes are used. One runs
-from the center to the rear of the elliptical frame and has an area of
-108 square feet.
-
-In addition to the vertical surface of 113 square feet at the rear of
-the elliptical frame, there is a fixed plane of 150 square feet at the
-rear of the gas bag. To fasten the two perpendicular planes at the
-rear of this gas bag, cloth flaps are sewed directly on the gas bag.
-Nickel-steel tubes are placed in the flaps, which are then laced over
-the tubes. With these tubes as a base, a light tube and wire framework
-is attached and waterproof cloth laced on this framework. Additional
-braces run from one surface to the other and from each surface to the
-gas bag. The rudder is at the rear under the gas bag. It has about 150
-square feet and is balanced.
-
-A movable horizontal plane near the center of gravity, above the
-car, is used to produce rising or descending motion, or to prevent
-an involuntary rising or falling of the air ship due to expansion or
-contraction of the gas or to other causes. After the adoption of this
-movable horizontal plane, the loss of gas and ballast was reduced to a
-minimum. Ballast is carried in 10- and 20-pound sandbags. A pipe runs
-through the bottom of the car from which the ballast is thrown.
-
-There are two long guide-ropes, one attached at the front of the
-elliptical frame and the other on the car. On landing, the one in front
-is seized first so as to hold the air ship with the head to the wind.
-The motor may then be stopped and the descent made by pulling down on
-both guide-ropes. A heavy rope 22 feet long, weighing 110 pounds, is
-attached at the end of a 164-foot guide-rope. This can be dropped out
-on landing to prevent coming to the ground too rapidly. The equipment
-of the car includes a “siren” speaking trumpet, carrier pigeons, iron
-pins and a rope for anchoring the air ship, reserve supply of fuel and
-water, and fire extinguisher.
-
-After being enlarged in September, 1907, the _Patrie_ made a number of
-long trips at an altitude of 2,500 to 3,000 feet. In November, 1907,
-she went from Paris to Verdun, near the German frontier, a distance of
-about 175 miles, in about 7 hours, carrying four persons. This trip was
-made in a light wind blowing from the northeast. Her course was east,
-so that the wind was unfavorable. On Friday, November 20, 1907, during
-a flight near Verdun, the motor stopped due to difficulty with the
-carburetor. The air ship drifted with the wind to a village about 10
-miles away, where she was safely landed. The carburetor was repaired on
-the 20th. Soon after, a strong wind came up and tore loose some of the
-iron pickets with which it was anchored. This allowed the air ship to
-swing broadside to the wind; it then tilted over on the side far enough
-to let some of the ballast bags fall out. The 150 or 200 soldiers who
-were holding the ropes were pulled along the ground until directed by
-the officer in charge to let go. After being released, it rose and was
-carried by the wind across the north of France, the English Channel
-and into the north of Ireland. It struck the earth there, breaking off
-one of the propellers, and then drifted to sea.
-
-
-                           The _République_
-
-This is the latest of the French military dirigible balloons, and
-differs but slightly from its predecessor, the _Patrie_. The volume has
-been increased by about 2,000 cubic feet. The length has been reduced
-to 200 feet and the maximum diameter increased to 35½ feet. The shape
-of the gas bag accounts for the 2,000 additional cubic feet of volume.
-The motor and propeller are as in the _Patrie_. The total lifting
-capacity is 9,000 pounds, of which 2,700 pounds are available for
-passengers, fuel, ballast, instruments, etc. Its best performance was a
-125-mile flight made in 6½ hours against an unfavorable wind.
-
-The material for the gas bag of the new air ship was furnished by the
-Continental Tire Company. It is made up as follows:
-
-                               Weight oz. per
-                                square yard.
-  Outer yellow cotton layer         3.25
-  Layer of vulcanized rubber        3.25
-  Layer of cotton cloth             3.25
-  Inner layer of rubber             0.73
-                                  ------
-      Total weight                 10.48
-
-It is interesting to note the changes which this type has undergone
-since the first one was built. The _Jaune_, constructed in 1902-3, was
-pointed at the rear and had no stability plane there; later it was
-rounded off at the rear and a fixed horizontal plane attached. Finally
-a fixed vertical plane was added. The gas bag has been increased in
-capacity from 80,670 cubic feet to about 131,000 cubic feet. The
-manufacturers have been able to increase the strength of the material
-of which the gas bag is made, without materially increasing the weight.
-The rudder has been altered somewhat in form. It was first pivoted on
-its front edge, but later on a vertical axis, somewhat to the rear of
-this edge. With the increase in size, has come an increase in carrying
-capacity and, consequently, a greater speed and more widely extended
-field of action.
-
-
-                           _Ville de Paris_
-
-This air ship was constructed for Mr. Deutsch de la Meurthe, of
-Paris, who has done a great deal to encourage aërial navigation. The
-first _Ville de Paris_ was built in 1902, on plans drawn by Tatin,
-a French aëronautical engineer. It was not a success. Its successor
-was built in 1906, on plans of Surcouf, an aëronautical engineer and
-balloon builder. The gas bag was built at his works in Billancourt,
-the mechanical part at the Voisin shop, also in Billancourt. The plans
-are based on those of Colonel Renard’s air ship, the _France_, built
-in 1884, and the _Ville de Paris_ resembles the older air ship in many
-particulars. In September, 1907, Mr. Deutsch offered the use of his air
-ship to the French Government. The offer was accepted, but delivery was
-not to be made except in case of war or emergency. When the _Patrie_
-was lost in November, 1907, the military authorities immediately took
-over the Deutsch air ship.
-
-_Gas Bag._—The gas bag is 200 feet long for a maximum diameter of 34½
-feet, giving a length of about 6 diameters, as in the _France_ and
-the _Patrie_. Volume, 112,847 cubic feet; maximum diameter at about
-⅜ of the distance from the front, approximately, as in the _Patrie_.
-The middle section is cylindrical with conical sections in front
-and rear. At the extreme rear is a cylindrical section with eight
-smaller cylinders attached to it. The ballonet has a volume of 21,192
-cubic feet or about ⅕ of the volume, the same proportion found in
-the _Patrie_. The ballonet is divided into three compartments from
-front to rear. The division walls are of permeable cloth, and are not
-fastened to the bottom so that when the middle compartment fills with
-air, and the ballonet rises, the division walls are lifted up from
-the bottom of the gas bag, and there is free communication between
-the three compartments. The gas bag is made up of a series of strips
-of perpendicular to a meridian line. These strips run around the
-bag, their ends meeting on the under meridian. This is known as the
-“barchistode” method of cutting out the material, and has the advantage
-of bringing the seams parallel to the line of greatest tension. They
-are therefore more likely to remain tight and not allow the escape
-of gas. The disadvantage lies in the fact that there is a loss of
-33⅓ per cent of material in cutting. The material was furnished by
-the Continental Tire Company, and has approximately the same tensile
-strength and weight as that used in the _Patrie_. It differs from the
-other in one important feature—it is diagonal thread, that is, the warp
-of the outer layer of cotton cloth makes an angle of 45 degrees with
-the warp of the inner layer of cotton cloth. The result is to localize
-a rip or tear in the material. A tear in the straight thread material
-will continue along the warp, or the weave, until it reaches a seam.
-
-_Valves._—There are five in all, made of steel, about fourteen inches
-in diameter; one on the top connected to the car by a cord, operated by
-hand only; two near the rear underneath. These are automatic but can
-be operated by hand from the car. Two ballonet valves directly under
-the middle are automatic and are also operated from the car by hand.
-The ballonet valves open automatically at a pressure of 2/3 inches of
-water; the gas valves open at a higher pressure.
-
-_Suspension._—This air ship has the “long” suspension. That is, the
-weight is distributed along practically the entire length of the gas
-bag. A doubled band of heavy canvas is sewn with six rows of stitches
-along the side of the gas bag. Hemp ropes running into steel cables
-transmit most of the weight of the car to these two canvas bands and
-thus to the gas bag. On both sides and below these first bands are
-two more. Lines run from these to points half way between the gas
-bag and the car, then radiate from these points to different points
-of attachment on the car. This gives the triangular or nondeformable
-system of suspension, which is necessary in order to have the car and
-gas bag rigidly attached to each other. With this “long” suspension,
-the _Ville de Paris_ does not have the deformation so noticeable in the
-gas bag of the _Patrie_.
-
-_The Car._—This is in the form of a trestle. It is built of wood with
-aluminum joints and O.12 inch wire tension members. It is 115 feet
-long, nearly 7 feet high at the middle and a little over 5½ feet wide
-at the middle. It weighs 660 pounds and is considered unnecessarily
-large and heavy. The engine and engineer are well to the front, the
-aëronaut with steering wheels is about at the center of gravity.
-
-_Motor._—The motor is a 70 to 75-horse-power _Argus_, and is
-exceptionally heavy.
-
-_Propeller._—The propeller is placed at the front end of the car. It
-thus has the advantage of working in undisturbed air; the disadvantage
-is the long transmission and difficulty in attaching the propeller
-rigidly. It has two blades and is 19.68 feet long with a pitch of
-26.24 feet. The blades are of cedar with a steel arm. The propeller
-makes a maximum of 250 turns per minute when the engine is making 900
-revolutions. Its great diameter and width compensate for its small
-speed.
-
-_Stability._—This is maintained entirely by the cylinders at the rear.
-Counting the larger one to which the smaller ones are attached, there
-are five, arranged side by side corresponding to the horizontal planes
-of the _Patrie_, and five vertical ones corresponding to the _Patrie’s_
-vertical planes. The volume of the small cylinders is so calculated
-that the gas in them is just sufficient to lift their weight, so they
-neither increase nor decrease the ascensional force of the whole. The
-horizontal projection of these cylinders is 1,076 square feet. The
-center of this projection is 72 feet from the center of gravity of the
-gas. The great objection to this method of obtaining stability, is the
-air resistance due to these cylinders, and consequent loss of speed.
-The stability of the _Ville de Paris_ in a vertical plane is said to be
-superior to that of the _Patrie_, due to the fact that the stability
-planes of the latter do not always remain rigid. The independent
-velocity of the _Ville de Paris_ probably never exceeded 25 miles an
-hour.
-
-_The Rudder._—The rudder has a double surface of 150 square feet placed
-at the rear end of the car, 72 feet from the center of gravity. It is
-not balanced, but is inclined slightly to the rear so that its weight
-would make it point directly to the rear if the steering gear should
-break. Two pairs of movable horizontal planes, one at the rear of the
-car having 43 square feet, and one at the center of gravity (as on the
-_Patrie_) having 86 square feet, serve to drive the air ship up or down
-without losing gas or ballast.
-
-_Guide-Ropes._—A 400-foot guide-rope is attached at the front end of
-the car. A 230-foot guide-rope is attached to the car at the center of
-gravity.
-
-About thirty men are required to maneuver the _Ville de Paris_ on the
-ground. The pilot has three steering wheels, one for the rudder and
-two for the movable horizontal planes. The instruments used are an
-aneroid barometer, a registering barometer giving heights up to 1,600
-feet, and an ordinary dynamometer, which can be connected either with
-the gas bag or ballonet by turning a valve. A double column of water
-is also connected to the tube to act as a check on the dynamometer.
-Due to the vibration of the car caused by the motor, these instruments
-are suspended by rubber attachments. Even with this arrangement, it is
-necessary to steady the aneroid barometer with the hand in order to
-read it. The vibration prevents the use of the statoscope.
-
-
-                                GERMANY
-
-Three different types of air ships are being developed in Germany. The
-_Gross_ is the design of Major Von Gross, who commands the Balloon
-Battalion at Tegel near Berlin. The _Parseval_ is being developed by
-Major Von Parseval, a retired German officer, and the _Zeppelin_ is the
-design of Count Zeppelin, also a retired officer of the German Army.
-
-
-                              The _Gross_
-
-The first air ship of this type made its first ascension on July 23,
-1907. The mechanical part was built at Siemen’s Electrical Works in
-Berlin; the gas bag by the Riedinger firm in Augsburg.
-
-_Gas Bag._—The gas bag is made of rubber cloth furnished by the
-Continental Tire Company similar to that used in the _Ville de Paris_.
-It is diagonal-thread, but there is no inner layer of rubber, as they
-do not fear damage from impurities in the hydrogen gas. Length, 131¼
-feet; maximum diameter about 39⅓ feet; volume, 63,576 cubic feet; the
-elongation is about 3⅓. The form is cylindrical with spherical cones at
-the ends, the whole being symmetrical.
-
-_Suspension._—The suspension is practically the same as that of the
-_Patrie_. A steel and aluminum frame is attached to the lower part of
-the gas bag, and the car is suspended on this by steel cables. The
-objection to this system is even more apparent in the _Gross_ than in
-the _Patrie_. A marked dip along the upper meridian of the gas bag
-shows plainly the deformation.
-
-_The Car._—The car is boat-shaped like that of the _Patrie_. It is
-suspended thirteen feet below the gas bag.
-
-_Motor._—The motor is a 20- to 24-horse-power, 4-cylinder
-Daimler-Mercedes.
-
-_Propellers._—There are two propellers 8³/₁₀ foot in diameter, each
-having two blades. They are placed one on each side, but well up under
-the gas bag near the center of resistance. The transmission is by belt.
-The propellers make 800 r. p. m.
-
-_Stability._—The same system, with planes, is used in the _Gross_ as
-in the _Patrie_, but it is not nearly so well developed. At the rear
-of the rigid frame, attached to the gas bag, are two fixed horizontal
-planes, one on each side. A fixed vertical plane runs down from between
-these horizontal planes, and is terminated at the rear by the rudder.
-A fixed horizontal plane is attached on the rear of the bags as in the
-_Patrie_. The method of attachment is the same, but the plane is put on
-before inflation in the _Gross_ air ship, afterwards in the _Patrie_.
-The stability of the _Gross_ air ship in a vertical plane is reported
-to be very good, but it is said to veer considerably in attempting to
-steer a straight course.
-
-The many points of resemblance between this dirigible and the Lebaudy
-type are worthy of notice. The suspension or means of maintaining
-stability, and the disposition for driving are in general the same. As
-first built, the _Gross_ had a volume of 14,128 cubic feet less than
-at present, and there was no horizontal plane at the rear of the gas
-bag. Its maximum speed is probably fifteen miles per hour. As a result
-of his experiments of 1907, Major Von Gross has this year produced a
-perfected air ship, built on the same lines as his first, but with
-greatly increased volume and dimensions. The latest one has a volume of
-176,000 cubic feet, is driven by two 75-horse-power Daimler motors, and
-has a speed of 27 miles per hour.
-
-On September 11th of this year, the _Gross_ air ship left Berlin at
-10.25 P.M., carrying four passengers, and returned the next day at
-11.30 A.M., having covered 176 miles in the period of a little over 13
-hours. This is the longest trip, both in point of time and distance,
-ever made by any air ship returning to the starting point.
-
-
-                            The _Parseval_
-
-The _Parseval_ air ship is owned and controlled by the Society for the
-Study of Motor Balloons. This organization, composed of capitalists,
-was formed practically at the command of the emperor, who is very much
-interested in aërial navigation. The society has a capital of 1,000,000
-marks, owns the _Parseval_ patents and is ready to construct air ships
-of the _Von Parseval_ type. The present air ship was constructed by the
-Riedinger firm at Augsburg, and is operated from the balloon house of
-this society at Tegel, adjoining the military balloon house.
-
-The gas bag is similar in construction to that of the _Drachen_
-balloon, used by the army for captive work. Volume, 113,000 cubic
-feet; length, 190 feet; maximum diameter, 30½ feet. It is cylindrical
-in shape, rounded at the front and pointed at the rear. The material
-was furnished by the Continental Tire Company. It is diagonal-thread,
-weighing about 11³/₁₀ ounces per square yard and having a strength of
-about 940 pounds per running foot. Its inner surface is covered with a
-layer of rubber.
-
-_Ballonets._—There are two ballonets, one at each end, each having a
-capacity of 10,596 cubic feet. The material in the ballonet weighs
-about 8¼ ounces per square yard, the cotton layers being lighter than
-in the material for the gas bag. Air is pumped into the rear ballonet
-before leaving the ground, so that the air ship operates with the front
-end inclined upward. The air striking underneath exerts an upward
-pressure, as on an aëroplane, and thus adds to its lifting capacity.
-Air is pumped into the ballonets from a fan operated by the motor.
-A complex valve, just under the middle of the gas bag, enables the
-engineer to drive air into either, or both ballonets. The valves also
-act automatically and release air from the ballonets at a pressure of
-about 0.9 inches of water.
-
-In the middle of the top of the gas bag is a valve for releasing the
-gas. It can be operated from the car, and open automatically at a
-pressure of about 2 inches of water. Near the two ends and on opposite
-sides are two rip strips controlled from the car by the cords.
-
-_Suspension._—The suspension is one of the characteristics of the air
-ships, and is protected by patents. The car has four trolleys, two on
-each side, which run on two steel cables. The car can run backwards
-and forwards on these cables, thus changing its position with relation
-to the gas bag. This is called “loose” suspension. Its object is to
-allow the car to take up, automatically, variations in thrust due to
-the motor, and variations in resistance due to the air. Ramifications
-of hemp rope from these steel cables are sewed onto a canvas strip,
-which in turn is sewed onto the gas bag. This part of the suspension is
-the same as in the _Drachen_ balloon. The weight is distributed over
-the entire length of the gas bag.
-
-_The Car._—The car is 16.4 feet long and is built of steel tubes and
-wire. It is large enough to hold the motor and three men, though four
-or five may be taken.
-
-_Motor._—The motor is a 110-horse-power Daimler-Mercedes. Sufficient
-gasoline is carried for a run of twelve hours.
-
-_Propeller._—The propeller, like the suspension, is peculiar to this
-air ship and is protected by patents. It has four cloth blades which
-hang limp when not turning. When the motor is running, these blades,
-which are carefully weighed with lead at certain points, assume the
-proper position due to the various forces acting. The diameter is 13¾
-feet. The propeller is placed above the rear of the car near the center
-of resistance. Shaft transmission is used. The propeller makes 500
-r. p. m. to 1,000 of the motor. There is a space of 6½ feet from the
-propeller blades to the gas bag, the bottom of the car being about 30
-feet from the gas bag. This propeller has the advantage of being very
-light. Its position, so far from the engine, necessarily incurs a great
-loss of power in transmission.
-
-The steering wheel at the front of the car has a spring device for
-locking it in any position.
-
-The 1908 model No. 1 of this air ship was constructed for the purpose
-of selling it to the government. Among other requirements is a 12-hour
-flight without landing, and a sufficient speed to maneuver against a
-22-mile wind. A third and larger air ship of this type is now under
-construction.
-
-
-                             UNITED STATES
-
-                    _Signal Corps Dirigible No. 1_
-
-Due to the lack of funds, the United States Government has not been
-able to undertake the construction of an air ship sufficiently large
-and powerful to compete with those of European nations. However,
-specifications were sent out last January for an air ship not over 120
-feet long and capable of making 20 miles per hour. Contract was awarded
-to Capt. Thomas S. Baldwin, who delivered an air ship last August to
-the Signal Corps, the description of which follows:
-
-_Gas Bag._—The gas bag is spindle shaped, 96 feet long, maximum
-diameter, 19 feet 6 inches, with a volume of 20,000 cubic feet. A
-ballonet for air is provided inside the gas bag, and has a volume of
-2,800 cubic feet. The material for the gas bag is made of two layers of
-Japanese silk, with a layer of vulcanized rubber between.
-
-_Car._—The car is made of spruce, and is 66 feet long, 2½ feet wide and
-2½ feet high.
-
-_Motor._—The motor is a 20-horse-power water-cooled Curtiss make.
-
-_Propeller._—The propeller is at the front end of the car, and is
-connected to the engine by a steel shaft. It is built of spruce, has
-a diameter of 10 feet, 8 inches, with a pitch of 11 feet, and turns
-at the rate of 450 r. p. m. A fixed vertical surface is provided at
-the rear end of the car to minimize veering, and a horizontal surface
-attached to the vertical rudder at the rear tends to minimize pitching.
-A double horizontal surface controlled by a lever and attached to the
-car in front of the engine, serves to control the vertical motion and
-also to minimize pitching.
-
-The position of the car very near to the gas bag, is one of the
-features of the Government dirigible. This reduces the length and
-consequently the resistance of the suspension, and places the propeller
-thrust near the center of resistance.
-
-The total lifting power of the air ship is 1,350 pounds of which
-500 pounds are available for passengers, ballast, fuel, etc. At its
-official trials a speed of 19.61 miles per hour was attained over a
-measured course and an endurance run lasting two hours, during which
-seventy per cent of the maximum speed was maintained.
-
-_Dirigible No. 1_, as this air ship has been named, has already served
-a very important purpose in initiating officers of the Signal Corps
-in the construction and operation of a dirigible balloon. With the
-experience now acquired, the United States Government is in a position
-to proceed with the construction and operation of an air ship worthy of
-comparison with any now in existence, but any efforts in this direction
-must await the action of Congress in providing the necessary funds.
-
-
-
-
-                              APPENDIX IV
-
-        THE RELATIONS OF WEIGHT, SPEED AND POWER OF FLYERS[82]
-
-                    _By Wilbur and Orville Wright_
-
-
-The flyer of 1903 carried a four-cylinder gasoline motor of four-inch
-bore and four-inch stroke. Complete with magneto, radiators, tanks,
-water, fuel, etc., the motor weighed a little over 200 pounds, and at
-1,200 revolutions per minute developed 16 horse power for the first 15
-seconds after starting. After a minute or two the power did not exceed
-13 or 14 horse power. At 1,020 revolutions per minute—the speed of the
-motor in the flights at Kitty Hawk on the 17th of December, 1903—it
-developed about 12 horse power.
-
-The flyer of 1904 was equipped with a motor similar to the first, but
-of 1/8-inch larger bore. This engine at 1,500 revolutions per minute
-developed 24 horse power for the first 15 seconds, but only 16 to 17
-horse power after a few minutes run. Complete with water, fuel and
-other accessories, it weighed 240 pounds.
-
-The same engine with a few modifications in the oiling device and the
-carburetor, was used in all the flights of 1905. A test of its power
-made soon after the flights of October, 1905, revealed a gain of 3
-horse power over tests made just before mounting it on the flyer
-in 1904. This gain is attributed to the increased smoothness of the
-cylinders and pistons produced by wear. The small output of these
-engines was due to lack of experience in building gasoline motors.
-
-During the past year further improvements have been made, and our
-latest engines of four-inch bore and four-inch stroke produce about 25
-horse power continuously. The improvement in the reliability of the
-motor has been even more marked, so that now flights of long distances
-can be attempted without danger of failure on account of the stopping
-of the motor.
-
-A comparison of the flyers of 1903, 1904 and 1905 show some interesting
-facts. The flyer of 1903 weighed, complete with operator, 745 pounds.
-Its longest flight was of 59 seconds duration, with a speed of 30 miles
-an hour and an expenditure of 12 horse power. The flyer of 1904 weighed
-about 900 pounds, including a load of 70 pounds in iron bars. A speed
-of more than 34 miles an hour was maintained for a distance of three
-miles with an expenditure of 17 horse power. The flyer of 1905 weighed,
-including load, 925 pounds. With an expenditure of 19 to 20 horse power
-it traveled over 24 miles at a speed of more than 38 miles an hour. The
-flights of 1904 and 1905 would have been slightly faster had they been
-made in a straight line, as were those of 1903.
-
-In 1903, 62 pounds per horse power were carried at a speed of 30 miles
-an hour; in 1904, 53 pounds, at 34 miles an hour; and in 1905, 46
-pounds at 38 miles an hour. It will be noted that the weight carried
-per horse power is almost exactly in inverse ratio to the speed, as
-theory demands—the higher the speed, the smaller the weight carried per
-horse power.
-
-Since flyers can be built with approximately the same dynamic
-efficiency for all speeds up to 60 miles an hour, a flyer designed to
-carry a total weight of 745 pounds at 20 miles an hour would require
-only 8 horse power or two thirds of the power necessary for 30 miles an
-hour. At 60 miles 24 horse power would be necessary—twice that required
-to carry the same weight at 30 miles an hour. At 120 miles an hour 60
-to 75 horse power would probably be necessary, and the weight carried
-per horse power would be only 10 or 12 pounds. At such high speed
-the resistance of the operator’s body and the engine is a formidable
-factor, consuming 64 times as much horse power as at 30 miles an hour.
-At speeds below 60 miles an hour this resistance is almost negligible.
-
-It is evident that the limits of speed have not as yet been closely
-approached in the flyers already built, and that in the matter of
-distance, the possibilities are even more encouraging. Even in the
-existing state of the art it is easy to design a practical and durable
-flyer that will carry an operator and supplies of fuel for a flight of
-over 500 miles at a speed of 50 miles an hour.
-
-
-
-
-                              APPENDIX V
-
-          CURTISS’S EXPERIMENTS IN RISING FROM THE WATER[83]
-
-
-During the past two years Glenn H. Curtiss, who, more than any other
-experimenter, has been given to developing the aëroplane for various
-uses, has experimented with floats for his biplane that would enable
-it to rise from the surface of the water. Something over a year ago he
-succeeded in developing a speed of about twenty miles an hour on the
-water, but this was insufficient to rise from the surface.
-
-At the beginning of the new year Mr. Curtiss moved to the Pacific Coast
-and set about endeavoring to develop suitable floats which would make
-it possible for his machine to rise from the surface of the water.
-These experiments have been carried on at San Diego, where Mr. Curtiss
-is instructing several naval and military officers in the art of flying.
-
-In his first experiments on the Pacific Coast Mr. Curtiss followed
-the successful experiments of this sort made by M. Henri Fabre at
-Marseilles, France, about a year ago, as far as the design of his
-floats was concerned. He constructed one large float six feet wide,
-five feet from front to rear, and one foot thick at its central point,
-and placed this under the center of the machine. The bottom of this
-float was perfectly flat and arranged at an incline of ten or twelve
-degrees. Some distance forward of the main float, at about the position
-of the front wheel in the land machine, another float six feet wide,
-by one foot from front to rear, and six inches deep, was placed; while
-at the extreme front end of the machine, on a special outrigger, was
-mounted a small elevating hydroplane six feet wide by eight inches
-in a fore-and-aft direction, and one and one-half inches thick. This
-hydroplane was fixed at an angle of about twenty-five degrees and was
-intended to lift the front part of the machine. A spray shield was
-fitted back of it, as shown in the diagram, page 333.
-
-The first experiments were made with these new floats on January 26th
-last; and although they made a considerable disturbance in the water,
-especially at low speed, the aviator was enabled to get up a speed on
-the surface of about forty-five miles an hour. He found that at as low
-a rate as ten miles the hydroplanes (which normally were submerged)
-rose to the surface, while as the speed increased only the rear edges
-of the two main planes were required to support the machine. The
-aëroplane readily attained sufficient speed to rise in the air, for
-as the speed increased and the floats emerged from the water, the
-head resistance of the floats diminished and there was only the skin
-friction of the water on a few inches of the rear edge of these floats,
-plus the air resistance, to be overcome.
-
-At the first try-out, while traveling over the water at high speed,
-Mr. Curtiss found himself suddenly nearing the shore, and to avoid
-running aground he turned his horizontal rudder sharply upward, with
-the result that the machine rose from the water with perfect ease.
-He soon alighted again, and in the second flight he made a circle
-and remained in the air a minute and twenty-one seconds. Two other
-experimental flights were made the first day, and on January 27th he
-made a three-and-one-half-minute flight and stated, upon alighting,
-that he found no difficulty in remaining aloft as long as he pleased.
-The machine showed a speed of fifty miles an hour in the air as against
-forty-five miles an hour when skimming over the surface of the water.
-
-PLATE XXXII.
-
-[Illustration: CURTISS STARTING FROM THE WATER.]
-
-[Illustration: CURTISS BIPLANE FOR LAND AND WATER.]
-
-[Illustration: CURTISS TRIPLANE RISEN FROM THE WATER.]
-
-Not satisfied with the several floats with which he had attained
-his first success in rising from the water, Mr. Curtiss immediately
-constructed a single float twelve feet long by two feet in width
-and twelve inches deep. This float is built of wood and resembles a
-flat-bottomed boat or scow, the top being covered with canvas to keep
-the water from getting in. Three feet from the front end the bottom
-is curved upward forming a bow the full width of the float, while at
-the same distance from the rear the float slants downward in a similar
-manner.
-
-This single float is placed under the aëroplane in such a position that
-the main weight of the machine and aviator is slightly to the rear of
-the center of the float, which causes the latter to incline upward
-slightly and thus gives the necessary angle for hydroplaning on the
-surface of the water. The weight of this new float is but fifty pounds,
-or less than half as much as that of the two floats that were used
-before.
-
-The paint was barely dry on the new float before Mr. Curtiss had it
-fitted to his machine and gave it a trial. This was done on February
-1st and the trial was thoroughly successful. The machine ran over the
-surface of the water with very much less disturbance than before and
-rose in the air readily. A glance at the photographs showing the new
-and the old floats in action will give one an excellent idea of the
-much less commotion caused by the single scow-shaped float. Besides
-being much more compact and creating less disturbance, this float or
-scow can be used for carrying articles or a passenger.
-
-In order to keep the aëroplane from tilting to one side or the other,
-an inclined stick four feet long and three inches wide, to which is
-attached on its upper side an inflated rubber tube, is fastened to the
-front edge of the lower plane at each end. By the use of these props
-the aëroplane does not tip readily when skimming along the surface,
-even though the scow-shaped float used is but two feet in width.
-
-After meeting with success with his new float, Mr. Curtiss, on February
-17th, made more flights with the motor and propeller placed at the
-front of his biplane and with his seat placed at the rear of the main
-planes. The chief of these flights was one which he made from North
-Island, where he is experimenting, over San Diego harbor to the cruiser
-_Pennsylvania_. He alighted upon the surface close beside the cruiser
-and his aëroplane was hauled up beside the warship and placed on her
-deck.
-
-After a short visit on the cruiser the aviator was again lowered to the
-surface in his machine. A sailor started the engine, and Mr. Curtiss
-flew back to his starting point in short order. The naval authorities
-were greatly pleased with his demonstration and it is probable that the
-Navy Department will purchase one of these machines in the near future
-and continue the instruction of its officers.
-
-After increasing the surface of his biplane Mr. Curtiss, on February
-24th, took up one of his naval pupils, Lieutenant T. G. Ellyson, as
-a passenger. He made a flight of one and one-half miles, rising to a
-height of one hundred feet and flying as slowly as twenty-five miles an
-hour, or as fast as fifty miles an hour, at will. Lieutenant Ellyson
-was seated on the pontoon below the aëroplane. He could look down
-in the water and see bottom at a depth of twenty-five feet, and he
-believes submarines can be easily located by flying over the water.
-The slow speed at which it is possible to fly will make the biplane
-especially useful for bomb dropping. As we go to press Mr. Curtiss is
-about to try his machine fitted with wheels and floats as well.
-
-
-
-
-                                 INDEX
-
-
-    Abbe, Cleveland, 200, 437.
-
-    Acosta, 10.
-
-    Ader, C. F., 222-226.
-
-    Aërial Experiment Association, 264-267, 305.
-
-    Aëro Club of America, 243, 244, 322, 323.
-      of France, 106, 256, 258, 259, 301.
-      of Great Britain, 287.
-
-    Aëro Corporation Limited, 322.
-
-    Aërodrome, 111, 194, 240, 292.
-
-    Aëronat, 126.
-
-    Aëronautic meteorology, 347 _et seq._
-
-    Aëronautic Society of New York, 284.
-
-    _Aëronautical Annual_, 215, 227, 427.
-
-    _Aëronautics_, 252.
-
-    _Aërophile_, 130, 166, 340.
-
-    Aëroplanes, Ader’s, 222-226.
-      advances in, in 1909, 283, 284.
-      Aërial Experiment Association’s, 264-267.
-      _Antoinette_, 288, 289, 320, 324.
-      Blériot’s, 267-270, 286, 287, 290-292, 299, 300, 309.
-      Bréguet’s, 313.
-      Chanute and Herring’s, 218-221.
-      Cody’s, 305.
-      competitive flying of, 283 _et seq._
-      cost of, 342.
-      Curtiss’, 264-266, 284-286, 294-300, 316, 317, 322, 333.
-      Delagrange’s flights with, 261-263.
-      _Demoiselle_, 324.
-      Deperdussin’s, 399.
-      earliest public flight of, 257.
-      Esnault-Pélterie’s, 304, 314, 337.
-      Etrich’s, 335, 336.
-      Fabre’s, 332, 335.
-      Farman’s, Henri, 259-264, 298, 303, 305, 321.
-      Farman’s, Maurice, 305, 311.
-      first tour in, 268-270.
-      first town-to-town flight in, 264.
-      Grade’s, 304.
-      Hanriot’s, 339.
-      Herring’s compressed air, 221, 222.
-      impossibility of, 12.
-      Langley’s, 239-243.
-      launching of, 202.
-      Le Bris’, 203-205.
-      Lilienthal’s, 207-209.
-      Mattullath’s, 235-239.
-      Maxim’s, 226-228.
-      model, 173 _et seq._
-      Montgomery’s, 251-255, 282.
-      Mouillard’s, 207-209.
-      Nieuport’s, 339.
-      nineteenth century, 202 _et seq._
-      Paulhan’s, 324, 325.
-      Pilcher’s, 216-218.
-      public flying, 256 _et seq._
-      reliability of, 341.
-      Santos-Dumont’s, 256-258, 303, 324.
-      stability of, 232-234.
-      stable and powerful, 235 _et seq._
-      Tellier’s, 312.
-      utility of, 341.
-      Voisin’s, 259, 267, 313.
-      Wright brothers’, 245-249, 270-282, 309, 324, 326, 329.
-      Zahm’s system of control of, 229-231.
-
-    Aërostal, 22.
-
-    Æschylus, 29.
-
-    Agobard, 22.
-
-    Ailerons, 286.
-
-    Air bag, 83.
-
-    Air friction, 238, 239.
-
-    Airscout, 11, 12.
-
-    Allen, Gen. James, 271.
-
-    Alps, Chavez’s flight across, 318, 319.
-
-    Altitude records, 307-309.
-
-    _American Engineer and Railway Journal_, 229.
-
-    American military dirigible, 138.
-
-    _Antoinette_ monoplane, 288, 289, 309, 320, 324, 340.
-
-    Archdeacon, Ernest, 256.
-
-    Archibald, Douglass, 77.
-
-    Archytas of Tarentum, 198.
-
-    Arlandes, Marquis de, 38-42.
-
-    Ascending trend of wind, 211.
-
-    Assman, Professor, 72.
-
-    Astra Society, 120, 123, 124.
-
-    Atmosphere, composition of, 348-350.
-      cyclones, tornadoes, waterspouts, 394 _et seq._
-      general circulation of, 376-380.
-      general properties of, 347 _et seq._
-      permanent and periodic winds, 376 _et seq._
-      temperature and pressure, 363 _et seq._
-      thunderstorms, windgusts, 422 _et seq._
-
-    Aubrun, Emile, 331.
-
-    Audemars, 324.
-
-    Automobile Club of France, 321.
-
-
-    Bacon, Roger, 20.
-
-    Balance, complete dynamical, 234.
-
-    Baldwin, F. W., 264, 266.
-      Thomas S., 138.
-
-    Ballonets, 95.
-
-    _Ballons sondes_, 72.
-
-    Balloon, dirigible:
-        Baumgarten and Wölfert’s, 99.
-        _Belgique_, 129.
-        Blanchard’s, 79, 80.
-        British and American, 130, 131.
-        _Clément-Bayard I_, 123.
-        _Clément-Bayard II_, 131, 132, 133.
-        combined with aëroplane, 123.
-        _Colonel Renard_, 124, 126.
-        development of rigid, 145 _et seq._
-        Dupuy de Lome’s, 19, 92, 93.
-        early experiments with Zeppelin, 147-150.
-        early gasoline driven, 10 _et seq._
-        electric, 92-97.
-        _España_, 124, 126, 127.
-        first designs for, 78-86.
-        general design of _Zeppelin_, 146, 147.
-        German aërial fleet, 141, 142.
-        German nonrigid, 138.
-        Giffard’s, 90, 91, 98.
-        Gross type of, 138, 139, 140, 471-473.
-        Hänlein’s, 98.
-        Hopkinson’s suggestion for, 84.
-        Italian, 130.
-        _Jaune_, 115, 116.
-        Jefferson’s suggestion for, 84.
-        Jullien’s model, 88.
-        _Lebaudy_, 116, 117.
-        Lebaudy’s, 115-120, 134-137.
-        _Liberté_, 120.
-        maneuvers at Cologne, 143, 144.
-        Meusnier’s designs for, 85, 86.
-        Miolan and Janinet’s, 81.
-        _Morning Post_, 134.
-        muscular driven, 80, 82, 85, 92.
-        Parseval type of, 138, 139, 140-143, 473-476.
-        _Patrie_, 115, 118, 119.
-        Porter’s, 86, 87.
-        practical development of nonrigid, 115 _et seq._
-        practical speed of, 101.
-        Renard and Krebs’, 93-97.
-        _Republique_, 115, 118, 119, 466.
-        Robert’s, 81, 82, 83.
-        _Russie_, 120.
-        Santos-Dumont’s, 102-114.
-        Schwartz’s, 99, 100.
-        steam, 87, 89.
-        successful military, 456.
-        two systems of, 101.
-        types of, 122.
-        _U. S. Military I_, 138, 476, 477.
-        _Ville de Nancy_, 124, 125.
-        _Ville de Paris_, 120-123, 467-471.
-        voyage of across English channel, 132, 136, 137.
-          in _Zeppelin_, 153-156.
-        _Zeppelin IV_, explosion, 157, 158.
-        _Zeppelin_ passenger service, 167-169.
-        _Zeppelin_ type of, 145-169.
-        _Zodiac_ type of, 127, 128, 129.
-      passive:
-        cabinet for lofty ascents in, 71, 72.
-        Charles’ passenger, 42, 43.
-        cruise of, from London to Weilburg, 54.
-        dragon fire-inflated, 20.
-        earliest conceptions of, 18, 29.
-        earliest experiments with, 30, 31, 32.
-        early history of, 29 _et seq._
-        first coal gas, 54.
-        first human passengers in, 38.
-        first hydrogen, 35.
-        first passengers in, 37.
-        first scientific ascension in, 44, 45.
-        Glashier’s observations in, 64-70.
-        highest ascent of, 69, 70, 71, 72.
-        instruments and adjuncts to, 76, 77.
-        largest hot air, 48-50.
-        largest gas, 70, 71.
-        longest voyage of, 74.
-        modern spherical, 75.
-        Nadar’s _Geant_, 60, 61.
-        practical development of, 54 _et seq_.
-        principle of, 18.
-        public inauguration of, 33, 34.
-        recent improvements in, 76, 77.
-        ripping panel of, 74, 75.
-        sounding and pilot, 72.
-        voyage across the Atlantic in, 74, 75.
-          across the English channel in, 50, 52.
-          Paris to Meaux in, 61, 62.
-          Paris to Nienburg in, 62, 63.
-
-    Balsan, 74.
-
-    Baltimore aviation meet, 319.
-
-    _Baltimore Sun_, 319.
-
-    Barometric pressure, 363 _et seq._
-      distribution of, 370-374.
-      gradient of, 370.
-      high and low areas of, 372.
-      hygrometric features of, 373.
-      mechanical features of, 373, 374.
-      modifying conditions of, 371, 373.
-      surfaces and lines of equal, 370, 371.
-
-    Basenach, 138.
-
-    Baumgarten, 99.
-
-    _Belgique_, the, 129.
-
-    Bell, A. G., 194, 244, 264-267.
-
-    Bell, Mrs. A. G., 264.
-
-    Belmont Park, 310, 322.
-
-    Bennett international contests, 75, 292-301, 325, 326.
-
-    Berson, Professor, 70.
-
-    Betheny Plain, 292.
-
-    Bielovucic, Jean, 313.
-
-    Bigelow, Professor, 412, 413.
-
-    Biplane, 174, 220.
-
-    Birds, armed against airships, 11.
-      as men carriers, 10, 11, 12.
-      major limit of, 11, 12.
-
-    Bishop, Cortlandt Field, 285.
-
-    Black, 29.
-
-    Blanchard, 15, 16, 18, 50, 79, 80.
-
-    Blériot, Louis, 267-270, 286, 287, 290-292, 299-300, 380-382.
-
-    Bréguet, Louis, 313.
-
-    Brookins, Walter, 309, 326.
-
-    Brown, D. S., 193.
-
-    Bubbles, soap and varnish, 30.
-
-
-    Calm belts, 381.
-
-    Cammerman, Lieutenant, 314.
-
-    Cardan, 10.
-
-    Catapult, 240, 338.
-
-    Cavallo, 30, 31.
-
-    Cavendish, 29.
-
-    Cayley, Sir George, 181, 182.
-
-    Chanute, Octave, 15, 181, 218-221, 245, 250, 256, 260.
-
-    Charles, 35.
-
-    _Charlière_, 42.
-
-    _Chauvière_, 125, 136, 331, 339.
-
-    Chavez, George, 318, 319.
-
-    _Circuit de l’Est_, 339, 331.
-
-    _Clément-Bayard_, the, 123, 131-133, 456-459.
-
-    Cody, S. F., 305.
-
-    _Colonel Renard_, the, 124, 126.
-
-    _Compagnie General Transaerienne_, 124.
-
-    Control, three rudder system of, 229-331.
-
-    Coulomb, 17, 18.
-
-    _Country Life_, 321.
-
-    Coxwell, 64-70.
-
-    Critical temperature and pressure, 351.
-
-    Cross-country records, 311-314.
-
-    Curtiss, Glenn H., 138, 264-266, 282, 284-286, 294-300, 316, 317,
-            322, 323, 481 _et seq._
-
-    Cyclone, frequency of, 403, 404.
-      motions and pressures in, 395, 400.
-      motive power of, 395.
-      nature of, 394.
-      progression of, 401-403.
-      stationary, 403.
-
-
-    Daedalus, 3, 4, 5, 6.
-
-    _Daily Mail_, London, 314.
-
-    Daimler engine, 99, 150.
-
-    Dante, J. B., 13, 14.
-
-    Dauberck, Dr. W., 403.
-
-    Da Vinci, 8, 9.
-
-    De Bacqueville, 13, 14.
-
-    Delagrange, Leon, 261-263.
-
-    Delcourt, Dupuis, 100.
-
-    De Laland, 16, 18.
-
-    De Lesseps, Count, 327, 328.
-
-    De Lome, Dupuis, 91, 92, 93.
-
-    _Demoiselle_ monoplanes, 324.
-
-    Déperdussin, 339.
-
-    Deutsche de la Meurthe, 120 259.
-
-    Dew point, 358.
-
-    Dientsbach, Carl, vii, 164.
-
-    Distance records, 311-314.
-
-    Doldrums, 381.
-
-    Doubleday, Page & Co., 478.
-
-    Drift, defined, 186.
-
-    Dubonnet, 312.
-
-    Du Cros, Arthur, 131.
-
-    Dutrieu, Helene, 321.
-
-    Dynamic flyers, 174.
-
-
-    Endurance records, 311-314.
-
-    Engine, Daimler, 99, 150, 163.
-      Gnome, 312.
-      Körting, 139.
-      Mercedes, 140.
-      Panhard-Levassor, 136.
-      Rénault, 311.
-      Vivinus, 129.
-
-    _Engineering News_, 435.
-
-    English Channel flights, 50-53, 56, 137, 289-292.
-
-    English military dirigibles, 130-137.
-
-    _Eole_, 223.
-
-    Equator of balloon, 76.
-
-    Equilibrium, of angels, 7, 8.
-
-    Esnault-Pélterie, Robert, 304, 314, 337, 340.
-
-    _España_, the, 124, 126, 127.
-
-    Espy, 419, 420.
-
-    Etrich, Igo, 335, 336.
-
-
-    Fabre, 332-335.
-
-    Farman, Henri, 259-264, 298, 303, 305, 321.
-      Maurice, 305, 311.
-
-    Federation Aëronautique International, 322, 323.
-
-    Fequant, Lieutenant, 312.
-
-    Ferber, Captain, 256.
-
-    Ferrel, W., 356, 376-379, 397, 413, 436.
-
-    Fin, 229.
-
-    _Flesselle_, the, 48, 49, 50.
-
-    Flexible balloons, 122, 123.
-
-    Fluctuating winds, 427-439.
-      cause of, 436-438.
-      impact of, 435, 436.
-
-    Flying machine, impossibility of, 12, 17.
-
-    Flying machine models, 173 _et seq._
-      Abbe’s proposed, 200.
-      Cayley’s aërial glider, 181, 182.
-      Da Vinci’s helicopter, 175.
-      Da Vinci’s parachute, 177, 178.
-      Forlanini’s helicopter, 200.
-      Garnerin’s parachute, 179.
-      Hargrave’s, 190, 191.
-      Helicopter, 198-201.
-      Henson’s aëroplane, 182-184.
-      Henson and Stringfellow’s, 184, 185, 187.
-      Langley’s, 192-197.
-      Launoy and Bienvenu’s, 198, 199.
-      Lenormand’s parachute, 177, 178.
-      Paper traveling parachutes, 180, 181.
-      Penaud’s toy, 188.
-      Phillips’ aëroplane, 191, 192.
-      Phillips’ helicopter, 199.
-      Tatin’s aëroplane, 189.
-      Veranzio’s parachute, 177, 178.
-      Wenham’s aëroplane, 185, 186.
-      Zanonia Macrocarpa, 180.
-
-    Forbes, A. Holland, 6.
-
-    Forlanini, Professor, 200.
-
-    Fort Myer flights, 138, 272, 275-281.
-
-    Foulois, Lieutenant Benjamin, 278.
-
-    _France_, the, 93-97.
-
-    Franklin, Benjamin, 48, 446.
-
-    Free air, composition of, 349.
-      conditions of precipitation in, 351, 352.
-      critical points of constituents of, 351.
-      dynamical properties of dry, 353, 356.
-      friction of, 239.
-      humidity and density of, 358-361.
-      kinds of expansion of, 361, 362.
-      properties of moist, 357, 361.
-
-    French Academy, 17, 35.
-
-    French dirigibles, 88-129.
-
-
-    Garnerin, Jacques, 179.
-
-    Garros, 324.
-
-    Gasnier, Réné, 340.
-
-    German Airship Society, 166, 167.
-
-    German dirigibles, 138-169.
-
-    Giffard, Henri, 71, 88, 89, 90, 91.
-
-    Glaisher, James, 68-70.
-
-    Gliding machines, 203-221, 245-248.
-
-    Gnome engine, 312, 331, 340.
-
-    Godard, 62, 74, 129.
-
-    Gold-beater skin balloons, 30, 88.
-
-    Grade, 314.
-
-    Grahame-White, Claude, 315, 316, 319, 325, 327, 328.
-
-    Gravitational stability, 233.
-
-    Green, Charles, 54.
-
-    Gross, Major von, 138.
-
-    Gross dirigibles, 138, 139, 140.
-
-    Guide rope, or drag rope, 56, 76, 111, 114.
-
-
-    Hailstorms and hailstones, 415-419.
-
-    Hamilton, C. K., 313.
-
-    Hammer, W. J., vii.
-
-    Hangar, 126.
-
-    Hänlein, 98, 99.
-
-    Hann, 365.
-
-    Hanriot, 339.
-
-    Hargrave, Lawrence, 190, 191, 250, 260, 339.
-
-    Harmon, Clifford B., 321.
-
-    Hawley, A. R., 75.
-
-    Hazen, Prof. H. A., 435.
-
-    Hearne, 131, 228.
-
-    Helicopters, 198-201.
-
-    Helmholtz, Prof. Ludvig von, 436-438.
-
-    Henson, 182-184.
-
-    Herring, A. M., 218-222, 245, 271.
-
-    Holland, Robert, 54.
-
-    Hopkinson, Francis, 84.
-
-    Horner, 414.
-
-    Hoxsey, Arch, 309, 324.
-
-    Huffaker, E. C., 247.
-
-    Hull, best forms of, 88, 97, 98, 113.
-      stiffening of, by internal pressure, 83, 86.
-
-    Humidity, absolute, 359.
-      percentage of, 358.
-
-    Humphreys, Dr. W. J., vii, 349, 370.
-
-    Hydro-aëroplanes, 332-334, 481 _et seq._
-
-    Hydrogen balloon, invention of, 29-31, 35.
-      first ascent of, 36.
-
-    Hydrogen bubbles, 29.
-
-
-    Icarus, 3, 4, 5.
-
-    Ice, launching from, 265.
-
-    Indian seed parachute, 180.
-
-    Inherent stability, 229.
-
-    Insolation, effect on density of air, 364.
-      quantity of, received, 364-366.
-
-    Isobaric lines and surfaces, 371.
-
-    Isothermal lines, surfaces, 366, 367.
-
-    Isothermal layer, 370.
-
-    Italian Aviation Society, 318.
-
-    Italian military dirigibles, 130.
-
-
-    _Jaune_, the, 115, 116.
-
-    Jefferson, Thomas, 84.
-
-    Jeffries, 50.
-
-    Johnstone, Ralph, 309, 324, 329.
-
-    Jullien, 88.
-
-    Julliot, Henri, 115, 134, 136.
-
-    _June Bug_, the, 266, 267.
-
-
-    Kai Kaoos, 8, 9, 10.
-
-    Kapferer, H., 120, 294.
-
-    Keel surface, 120.
-
-    Kinet, Daniel, 312.
-
-    Kinetic stability, 233.
-
-    Kite balloon, 77.
-
-    Körting, 139.
-
-    Krebs, Captain, 93-97.
-
-    Kress, Wilhelm, 214.
-
-
-    _La Belgique_, 129.
-
-    _La España_, 124, 126, 127.
-
-    _La Flesselle_, 48, 49, 50.
-
-    _La France_, 93-97.
-
-    Lahm, Lieutenant Frank P., 272, 277.
-
-    _La Liberté_, 120.
-
-    Lambert, Count de, 273, 302.
-
-    Lana, 23, 24.
-
-    _La Nature_, 312.
-
-    Land-and-sea breezes, 392.
-
-    Landelle, G. de la, 203.
-
-    Langley, S. P., 187, 192-197, 211, 231, 232, 239-245, 251, 427,
-            433, 434, 439.
-
-    _La Patrie_, 115, 118, 119, 459-465.
-
-    _La République_, 115, 118, 119.
-
-    _La Russie_, 120.
-
-    Latent heat of condensation, 364.
-
-    Lateral balance of aëroplane, 229-231.
-
-    Latham, Hubert, 283, 288-290, 291, 319, 320, 324.
-
-    Launching an aëroplane, 202, 230, 256, 258, 259, 265.
-
-    Launching methods, 202, 240, 258, 259, 265.
-
-    Launoy and Bienvenu, 198, 199.
-
-    Laurens, 314.
-
-    _La Ville de Paris_, 120-123.
-
-    _Lebaudy_, the, 116, 117.
-
-    Le Blanc, Alfred, 273, 290, 310, 313, 326, 331.
-
-    _Le Clément-Bayard_, 123, 131-133, 456-459.
-
-    _Le Colonel Renard_, 124, 126.
-
-    Lefebvre, 293.
-
-    Leganeaux, U. G., 311, 319.
-
-    Lenormand, Sebastien, 177, 178.
-
-    Levino, A. S., vii.
-
-    Lift, defined, 186.
-
-    Lilienthal, Otto, 210-216, 250.
-
-    _London Daily Mail_, 289.
-
-    Loomis, 402, 414.
-
-    Lord Rayleigh, 6, 427.
-
-
-    McCurdy, J. A. D., 264.
-
-    MacMechen, 164.
-
-    Madison, James, 84.
-
-    Malecot, 123.
-
-    Maloney, D., 251-255.
-
-    Manley, Charles M., 242, 245, 251, 285.
-
-    Marconnet, Captain, 312.
-
-    Marey, Professor, 427.
-
-    Marvin, Prof. C. F., 435.
-
-    Mason, Monck, 55.
-
-    Mattullath, Hugo, 231, 235-239.
-
-    Maxim, Sir Hiram S., 226-228, 245.
-
-    Mendoza, 19.
-
-    Mercedes, 140.
-
-    _Meteorological Journal_, 435.
-
-    Meusnier, General, 85, 86.
-
-    Michelin prize, 273, 303, 311, 314, 321.
-
-    Milton, 7.
-
-    Moisant, John, 31, 328.
-
-    Monaco, Prince of, 111.
-
-    Monge, Marey, 100.
-
-    Monoplane, 174.
-
-    Monsoons, 385-391.
-
-    Montgolfier, 29, 37, 50.
-
-    _Montgolfière_, 42.
-
-    Montgomery, Prof. J. J., 251-255, 282, 339.
-
-    Moore, Willis L., 349, 405, 422.
-
-    Morane, 310.
-
-    _Morning Post_, 131, 134-137.
-
-    Motors, 340.
-      Antoinette, 254, 258.
-      Clément-Bayard, 458.
-      Daimler, 99, 150, 163.
-      Electrical, 92, 95.
-      Gnome, 312.
-      Körting, 139.
-      Mercedes, 140.
-      Panhard-Levassor, 136.
-      Rénault, 311.
-      steam, 228, 234.
-      Vivinus, 129.
-
-    Mouillard, L. P., 206-209.
-
-    Mountain-and-valley winds, 293.
-
-    Munn & Co., 481.
-
-    Muscular flight, 3-7.
-
-
-    Nadar’s balloon, the _Geant_, 60.
-
-    _Nassau, Great Balloon of_, 55.
-
-    _Nature_, 217, 427.
-
-    Nieuport, 339.
-
-    Northcliffe, Lord, 305.
-
-
-    Olieslaegers, Jan, 311.
-
-    Orthopters, 174.
-
-    Ovid, 3.
-
-
-    Panhard-Levassor, 136.
-
-    Parachutes, 176-81.
-
-    Parseval dirigibles, 138, 140-143.
-
-    Parseval, Major von, 77, 138.
-
-    Passive fliers, 174.
-
-    _Patrie_, the, 115, 118, 119, 459-465.
-
-    Paulhan, Louis, 284, 293-296, 305, 311, 315, 316, 317, 324, 325.
-
-    Peltier, H., 456.
-
-    Pénaud, A., 188.
-
-    Pendular stability, 233.
-
-    _Philadelphia Ledger_, the, 313.
-
-    Phillips, Horatio, 191, 192, 199.
-
-    Picardie military maneuvers, 131.
-
-    Pilcher, 216-218, 246.
-
-    Polignac, Marquis de, 301.
-
-    Porter, Rufus, 86, 87.
-
-    Post, Augustus, 6, 75.
-
-    Power expended in flight, 6, 7.
-
-    Power flyers, 174.
-
-    Pressure, critical, 351.
-      atmospheric, 370-374.
-
-    _Preussen_, the, 70.
-
-    Projectile stability, 232.
-
-    Propeller, Chauvière, 125, 136.
-
-    Puy de Dome, 314.
-
-    Pylons, 292.
-
-
-    Rayleigh, Lord, 6, 427.
-
-    Records, aëroplane,
-      altitude, 307-309.
-      cross-country, 311-314.
-      distance, 311.
-      duration, 311-314.
-      load, 311-314.
-      speed, 310-311.
-
-    _Red Wing_, 265, 266.
-
-    Relative humidity, 358.
-
-    Renard, Captain, 93-97, 210.
-
-    _République_, the, 115, 118, 119.
-
-    Reye, Dr., 414.
-
-    Rheims aviation contests, 292-301.
-
-    Riedinger, August, 140.
-
-    Rigid balloons, 122.
-
-    Robert, 42, 45, 81, 82, 83.
-
-    Roc, 11.
-
-    Rolls, Hon. C. S., 321.
-
-    Romain, 52.
-
-    Rotch, A. Lawrence, 380-382.
-
-    Rougier, 302.
-
-    Rozier, Pilâtre de, 38, 52.
-
-    Rudders, aëroplane, 245, 246.
-      three-torque, 229-231, 247, 248.
-
-    Ruskin, John, 7.
-
-    _Russie_, the, 120.
-
-    Ryan, Allan A., 327.
-      Thomas F., 327.
-
-
-    Sabathier, 131, 132.
-
-    Saddle bird, 8.
-
-    Saint-Marcq, Com. Le Clément, 438.
-
-    Sandt, Emile, 153.
-
-    Santos-Dumont, Alberto, 102-114, 303, 324, 356-359.
-
-    Saturation, 358.
-
-    Scaliger, 10.
-
-    Schottus, 19.
-
-    Schwartz, 99, 100.
-
-    _Scientific American_, 86, 153, 443, 481.
-
-    Screw, da Vinci’s, 176.
-      metal, 340.
-      radial-arm, 129, 242, 340.
-      wooden, 339.
-
-    Selfridge, Lieutenant T., 264, 265.
-
-    _Signal Corps Dirigible No. 1_, 138, 476, 477.
-
-    Signal Corps, U. S., vi, 271, 272, 276-281.
-
-    Signal Service, U. S., 417-419.
-
-    Sigsfeld, Captain von, 77.
-
-    _Silver Dart_, 305.
-
-    Skin-friction, 238, 239.
-
-    Soaring, early attempts at, 13.
-      winds helpful to, 303, 393, 403, 431, 425-459.
-
-    Society for the Study of Motor Air Ships, 138.
-
-    Sommer, Roger, 284, 293.
-
-    Sopwith, Thomas, 314.
-
-    Speed records, 310, 311.
-
-    Spratt, G. A., 247.
-
-    Squier, Major George Owen, 279, 459.
-
-    St. Louis tornado, 412, 413.
-
-    Stabilizing planes, 86.
-
-    Stability and steadiness, artificial, 229-231.
-      automatic, 218, 220, 229.
-      three-axial, 229, 234.
-
-    Statoscope, 76.
-
-    Statue of Liberty Prize, 325.
-
-    Stringfellow, 184, 185, 187.
-
-    Surcouf, 115.
-
-    Süring, Dr., 70.
-
-
-    Tabuteau, Maurice, 311.
-
-    Tasso, 3.
-
-    Tatin, Victor, 189.
-
-    Tellier monoplane, 312.
-
-    Temperature, critical, 351.
-      distribution of, 366-370.
-      gradient, 367.
-      vertical gradient, 367-369.
-
-    Temperature of the air, 363 _et seq._
-
-    Teisserenc de Bort, 380-382.
-
-    _The New York Times_, 313.
-
-    Three-rudder principle, 229-232.
-
-    Thunderstorms, genesis and propagation of, 423, 424.
-      nature of, 422 _et seq._
-
-    Tidswell, Ella, 216.
-
-    Tissandier, Gaston, 273, 283, 293.
-
-    Tornadoes, bursting of, 419-420 _et seq._
-      destructive power of, 409, 410.
-      dry, 420, 421.
-      dynamics of, 406-409.
-      genesis of, 405-406.
-      hail and snow, 415-419.
-      misty, 411 _et seq._
-      nature of, 404.
-      sections of, 409-417.
-
-    Tractional balance, 254.
-
-    Trade-winds and antitrade, 380-383.
-
-    Transatlantic voyages, 74, 75, 381, 383.
-
-    Triplanes, 175.
-
-    Types of flyers, 174.
-      balloons, 122.
-
-
-    United States Signal Corps, vi, 271, 272, 276-281.
-
-    United States War Department, 138, 196, 271, 272, 275-281.
-
-    United States Weather Bureau, iv.
-
-
-    Vacuum balloon, 18, 24, 25, 443-445.
-
-    Van der Born, 312.
-
-    Varnish bubbles, 30.
-
-    Vaulx, Count de la, 74, 127, 129.
-
-    Veranzio, Fauste, 177.
-
-    _Ville de Nancy_, the, 124, 125.
-
-    _Ville de Paris_, the, 120-123.
-
-    Vivinus, 129.
-
-    Voisin, 259, 267, 313.
-
-    Von Bezold, 424.
-
-
-    Waterspouts, analysis of St. Louis, 412, 413.
-      nature of, 411 _et seq._
-
-    Weiller prize, 314.
-
-    Wellman, Walter, 25, 75, 383.
-
-    Wenham, 185, 186, 245.
-
-    Weyman, 314, 331.
-
-    _White Wing_, the, 266.
-
-    Wilkins, 10.
-
-    Winans, Ross, 320.
-
-    Wind gusts, distribution of, 425, 426.
-      energy of, 435, 436.
-      instrumental study of, 427-459.
-      nature of, 425 _et seq._
-      soaring value of, 426, 427, 439.
-      sustaining force of, 426.
-
-    Winds, ascending trend of, 211.
-      cause of periodic, 383.
-      cyclonic, 394 _et seq._
-      diurnal, 392-393.
-      dry whirl, 420, 421.
-      fluctuations of, 427-439.
-      general cause of, 363, 364.
-      kinds of permanent, 380.
-      kinds of periodic, 383.
-      monsoon, 385, 391.
-      nonperiodic, 394 _et seq._
-      nonvortical, 422 _et seq._
-      permanent and periodic, 376 _et seq._
-      prevailing westerlies, 380, 382, 383.
-      trade-winds and antitrade, 380, 381.
-      useful for voyages, 381, 383.
-        in soaring, 303, 393, 403, 421, 425-439.
-
-    Wise, John, 73, 74, 383, 415, 416.
-
-    Wölfert, 99.
-
-    _World_, the New York, 313, 316.
-
-    Wright brothers, 245-251, 270-282, 309, 324, 326, 329, 338, 478.
-
-    Wynmalen, Henri, 321.
-
-
-    Zahm, 30, 97, 113, 221, 229-231, 239, 245, 334, 427-432, 443.
-
-    Zanonia Macrocarpa, 180.
-
-    Zeppelin, Count Ferdinand von, 102.
-
-    Zeppelin Airship Construction Co., 158, 161.
-
-    Zeppelin dirigibles, 145, 169.
-
-    Zodiac balloons, 127, 128, 129.
-
-
-
-
-+----------------------------------------------------------------------+
-|                                                                      |
-|                            FOOTNOTES:                                |
-|                                                                      |
-| [1] With apologies to the California professor who will ride on      |
-|     wings worked by muscular force alone.                            |
-|                                                                      |
-| [2] Mr. A. Holland Forbes and Mr. Augustus Post, in the              |
-|     international balloon race of 1908, used a balloon having too    |
-|     long a neck, thus causing such pressure at its top as to burst   |
-|     the bag. A dreadful plunge ensued, landing them on a house, but  |
-|     without injury, as the netting and collapsed bag dampened their  |
-|     speed of fall. It is reported that they crashed through the      |
-|     skylight, and that the lady of the house regretted not being     |
-|     there to receive them.                                           |
-|                                                                      |
-| [3] _Mechanical Principles of Flight._                               |
-|                                                                      |
-| [4] The reader may like to know that the basis of so much confidence |
-|     was that ancient Euclidean theorem connecting the surfaces and   |
-|     volumes of similar figures with certain powers of their          |
-|     homologous linear dimensions.                                    |
-|                                                                      |
-| [5] The writer has made hydrogen-inflated varnish bubbles a foot     |
-|     in diameter which ascended swiftly to the ceiling; also,         |
-|     air-inflated varnish bubbles a foot and a half in diameter       |
-|     which lasted an hour. These, if suitably heated, may be made     |
-|     to ascend; but this experiment is more difficult.                |
-|                                                                      |
-| [6] Both had studied science in college. Stephen was an              |
-|     accomplished architect; Joseph, the author of many important     |
-|     inventions, among others the common lamp chimney, the            |
-|     hydraulic press, etc.                                            |
-|                                                                      |
-| [7] A long patch on the balloon that can be ripped open for the      |
-|     sudden release of gas.                                           |
-|                                                                      |
-| [8] The equator of such a balloon is its horizontal great circle.    |
-|                                                                      |
-| [9] A similar suggestion was made by Thomas Jefferson in a letter    |
-|     to Prof. James Madison, and dated from Paris in 1785: “I went    |
-|     some time ago to see a machine which offers something new. A     |
-|     man had applied to a light boat a very large screw, the thread   |
-|     of which was a thin plate, two feet broad, applied by its edge   |
-|     spirally around a small axis. It somewhat resembled a bottle     |
-|     brush, if you will suppose the hairs of the bottle brush         |
-|     joining together, and forming a spiral plane. This, turned on    |
-|     its axis in the air, carried the vessel across the Seine. It     |
-|     is, in fact a screw which takes hold of the air and draws        |
-|     itself along by it; losing, indeed, much of its effort by the    |
-|     yielding nature of the body it lays hold of to pull itself on    |
-|     by. I think it may be applied in the water with much greater     |
-|     effect and to very useful purposes. Perhaps it may be used       |
-|     also for the balloon.”                                           |
-|                                                                      |
-| [10] _La Navigation Aerienne_, Gaston Tissandier.                    |
-|                                                                      |
-| [11] The motive power equals the product of the speed and            |
-|     resistance. But in the assumed case, the speed is doubled and    |
-|     the resistance quadrupled; hence, the power required is          |
-|     eightfold.                                                       |
-|                                                                      |
-| [12] Santos-Dumont, _My Airships_.                                   |
-|                                                                      |
-| [13] m^3 signifies cubic meters. One cubic meter equals 35.3166      |
-|     cubic feet.                                                      |
-|                                                                      |
-| [14] Hangar, an airship harbor, or garage.                           |
-|                                                                      |
-| [15] Aëronat, an airship of the lighter-than-air kind.               |
-|                                                                      |
-| [16] Hearne, _Airships in Peace and War_.                            |
-|                                                                      |
-| [17] _Over Sea by Air-Ship_, MacMechen and Dienstbach, _The          |
-|     Century_, May, 1910.                                             |
-|                                                                      |
-| [18] A mathematical argument against this device is presented in     |
-|     Appendix I.                                                      |
-|                                                                      |
-| [19] It is commonly reported by navigators that the albatross        |
-|     “sports in the tempest” on unbeating pinions; but it may be      |
-|     questioned whether any bird can make headway against the         |
-|     swiftest winds.                                                  |
-|                                                                      |
-| [20] The “drift” and “lift” are the components of surface            |
-|     wind-pressure respectively in the direction of flight and at     |
-|     right angles to it.                                              |
-|                                                                      |
-| [21] The tandem monoplane, or two lifting planes arranged in         |
-|     tandem, was invented by D. S. Brown and exhibited to the         |
-|     Aëronautical Society of Great Britain in 1873.                   |
-|                                                                      |
-| [22] This gasoline aëroplane model was previously tested in          |
-|     private many times, both with single surface wings, and with     |
-|     superposed surfaces.                                             |
-|                                                                      |
-| [23] Abbe, _Helicopters for Aërial Research_, _Aëronautics_, Feb.    |
-|     1909.                                                            |
-|                                                                      |
-| [24] _L’Empire de l’Air._                                            |
-|                                                                      |
-| [25] _Progress in Flying Machines_, Chanute.                         |
-|                                                                      |
-| [26] The air rises with increased temperature, hence with            |
-|     increased volume displacement, thus causing the wind in          |
-|     general to have a slightly ascending trend.                      |
-|                                                                      |
-| [27] _Aëronautical Annual, 1897._                                    |
-|                                                                      |
-| [28] Ella Tidswell, _The Aëronautical Journal_, July, 1909.          |
-|                                                                      |
-| [29] W. J. S. Lockyer, _Nature_, August 12, 1897.                    |
-|                                                                      |
-| [30] Wenham used superposed planes, Stringfellow superposed          |
-|     planes trussed by vertical rods and diagonal wires, Phillips,    |
-|     Lilienthal and Hargrave superposed arched surfaces.              |
-|                                                                      |
-| [31] See _Aëronautic Annual_, 1896.                                  |
-|                                                                      |
-| [32] _Aërial Warfare_, Hearne, p. 77.                                |
-|                                                                      |
-| [33] Published by the _American Engineer and Railway Journal._       |
-|                                                                      |
-| [34] This kind of automatic stability may be called inherent         |
-|     stability.                                                       |
-|                                                                      |
-| [35] Models embodying the above devices had been made and flown      |
-|     by the writer some years previously; but aside from these it     |
-|     is obvious that a Phillips’s aëroplane and other kinds can       |
-|     be effectively controlled in flight by the above-proposed        |
-|     three-torque system.                                             |
-|                                                                      |
-| [36] This idea was later materialized in Langley’s gasoline          |
-|     biplane.                                                         |
-|                                                                      |
-| [37] The means for balancing here suggested in italics was           |
-|     claimed some years later in Mr. Hugo Mattullath’s patent         |
-|     application in which the inventor had the assistance of the      |
-|     present writer.                                                  |
-|                                                                      |
-| [38] A nearly equivalent vertical surface was used in Dr.            |
-|     Langley’s large “aërodrome.” It was a wind-vane rudder placed    |
-|     well below and to the rear of the centroid, to be used in        |
-|     turning corners. The pressure on this rudder would tilt the      |
-|     aëroplane toward the center of curvature of the path, and turn   |
-|     it about the vertical axis, but would conspire with the          |
-|     centrifugal force. If placed above and forward, it would give    |
-|     the desired moments, but oppose the centrifugal force.           |
-|                                                                      |
-| [39] He died of apoplexy, January 31, 1902.                          |
-|                                                                      |
-| [40] The first flights were to be made from the water.               |
-|                                                                      |
-| [41] It can be shown that the angle of flight requiring the least    |
-|     motive power is that which makes the wing resistance, or         |
-|     drift, three fourths of the entire resistance to progression.    |
-|                                                                      |
-| [42] _Atmospheric Resistance on Even Surfaces_, by A. F. Zahm,       |
-|     _Phil. Soc. Washington_.                                         |
-|                                                                      |
-| [43] The term “aërodrome” is now commonly applied to an aviation     |
-|     field.                                                           |
-|                                                                      |
-| [44] On August 25, 1909, Louis Paulhan, in the aviation contest      |
-|     at Rheims, flew 82 miles in 2 hours, 43 minutes and 24           |
-|     seconds, preserving his lateral balance without the aid of       |
-|     torsion-wing mechanism and in a turbulent atmosphere.            |
-|                                                                      |
-| [45] _Aërial Locomotion_, A. G. Bell, Washington Academy of          |
-|     Science, March 4, 1907.                                          |
-|                                                                      |
-| [46] The Wrights in 1910 adopted the rear horizontal and vertical    |
-|     rudder, thus returning to the design of their predecessors.      |
-|                                                                      |
-| [47] On July 18, 1905.                                               |
-|                                                                      |
-| [48] These glides were abandoned as too dangerous and roundabout,    |
-|     in favor of direct tentative flights with a motor.               |
-|                                                                      |
-| [49] Falling weights pulling a cord that accelerates the             |
-|     aëroplane at starting.                                           |
-|                                                                      |
-| [50] _Present Status of Military Aëronautics_, _Journal of the       |
-|     American Society of American Engineers_, December, 1908.         |
-|                                                                      |
-| [51] On September 18, 1906, Montgomery received a U. S. patent on    |
-|     an aëroplane having curved wings and three-rudder control, the   |
-|     Wright brothers having on May 22, 1906, received a patent on     |
-|     an aëroplane having normally flat wings and three-rudder         |
-|     control.                                                         |
-|                                                                      |
-| [52] The daring aviator escaped without a scratch, but his           |
-|     propeller and running gear were damaged slightly.                |
-|                                                                      |
-| [53] This was an official record, but Brookins had flown 4939        |
-|     feet high, at Indianapolis, on June 17th.                        |
-|                                                                      |
-| [54] This record was made with an uncalibrated barograph, and        |
-|     hence was unofficial and unaccepted as a world’s record.         |
-|                                                                      |
-| [55] The present writer, in his paper quoted on page 229, pointed    |
-|     out the equilibrative and steadying quality of torsionally       |
-|     elastic wings, and some years previously had proved this by      |
-|     gliding models having sustainers with flexible rear margins.     |
-|                                                                      |
-| [56] The whole water vapor in the atmosphere of our latitude in      |
-|     summer is equivalent to about one inch of rainfall.              |
-|                                                                      |
-| [57] Computed by W. J. Humphreys for Moore’s _Descriptive            |
-|     Meteorology_.                                                    |
-|                                                                      |
-| [58] Ferrel, _Popular Treatise on Winds_.                            |
-|                                                                      |
-| [59] Solar radiation received by the earth.                          |
-|                                                                      |
-| [60] W. J. Humphreys, _Astro. Phys. Journ._, January, 1909.          |
-|                                                                      |
-| [61] An isobar is a line of intersection of an isobaric surface      |
-|     with a water level surface at any altitude.                      |
-|                                                                      |
-| [62] _A Popular Treatise on the Winds._                              |
-|                                                                      |
-| [63] _The Conquest of the Air._                                      |
-|                                                                      |
-| [64] By this current John Wise, in 1870, and Walter Wellman, in      |
-|     1910, proposed to voyage across the Atlantic; Wise in a free     |
-|     balloon, Wellman in a motor balloon with drag rope. See pp.      |
-|     74, 75.                                                          |
-|                                                                      |
-| [65] It is reported that once during the month of August the         |
-|     rainfall totaled thirty-two feet; and it is believed that the    |
-|     annual fall exceeds fifty feet.                                  |
-|                                                                      |
-| [66] The “eye” is most noticeable at sea, where the cyclones are     |
-|     more symmetrical, and particularly in lower latitudes, where     |
-|     they are more concentrated.                                      |
-|                                                                      |
-| [67] The destructive one that visited Galveston in 1900 is a         |
-|     well-known example.                                              |
-|                                                                      |
-| [68] _Contributions to Meteorology._                                 |
-|                                                                      |
-| [69] Dr. W. Dauberck, _Met. Zeitschrift_, April, 1866.               |
-|                                                                      |
-| [70] Moore’s _Meteorology_, p. 164.                                  |
-|                                                                      |
-| [71] Von Bezold, on the _Thermodynamics of the Atmosphere_.          |
-|                                                                      |
-| [72] Chanute, _Aeronautical Annual_, 1897, p. 101.                   |
-|                                                                      |
-| [73] _Nature_, April 5, 1883.                                        |
-|                                                                      |
-| [74] _Vol des Oiseaux._                                              |
-|                                                                      |
-| [75] _Internal Work of the Wind._                                    |
-|                                                                      |
-| [76] _Engineering News_, December 13, 1890.                          |
-|                                                                      |
-| [77] _Meteorological Journal_, November, 1891.                       |
-|                                                                      |
-| [78] On _Atmospheric Movements_ (Abbe’s translation).                |
-|                                                                      |
-| [79] From _Scientific American_, March 13, 1909, by permission of    |
-|     Munn & Co.                                                       |
-|                                                                      |
-| [80] For a fuller account of this fine airship see H. Peltier’s      |
-|     article in _L’Aérophile_, December 1, 1910.                      |
-|                                                                      |
-| [81] This description and the following are from _Present Status     |
-|     of Military Aëronautics_, by Major G. O. Squier.                 |
-|                                                                      |
-| [82] From _Navigating the Air_, by permission of Doubleday, Page     |
-|     & Co.                                                            |
-|                                                                      |
-| [83] From _Scientific American_ of March 4, 1911, by permission      |
-|     of Munn & Co.                                                    |
-|                                                                      |
-+----------------------------------------------------------------------+
-
-
-  Transcriber’s Notes:
-   - Text enclosed by underscores is in italics (_italics_).
-   - Redundant title page has been removed.
-   - Blank pages have been removed.
-   - Silently corrected typographical errors.
-
-
-
-
-
-End of Project Gutenberg's Aërial Navigation, by Albert Francis Zahm
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-<pre>
-
-The Project Gutenberg EBook of Aërial Navigation, by Albert Francis Zahm
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Aërial Navigation
-       A Popular Treatise on the Growth of Air Craft and on
-              Aëronautical Meteorology
-
-Author: Albert Francis Zahm
-
-Release Date: September 13, 2019 [EBook #60277]
-
-Language: English
-
-Character set encoding: UTF-8
-
-*** START OF THIS PROJECT GUTENBERG EBOOK AËRIAL NAVIGATION ***
-
-
-
-
-Produced by ellinora, Robert Tonsing, and the Online
-Distributed Proofreading Team at http://www.pgdp.net (This
-file was produced from images generously made available
-by The Internet Archive/American Libraries.)
-
-
-
-
-
-
-</pre>
-
-  <div class="figcenter">
-    <img id="coverpage" src="images/cover.jpg" width="513" height="800" alt="cover" />
-  </div>
-
-  <hr class="page" />
-
-  <h1>AËRIAL NAVIGATION</h1>
-
-  <div class="center">A POPULAR TREATISE<br />
-    ON THE GROWTH OF AIR CRAFT AND<br />
-    ON AËRONAUTICAL METEOROLOGY</div>
-
-  <div class="center small mt10">BY</div>
-
-  <div class="center xlarge smcap">Albert Francis Zahm, A.M., M.E., Ph.D.</div>
-
-  <div class="center xsmall mb10">SECRETARY OF THE AËRO CLUB OF WASHINGTON; GOVERNOR OF THE AËRO CLUB<br />
-    OF AMERICA; GENERAL SECRETARY OF THE INTERNATIONAL CONFERENCES<br />
-    ON AËRIAL NAVIGATION IN 1893 AND 1907; OFFICIAL AMERICAN<br />
-    DELEGATE TO THE AËRONAUTIC CONGRESS OF 1900; FORMERLY<br />
-    LECTURER ON MECHANICS IN THE UNITED STATES BUREAU<br />
-    OF STANDARDS, AND PROFESSOR OF MECHANICS<br />
-    IN THE CATHOLIC UNIVERSITY<br />
-    OF AMERICA</div>
-
-  <div class="figcenter">
-    <img src="images/i_title.jpg" width="100" height="121" alt="" />
-  </div>
-
-  <div class="center mt10 lh2"><span class="gespertt">NEW YORK AND LONDON<br />
-    D. APPLETON AND COMPANY</span><br />
-    1911</div>
-
-  <hr class="page" />
-
-  <div class="center page small mt20 lh2"><span class="smcap">Copyright, 1911, by<br /></span>
-    D. APPLETON AND COMPANY</div>
-
-  <p class="center small mt20"><i>Published September, 1911</i></p>
-
-  <div class="center small mt20">Printed in the United States of America</div>
-
-  <hr class="page" />
-  <div class="chapter" id="PREFACE.">
-    <span class="pagenum" id="Page_v">v</span>
-    <h3 class="gespertt">PREFACE</h3>
-  </div>
-  <hr class="short mb5" />
-
-  <p><span class="smcap">The</span> purpose of this work is to portray in popular terms the
-    substantial progress of aëronautics from its earliest beginning to
-    the present time. Beyond the introductory account, little note is
-    taken of experiments, however picturesque or clever, which constitute
-    no advance in the art, or lead to no useful result. At times some
-    minutiæ are presented to complete the story of an important series of
-    achievements; but the unproductive efforts of impractical zealots,
-    however prominent or widely known in their day, receive scant, if any,
-    attention. Failures and tragedies where introduced, are described for
-    the lessons involved rather than for any curious interest investing
-    them. The griefs and grotesque follies of aëronautic imbeciles form a
-    long story, but a futile and unprofitable one, of slight concern in the
-    evolutionary history of a veritable science.</p>
-
-  <p>A general history of aërial locomotion would naturally be divided
-    into four parts, treating respectively of passive balloons, power
-    balloons, passive flyers, and power flyers; but in this work a separate
-    treatment has not been allotted to passive flyers because of their too
-    backward state of development. Passive gliders which maneuver in the
-    air merely by virtue of gravitational force, or acquired momentum, are
-    familiar enough; but the much more interesting passive flyers of human
-    construction, adapted to rise without motive power considerably beyond
-    their initial level, or to soar far aloft, and sail long distances by
-    virtue of favorable winds, are still in their infancy. It may be hoped,
-    however, that the vulture’s art which now is
-    <span class="pagenum" id="Page_vi">vi</span> well nigh overlooked,
-    because of the triumphant advance of dynamic flight, will soon receive
-    such attention that future treatises may relate human achievements
-    in soaring that shall rival the dexterous and marvelous feats of
-    the condor and albatross, even as the majestic sweep of the dynamic
-    aëroplane now rivals the powerful rowing flight of the strongest birds
-    of prey.</p>
-
-  <p>Following the story of the evolution of air ships, a brief account
-    of the medium they navigate has been added. In particular, the
-    circumstances which affect the density and motion of the air have been
-    studied; for the density of the air determines the static lift of air
-    ships; the density and speed of impact of the air together determine
-    the dynamic lift and the resistance to progression; while the velocity
-    of the air current conditions the possible speed of travel in any
-    direction. It is important, therefore, that the aëronautical student
-    should have some acquaintance with the general properties of the air
-    which affect its density, and some knowledge of the generation and
-    prevalence both of the great currents of the atmosphere, and of the
-    local winds and invisible turmoils which so nearly concern the safety
-    and effective progress of the aërial navigator.</p>
-
-  <p>The French units of measurement have been freely used, as well as the
-    English. This seems advisable because the official rules and records
-    of international aëronautic events are partly expressed in the metric
-    system. Moreover, the navigation of a universal medium seems to call
-    for such universal standards. Indeed a peculiar mission of world travel
-    is to eliminate provincialism, and to promote universalism of thought,
-    of sentiment, and of custom.</p>
-
-  <p>In order to lighten the book for the popular reader, some interesting
-    historical facts and much important quantitative data are placed in the
-    Appendices, where they may be available to the technical or special
-    student.</p>
-
-  <p>It is a pleasant duty to acknowledge here my obligations to the U.
-    S. Signal Corps, the Smithsonian Institution, and the U. S. Weather
-    Bureau, for much assistance in collecting
-    <span class="pagenum" id="Page_vii">vii</span>the materials for this work.
-    Dr. W. J. Humphreys, of the U. S. Weather Bureau, has very kindly read
-    the manuscript for the chapters on the atmosphere.</p>
-
-  <p>My thanks are due also to the <cite>Scientific American</cite> and to
-    <cite>Aëronautics</cite> for the use of photographs for the illustrations, as also
-    to the manufacturers of various aircraft, and to Mr. W. J. Hammer, Mr.
-    Carl Dientsbach, and Mr. A. S. Levino.</p>
-
-  <div class="smcap right">A. F. Zahm.</div>
-  <p class="small ml3"><span class="smcap">Cosmos Club<br />
-    Washington, D. C.</span>,<br />
-    &nbsp;&nbsp;&nbsp;&nbsp;January, 1911.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="CONTENTS.">
-    <span class="pagenum" id="Page_ix">ix</span>
-    <h3>CONTENTS</h3>
-  </div>
-  <hr class="short mb5" />
-
-  <table id="contents" summary="Contents">
-    <tbody>
-      <tr>
-        <td colspan="2" class="pl5 xsmall"><b>CHAPTER</b></td>
-        <td class="tdr xsmall"><div><b>PAGE</b></div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc"><div>INTRODUCTION</div></td>
-      </tr>
-      <tr>
-        <td colspan="2"><a href="#introduction" title="Go to Introduction"><span class="smcap">Introduction</span></a></td>
-        <td class="tdr"><div>3</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc pt2"><div>PART I</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc small"><div>GROWTH OF AËROSTATION</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>I.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_I" title="Go to chapter 1">Early History of Passive Balloons</a></td>
-        <td class="tdr"><div>29</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>II.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_II" title="Go to chapter 2">Practical Development of Passive Balloons</a></td>
-        <td class="tdr"><div>54</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>III.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_III" title="Go to chapter 3">Early History of Power Balloons</a></td>
-        <td class="tdr"><div>78</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>IV.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_IV" title="Go to chapter 4">Introduction of Gasoline-Driven Dirigibles</a></td>
-        <td class="tdr"><div>101</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>V.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_V" title="Go to chapter 5">Practical Development of Non-Rigid Dirigibles</a></td>
-        <td class="tdr"><div>115</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>VI.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_VI" title="Go to chapter 6">Development of Rigid Dirigibles</a></td>
-        <td class="tdr"><div>145</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc pt2"><div>PART II</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc small"><div>GROWTH OF AVIATION</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>VII.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_VII" title="Go to chapter 7">Model Flying Machines</a></td>
-        <td class="tdr"><div>173</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>VIII.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_VIII" title="Go to chapter 8">Nineteenth Century Man-Flyers</a></td>
-        <td class="tdr"><div>202</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>IX.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_IX" title="Go to chapter 9">Aëroplanes of Adequate Stability and Power</a></td>
-        <td class="tdr"><div>235</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>X.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_X" title="Go to chapter 10">Advent of Public Flying</a></td>
-        <td class="tdr"><div>256</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XI.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XI" title="Go to chapter 11">Strenuous Competitive Flying</a></td>
-        <td class="tdr"><div>283</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XII.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XII" title="Go to chapter 12">Forcing the Art</a></td>
-        <td class="tdr"><div>307</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc pt2"><span class="pagenum" id="Page_x">x</span><div>PART III</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc small"><div>AËRONAUTIC METEOROLOGY</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XIII.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XIII" title="Go to chapter 13">General Properties of Free Air</a></td>
-        <td class="tdr"><div>347</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XIV.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XIV" title="Go to chapter 14">General Distribution of Heat and Pressure</a></td>
-        <td class="tdr"><div>363</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XV.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XV" title="Go to chapter 15">Permanent and Periodic Winds</a></td>
-        <td class="tdr"><div>376</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XVI.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XVI" title="Go to chapter 16">Cyclones, Tornadoes, Waterspouts</a></td>
-        <td class="tdr"><div>394</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>XVII.</div></td>
-        <td class="tdl smcap">—<a href="#chapter_XVII" title="Go to chapter 17">Thunderstorms, Wind Gusts</a></td>
-        <td class="tdr"><div>422</div></td>
-      </tr>
-      <tr>
-        <td colspan="3" class="tdc pt2"><div>APPENDICES</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>I.</div></td>
-        <td class="tdl smcap">—<a href="#appendix_I" title="Go to appendix 1">Stress in a Vacuum Balloon</a></td>
-        <td class="tdr"><div>443</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>II.</div></td>
-        <td class="tdl smcap">—<a href="#appendix_II" title="Go to appendix 2">Aëronautic Letters of Benjamin Franklin</a></td>
-        <td class="tdr"><div>446</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>III.</div></td>
-        <td class="tdl smcap">—<a href="#appendix_III" title="Go to appendix 3">Successful Military Dirigible Balloons</a></td>
-        <td class="tdr"><div>456</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>IV.</div></td>
-        <td class="tdl smcap">—<a href="#appendix_IV" title="Go to appendix 4">The Relations of Weight, Speed, and Power of Flyers</a></td>
-        <td class="tdr"><div>478</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>V.</div></td>
-        <td class="tdl smcap">—<a href="#appendix_V" title="Go to appendix 5">Curtiss’ Hydro-Aëroplane Experiments</a></td>
-        <td class="tdr"><div>481</div></td>
-      </tr>
-      <tr>
-        <td colspan="2"><a href="#index" title="Go to index"><span class="smcap">INDEX</span></a></td>
-        <td class="tdr"><div>487</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <hr class="page" />
-  <div class="chapter" id="LIST_OF_PLATES.">
-    <span class="pagenum" id="Page_xi">xi</span>
-    <h3>LIST OF PLATES</h3>
-  </div>
-  <hr class="short mb5" />
-
-  <table summary="List of plates">
-    <tbody>
-      <tr>
-        <td colspan="2" class="tdrt xsmall"><div><b>FACING<br />PAGE</b></div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_I" title="Go to plate 1"><span class="smcap">Plate I</span></a><br />
-          Glaisher and Coxwell.<br />
-          Parseval Kite Balloon.
-        </td>
-        <td class="tdrt"><div>66</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_II" title="Go to plate 2"><span class="smcap">Plate II</span></a><br />
-          Haenlein’s Gas-driven Dirigible.<br />
-          Wölfert’s Benzine-driven Dirigible.<br />
-          Santos-Dumont’s Dirigible, <i>No. 16</i>.
-        </td>
-        <td class="tdrt"><div>98</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_III" title="Go to plate 3"><span class="smcap">Plate III</span></a><br />
-          The <i>Lebaudy</i>.<br />
-          <i>La Patrie.</i><br />
-          Lebaudy’s <i>Morning Post</i>.
-        </td>
-        <td class="tdrt"><div>116</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_IV" title="Go to plate 4"><span class="smcap">Plate IV</span></a><br />
-          <i>La Ville de Paris.</i><br />
-          <i>Colonel Renard.</i>
-        </td>
-        <td class="tdrt"><div>124</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_V" title="Go to plate 5"><span class="smcap">Plate V</span></a><br />
-          <i>Zodiac III.</i><br />
-          <i>Zodiac IV.</i>
-        </td>
-        <td class="tdrt"><div>128</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_VI" title="Go to plate 6"><span class="smcap">Plate VI</span></a><br />
-          <i>La Belgique.</i><br />
-          Italian Military Dirigible <i>No. I bis</i>.
-        </td>
-        <td class="tdrt"><div>130</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_VII" title="Go to plate 7"><span class="smcap">Plate VII</span></a><br />
-          <i>Clément-Bayard I.</i><br />
-          <i>Clément-Bayard II.</i>
-        </td>
-        <td class="tdrt"><div>132</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_VIII" title="Go to plate 8"><span class="smcap">Plate VIII</span></a><br />
-          <i>U. S. Signal Corps Dirigible I.</i><br />
-          <i>Gross II.</i>
-        </td>
-        <td class="tdrt"><div>138</div></td>
-      </tr>
-      <tr>
-        <td class="tdl"><span class="pagenum" id="Page_xii">xii</span>
-          <a href="#Plate_IX" title="Go to plate 9"><span class="smcap">Plate IX</span></a><br />
-          <i>Parseval I.</i><br />
-          <i>Parseval II.</i>
-        </td>
-        <td class="tdrt"><div>140</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_X" title="Go to plate 10"><span class="smcap">Plate X</span></a><br />
-          <i>Gross III.</i><br />
-          Zeppelin Airship Structure.
-        </td>
-        <td class="tdrt"><div>146</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XI" title="Go to plate 11"><span class="smcap">Plate XI</span></a><br />
-          Zeppelin Dirigible Resting on the Water.<br />
-          Zeppelin Dirigible over Zürich.
-        </td>
-        <td class="tdrt"><div>160</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XII" title="Go to plate 12"><span class="smcap">Plate XII</span></a><br />
-          Henson’s Aëroplane.<br />
-          Ader’s Aëroplane.
-        </td>
-        <td class="tdrt"><div>182</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XIII" title="Go to plate 13"><span class="smcap">Plate XIII</span></a><br />
-          Stringfellow’s Aëroplane (Front).<br />
-          Stringfellow’s Aëroplane (Side).
-        </td>
-        <td class="tdrt"><div>186</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XIV" title="Go to plate 14"><span class="smcap">Plate XIV</span></a><br />
-          Phillips’s Tethered Aëroplane.<br />
-          Phillips’s Aëroplane.
-        </td>
-        <td class="tdrt"><div>192</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XV" title="Go to plate 15"><span class="smcap">Plate XV</span></a><br />
-          Langley’s Steam Model.<br />
-          Langley’s Gasoline Model.<br />
-          Langley’s Two Surface Gasoline Model.
-        </td>
-        <td class="tdrt"><div>194</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XVI" title="Go to plate 16"><span class="smcap">Plate XVI</span></a><br />
-          Lilienthal’s Monoplane Glider.<br />
-          Lilienthal’s Biplane Glider.<br />
-          Pilcher’s Monoplane Glider.
-        </td>
-        <td class="tdrt"><div>212</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XVII" title="Go to plate 17"><span class="smcap">Plate XVII</span></a><br />
-          Chanute’s Five-Deck Glider.<br />
-          Herring in Chanute Biplane.<br />
-          Herring’s Compressed-air Biplane.
-        </td>
-        <td class="tdrt"><div>218</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XVIII" title="Go to plate 18"><span class="smcap">Plate XVIII</span></a><br />
-          Maxim’s Aëroplane.<br />
-          Langley’s Large Aëroplane.
-        </td>
-        <td class="tdrt"><div>226</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XIX" title="Go to plate 19"><span class="smcap">Plate XIX</span></a><br />
-          First Wright Glider.<br />
-          Second Wright Glider.
-        </td>
-        <td class="tdrt"><div>246</div></td>
-      </tr>
-      <tr>
-        <td class="tdl"><span class="pagenum" id="Page_xiii">xiii</span>
-          <a href="#Plate_XX" title="Go to plate 20"><span class="smcap">Plate XX</span></a><br />
-          First Wright Aëroplane (Rear).<br />
-          First Wright Aëroplane (Side).
-        </td>
-        <td class="tdrt"><div>248</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXI" title="Go to plate 21"><span class="smcap">Plate XXI</span></a><br />
-          Montgomery’s Aëroplane.
-        </td>
-        <td class="tdrt"><div>252</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXII" title="Go to plate 22"><span class="smcap">Plate XXII</span></a><br />
-          Santos-Dumont’s Biplane.<br />
-          Santos-Dumont’s <i>Demoiselle</i>.
-        </td>
-        <td class="tdrt"><div>258</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXIII" title="Go to plate 23"><span class="smcap">Plate XXIII</span></a><br />
-          Farman Biplane, 1908.<br />
-          Farman Biplane, 1909.<br />
-          Harmon in Farman Biplane.
-        </td>
-        <td class="tdrt"><div>260</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXIV" title="Go to plate 24"><span class="smcap">Plate XXIV</span></a><br />
-          The <i>Red Wing</i>.<br />
-          Curtiss Biplane.<br />
-          Curtiss Biplane with Pontoons.
-        </td>
-        <td class="tdrt"><div>264</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXV" title="Go to plate 25"><span class="smcap">Plate XXV</span></a><br />
-          Blériot Flying Over Toury-Artenay Circuit.<br />
-          Blériot Monoplane <i>No. VIII</i>.<br />
-          Blériot Monoplane <i>No. IX</i>.
-        </td>
-        <td class="tdrt"><div>268</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXVI" title="Go to plate 26"><span class="smcap">Plate XXVI</span></a><br />
-          Wright Biplane of 1908.<br />
-          Standard Wright Biplane of 1910.<br />
-          Wright Racing Biplane of 1910.
-        </td>
-        <td class="tdrt"><div>272</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXVII" title="Go to plate 27"><span class="smcap">Plate XXVII</span></a><br />
-          <i>Blériot XI</i> with Moisant Aviator on Mexican Border.<br />
-          <i>Blériot XII.</i>
-        </td>
-        <td class="tdrt"><div>286</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXVIII" title="Go to plate 28"><span class="smcap">Plate XXVIII</span></a><br />
-          <i>Antoinette</i> Monoplane of 1909.<br />
-          <i>Antoinette</i> Monoplane of 1910.
-        </td>
-        <td class="tdrt"><div>288</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXIX" title="Go to plate 29"><span class="smcap">Plate XXIX</span></a><br />
-          Esnault-Pélterie Monoplane, Early Pattern.<br />
-          Esnault-Pélterie Monoplane of 1910.
-        </td>
-        <td class="tdrt"><div>302</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXX" title="Go to plate 30"><span class="smcap">Plate XXX</span></a><br />
-          Grade Monoplane.<br />
-          Cody Biplane.
-        </td>
-        <td class="tdrt"><div>304</div></td>
-      </tr>
-      <tr>
-        <td class="tdl"><span class="pagenum" id="Page_xiv">xiv</span>
-          <a href="#Plate_XXXI" title="Go to plate 31"><span class="smcap">Plate XXXI</span></a><br />
-          Fabre Hydro-aëroplane.<br />
-          Paulhan Hydro-aëroplane.<br />
-          Moisant Metal Monoplane.
-        </td>
-        <td class="tdrt"><div>332</div></td>
-      </tr>
-      <tr>
-        <td class="tdl">
-          <a href="#Plate_XXXII" title="Go to plate 32"><span class="smcap">Plate XXXII</span></a><br />
-          Curtiss Starting from the Water.<br />
-          Curtiss Biplane for Land and Water.<br />
-          Curtiss Triplane Risen from the Water.
-        </td>
-        <td class="tdrt"><div>482</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <hr class="page" />
-  <div class="chapter" id="LIST_OF_ILLUSTRATIONS_IN_TEXT.">
-    <span class="pagenum" id="Page_xv">xv</span>
-    <h3>LIST OF ILLUSTRATIONS IN TEXT</h3>
-  </div>
-  <hr class="short mb5" />
-
-  <table summary="Illustrations in text">
-    <tbody>
-      <tr>
-        <th class="xsmall chapnum"><div>FIG.</div></th>
-        <th>&nbsp;</th>
-        <th class="tdr"><div class="xsmall">PAGE</div></th>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>1.</div></td>
-        <td class="tdl">—<a href="#Fig_01" title="Go to figure 1">Da Vinci’s designs for human flying-gear</a></td>
-        <td class="tdr"><div>9</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>2.</div></td>
-        <td class="tdl">—<a href="#Fig_02" title="Go to figure 2">A possible air-scout</a></td>
-        <td class="tdr"><div>12</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>3.</div></td>
-        <td class="tdl">—<a href="#Fig_03" title="Go to figure 3">Blanchard’s flying-machine</a></td>
-        <td class="tdr"><div>17</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>4.</div></td>
-        <td class="tdl">—<a href="#Fig_04" title="Go to figure 4">Lana’s proposed vacuum balloon</a></td>
-        <td class="tdr"><div>24</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>5.</div></td>
-        <td class="tdl">—<a href="#Fig_05" title="Go to figure 5">Montgolfier’s experimental balloon</a></td>
-        <td class="tdr"><div>34</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>6.</div></td>
-        <td class="tdl">—<a href="#Fig_06" title="Go to figure 6">Charles’ first hydrogen balloon</a></td>
-        <td class="tdr"><div>36</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>7.</div></td>
-        <td class="tdl">—<a href="#Fig_07" title="Go to figure 7">Montgolfier’s passenger balloon</a></td>
-        <td class="tdr"><div>39</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>8.</div></td>
-        <td class="tdl">—<a href="#Fig_08" title="Go to figure 8">Charles’ passenger balloon</a></td>
-        <td class="tdr"><div>43</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>9.</div></td>
-        <td class="tdl">—<a href="#Fig_09" title="Go to figure 9">La Flesselle</a></td>
-        <td class="tdr"><div>50</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>10.</div></td>
-        <td class="tdl">—<a href="#Fig_10" title="Go to figure 10"><i>The Great Balloon of Nassau</i></a></td>
-        <td class="tdr"><div>55</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>11.</div></td>
-        <td class="tdl">—<a href="#Fig_11" title="Go to figure 11">Car of Nadar’s balloon</a></td>
-        <td class="tdr"><div>61</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>12.</div></td>
-        <td class="tdl">—<a href="#Fig_12" title="Go to figure 12">Diagram of a modern spherical balloon with ripping panel</a></td>
-        <td class="tdr"><div>75</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>13.</div></td>
-        <td class="tdl">—<a href="#Fig_13" title="Go to figure 13">Blanchard’s dirigible balloon, 1784</a></td>
-        <td class="tdr"><div>80</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>14.</div></td>
-        <td class="tdl">—<a href="#Fig_14" title="Go to figure 14">Robert Brothers’ dirigible, 1784</a></td>
-        <td class="tdr"><div>82</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>15.</div></td>
-        <td class="tdl">—<a href="#Fig_15" title="Go to figure 15">General Meusnier’s proposed dirigible, 1784</a></td>
-        <td class="tdr"><div>85</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>16.</div></td>
-        <td class="tdl">—<a href="#Fig_16" title="Go to figure 16">Rufus Porter’s dirigible, 1820</a></td>
-        <td class="tdr"><div>87</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>17.</div></td>
-        <td class="tdl">—<a href="#Fig_17" title="Go to figure 17">Jullien’s model dirigible, 1850</a></td>
-        <td class="tdr"><div>88</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>18.</div></td>
-        <td class="tdl">—<a href="#Fig_18" title="Go to figure 18">Giffard’s steam dirigible, 1852</a></td>
-        <td class="tdr"><div>89</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>19.</div></td>
-        <td class="tdl">—<a href="#Fig_19" title="Go to figure 19">Dupuy de Lome’s dirigible, 1872</a></td>
-        <td class="tdr"><div>92</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>20.</div></td>
-        <td class="tdl">—<a href="#Fig_20" title="Go to figure 20">Renard’s dirigible, <i>La France</i>, 1884</a></td>
-        <td class="tdr"><div>94</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><span class="pagenum" id="Page_xvi">xvi</span><div>21.</div></td>
-        <td class="tdl">—<a href="#Fig_21" title="Go to figure 21"><i>La Ville de Paris</i></a></td>
-        <td class="tdr"><div>121</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>22.</div></td>
-        <td class="tdl">—<a href="#Fig_22" title="Go to figure 22"><i>Le Petit Journal</i>, Zodiac type</a></td>
-        <td class="tdr"><div>128</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>23.</div></td>
-        <td class="tdl">—<a href="#Fig_23" title="Go to figure 23"><i>Clément-Bayard II</i>, 1910</a></td>
-        <td class="tdr"><div>133</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>24.</div></td>
-        <td class="tdl">—<a href="#Fig_24" title="Go to figure 24"><i>Morning Post</i> dirigible, 1910</a></td>
-        <td class="tdr"><div>135</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>25.</div></td>
-        <td class="tdl">—<a href="#Fig_25" title="Go to figure 25">Route of British military dirigibles from France to England, 1900</a></td>
-        <td class="tdr"><div>137</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>26.</div></td>
-        <td class="tdl">—<a href="#Fig_26" title="Go to figure 26">Da Vinci’s helicopter</a></td>
-        <td class="tdr"><div>175</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>27.</div></td>
-        <td class="tdl">—<a href="#Fig_27" title="Go to figure 27">Da Vinci’s parachute</a></td>
-        <td class="tdr"><div>176</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>28.</div></td>
-        <td class="tdl">—<a href="#Fig_28" title="Go to figure 28">Veranzio’s parachute</a></td>
-        <td class="tdr"><div>178</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>29.</div></td>
-        <td class="tdl">—<a href="#Fig_29" title="Go to figure 29">Lenormand’s parachute, 1784</a></td>
-        <td class="tdr"><div>179</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>30.</div></td>
-        <td class="tdl">—<a href="#Fig_30" title="Go to figure 30">Paper traveling parachute</a></td>
-        <td class="tdr"><div>181</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>31.</div></td>
-        <td class="tdl">—<a href="#Fig_31" title="Go to figure 31">Wenham’s aëroplane, 1866</a></td>
-        <td class="tdr"><div>185</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>32.</div></td>
-        <td class="tdl">—<a href="#Fig_32" title="Go to figure 32">Penaud’s aëroplane toy, 1871</a></td>
-        <td class="tdr"><div>187</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>33.</div></td>
-        <td class="tdl">—<a href="#Fig_33" title="Go to figure 33">Tatin’s aëroplane model, 1879</a></td>
-        <td class="tdr"><div>188</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>34.</div></td>
-        <td class="tdl">—<a href="#Fig_34" title="Go to figure 34">Hargrave’s model screw monoplane, 1891</a></td>
-        <td class="tdr"><div>190</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>35.</div></td>
-        <td class="tdl">—<a href="#Fig_35" title="Go to figure 35">Hargrave’s kite</a></td>
-        <td class="tdr"><div>191</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>36.</div></td>
-        <td class="tdl">—<a href="#Fig_36" title="Go to figure 36">Launoy and Bienvenu’s helicopter, 1784</a></td>
-        <td class="tdr"><div>198</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>37.</div></td>
-        <td class="tdl">—<a href="#Fig_37" title="Go to figure 37">Forlanini’s helicopter, 1878</a></td>
-        <td class="tdr"><div>200</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>38.</div></td>
-        <td class="tdl">—<a href="#Fig_38" title="Go to figure 38">Le Bris’ aëroplane, 1855</a></td>
-        <td class="tdr"><div>204</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>39.</div></td>
-        <td class="tdl">—<a href="#Fig_39" title="Go to figure 39">Mouillard’s aëroplane</a></td>
-        <td class="tdr"><div>208</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>40.</div></td>
-        <td class="tdl">—<a href="#Fig_40" title="Go to figure 40">Blériot’s Toury-Artenay aëroplane circuit, 1908</a></td>
-        <td class="tdr"><div>269</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>41.</div></td>
-        <td class="tdl">—<a href="#Fig_41" title="Go to figure 41">Map of the “Circuit de l’Est”</a></td>
-        <td class="tdr"><div>330</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>42.</div></td>
-        <td class="tdl">—<a href="#Fig_42" title="Go to figure 42">Diagram of Curtiss hydro-aëroplane</a></td>
-        <td class="tdr"><div>333</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>43.</div></td>
-        <td class="tdl">—<a href="#Fig_43" title="Go to figure 43">The Etrich monoplane of 1910</a></td>
-        <td class="tdr"><div>336</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>44.</div></td>
-        <td class="tdl">—<a href="#Fig_44" title="Go to figure 44">Summer and winter average vertical temperature gradients</a></td>
-        <td class="tdr"><div>369</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>45.</div></td>
-        <td class="tdl">—<a href="#Fig_45" title="Go to figure 45">General circulation of the atmosphere</a></td>
-        <td class="tdr"><div>378</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>46.</div></td>
-        <td class="tdl">—<a href="#Fig_46" title="Go to figure 46">Normal Wind direction and velocity for January and February (Köppen)</a></td>
-        <td class="tdr"><div>381</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><span class="pagenum" id="Page_xvii">xvii</span><div>47.</div></td>
-        <td class="tdl">—<a href="#Fig_47" title="Go to figure 47">Normal Wind direction and velocity for July and August (Köppen)</a></td>
-        <td class="tdr"><div>383</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>48.</div></td>
-        <td class="tdl">—<a href="#Fig_48" title="Go to figure 48">Trade and counter-trade winds</a></td>
-        <td class="tdr"><div>384</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>49.</div></td>
-        <td class="tdl">—<a href="#Fig_49" title="Go to figure 49">Velocity diagram in horizontal section of a cyclone</a></td>
-        <td class="tdr"><div>398</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>50.</div></td>
-        <td class="tdl">—<a href="#Fig_50" title="Go to figure 50">Funnel-like cloud sometimes observed in a tornado</a></td>
-        <td class="tdr"><div>409</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>51.</div></td>
-        <td class="tdl">—<a href="#Fig_51" title="Go to figure 51">Vertical section of the St. Louis, Mo., tornado of May 27, 1896</a></td>
-        <td class="tdr"><div>411</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>52.</div></td>
-        <td class="tdl">—<a href="#Fig_52" title="Go to figure 52">Horizontal section of St. Louis tornado of May 27, 1896</a></td>
-        <td class="tdr"><div>412</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>53.</div></td>
-        <td class="tdl">—<a href="#Fig_53" title="Go to figure 53">Vertical section of short tornado</a></td>
-        <td class="tdr"><div>414</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>54.</div></td>
-        <td class="tdl">—<a href="#Fig_54" title="Go to figure 54">Vertical section of a tall tornado</a></td>
-        <td class="tdr"><div>415</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>55.</div></td>
-        <td class="tdl">—<a href="#Fig_55" title="Go to figure 55">Vertical section of a hail tornado</a></td>
-        <td class="tdr"><div>417</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>56.</div></td>
-        <td class="tdl">—<a href="#Fig_56" title="Go to figure 56">Universal anemograph</a></td>
-        <td class="tdr"><div>428</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>57.</div></td>
-        <td class="tdl">—<a href="#Fig_57" title="Go to figure 57">Records of wind variation in horizontal and vertical direction</a></td>
-        <td class="tdr"><div>429</div></td>
-      </tr>
-      <tr>
-        <td class="chapnum"><div>58.</div></td>
-        <td class="tdl">—<a href="#Fig_58" title="Go to figure 58">Records of Wind speed obtained by Langley</a></td>
-        <td class="tdr"><div>433</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <hr class="page" />
-  <div class="chapter" >
-    <span class="pagenum" id="Page_1">1</span>
-    <h2 class="xlarge">INTRODUCTION</h2>
-  </div>
-
-  <hr class="page" />
-  <div class="chapter" id="introduction">
-    <span class="pagenum" id="Page_3">3</span>
-    <h3>INTRODUCTION</h3>
-    <span class="small">FANCY AND FOLK-LORE</span>
-  </div>
-
-  <div class="center-container">
-    <div class="poetry">
-      <div class="stanza">
-        <div class="i0">Of silver wings he took a shining pair,</div>
-        <div class="i2">Fringed with gold, unwearied, nimble, swift;</div>
-        <div class="i0">With these he parts the winds, the clouds, the air,</div>
-        <div class="i2">And over seas and earth himself doth lift.</div>
-        <div class="i0">Thus clad he cuts the spheres and circles fair,</div>
-        <div class="i2">And the pure skies with sacred feathers clift;</div>
-        <div class="i0">On Lebanon at first his feet he set</div>
-        <div class="i2">And shook his wings with rosy may-dews wet.</div>
-      </div>
-    </div>
-  </div>
-  <div class="smcap right">Tasso, Canto I, XIV.</div>
-
-  <p><span class="smcap">How</span> beautiful! May we hope ever to journey thus, on wings actuated by
-    human power? It is an old question, once dear to the philosopher and
-    fool alike, but now important mainly to the fool. Or say more kindly it
-    is the affair of untechnical inventors—the amateur, the rustic, the man
-    of chimerical dreams. For the wise aëronaut now numbers that project
-    among the roseate illusions of his youth.<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a></p>
-
-  <p>Ovid relates a story, doubtless credible in his day, of a clever
-    craftsman who with his son flew bravely aloft, the very first time they
-    put on wings. Daedalus, a Greek architect, having fled from Athens for
-    murder, went with his son Icarus to the island of Crete, where he built
-    the celebrated labyrinth for Minos, the king. He offended that monarch
-    and was cast into prison. In order to escape he made wings for himself
-    and his son, with which they flew far <span class="pagenum" id="Page_4">4</span>over the sea. But Icarus, in his
-    elation, soared too near the sun, ruined his wings, fell into the sea
-    and was drowned. For proof of this we have the Icarian Sea, named after
-    the unfortunate boy. Also we have Ovid’s charming poem:</p>
-
-  <div class="center-container">
-    <div class="poetry">
-      <div class="stanza">
-        <div class="i0">In tedious exile now too long detain’d</div>
-        <div class="i0">Daedalus languish’d for his native land;</div>
-        <div class="i0">The sea foreclosed his flight, yet thus he said;</div>
-        <div class="i0">“Though earth and water in subjection laid,</div>
-        <div class="i0">O cruel Minos, thy dominion be,</div>
-        <div class="i0">We’ll go through air; for sure the air is free.”</div>
-        <div class="i0">Then to new arts his cunning thought applies,</div>
-        <div class="i0">And to improve the work of nature tries.</div>
-        <div class="i0">A row of quills, in gradual order placed,</div>
-        <div class="i0">Rise by degrees in length from first to last;</div>
-        <div class="i0">As on a cliff the ascending thicket grows;</div>
-        <div class="i0">Or different reeds the rural pipe compose:</div>
-        <div class="i0">Along the middle runs a twine of flax,</div>
-        <div class="i0">The bottom stems are join’d by plaint wax;</div>
-        <div class="i0">Thus, well compact, a hollow bending brings</div>
-        <div class="i0">The fine composure into real wings.</div>
-        <div class="i4">His boy, young Icarus, that near him stood,</div>
-        <div class="i0">Unthinking of his fate, with smiles pursued</div>
-        <div class="i0">The floating feathers, which the moving air</div>
-        <div class="i0">Bore loosely from the ground, and wafted here and there:</div>
-        <div class="i0">Or with the wax impertinently play’d,</div>
-        <div class="i0">And with his childish tricks the great design delay’d.</div>
-        <div class="i4">The final masterstroke at last imposed,</div>
-        <div class="i0">And now, the great machine completely closed;</div>
-        <div class="i0">Fitting his pinions on, a flight he tries,</div>
-        <div class="i0">And hung self-balanced in the beaten skies.</div>
-        <div class="i0">Then thus instructs his child: “My boy, take care</div>
-        <div class="i0">To wing your course along the middle air:</div>
-        <div class="i0">If low, the surges wet your flagging plumes;</div>
-        <div class="i0">If high, the sun the melting wax consumes.</div>
-        <div class="i0">Steer between both: nor to the northern skies,</div>
-        <div class="i0">Nor South Orion, turn your giddy eyes,</div>
-        <div class="i0">But follow me; let me before you lay</div>
-        <div class="i0">Rules for the flight, and mark the pathless way.”</div><span class="pagenum" id="Page_5">5</span>
-        <div class="i0">Thus teaching, with a fond concern, his son,</div>
-        <div class="i0">He took the untried wings, and fix’d them on:</div>
-        <div class="i0">But fix’d with trembling hands; and, as he speaks,</div>
-        <div class="i0">The tears roll gently down his aged cheeks;</div>
-        <div class="i0">Then kiss’d, and in his arms embraced him fast,</div>
-        <div class="i0">But knew not this embrace must be the last;</div>
-        <div class="i0">And mounting upward, as he wings his flight,</div>
-        <div class="i0">Back on his charge he turns his aching sight;</div>
-        <div class="i0">As parent birds, when first their callow care</div>
-        <div class="i0">Leave the high nest to tempt the liquid air;</div>
-        <div class="i0">Then cheers him on, and oft, with fatal art,</div>
-        <div class="i0">Reminds the stripling to perform his part.</div>
-        <div class="i0">These, as the angler at the silent brook,</div>
-        <div class="i0">Or mountain shepherd leaning on his crook,</div>
-        <div class="i0">Or gaping ploughman, from the vale descries,</div>
-        <div class="i0">They stare, and view them with religious eyes,</div>
-        <div class="i0">And straight conclude them gods; since none but they</div>
-        <div class="i0">Through their own azure skies could find a way.</div>
-        <div class="i0">Now Delos, Paros, on the left are seen,</div>
-        <div class="i0">And Samos, favour’d by Jove’s haughty queen;</div>
-        <div class="i0">Upon the right, the isle Lebynthos named,</div>
-        <div class="i0">And fair Calymne for its honey famed.</div>
-        <div class="i0">When now the boy, whose childish thoughts aspire</div>
-        <div class="i0">To loftier aims, and make him ramble higher,</div>
-        <div class="i0">Grown wild and wanton, more embolden’d flies</div>
-        <div class="i0">Far from his guide, and scars among the skies:</div>
-        <div class="i0">The softening wax, that felt a nearer sun,</div>
-        <div class="i0">Dissolved apace, and soon began to run:</div>
-        <div class="i0">The youth in vain his melting pinion shakes,</div>
-        <div class="i0">His feathers gone, no longer air he takes:</div>
-        <div class="i0">“Oh! father, father!” as he strove to cry,</div>
-        <div class="i0">Down to the sea he tumbled from on high,</div>
-        <div class="i0">And found his fate; yet still subsists by Fame,</div>
-        <div class="i0">Among those waters that retain his name.</div>
-        <div class="i0">The Father, now no more a father, cries:</div>
-        <div class="i0">“Ho, Icarus! where are you?” as he flies;</div>
-        <div class="i0">“Where shall I seek my boy?” he cries again,</div>
-        <div class="i0">And saw his feathers scatter’d on the main;</div>
-        <div class="i0">Then cursed his art; and funeral rites conferr’d</div>
-        <div class="i0">Naming the country from the youth interr’d.</div>
-      </div>
-    </div>
-  </div>
-
-  <p><span class="pagenum" id="Page_6">6</span></p>
-  <p>How tender and apprehensive that gentleman’s farewell, compared with
-    the modern vogue in like circumstances! Of the two Americans at Berlin
-    who fell four thousand feet in a balloon, it is not recorded that they
-    either kissed or wept.<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a> But some Teutonic Ovid may yet adorn the tale
-    with quaint embellishments.</p>
-
-  <p>Taking more serious note of Daedalus, it will be observed that he
-    has had few imitators. It is because he never really flew, and no
-    one else can fly, in such manner. That is to say, no man can achieve
-    practical flight on wings actuated by his own muscular power. It may be
-    physically possible for an athlete putting forth herculean energy for
-    a few seconds to sustain himself on wings of enormous spread; but in
-    every lightest zephyr he would be as helpless as a thistle seed.</p>
-
-  <p>The actual area of wing required for a man of given weight and power
-    may be roughly estimated; at least its lower limit of size can be
-    determined. Lord Rayleigh,<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a> on purely theoretical ground, has
-    computed that a man operating a screw propeller 280 feet in diameter,
-    moving without frictional loss, could sustain his weight for a period
-    of eight hours a day at a comfortable rate of work. But that estimate
-    does not include the weight of the propeller. By exerting ten times his
-    normal power the man could support his weight with a 28-foot propeller.</p>
-
-  <p>The physical basis of the computation is the same for every type of
-    flyer, whether bird, man, or machine.<span class="pagenum" id="Page_7">7</span> Its weight must be sustained by
-    hurling the air downward. The humming bird in its aërial pause, the bee
-    floating beside a blossom, rests on a down-driven column of air. The
-    home-gliding eagle at dusk may encounter a medium in stillest repose,
-    but he leaves behind him a down-flowing wake, viewless, maybe, but none
-    the less real. In all cases the downward impulse per second given to
-    the air must equal the weight supported by its reaction. If the wings
-    be very extensive a proportionate mass of air may be struck down, and
-    yield support with so much the less exertion.</p>
-
-  <p>Horizontal flight promises little more than direct screw lift, with the
-    feeble energy of the human muscle. The best modern aëroplanes carry
-    less than 100 pounds per horse power, while an average man must weigh,
-    with a light machine, not less than 200 pounds, and must therefore
-    exert upwards of two horse power during flight. Such an output of
-    energy would exhaust a powerful athlete in a few seconds. Hence from
-    every point of view it appears that Daedalean flight, which still has
-    its devotees in some form, was and always will be utterly impracticable.</p>
-
-  <p>Ruskin finds another objection to the disciples of the winged arm.
-    In his disquisition on the equilibrium of angels he complains that
-    those of the traditional two-wing type are devoid of gravitational
-    balance. Such creatures vex the imagination with apprehensions for
-    their stability; hence they cannot be entirely beautiful. The centroid
-    of an angel is in the small of its back, whereas the center of wing
-    support is well forward; therefore the horizontal poise is absurd and
-    unæsthetic. The scientific artist, consequently, views with pain the
-    picture of a fair lady floating level through space supported only at
-    her front end.</p>
-
-  <p>Milton adroitly forestalls this censure. In the<span class="pagenum" id="Page_8">8</span> conception of his
-    glorious Raphael, he provides consummately for uniform and adequate
-    support:</p>
-
-  <div class="center-container">
-    <div class="poetry">
-      <div class="stanza">
-        <div class="i4">Six wings he wore, to shade</div>
-        <div class="i0">His lineaments divine; the pair that clad</div>
-        <div class="i0">Each shoulder broad, came mantling o’er his breast</div>
-        <div class="i0">With regal ornament; the middle pair</div>
-        <div class="i0">Girt like a starry zone his waist, and round</div>
-        <div class="i0">Skirted his loins and thighs with downy gold,</div>
-        <div class="i0">And colors dipped in Heaven; the third his feet</div>
-        <div class="i0">Shadowed from either heel with feathered mail,</div>
-        <div class="i0">Sky-tinctured grain. Like Maia’s son he stood,</div>
-        <div class="i0">And shook his plumes, that heavenly fragrance filled</div>
-        <div class="i0">The circuit wide.</div>
-      </div>
-    </div>
-  </div>
-
-  <p>Leonardo da Vinci, who was a gifted engineer as well as an artist,
-    devised a flying gear for man which shows some dynamic improvement over
-    the mechanism of the old-time angels, flying gods, and hobgoblins. As
-    shown in the accompanying sketch, it provided for gravitational balance
-    by use of an expanding tail projecting well to the rear. Moreover, the
-    propulsion was to employ both arms and legs. This design is considered
-    very remarkable for the time in which it was produced, probably a few
-    years before the discovery of America; and yet it is but one of Da
-    Vinci’s quaint aëronautical inventions, as will appear later.</p>
-
-  <p>A less futile scheme of aviation may be to saddle the birds. If one
-    eagle can float a child, a few may possibly carry a man. They are
-    physically able; they are inexpensive; they are unwearied, nimble,
-    swift. Some harness, some tuition may be required; but these come
-    to the industrious. Apparently, such locomotion is a sport worth
-    developing; a royal art, if you please; for who would not course the
-    sky in a purple palanquin borne by imperial eagles?</p>
-
-  <p>Kai Kaoos, the King of Persia, is credited with a<span class="pagenum" id="Page_9">9</span> voyage of this kind,
-    as described in the <cite>Shah-Nemeh</cite>, or <cite>King-Book</cite>, written in the tenth
-    century:</p>
-
-  <blockquote>
-    <p>“To the king it became a matter of great concern how he might be
-      enabled to ascend the heavens, without <span class="pagenum" id="Page_10">10</span>wings; and for that purpose he
-      consulted the astrologers, who presently suggested a way in which his
-      desires might be successfully accomplished.</p>
-  </blockquote>
-
-  <div class="figcenter">
-    <a id="Fig_01"><img src="images/i_027.jpg" width="461" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 1.—Da Vinci’s Designs for Human Flying-Gear.</div>
-  </div>
-
-  <blockquote>
-    <p>“They contrived to rob an eagle’s nest of its young, which they reared
-      with great care, supplying them with invigorating food.</p>
-
-    <p>“A frame of aloes-wood was then prepared, and at each of the four
-      corners was fixed perpendicularly a javelin surmounted on the point
-      with the flesh of a goat. At each corner again one of the eagles was
-      bound, and in the middle the king was seated with a goblet of wine
-      before him. As soon as the eagles became hungry they endeavored to get
-      at the goat’s flesh upon the javelins, and by flapping their wings, and
-      flying upwards they quickly raised the throne from the ground. Hunger
-      still pressing on them, and still being distant from their prey, they
-      ascended higher and higher in the clouds, conveying the astonished king
-      far beyond his own country. But after a long and fruitless exertion,
-      their strength failed them, and, unable to keep their way, the whole
-      fabric came tumbling down from the sky, and fell upon a dreary solitude
-      in the Kingdom of Chin, where Kai Kaoos was left a prey to hunger,
-      alone, and in utter despair.”</p>
-  </blockquote>
-
-  <p>One might prefer a single bird, which could be ridden bareback by a man
-    or woman of common equestrian skill. The early philosophers, therefore,
-    sought with some care for such a creature. The following is related by
-    Bishop Wilkins:</p>
-
-  <blockquote>
-    <p>“Cardan and Scaliger doe unanimously affirm, that there is a bird
-      amongst the Indians of so great a bignesse, that his beak is often
-      used to make a sheath or scabbard for a sword. And Acosta tells us of
-      a fowl in Peru called Condores, which will of themselves kill and eat
-      up a whole calf at a time. Nor is there any reason why any other body
-      may not<span class="pagenum" id="Page_11">11</span> be supported and carried in the air, though it should as much
-      exceed the quantity of these fowls as they do the quantity of a flie.
-      Marcus Polus mentions a fowl in Madagascar which he cals a Ruck, the
-      feathers of whose wings are 12 paces, or threescore foot long, which
-      can with as much ease scoop up an elephant as our kites do a mouse.
-      If this relation was anything credible, it might serve as an abundant
-      proof for the present quaere.”</p>
-  </blockquote>
-
-  <p>As the roc has proved a myth, one questions whether a saddle bird
-    may not be evolved by judicious breeding. But opposed to this is the
-    square-cube law of the Greek geometer, by which a learned geologist
-    demonstrated that nature has reached the limit of her resources in the
-    production of large flyers, the ostrich, for example, being too bulky
-    to navigate at all. As a last resource, then, the human dwarf may
-    breed his weight downward to accommodate the bird. Assuredly, the most
-    powerful flyer can carry the lightest human dwarf without difficulty.</p>
-
-  <p>Such aërial cavalry has been projected occasionally, and if fairly
-    developed might have interesting employment. Its military value, to
-    say nothing of its civil uses, would be considerable. An aërial scout
-    that could hide in a tree top, or small cloud, then flit home with full
-    intelligence of the enemy, would be effective and unique. In aggressive
-    warfare it would serve the plan of that ingenious Englishman who
-    proposes to repel a German invasion by dispatching birds to peck holes
-    in the enemy’s war balloons. But here the dwarf might be omitted, if
-    the birds were taught to have a definite interest in attacking aërial
-    cruisers with their beaks, or with steel-armed spurs like those of the
-    Spanish fighting cock, or with talons treated chemically to strike
-    fire. Sparrows with sulphur-pointed toes could easily annihilate an
-    aërial squadron at all combustible.</p>
-
-  <p><span class="pagenum" id="Page_12">12</span></p>
-
-  <p>Recurring to the geologist, it may be added that, having discovered the
-    major limit of feathered navigators, he concluded, as a corollary, that
-    human flight is forever impossible. That was in the latter eighties.
-    In 1901 a versatile astronomer adduced the same law to prove that an
-    aëroplane could not be made to carry a man. Presently, learning that
-    this had been achieved, he proved, in a second mellifluous paper, that
-    an aëroplane could not carry, several men.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a> Having erred twice, he
-    wrote a final article announcing that a flyer is fatuous, anyhow,
-    because she cannot repair her engines in the sky!</p>
-
-  <div class="figcenter">
-    <a id="Fig_02"><img src="images/i_030.jpg" width="600" height="422" alt="" /></a>
-    <div class="caption smcap">Fig. 2.—A Possible Air-scout.</div>
-  </div>
-
-  <p>Of the numerous daring and industrious inventors who, during remote
-    generations, have launched <span class="pagenum" id="Page_13">13</span>themselves in the air on some species of
-    rigid or vibrant wings, a few were men of considerable equipment in
-    philosophy, or mechanics, and enjoyed a sufficient measure of success
-    to deserve passing notice; though it seems that no man before the
-    middle of the eighteenth century made a permanent contribution to the
-    real art of mechanical flight, if we except the ingenious suggestive
-    devices of Leonardo da Vinci. However skilfully their flying apparatus
-    may have been planned, or operated, the results were lost to the world,
-    due to inaccurate or inadequate description. Such inventors were J. B.
-    Dante, in the fifteenth century, and the Marquis de Bacqueville, in the
-    seventeenth. Each of these made one, or more, considerable flights, if
-    we may credit the unwavering testimony of their contemporaries; but
-    neither has left a sketch of his device, nor a school of followers to
-    continue his spectacular practice.</p>
-
-  <p>Jean-Baptiste Dante, a shrewd observer and profound mathematician, who
-    flourished toward the end of the fifteenth century, a contemporary of
-    Da Vinci and Columbus, is reported by the historians of that day to
-    have sailed successfully through the air on nonvibrant wings designed
-    by himself after a careful study of the great soaring birds. Perching
-    above a steep crag on the shore of Lake Trasimene, he set his wings
-    to the wind at a nice angle, as one sets the sails of a vessel; then,
-    lifted by the swelling breeze, he rose grandly aloft and floated far
-    over the waters. Again and again he repeated the experiment, until
-    the fame thereof secured for him a request to make the demonstration
-    at the marriage fêtes of the illustrious general, Barthelmi Alviano.
-    He accepted the invitation, and, starting from the top of the highest
-    tower in the city of Perugia, he sailed over the public square,
-    and balanced himself for a long time in space, amid the shouts and
-    acclamations of the multitude, <span class="pagenum" id="Page_14">14</span>attracted to Perugia by the novelty of
-    his performance. But, sad to relate, the very first time he performed
-    these wonderful maneuvers above the solid ground instead of the lake,
-    one of the levers used to alter the impact angle of his wings gave way,
-    disturbing his aërial poise, and causing him to pitch down upon Notre
-    Dame church, breaking one of his legs. After this he taught mathematics
-    at Venice, where he died of fever at the age of forty years.</p>
-
-  <p>In 1742, the Marquis de Bacqueville, at the age of sixty-two years,
-    announced that on a certain day he would fly from his house on the
-    Seine, traverse the river, and land in the Garden of the Tuileries. A
-    great multitude assembled, crowding both shores and the two bridges.
-    At the appointed moment the Marquis appeared with his pinions, and
-    launched himself from the terrace. He sailed forth in majestic and
-    serene poise, on graceful wings not unlike those of the traditional
-    angels. He was gliding directly toward the Tuileries, and he enjoyed a
-    happy cruise quite to the middle of the river. Then something happened;
-    his movements became fitful and uncertain; he plunged downward and
-    broke his leg on a laundry boat. The reason for his stopping there can
-    only be surmised, for he had nothing to report. He did not quite fulfil
-    his program, but he flew nine hundred feet delightfully, and he landed
-    without getting wet.</p>
-
-  <p>Commentators have marveled as to the nature of the mechanism used by
-    Dante and by De Bacqueville. Historians have strongly attested the
-    fact of the flights, but have overlooked the means. The inventors must
-    have employed aërial gliders of some kind, for adequate motive power
-    was not available before the end of the nineteenth century. Even as
-    an experiment in gliding, or soaring, the achievement of Dante was
-    most daring and wonderful, eclipsing the<span class="pagenum" id="Page_15">15</span> best performances up to the
-    twentieth century. It is strange that in that period of science the
-    survivor of such an experience, and a college professor, should not
-    have left to the world a careful account of such an extraordinary
-    performance. The alleged flights, however, were unquestionably
-    feasible, even in that remote period, for the construction of an
-    aërial glider is a simple task not beyond the capacity of craftsmen
-    in the fifteenth century <span class="smcap">A.D.</span>, or even the fifteenth century
-    <span class="smcap">B.C.</span>, directed by a skilful designer.</p>
-
-  <p>Besides the wing-armed scheme of flight credited to Daedalus, and
-    contemplated by Da Vinci, various other plans were evolved in
-    succeeding years. Aërial chariots and flying machines were devised for
-    the more advantageous use of muscular energy. In all these, of course,
-    the passenger could be both power plant and captain of the ship.</p>
-
-  <p>One of the earliest authenticated devices of this kind was the
-    invention of Blanchard, described by him in the <cite>Journal de Paris</cite>,
-    August 28, 1781, nearly two years before the invention of the hot-air
-    balloon, of which he became later an enthusiastic votary. As his device
-    is but one of a large number that appeared before the close of the
-    nineteenth century, and the advent of light motors, the reader who
-    wishes fuller acquaintance with man-driven airships may be referred
-    to Mr. Chanute’s book, entitled <cite>Progress in Flying-Machines</cite>, which
-    describes a large variety of such inventions, and discusses the merit
-    and weakness of each.</p>
-
-  <p>Blanchard prefaces the description of his machine by answering some
-    criticisms of his project, apparently ventured by his neighbors. “They
-    object to me,” he writes, “that flying is not the business of man, but
-    rather of the feathered birds. I reply that feathers are not at all
-    necessary to the bird for flight; any fabric suffices. The fly, the
-    butterfly, the bat,<span class="pagenum" id="Page_16">16</span> etc., fly without feathers and with fanlike wings
-    of material resembling horn. It is, then, neither the material nor
-    the form that causes flight, but the volume and the celerity of the
-    movement, which should be as lively as possible.</p>
-
-  <p>“They object, moreover, that a man is too heavy to lift himself alone
-    with wings, much less in a vessel which of itself presents enormous
-    weight. I reply that my ship is extremely light; as to the man’s
-    weight, I pray that attention be given to that which M. de Buffon says
-    in his <cite>Histoire Naturelle</cite>, on the subject of the condor; this bird,
-    though of enormous weight, easily lifts a two-year-old heifer weighing
-    at least a hundred pounds, the whole with wings of about thirty to
-    thirty-six feet expanse.”</p>
-
-  <p>He then describes the vessel as a little ship four feet long by two
-    feet wide, having on either side two posts, each supporting a wing ten
-    feet long, the whole forming a parasol twenty feet in diameter. The
-    construction was illustrated by an engraver, who had seen the vessel
-    and was convinced of its practicability. In conclusion, the inventor
-    writes that people shall see him cleave the air with more speed than
-    the crow, and that without losing his breath, being protected by a
-    pointed mask of peculiar construction. But, as he failed to make good
-    his promises, he was subjected to ridicule, as well as praise, by the
-    local press, one of the caricatures portraying him in the act of making
-    an ascension before a concourse of bulging-eyed savants and long-eared
-    jackasses, wearing spectacles to accentuate the appearance of wisdom
-    and solemnity.</p>
-
-  <p>The scientific coterie of Paris were apparently impatient of the
-    attention shown Blanchard by the press and people. Accordingly, in May,
-    1782, the distinguished astronomer, De Laland, of the French Academy,
-    administered a mild rebuke to the editors<span class="pagenum" id="Page_17">17</span> of the <cite>Paris Journal</cite>.
-    “Gentlemen,” he wrote, “you have given so much time to air ships and
-    divination rods that one might eventually think that you believe in
-    these follies, or that the scientists who coöperate with your journal
-    have nothing to say to dispel these absurd pretensions. Permit me,
-    therefore, gentlemen, to occupy some lines in your journal to assure
-    your readers that if the savants are silent it is only because of their
-    contempt.</p>
-
-  <div class="figcenter">
-    <a id="Fig_03"><img src="images/i_035.jpg" width="480" height="522" alt="" /></a>
-    <div class="caption smcap">Fig. 3.—Blanchard’s Flying-machine.</div>
-  </div>
-
-  <p>“It has been demonstrated to be impossible for a man in any manner
-    whatever to raise himself, or even to sustain himself, in the air. M.
-    Coulomb, of the Academy of Sciences, at one of our meetings a year ago,
-    read a paper in which he showed clearly, by calculating the power of
-    a man, determined by experiments, that he would require wings two or
-    three<span class="pagenum" id="Page_18">18</span> thousand feet long moved three feet per second; hence no one but
-    an ignoramus would make an attempt of this kind.”</p>
-
-  <p>Not many months after this lofty deliverance, Blanchard took De Lalande
-    up in a balloon—“the dead borne by the dumb.”</p>
-
-  <p>Coulomb’s calculation that a man’s pinions should be half a mile long
-    must have been discouraging to those inventors who believed in him;
-    for, granting that such wings could lift a man, who could lift the
-    wings? And at that date the steam engine was only beginning to develop;
-    the petroleum engine was hardly thought of. No wonder that people
-    turned eagerly to the balloon when it finally appeared.</p>
-
-  <p>There has been some controversy as to what person first clearly
-    conceived a feasible design for a balloon. The conception was
-    certainly not new to the world in 1783, when Joseph Montgolfier made
-    his classical experiment. Indeed, prior to that date three distinct
-    principles of aërial flotation had been entertained by natural
-    philosophers; first, that a boat could be so formed of heavy material
-    as to ride on the upper surface of the atmosphere, as a metallic vessel
-    floats on the water; second, that a closed hull, comprising a partial,
-    or complete, vacuum, could be made light enough to rise; third, that
-    a bag could be made buoyant by filling it with material lighter than
-    air. Of course, it is now clear to men versed in mathematics that only
-    the light-gas principle is mechanically applicable. But the vacuum
-    principle still has adherents among inventors who are too “practical”
-    to understand, or trust, exact computation; and the first principle,
-    though now discarded by everyone, was plausible enough, even to
-    accomplished scientific men, before the experiments of Torricelli, and
-    his invention of the barometer, made in 1643. It may, therefore, be
-    interesting to notice some of the<span class="pagenum" id="Page_19">19</span> proposed, or reported, air ships
-    based upon these various principles. The following is from <cite>Mendoza,
-    Viridario, libri III, probl. 47</cite>:</p>
-
-  <blockquote>
-    <p>“Any brass vessel full of air, which otherwise would sink, is sustained
-      on the surface of the water, though naturally of much greater specific
-      gravity; consequently a wooden ship, or one of any other material,
-      placed on the summit of an aërial superficies and filled with
-      elementary fire, will be sustained in that position till the gravity
-      of the vessel becomes greater than the sustaining power of the fire it
-      contains.”</p>
-    </blockquote>
-
-  <p>This is a clear scientific exposition of a plan for navigating the
-    atmosphere on its upper surface, assuming a distinct upper surface
-    to exist. In commenting on this passage, the Jesuit Schottus, in his
-    <cite>Magia Universalis</cite>, uses an expression which indicates his belief that
-    a vessel can be made to <em>float in the air</em> by filling it with ether, or
-    the element of fire. He says:</p>
-
-  <blockquote>
-    <p>“In such terms has this matter been treated by Mendoza (died 1626); nor
-      is there any improbability involved in his view, whether the element
-      of fire be placed above the air, or, what is still more credible, the
-      ether—that is, the purest air. Although any wood, iron, copper, lead,
-      and such like metals are weightier than an equal volume of water, and
-      for that reason will sink in water when placed there alone, yet if
-      fabricated into hollow shapes, and filled with our impure and heavy
-      air, they swim upon waters, and are adapted to the construction of
-      ships, and are sustained by water without danger of immersion; thus,
-      although these bodies are of greater specific gravity than our air,
-      nevertheless, when shaped into a boat and filled with that very light
-      material, they can <em>float in the air</em>, and are suitable material for
-      the construction of small ships, because<span class="pagenum" id="Page_20">20</span> the entire work composed of
-      the little ship and the ether can be made lighter than an equal volume
-      of our impure air, even in the highest region.”</p>
-    </blockquote>
-
-  <p>As Roger Bacon proposed a similar device in 1542, Mendoza’s was not
-    entirely new and may not have been original. Bacon, describing his
-    aërial vessel, says: “It must be a large, hollow globe of copper, or
-    other suitable metal, wrought extremely thin, in order to have it
-    as light as possible. It must then be filled with ‘ethereal air or
-    liquid fire,’ and then be launched from some elevated point into the
-    atmosphere, where it will float like a vessel on water.”</p>
-
-  <p>In the year 1646 another learned Jesuit published a book, <cite>Ars Magna
-    Lucis et Umbræ in Mundo</cite>, in which he relates an episode indicating
-    that one of his order had made use of a hot-air balloon to intimidate
-    some ignorant pagans. The following demonstration, if reported by a
-    modern missionary, would be accepted as a matter of course; why, then,
-    should we gravely question the story, since it describes an achievement
-    quite possible at the time, assuming that the necessary materials were
-    available? And even assuming the report to be fictitious, still it is a
-    scientific description of a practicable hot-air balloon, presented and
-    credited by a learned scholar and accomplished mathematician more than
-    a century before the balloon was publicly exhibited by the illustrious
-    Frenchmen. He writes:</p>
-
-  <blockquote>
-    <p>“I know that many of our fathers have been rescued from the most
-      imminent dangers amongst the barbarians of India by such inventions.
-      These were cast into prison, and whilst they continued ignorant of
-      any means of effecting their liberation, some one, more cunning than
-      the rest, invented an extraordinary machine, and then threatened the
-      barbarians, unless they liberated his companions, that they would
-      behold in a short time some extraordinary portents,<span class="pagenum" id="Page_21">21</span> and experience
-      the visible anger of the Gods. The barbarians laughed at the threat.
-      He then had constructed a dragon of the most volatile paper, and in
-      this he enclosed a mixture of sulphur, pitch, wax, and so artistically
-      prepared all his materials, that, when ignited, it would illumine
-      the machine, and exhibit the following legend in their vernacular
-      idiom, <em>The Anger of God</em>. The body being formed and the ingredients
-      prepared, he then affixed a long tail, and committed the machine to
-      the heavens, and, favored by the wind, it soared aloft towards the
-      clouds. The spectacle of the dragon so brilliantly lit was terrific.
-      The barbarians, beholding the unusual motion of the apparition, were
-      smitten with the greatest astonishment, and now, remembering the
-      threatened anger of Deity and the words of the father, they were in
-      fear of expiating the punishment he had prognosticated for them.
-      Therefore, without delay, they threw open the gates, they suffered
-      their prisoners to go forth in peace and enjoy their freedom. In the
-      meantime the fire seized on the machine and set it in a blaze, and
-      with an explosion, which was interpreted as an expiring declaration of
-      satisfaction, it, apparently of its own accord, vanished from sight,
-      as if it had accomplished its supernatural mission. Thus the fathers,
-      through the apprehension which this natural manifestation inspired,
-      obtained that which could not be purchased with a large amount of gold.”</p>
-  </blockquote>
-
-  <p>Perhaps the reader will permit another anecdote, not entirely for its
-    scientific value, but because he may like to compare the attitude of
-    people toward aërial navigation in the dark ages with the attitude of
-    his neighbors at the opening of the twentieth century. In two histories
-    by Jef le Ministre and De Colonia, of the town of Lyons, the following
-    account is given:</p>
-
-  <blockquote>
-    <p>“Toward the end of Charlemagne’s reign, persons <span class="pagenum" id="Page_22">22</span>who lived near Mount
-      Pilate in Switzerland, knowing by what means pretended sorcerers
-      traveled through the air, resolved to try the experiment, and compelled
-      some poor people to ascend in an aërostal. This descended in the town
-      of Lyons, where they were immediately hurried to prison, and the
-      mob desired their death as sorcerers. The judges condemned them to
-      be burned; but the Bishop Agobard suspended the execution, and sent
-      for them to his palace, that he might question them. They answered:
-      ‘Qu’ils sont du pays meme, que des personnes de consideration les ont
-      forcés de se laisser conduire, leur promettent qu’ils verroient des
-      chose merveilleuses; et qu’ils sont veritablement descendu par l’air.’
-      Agobard, though he could not believe this fact, gave credence to their
-      innocence, and allowed them to escape. On this occasion he wrote a
-      work on the superstition of the time, in which he demonstrated the
-      impossibility of rising in the air; that it is an error to believe in
-      the power of magic; and that it has its existence in the credulity
-      solely of the people.”</p>
-  </blockquote>
-
-  <p>One of the first men to make an aërial model like a fire balloon was
-    the celebrated Brazilian, Bartholomeo-Lourenco de Gusmao, who in his
-    day was nicknamed the “flying man,” and who is reported to have made
-    a remarkable experiment in aërial locomotion at Lisbon. The following
-    account of it is found in a manuscript of Ferreira:</p>
-
-  <blockquote>
-    <p>“Gusmao made his experiment on August 8, 1709, in the court of the
-      Palace of the Indies, before his majesty and a large and distinguished
-      audience, with a globe which lifted itself softly to the height of the
-      hall of the Ambassadors, then descended in like manner. It was borne up
-      by certain materials which burned and which the inventor himself had
-      ignited.”</p>
-  </blockquote>
-
-  <p>All the details of this description, which was written <span class="pagenum" id="Page_23">23</span>a generation
-    or more before the Montgolfier experiment, suggest at once a hot-air
-    balloon. But a note printed in 1774 and cited by Cavallo explains that
-    the globes must have been transported by gas. It is certain that early
-    in 1709 Gusmao applied to the King for a patent and sole right to some
-    such invention, desiring an injunction and severe penalty against
-    all infringements. The application sets forth a machine capable of
-    journeying through the air faster than over land or sea, competent
-    to carry messages five or six hundred miles a day to troops, or the
-    most distant countries, and even adequate to explore regions about the
-    poles. Quite a modern promoter Señor Gusmao. The King in reply issued
-    the following decree:</p>
-
-  <blockquote>
-    <p>“Agreeably to the advice of my council, I order the pain of death
-      against the transgressor. And in order to encourage the suppliant to
-      apply himself with zeal toward improving the machine which is capable
-      of producing the effects mentioned by him, I also grant him the first
-      Professorship of Mathematics in my University of Coimbra, and the first
-      vacancy in my College of Barcelona, with the annual pension of 600,000
-      reis during his life.”</p>
-  </blockquote>
-
-  <p>The “patent” seemed liberal enough, and yet Gusmao never resumed
-    his aërial experiments. He was accused of magic, and may have
-    feared persecution on that account; accordingly he engaged in naval
-    construction till 1724, when he left Portugal.</p>
-
-  <p>The first vacuum balloon was proposed by the Jesuit father, Francis
-    Lana, and described in his book <cite>Podromo dell’Arte Maestra Brecia</cite>,
-    which appeared in 1670. Though not a practical project like Gusmao’s,
-    it was very ingenious, and marks an interesting phase in the evolution
-    of the fundamental idea of the air ship, or “balloon” as it was called
-    by the inventor, who then coined the word now in common <span class="pagenum" id="Page_24">24</span>use. Lana
-    proposed to use four copper spheres each 25 feet in diameter and
-    1/225 inches in wall thickness, quite well exhausted of air, to give
-    ascensional force which he computed at 1,200 pounds aggregate for the
-    four spheres. From these he would suspend the passengers in a boat
-    having a mast and sail to propel the ship in time of favorable wind.
-    Having computed the buoyancy according to well-known physical laws, he
-    could see no possible objection to his project “unless,” he writes,
-    “it be that God would never permit this invention to be practically
-    applied, in order to prevent the consequences that would ensue
-    therefrom in the civil and political government of men.”</p>
-
-  <div class="figcenter">
-    <a id="Fig_04"><img src="images/i_042.jpg" width="352" height="505" alt="" /></a>
-    <div class="caption smcap">Fig. 4.—Lana’s Proposed Vacuum Balloon.</div>
-  </div>
-
-  <p>Of recent years inventors having less delicate scruples about
-    embarrassing Providence, have revived <span class="pagenum" id="Page_25">25</span>Lana’s project with
-    improvements. It has been proposed to replace the sail by a
-    motor-driven propeller, and to ensure the hull against collapse from
-    the prodigious external air pressure—a ton per square foot—by ample
-    internal bracing. Even within the past twelve months this scheme has
-    been soberly advocated by several technical journals and by the author
-    of an elaborate book on aërial warfare. To a mathematician this is
-    amusing, when not too pathetic; for it can be rigorously proved that
-    no vacuum balloon of present day material, whatever its design, can
-    possibly resist crushing if made light enough to float.</p>
-
-  <p>In 1887 Walter Wellman described in the <cite>Associated Press</cite> a steel
-    vacuum balloon 144 feet in diameter and 654 feet long in which a
-    Chicago doctor proposed to carry passengers to the North Pole, at
-    incredible speed, if they would furnish him $130,000 to meet the
-    expenses of construction. “Here is a most excellent opportunity,” wrote
-    Wellman, “for all who would like to win fame by being one of the party
-    which shall set foot upon that icy <i xml:lang="la">ignis fatuus</i> of many nations and
-    two centuries.” Two decades later Mr. Wellman organized, after his own
-    ideas, an aërial expedition to the North Pole; but he no longer favored
-    starting from Chicago in a vacuum balloon with a party of stockholders.</p>
-
-  <p>It may be added that the inventor of the great steel vacuum balloon,
-    after organizing the Trans-Continental Aërial Navigation Company, and
-    failing to raise all of the $130,000, sought aid from the national
-    government. Here was an interesting situation; a doctor ignorant
-    of mechanics, with the plans for a mammoth and impossible balloon,
-    appealing for aid to a congress, supremely shy of air ships, even
-    though recommended by its ablest military advisers. But in this case
-    there was a capable lobby. The bill<span class="pagenum" id="Page_26">26</span> for this physically impossible
-    balloon actually passed the House, and was finally defeated only by
-    the timely effort of a few scientific men who, by easy calculation,
-    proved the absurdity of the invention. As the reader may like to see a
-    mathematical proof of the impossibility of a vacuum balloon, since such
-    projects arise frequently, the argument is given in <a href="#appendix_I">Appendix I</a>.</p>
-
-  <hr class="page" />
-  <div class="chapter" >
-    <span class="pagenum" id="Page_27">27</span>
-    <h2>PART I<br />
-      <span class="xlarge">GROWTH OF AËROSTATION</span></h2>
-  </div>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_I">
-    <span class="pagenum" id="Page_29">29</span>
-    <h3>CHAPTER I<br />
-    <small>EARLY HISTORY OF PASSIVE BALLOONS</small></h3>
-  </div>
-
-  <div class="center-container">
-    <div class="poetry">
-      <div class="stanza">
-        <div class="i0">Oh, that I could as smoke arise,</div>
-        <div class="i0">That rolls its black wreathes through the air;</div>
-        <div class="i0">Mix with the clouds, that o’er the skies</div>
-        <div class="i0">Show their light forms, and disappear:</div>
-        <div class="i0">Or like the dust be tossed</div>
-        <div class="i0">By every sportive wind till all be lost!</div>
-      </div>
-    </div>
-  </div>
-
-  <div class="smcap right2 mb2">—Æschylus.</div>
-
-  <p><span class="smcap">If</span> desire is sometimes the mother of invention, doubtless the wish to
-    “mix with the clouds,” or “as smoke arise,” suggested to man his first
-    means of aërial locomotion. Indeed this is openly avowed by Joseph
-    Montgolfier. “Smoke rises in the chimney; why not encage this smoke,
-    and have an available force.” But before describing his fundamental
-    experiments of 1783, let us notice the less conspicuous ones,
-    though not less philosophical, of his immediate predecessors in the
-    development of aëronautic science.</p>
-
-  <p>It has been seen, that many years before 1783, inventors had clearly
-    conceived the true principle of the balloon, and would be glad to
-    avail themselves of an element of sufficiently low specific gravity
-    for aërial flotation. The desired opportunity came when, in 1766,
-    Henry Cavendish published his experiments, proving that hydrogen is
-    many times lighter than air. Immediately after this, Dr. Black, the
-    famous chemist and natural philosopher of Edinburgh, conceived the
-    idea that a thin light vessel filled<span class="pagenum" id="Page_30">30</span> with hydrogen should be able to
-    float and rise in the atmosphere, ideas that he conveyed to his friends
-    and expressed in his lectures a year or two after the appearance of
-    Cavendish’s publication. But he contented himself with merely pointing
-    the way to an obviously practicable invention, leaving, as a university
-    professor should, the development of the scientific idea to inventors
-    and constructive engineers.</p>
-
-  <p>Intermediate between Dr. Black, the pure scientist, and the Montgolfier
-    brothers manufacturers, came Tiberius Cavallo, an Italian philosopher
-    living in England, who made the first small hydrogen balloons. In
-    a note presented to the Royal Society of London, June 20, 1782, he
-    relates experiments that seem to entitle him to all the credit of
-    inventing the balloon except success on a practical scale. He made
-    hydrogen soap bubbles which rose beautifully in the air, an experiment
-    that has been repeated throughout the world in every chemical
-    laboratory since his day. He made a variety of gum bubbles and varnish
-    bubbles inflated with hydrogen; but curiously enough these failed
-    to rise, though it is known that such bubbles can be made to float
-    handsomely.<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">[5]</a> He inflated carefully prepared gold-beater skin and
-    failed, though gold-beater skin balloons, both large and small, are now
-    a marketable commodity. Finally he constructed paper balloons which he
-    tried to float by use of hydrogen, but without success, though a year
-    later the Montgolfier brothers easily made paper bags arise with hot
-    air, and Professor Charles ascended in a large silk balloon inflated
-    with hydrogen.</p>
-
-  <p><span class="pagenum" id="Page_31">31</span></p>
-
-  <p>The cause of Cavallo’s interesting failures reveals itself in his own
-    account of one of his pioneer experiments. In his <cite>History and Practice
-    of Aërostation</cite>, he relates that he constructed, of fine Chinese paper,
-    a cylindrical balloon having short conical ends and a calculated
-    buoyancy of twenty-five grains, when properly inflated with hydrogen.
-    This bag, carefully deflated of air by compression between the hands,
-    he suspended above a large bottle connected with it by a glass tube,
-    and supplied with materials for generating hydrogen; in this case a
-    mixture of dilute sulphuric acid and iron filings. When the hydrogen
-    was evolving quite rapidly, he expected to see the paper sac expand
-    and fill out with proportionate speed; but to his surprise it remained
-    perfectly flat, while the room filled with the strong and disagreeable
-    odor of the “inflaminable air.” He then realized that the carefully
-    made sac of paper, which could be so easily inflated with air, was very
-    permeable to hydrogen, allowing it to escape instantly, as through
-    porous cloth, or netting.</p>
-
-  <p>Cavallo desisted when the goal was within reach. His plans were
-    practicable, but he abandoned them too readily. Why did he not varnish
-    his balloon when it leaked? He could thus so easily have inaugurated
-    the art of aërial navigation. But after salting the bird’s tail he let
-    it escape.</p>
-
-  <p>Various accounts have been given of the steps by which the Montgolfiers
-    were led to their invention of the balloon. They are said to have
-    studied and discussed projects for aërial locomotion a decade before
-    hitting upon their first successful device; at one time filling a paper
-    bag with smoke ineffectually; again with steam, and again trying, but
-    in vain, to employ hydrogen. The following apparently reliable account
-    is given by a friend of the Montgolfiers, Baron Gernando, in his
-    biographical notice of Joseph<span class="pagenum" id="Page_32">32</span> Montgolfier, having obtained the story
-    from the inventor himself.</p>
-
-  <p>Joseph Montgolfier found himself at Abignon, and it was at the time
-    when the combined armies held the siege of Gibraltar. Alone, in the
-    chimney corner, dreaming, as usual, he was contemplating a sort of cut
-    that represented the work of the siege; he grew impatient observing
-    that one could not reach the body of the place either by land or
-    sea. “But could not one arrive there through the air? Smoke rises in
-    the chimney; why not store this smoke in such a manner as to form an
-    available force?” His mind calculated instantly the weight of a given
-    surface of paper, or taffeta; he constructed without delay his little
-    balloon, and saw it rise from the floor, to the great surprise of his
-    hostess, and with a peculiar joy. He wrote on the spot, to his brother
-    then at Annonay: “Prepare immediately a supply of taffeta and cordage,
-    and you shall see the most astonishing thing in the world.”</p>
-
-  <p>A quainter story is told by Brisson in his <cite>Dictionary of Physics</cite>. He
-    says: “I can only repeat what the citizen Montgolfier himself told me,
-    when he came to Paris to announce his discovery; that the citizeness
-    Montgolfier having placed a skirt on an open-wicker basket, such as
-    women use to dry linen, the skirt was lifted to the ceiling. It is from
-    this fact that the citizens Montgolfier started.”</p>
-
-  <p>Whatever the preliminaries, the Montgolfier brothers finally made the
-    experiment of holding a paper bag over a fire fed with wet straw and
-    wool. It is doubtful whether they purposed to fill it with smoke, or
-    with hot air or an electrical cloud. They knew that a cloud of some
-    kind rises from such a fire, and they wanted to harness it. Their
-    first balloon took fire and went up as smoke. But they were rich
-    paper manufacturers, and soon had another balloon <span class="pagenum" id="Page_33">33</span>of 700 cubic feet
-    capacity. This rose from the fire to a height of 1,000 feet, carrying
-    no fuel with it. Thus two practical<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">[6]</a> men had made fire lift a paper
-    sac; let the Academy explain how. The baby Aërostation was born.</p>
-
-  <p>How fortuitous the primal steps of science! Galvanism from the twitch
-    of a frog’s leg; aërostation from the puff of a petticoat! There had
-    been no year in thirty centuries when people could not easily have
-    built a hot-air balloon. All the materials were available; only a
-    little thought was wanting. A simple sketch sent to a Roman tailor,
-    or tent-maker, could have furnished a woven bag competent to lift
-    passengers from the heart of the Coliseum, to the wonder and delight
-    of a hundred thousand spectators. Yet the genius that could design the
-    Coliseum, or cover its vast enclosure with canvas, failed to think of
-    the magic bag that would have enhanced so much the ingenious shows of
-    a show-loving people. That device was an inspiration destined to a
-    common Frenchman at no uncommon period of science. The hydrogen balloon
-    arrived in the natural and logical order of scientific progression;
-    but the hot-air bag might have presented itself at any time since the
-    birth of weaving. It was a happy thought, like the ophthalmoscope,
-    or jack-knife—quaint modern creations of constant use or comfort to
-    mankind.</p>
-
-  <p>The public inauguration of aëronautics occurred on June 5, 1783, at
-    Annonay, the home of the Montgolfier family, 36 miles from Lyons.
-    The states of Vivarais being assembled at that place, were invited
-    to witness the ascension. The Deputies and many spectators found in
-    the public square an enormous <span class="pagenum" id="Page_34">34</span>bag which, with its frame, weighed 300
-    pounds, and would inflate to a ball 35 feet in diameter. When told
-    that this huge mass would rise to the clouds they were astonished and
-    incredulous. The Montgolfiers, however, lit a fire beneath and let the
-    bag speak for itself. It gradually distended, assuming a beautiful
-    form, and struggling to free itself from the men who were holding it.
-    At a given signal it was released; it ascended rapidly, and in ten
-    minutes<span class="pagenum" id="Page_35">35</span> attained a height of 6,000 feet. It drifted a mile and a half
-    and sank gently to the ground.</p>
-
-  <div class="figcenter">
-    <a id="Fig_05"><img src="images/i_052.jpg" width="351" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 5.—Montgolfier’s Experimental Balloon.</div>
-  </div>
-
-  <p>When the French Academy learned of this event they desired to have
-    an ascension in Paris, and at once started a public subscription to
-    defray the expense of constructing and inflating a balloon. They
-    placed the work in charge of the physicist Charles, after inviting the
-    Montgolfiers to Paris, and finding they could not come immediately.
-    Charles proved more than a substitute; he became a fertile inventor and
-    a rival in the new field. Aided by the skill of the Robert brothers, he
-    made a silk globe varnished with dissolved rubber, and filled it with
-    hydrogen, which is many times lighter than hot air. The operation of
-    filling occupied three days, consuming 500 pounds of sulphuric acid and
-    half a ton of iron. The globe was 13 feet in diameter, and designated
-    a “balloon,” or big ball. This had next to be moved from the place of
-    filling, in the Place des Victoires, to the Champ de Mars, two miles
-    distant, in order to have space enough to accommodate the increasing
-    crowd of spectators. Accordingly, on the 26th it was conveyed thither,
-    in the dead of night, preceded by lighted torches, surrounded by a
-    cortege, and escorted by foot and horse guards. Impressive and weird,
-    indeed, was this nocturnal caravan of troops and towering globe
-    advancing slowly through the dark and silent streets. The astonished
-    cab drivers knelt humbly, hat in hand, while the procession passed.</p>
-
-  <p>The ascent of this, the first hydrogen balloon, was a popular and
-    a memorable event. The field was lined with troops. The curious
-    spectators had thronged every thoroughfare and darkened every housetop.
-    It was an all day festival, inaugurating a peculiarly French science,
-    with French animation. The booming of cannon announced to all Paris
-    the<span class="pagenum" id="Page_36">36</span> impending flight of the balloon. At five o’clock, in the presence
-    of 50,000 spectators, and in a shower of rain, the balloon rose more
-    than half a mile and entered the clouds. The people overwhelmed with
-    surprise and enthusiasm, stood gazing upward, despite the rain,
-    observing every maneuver till the vessel had ascended and faded from
-    view.</p>
-
-  <div class="figcenter">
-    <a id="Fig_06"><img src="images/i_054.jpg" width="308" height="419" alt="" /></a>
-    <div class="caption smcap">Fig. 6.—Charles’ First Hydrogen Balloon.</div>
-  </div>
-
-  <p>The landing of this little balloon did not leave it in a condition to
-    exhibit proudly to future generations. After drifting three quarters
-    of an hour, it fell in a field near Gonesse, a village fifteen miles
-    from the place of ascension, apparently ruptured from overdistention.
-    The villagers flocked about it with curiosity and trepidation, ignorant
-    of its nature, whether of bird kind or monster; and doubtful of its
-    origin, whether natural or satanic. They fell upon it with flails and
-    pitchforks. When struck it smelt strongly of sulphur, indicating a
-    diabolic source. They finally hitched it to the tail of a horse which
-    galloping away in terror, badly damaged it.<span class="pagenum" id="Page_37">37</span> Whether this destruction
-    was wrought through fear or rustic hilarity, it induced the government
-    of France to issue a notice to the public explaining the innocuous
-    nature of a simple balloon.</p>
-
-  <p>In the meantime Joseph Montgolfier, having reached Paris, had
-    constructed a waterproof linen balloon 46 feet in diameter and
-    ornamented in oil colors, which was to be publicly launched at
-    Versailles. On September 19, 1783, the king and queen, the court and a
-    vast throng of people of every rank and age, assembled to witness the
-    ascension. Montgolfier explained to them every detail, and finally lit
-    the fire, about one o’clock. The great bag gradually expanded, rounding
-    out in eleven minutes to a beautiful globular form, tugging upward with
-    a force of seven hundred pounds. Beneath was suspended a wicker cage
-    containing the first aërial passengers—a sheep, a rooster and a duck.
-    The vessel rose majestically above the applauding multitude to a height
-    of fourteen hundred feet, and drifted some two miles in eight minutes,
-    descending gradually in the wood at Vaucresson. The animals were tipped
-    out on landing; but, when found by two game-keepers, they were none the
-    worse for their strange journey. The sheep was grazing and the cock
-    crowing, says one report, while another relates that the sheep had
-    trampled on the rooster and lamed him.</p>
-
-  <p>Stephen Montgolfier now wishing to send up human passengers, made a
-    balloon of 100,000 cubic feet capacity. It was shaped like a full lemon
-    pointing upward, with a cylindrical neck below, 16 feet in diameter.
-    Around this neck was a wicker balcony three feet wide, to carry the
-    aëronauts, bundles of straw for fuel, pails of water and sponges to
-    extinguish incipient conflagrations, here and there in the balloon,
-    during a journey. Through stokeholes in<span class="pagenum" id="Page_38">38</span> the side of the neck sheaves
-    of straw could be forked to the grate suspended centrally below by
-    radial chains. During inflation the base of the balloon rested on a
-    platform, and its top was supported by a rope stretched between two
-    poles. The vessel when completed, in a garden of the Faubourg St.
-    Antoine, was 85 feet high by 48 feet across, and weighed 1,600 pounds.
-    About its zone, painted in oil, were elegant decorations; portraits,
-    cyphers of the king’s name, fleur-de-lis, with fancy borders below and
-    above; while higher still, on the arching dome of the bag, were all the
-    signs of the celestial zodiac.</p>
-
-  <p>The handsome vessel was now ready; but what daring captain should
-    navigate her? King Louis proposed two prisoners who were under sentence
-    of death, and had to be killed somehow. But the brave Pilâtre de
-    Rozier protested indignantly: “Eh quoi! de vils criminels auraient
-    les premiers la gloire de senlever dans les airs! Non, non, cela ne
-    sera point.” He stirred up the city, and finally prevailed, through
-    the entreaties of the Marquis d’Arlandes, who secured from the king
-    permission to accompany his friend.</p>
-
-  <p>After some days of preliminary practice in maneuvering the tethered
-    balloon, these gentlemen were ready for an aërial voyage. On November
-    21, 1783, the balloon was inflated in the garden of La Muette palace,
-    and stocked with enough straw for an hour’s journey. When all was ready
-    Pilâtre de Rozier and the Marquis d’Arlandes stepped with eager courage
-    into the gallery taking opposite sides to ensure proper balance. At two
-    o’clock they rose splendidly, amid the acclamations of a vast throng
-    of spectators, and at the height of 280 feet, removing their hats,
-    saluted the surprised multitude. Encountering a south blowing wind,
-    they drifted five miles in some twenty minutes, and landed safely in a<span class="pagenum" id="Page_39">39</span>
-    field. The apparatus was soon assembled on a cart and returned to the
-    Faubourg St. Antoine, where it was originally constructed. The details
-    of this first human voyage in a balloon are very interesting and well
-    told in a letter written by the Marquis d’Arlande to a member of the
-    French Academy.</p>
-
-  <div class="figcenter">
-    <a id="Fig_07"><img src="images/i_057.jpg" width="496" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 7.—Montgolfier’s Passenger Balloon.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_40">40</span>“At this time M. Pilâtre said: ‘You do nothing, and we shall not
-    mount.’ ‘Pardon me,’ I replied. I threw a truss of straw upon the
-    fire, stirring it a little at the same time, and then quickly turned
-    my face back again; but I could no longer see La Muette. Astonished,
-    I gave a look to the direction of the river.... M. Pilâtre then said,
-    ‘See, there is the river, and observe that we descend.’ ‘Well, then,
-    my friend, let us increase the fire;’ and we worked away. But instead
-    of crossing the river, as our direction seemed to indicate, which
-    carried us over the house of the Invalides, we passed along the island
-    of Cygnes, reëntered over the principal bed of the river, and advanced
-    up it as far as the gate de la Conference. I said to my intrepid
-    companion: ‘See, there is the river &amp;c.’ I stirred the fire, and took
-    with the fork a truss of straw, which from being too tight, did not
-    take fire very easily. I lifted it and shook it in the middle of the
-    flame. The next moment I felt as if I were lifted up from under the
-    arms, and said to my companion, ‘Now we mount, &amp;c.’ At the same time
-    I heard a noise toward the top of the machine, as if it were going to
-    burst; I looked, but did not see anything. However, as I was looking
-    up, I felt a shock, which was the only one I experienced. The direction
-    of the motion was from the upper part downwards. I said then: ‘What
-    are you doing? Are you dancing?’ ‘I don’t stir,’ said he. ‘So much the
-    better,’ I replied, ‘it is then a new current, which, I hope, will push
-    us over the river.’ In fact, I turned myself in order to see where we
-    were, and I found myself between l’École Militaire and les Invalides,
-    beyond which place we had already gone about 2,500 feet. M. Pilâtre
-    said at the same time: ‘We are on the plain.’ ‘Yes,’ said I, ‘and
-    we<span class="pagenum" id="Page_41">41</span> advance.’ ‘Work on,’ said he. I then heard another noise in the
-    machine, which appeared to be the effect of a rope breaking. This fresh
-    admonition made me examine attentively the interior of our habitation.
-    I saw that the part of the machine which was turned toward the south
-    was full of round holes, many of which were of a considerable size. I
-    then said: ‘We must descend,’ and at the same time I took the sponge
-    and easily extinguished the fire, which was round some holes that I
-    could reach; but leaning on the lower part of the linen, to observe
-    whether it adhered firmly to the surrounding circle, I found that the
-    linen was easily separated from it, on which I repeated that it was
-    necessary to descend. My companion said: ‘We are over Paris.’ ‘Never
-    mind that,’ said I, ‘but look if there appears any danger for you on
-    your side—are you safe?’ He said: ‘Yes.’ I examined my side, and found
-    that there was no danger to apprehend. Farther, I wetted with a sponge
-    those cords which were within my reach. They all resisted, except two,
-    which gave way. I then said: ‘We may pass over Paris.’ In doing this,
-    we approached the tops of houses very sensibly; we increased the fire,
-    and rose with the greatest ease. I looked below me, and perfectly
-    discovered the Mission Étranger. It seemed as if we were going toward
-    Saint-Sulpice, which I could perceive through the aperture of our
-    machine. On rising a current of air made us leave this direction, and
-    carried us toward the south. I saw on my left a sort of forest, which
-    I took to be the Luxembourg; we passed over the Boulevard, and then I
-    said: ‘Let us now descend.’ The fire was nearly extinguished; but the
-    intrepid M. Pilâtre, who never loses his presence of mind, and who
-    went forward, imagining that we were going against the mills that are
-    between Petite Gentilly and the Boulevard, admonished me.<span class="pagenum" id="Page_42">42</span> I threw a
-    bundle of straw on the fire, and shaking it in order to inflame it more
-    easily, we rose, and a new current carried us a little toward our left.
-    M. Rozier said again: ‘Take care of the mills’; but as I was looking
-    through the aperture of the machine, I could observe more accurately
-    that we could not meet with them, and said: ‘We are there.’ The moment
-    after, I observed that we went over a piece of water, which I took
-    for the river, but after landing, I recollected that it was the piece
-    of water, &amp;c. The moment we touched the ground, I raised myself up to
-    the gallery and perceived the upper part of the machine to press very
-    gently on my head, I pushed it back, and jumped out of the gallery, and
-    on turning toward the machine, expected to find it distended, but was
-    surprised to find it perfectly emptied and quite flattened, &amp;c.”</p>
-
-  <p>While the foregoing experiment was in progress, plans were matured for
-    the construction of a hydrogen balloon large enough to support two
-    passengers and remain aloft many hours, without the need of carrying
-    dangerous fuel. This type of balloon, called a <i>Charlière</i>, after its
-    inventor, was destined largely to supersede the hot-air type, known
-    as the <i>Montgolfière</i>, and indeed, to replace it entirely for free
-    voyages of considerable endurance and for most power voyages. The
-    construction after the plan of Professor Charles was delegated to two
-    very intelligent mechanics, the Robert brothers who also had succeeded
-    in dissolving caoutchouc, and thus producing a very superior balloon
-    varnish. The project was first announced in the <cite>Journal de Paris</cite> of
-    the 19th of November 1783. As usual in those days of public enthusiasm,
-    a subscription was opened to defray the expenses of the experiment,
-    estimated to cost about ten thousand francs.</p>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_43">43</span>
-    <a id="Fig_08"><img src="images/i_061.jpg" width="454" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 8.—Charles’ Passenger Balloon.</div>
-  </div>
-
-  <p>This balloon was a truly scientific creation, which advanced
-    aërostation from tottering infancy almost to full prime. The bag was
-    a sphere 27½ feet in diameter made of gores of varnished silk. A net
-    covered the upper half and was fastened to a horizontal <span class="pagenum" id="Page_44">44</span>hoop girding
-    the middle of the globe, and called the “equator.” From the equator
-    depended ropes which supported, just below the spherical bag, a wicker
-    boat measuring eight feet by four, covered with painted linen and
-    beautifully ornamented. The balloon had at the bottom a silk neck 7
-    inches in diameter, to admit the gas during inflation, and at the top,
-    a valve which could be opened by means of a cord in the boat to let
-    out gas during a voyage, so as to lower the balloon, or to relieve
-    excessive pressure. In the boat were carried sand ballast to regulate
-    the height of ascension, a barometer to measure the elevation, anchor
-    and rope for landing, a thermometer, notebook, provisions, and all the
-    paraphernalia of a scientific voyage. Barring the fancy boat, this is
-    almost a description of a good modern balloon.</p>
-
-  <p>The inflation and ascension occurred in the Garden of the Tuileries,
-    where the limp bag was initially suspended from a rope stretched
-    between two trees. For three days and nights the hydrogen, drawn from
-    twenty barrels containing iron and dilute sulphuric acid, poured upward
-    through the silken neck into the distending globe, which swelled in
-    volume to 1,400 cubic feet. Finally on a beautiful day, the first of
-    December 1783, the Tuileries and all the neighborhood were crowded with
-    spectators. A numerous guard of soldiers, stationed about the apparatus
-    and grounds, preserved order. The fashion and nobility of Paris were
-    there, in ample splendor, attracted by the novelty and importance
-    of the experiment, and the fame of the inventor. Shortly before two
-    o’clock Professor Charles presented to his friend, Montgolfier, a pilot
-    balloon six feet in diameter, saying, “It is your prerogative to blaze
-    the way through the sky.” The pilot balloon was released, showing to
-    everyone the direction of the aërial <span class="pagenum" id="Page_45">45</span>currents. Charles and Roberts
-    stepped into the boat, seated themselves, and quickly rose into the
-    sky. The multitude gazed in silent wonder. Presently they observed two
-    pennants waving high above them, though the navigators were scarcely
-    visible; whereupon they burst forth into wild enthusiasm and thunderous
-    applause.</p>
-
-  <p>Immediately a cavalcade set out in hot pursuit of the venturesome
-    sailors. It was the first chase after an air ship, and a most vigorous
-    one. The balloon drifting northwestward at a speed of fifteen miles
-    an hour, crossed the Seine, passed over several towns and villages,
-    to the great astonishment of the inhabitants, and landed in a field
-    near Nesle. Here it was securely held by friendly peasants, to await
-    the advent of the official witnesses. Presently these arrived, drew
-    up a certificate of descent and signed it. The Duke de Chartres, and
-    the Duke de Fitz-James, who had followed less swiftly, now rode up
-    and signed the formal document, to the great gratification of the
-    aëronauts. The aërial journey had been a most delightful one, lasting
-    about two hours and covering nearly thirty miles.</p>
-
-  <p>After receiving the felicitations of his friends, Charles determined
-    to reascend, in order to obtain further scientific observations. Owing
-    to leakage and loss of buoyancy, he must now leave behind his pleasant
-    companion. He had proposed replacing with earth, or stones, a part
-    of Mr. Robert’s weight, but, finding none at hand, he signaled the
-    peasants to let go, whereupon he rose with unusual speed. The remainder
-    of this first and very remarkable scientific voyage is well told by the
-    navigator himself:</p>
-
-  <blockquote>
-    <p>“In twenty minutes I was 1,500 fathoms high; out of sight of all
-      terrestrial objects. I had taken the necessary precautions against
-      the explosion of<span class="pagenum" id="Page_46">46</span> the globe, and prepared to make the observations
-      which I had promised myself. In order to observe the barometer and
-      thermometer, placed at the end of the car, without altering the center
-      of gravity, I knelt down in the middle, stretching forward my body and
-      one leg, holding my watch in my left hand, and my pen and the string
-      of the valve in my right, waiting for the event. The globe, which,
-      at my setting out, was rather flaccid, swelled insensibly. The air
-      escaped in great quantities at the silken tube. I drew the valve from
-      time to time, to give it two vents; and I continued to ascend, still
-      losing air, which issued out hissing, and became visible, like a warm
-      vapor in a cold atmosphere. The reason of this phenomenon is obvious.
-      On earth, the thermometer was 47°, or 15° above freezing point; after
-      ten minutes’ ascent it was only 21°, or 11° below. The inflammable
-      air had not had time to recover the equilibrium of its temperature.
-      Its elastic equilibrium being quicker than that of the heat, there
-      must escape a greater quantity than that which the external dilatation
-      of the air could determine by its least pressure. For myself, though
-      exposed to the open air, I passed in ten minutes from the warmth of
-      spring to the cold of winter; a sharp dry cold, but not too much
-      to be borne. I declare that, in the first moment, I felt nothing
-      disagreeable in the sudden change. When the barometer ceased to fall,
-      I marked exactly 18 inches 10 lines (20-01 in. English), the mercury
-      suffering no sensible oscillation. From this I deduce a height of
-      1,524 fathoms (3,100 yards), or thereabouts, till I can be more exact
-      in my calculation. In a few minutes more, my fingers were benumbed by
-      the cold, so that I could not hold my pen. I was now stationary as to
-      the rising and falling, and moved only in an horizontal direction. I
-      rose up in the middle of the car to contemplate the<span class="pagenum" id="Page_47">47</span> scene around me.
-      At my setting out the sun was set on the valleys; he soon rose for me
-      alone, who was the only luminous body in the horizon, and all the rest
-      of nature in shade; he, however, presently disappeared, and I had the
-      pleasure of seeing him set twice in the same day. I beheld, for a few
-      seconds, the circumambient air and the vapors rising from the valleys
-      and rivers. The clouds seemed to rise from the earth and collect one
-      upon the other, still preserving their usual form, only their color
-      was gray and monotonous from the want of light in the atmosphere. The
-      moon alone enlightened them, and showed me that I was tacking about
-      twice; and I observed certain currents that brought me back again.
-      I had several sensible deviations; and observed, with surprise, the
-      effects of the wind, and saw the streamers of my banners point upwards.
-      This phenomenon was not the effect of the ascent or descent, for then I
-      moved horizontally. At that instant I conceived, perhaps a little too
-      hastily, the idea of being able to steer one’s course. In the midst
-      of my transport I felt a violent pain in my right ear and jaw, which
-      I ascribed to the dilatation of the air, in the cellular construction
-      of those organs, as much as to the cold of the external air. I was in
-      a waistcoat and bareheaded. I immediately put on a woolen cap, yet
-      the pain did not go off but as I gradually descended. For seven or
-      eight minutes I had ceased to ascend; the condensation of the internal
-      inflammable air rather made me descend. I now recollected my promise to
-      return in half an hour, and, pulling the string of the valve, I came
-      down. The globe was now so much emptied, that it appeared only a half
-      globe. I perceived a fine ploughed field near the wood of Tour du Lay,
-      and hastened my descent. When I was between twenty or thirty fathoms
-      from the earth I threw out hastily<span class="pagenum" id="Page_48">48</span> two or three pounds of ballast,
-      and became for a moment stationary, till I descended gently in the
-      field, about a league from the place whence I set out. The frequent
-      deviations and turnings about make me imagine that the voyage was near
-      three leagues, and I was gone about thirty-three minutes. Such is the
-      certainty of the combinations of our aërostatic machine, that I might
-      have kept in the air at least for twenty-four hours longer.”</p>
-  </blockquote>
-
-  <p>Further interesting details of the first balloon experiments at Paris
-    are furnished by Dr. Benjamin Franklin, then American Minister to
-    France, in his letters written to Sir Joseph Banks, President of
-    the Royal Society of London, and presented in <a href="#appendix_II">Appendix II</a> of this
-    book. These quaint and substantial stories are well worth perusal
-    as the expressions of a great diplomat and philosopher who, in the
-    midst of social and political activities, found time for scientific
-    correspondence with his friends in both hemispheres.</p>
-
-  <p>Aërial navigation was now become a practical art which should advance
-    rapidly in popularity, in both Europe and America. Very soon ascensions
-    were made everywhere, for private amusement and for public exhibitions.
-    Not a few were made for scientific, for military and for topographical
-    purposes; thus giving the art a utilitarian as well as a sporting
-    feature. It will be interesting to note some of the more conspicuous
-    ascensions, voyages and improvements made in passive balloons
-    subsequently to the invention of <i>Montgolfières</i> and <i>Charlières</i>.</p>
-
-  <p>The largest hot-air balloon ever constructed, <i>La Flesselle</i>, was
-    launched from the suburbs of the city of Lyons on January 19, 1784,
-    just two months after the ascent of the first human passengers. It was
-    also one of the most troublesome to assemble and keep in repair. Day by
-    day, for more than a week, the balloon was inflated for the purpose of
-    attaching<span class="pagenum" id="Page_49">49</span> the ropes to support the great gallery. But the wind blew
-    dreadfully at times; rain and snow fell on the machine; frost and ice
-    covered the huge bag; many rents ensued, demanding frequent repairs.
-    On one occasion, when fed too freely with flame from straw sprinkled
-    with alcohol, the monstrous ship rose so vigorously as to drag fifty
-    men with it some distance along the ground. Finally on the 19th of
-    January, when the weather moderated, the operators built small fires
-    under the scaffold below the balloon, and thawed away the ice from
-    the drenched and frozen bag. Then they stocked its gallery with straw
-    and pitchforks, with fire extinguishers, and other provisions for the
-    journey. The inflation beginning about noon, occupied but seventeen
-    minutes. The balloon swelled out rapidly, with the roaring flames
-    ascending inside, and at last stood forth huge and majestic before
-    the admiring multitude—a towering thing of magic growth, 100 feet in
-    diameter by 130 feet high.</p>
-
-  <p>The ascension of this gigantic vessel was immensely spectacular; but
-    it was also most adventurous and foolhardy. The great bag, which at
-    best was made of poor materials, was in bad repair after its frequent
-    inflations. But of the six passengers in the gallery not one could be
-    induced to remain behind to lessen the risk to the others. Their pilot,
-    M. de Rozier, remonstrated with them; the proprietor M. C. Flesselle
-    wished them to cast lots; but no one would abandon the journey. So,
-    with fear and reluctance, the pilot ordered the mooring ropes to be
-    cut. Just as the ascent began, a seventh passenger, M. Fontaine, sprang
-    into the gallery and sailed aloft with the others. By vigorous stoking
-    the aërial sailors urged their fiery vessel upward three thousand feet,
-    whence, apparently without fear, they waved their hats to the vast
-    throng below.</p>
-
-  <p><span class="pagenum" id="Page_50">50</span></p>
-
-  <div class="figcenter">
-    <a id="Fig_09"><img src="images/i_068.jpg" width="447" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 9.—La Flesselle.</div>
-  </div>
-
-  <p>The spectators were now in a frenzy of excitement. For more than a week
-    they had vacillated between <span class="pagenum" id="Page_51">51</span>hope and disappointment; but now they saw
-    the huge ship soaring into the sky, perhaps on her way to destruction.
-    They heard the blast of martial music and the booming of mortars. Then
-    the accumulated emotion of the multitude burst forth. Exclamations
-    of joy, shrieks of fear, thunders of applause resounded above the
-    sea of people. Finally the balloon began to burst, a dangerous rent
-    running vertically along her side. The machine descended with great
-    rapidity, to the alarm of everyone. It is reported that not fewer than
-    sixty thousand people ran to the place of landing, with the greatest
-    apprehension for the lives of the travelers. But the adventurous men
-    stepped forth from the gallery, after a fifteen minutes’ voyage,
-    without hurt of any kind, save an insignificant scratch borne by Joseph
-    Montgolfier, who on this occasion made his first and last ascension.
-    This was also the first and last ascension of that gigantic fire
-    balloon; for although it furnished a world of delirious emotion and
-    excitement, the trouble of inflating the vessel was too great to be
-    repeated.</p>
-
-  <p>The crossing of the English Channel by balloon had been contemplated
-    many months by various adventurous spirits; and at length, on a fine
-    day, the seventh of January, 1785, this feat was attempted by two
-    intrepid men, the French aëronaut, M. Blanchard, and an American
-    physician, Dr. Jeffries, who had graduated at Harvard in 1763, and
-    was practicing medicine in England. Starting from the perpendicular
-    cliff at Dover Castle, at one o’clock, they sailed in the direction of
-    Calais, having with them only thirty pounds of sand ballast. This was
-    too little for so long a voyage; but it would doubtless carry them a
-    few miles, in the favorable breeze then blowing. To their surprise,
-    the atmosphere seemed to grow lighter as they advanced over the water,
-    letting <span class="pagenum" id="Page_52">52</span>them sink too freely. As they approached mid-channel they
-    were compelled to discharge all their ballast in order to maintain
-    their level. But the balloon still descended, seemingly attracted by
-    the water. Then they ejected a parcel of books to gain a moment’s
-    relief. When three-fourths across the Channel they sighted the French
-    Coast, which now they yearned to see at closer range; for the balloon
-    was contracting and sinking rapidly. They threw out from the boat
-    everything available, wings, anchors, cords, provisions; yet they saw
-    the vessel persistently approaching the sea. Finally they cast off part
-    of their clothing, fastened themselves to the cords suspended from
-    the balloon-ring, and prepared to cut away the boat. But presently
-    approaching the coast near Calais, they began to rise; then ascended
-    rapidly, soaring in a magnificent arch above the high grounds. At
-    last they descended gradually above the forest of Guines, seized the
-    branches of a tree to stop their flight, and at three o’clock were
-    happily landed. It was a thrilling voyage of two hours, and made a
-    profound impression at the time. As a mark of appreciation the King
-    presented Blanchard a sum of 12,000 francs and a pension of 1,200
-    francs per year. The people erected a monument on the place of landing
-    to commemorate this extraordinary voyage.</p>
-
-  <p>This splendid achievement incited two Frenchmen to attempt a counter
-    voyage which ended disastrously. On June 15, 1785, Pilâtre de Rozier
-    and M. Romain set out from Boulogne on a voyage from France to
-    England, in a compound balloon composed of a hydrogen balloon forty
-    feet in diameter, below which was suspended a fire balloon ten feet
-    in diameter. They hoped by judicious stoking of the lower balloon to
-    obviate the sinking tendency suffered by Blanchard and Jeffries. But
-    the smaller<span class="pagenum" id="Page_53">53</span> globe proved a fatal auxiliary. Scarcely a quarter of an
-    hour after launching, the whole apparatus was aflame at an altitude of
-    3,000 feet, and presently fell in charred and hideous fragments upon
-    the seashore. M. Romain still showed some signs of life, but Pilâtre
-    de Rozier was completely dead and all his bones were broken. They were
-    the first martyrs in the cause of the new science. Poor De Rozier
-    knew on starting that his apparatus was in bad condition, but he had
-    received for the purpose a sum of money from a distinguished patron,
-    and therefore felt obliged in honor to attempt the voyage. He was
-    twenty-eight years old and engaged to be married to a young lady in the
-    convent at Boulogne, who eight days after the catastrophe which robbed
-    her of her fiancé, died brokenhearted and in convulsions.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_II">
-    <span class="pagenum" id="Page_54">54</span>
-    <h3>CHAPTER II</h3>
-    <span class="small">PRACTICAL DEVELOPMENT OF PASSIVE BALLOONS</span>
-  </div>
-
-  <p><span class="smcap">The</span> next important advance in practical ballooning was made by the
-    substitution of coal gas for hydrogen. This was England’s contribution
-    to an art which previously had not greatly flourished west of the
-    Channel. It was a contribution following the natural growth of science;
-    for in 1814 coal gas began generally to be used for lighting London,
-    and seven years later for inflating balloons. This valuable innovation
-    was made by the famous aëronaut, Charles Green, on the occasion of his
-    first ascension, made July 19, 1821, the coronation day of George IV.
-    The new method largely superseded the old, extending throughout the
-    world with the spread of gas lighting; and it gave a powerful stimulus
-    to aëronautics by rendering inflation cheap and convenient. Mr. Green
-    himself made 526 ascensions during his life, or at the rate of one
-    cruise a month for nearly forty-four years. In due time, every country
-    had its professional aëronauts, and finally its amateurs, who, forming
-    themselves into aëro clubs, devoted themselves to racing in free
-    balloons, inflated quite usually from a city gas supply.</p>
-
-  <p>In 1836 Mr. Robert Holland organized an expedition designed to test the
-    utmost capabilities of the balloon of his day, particularly in points
-    of endurance and control. Engaging as pilot the first aëronaut of the
-    age, Mr. Charles Green, and employing the largest gas balloon that ever
-    had been constructed, <span class="pagenum" id="Page_55">55</span>stocked with provisions enough to last three
-    men a fortnight, he invited a third person, Mr. Monck Mason, to join
-    them on a cruise from London to wherever the wind would take them, but
-    preferably to land near Paris, as the balloon was to be delivered there
-    after the voyage.</p>
-
-  <div class="figcenter">
-    <a id="Fig_10"><img src="images/i_073.jpg" width="450" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 10.—The Great Balloon of Nassau.</div>
-  </div>
-
-  <p>The vessel selected for that famous cruise was <i>The Great Balloon of
-    Nassau</i>, then recently built by Mr. Green and representing all that his
-    skill and experience could devise. It was of pear shape, formed<span class="pagenum" id="Page_56">56</span> of
-    the finest crimson and white silk, “spun, wove and dyed expressly for
-    the purpose,” and comprising when distended a volume of 85,000 cubic
-    feet. From its stout balloon-ring six feet in diameter was suspended a
-    wicker car measuring nine feet long by four wide, having a seat across
-    either end, and a cushioned bottom to serve as a bed, if such should be
-    needed. Across the middle of the car was a plank supporting a windlass
-    for raising or lowering the guide-rope, that is a heavy rope which
-    could be trailed over land, or water, to keep the balloon at a nearly
-    constant level without expenditure of ballast, and to check its speed
-    on landing. This valuable device invented by Mr. Green in 1820, was
-    now to receive adequate trial, which, indeed, formed one of the chief
-    purposes of the cruise. Other paraphernalia of the voyage were food
-    and drink, warm clothing, lamps, trumpets, telescopes, barometers, a
-    quicklime coffee-heater, a grapnel and cable, and a ton of sand ballast
-    in bags.</p>
-
-  <p>The voyage proved well worthy of the elaborate preparations. At
-    one-thirty o’clock on November 7th, the three navigators arose
-    from London, in presence of a mighty multitude, and drifted in a
-    southeasterly direction traversing the cultivated plains of Kent, and
-    in two hours passed the environs of Canterbury. Here they dropped
-    a parachute with a letter for the Mayor, which he duly received.
-    Continuing their journey they floated leisurely above the tree tops,
-    talking to the inhabitants of the country, startling the fleet-winged
-    quail, terrifying a colony of rooks, and finally reaching Dover at
-    sundown, where they again dropped a letter for the Mayor of the city,
-    which also was duly delivered.</p>
-
-  <p>Without a moment’s pause they drifted over the Channel into the
-    gathering darkness. Before them<span class="pagenum" id="Page_57">57</span> rose a huge wall of vapor and black
-    clouds standing on the bosom of the sea; behind them the twinkling
-    lights and the music of breakers rolling on a hospitable shore.
-    Presently they were immersed in a region of absolute silence and
-    impenetrable darkness. At times this deep stratum would slowly
-    dissolve, revealing a glimpse of the dusky ocean and a passing ship;
-    then some huge wreath of vapor would involve them in bottomless gloom,
-    without perspective, without apparent motion, without a sound to cheer
-    or mark their dubious course. Now to avoid the risk of settling too
-    near the sea, as Blanchard and Jeffries had done, they were preparing
-    to let down the guide-rope with floating ballast attached, when
-    suddenly they emerged from the pall of darkness, and were greeted by
-    the glittering lights of Calais, and the gentle sound of waters dashing
-    upon the beach. They had crossed the Channel in one hour, and were
-    soaring serenely three thousand feet above the ocean, not having to
-    lower the guide-rope to preserve their elevation.</p>
-
-  <p>Now came the preparations for a night voyage over an obscurely defined
-    land route. A simple rope one thousand feet long without ballast was
-    allowed to trail beneath them. A lamp was lit. Coffee was heated by the
-    slacking of quicklime. An ample store of viands and wine was spread on
-    the board in the middle of the car. The strenuous period of thought and
-    labor was past, and now three hungry men sat leisurely at dinner, after
-    a fast of twelve long hours. However sparing of bones and bottles,
-    which later might serve as ballast, they were not economical of food
-    and wine that evening. For the present they had only to live and be
-    happy as bachelors. Muffled in soft garments, well fed, abundantly
-    served with divine beverages, hot or cold; what finer picture of
-    masculine comfort and delight?</p>
-
-  <p><span class="pagenum" id="Page_58">58</span></p>
-
-  <p>They were now floating tranquilly in the vast solitude of heaven, over
-    a teeming continent mantled in night and mystery. Far along earth’s
-    sable surface gleam the scattered fires of many villages; and above
-    it the lovelier fires of a moonless sky. Unseen, unsuspected, they
-    survey kingdoms and cities, trailing their long rope serpent-like
-    over woodland, field and quiet homestead. Now on the horizon before
-    them looms a greater fire, like a distant conflagration, widening as
-    they approach. Gradually it expands into a model city, shooting out
-    long lines of illuminated streets; here the public squares, markets
-    and theatres; there the rumbling iron mills with blazing furnaces.
-    They are above Liege at her festive hour, murmuring with animation
-    and busy life. Again they drift into the dark regions of slumber,
-    lapped in silence and deep tranquillity, where the lights of men are
-    extinguished, and the stars, redoubling their lustre, gleam whitest
-    silver in heaven’s jetty dome. Midnight involves the world; an abyss
-    of darkness enfolds it; their solitary lamp seems to melt its way
-    through solid space of blackest marble. For hours they undulate over
-    the rolling hills, rising and falling a thousand cubits, held always to
-    earth by the trailing rope. At times they are so near as to trace the
-    landscape dimly; here a white tract covered lightly with snow, here a
-    dark valley or forest, here a tortuous river, probably the Rhine, with
-    its multitudinous thunder of waters. But in all that weird and obscure
-    wandering no joyous note of human or animal life ascends ere dawn to
-    cheer their solitary course in the sky.</p>
-
-  <p>At last the paling of the morning star, and a faint tingeing of the
-    eastern cumuli, announce the expected day. With sudden bound the
-    great ship mounts aloft twelve thousand feet, into the glory of the
-    blazing sun, new risen among clouds of amber<span class="pagenum" id="Page_59">59</span> and purple. Far below,
-    twilight and mist still mantle the half-awakened world, presenting a
-    stupendous panorama, vast as an empire. Presently down they plunge into
-    the vaporous and obscure atmosphere, drifting carelessly, but soon
-    reascending into the splendor of morning. Thus after making the sun
-    rise three times and set twice, they float contentedly along the misty
-    landscape, marveling what region lies below them, whether a barren
-    wilderness, or the abode of civilized life, with human comforts and a
-    ready means of transportation. A hot breakfast would be very welcome
-    now; for they had accidentally dropped the lime pot and had spent the
-    latter half of the night without warm beverage in a region where oil
-    and water had frozen.</p>
-
-  <p>At length through the clearing vapor they perceive the country well
-    tilled and populous; a good place to land to shorten their route to
-    Paris, and avoid the wide plains of Poland or Russia. They raise the
-    guide-rope, lower the cable and anchor, open the valve, and descend
-    in a grassy field near Weilburg, in the Duchy of Nassau. It is now
-    seven-thirty o’clock, just eighteen hours since starting; and they
-    have traveled five hundred miles, the longest aërial voyage thus
-    far recorded. Very soon they are surrounded by a wondering crowd of
-    pipe-puffing, shaggy-headed, German peasants, by whose willing aid they
-    finally deflate the balloon, pack it in the bottom of the car, and
-    mount it on a one-horse cart for Weilburg. Thence the aëronauts, after
-    a week of festivities in their honor, and distinguished attentions from
-    the highest officials of the town, embarked with their balloon for
-    Paris. This famous craft now bore its permanent title; for a few days
-    previously the lovely daughter of the Baron de Bibra, with seven other
-    young ladies and Mr. Green, had stood within the air-inflated vessel,
-    poured a generous libation <span class="pagenum" id="Page_60">60</span>of wine, and christened the hardy cruiser
-    <i>The Great Balloon of Nassau</i>.</p>
-
-  <p>It was in truth a great balloon in various ways; in solidity and
-    strength, in workmanship, in completeness of appointment, in endurance
-    and control. Having accomplished that long journey without a sign
-    of weakness or defect, it was still in prime condition, proudly
-    heading for the farthest verge of Europe. It had not, of course, the
-    instrumental equipment of a modern balloon; but it did possess the
-    elements essential for a long and hard cruise. Since the day of its
-    launching many additions have been added to the art, but these, for
-    the most part, are special adjuncts. The more important features of a
-    good balloon are practically the same to-day as when they were first
-    introduced by Professor Charles and sturdy old Mr. Green.</p>
-
-  <p>A still more elaborate and colossal air ship was the <i>Geant</i>,
-    constructed in 1863, for A. Nadar of Paris. It was made of a double
-    layer of white silk, had a volume of 215,000 cubic feet and a buoyancy
-    of 4½ tons. The car was a wicker cabin 13 feet wide by 7 feet high,
-    with a wicker balcony round the top so that the roof could be used
-    as an observation deck—a delightful place to loll in the starlight,
-    or watch the morning sun “flatter the mountain tops with sovereign
-    eye.” The closed car comprised two main rooms with a hallway between
-    them, one containing the captain’s bed and baggage, the other having
-    three superposed berths for passengers. Minor divisions of the car
-    were reserved for provisions, a lavatory, photography and a printing
-    press, the latter to be used for the dissemination of news from the
-    sky, as the navigators floated from state to state. A compensator
-    balloon of 3,500 cubic feet, just below the main bag and connected
-    with it, received the escaping gas during expansion with increase of
-    tempera<span class="pagenum" id="Page_61">61</span>ture or altitude, and gave it back on contraction. In fact
-    as well as in name, Nadar’s vessel was a giant. Curiously enough, he
-    called it the “last balloon,” for he expected to realize enough money
-    by exhibiting it, to inaugurate successful flying by means of the
-    helicopter, and thus banish ballooning from the world of futile effort
-    to the domain of bygone dreams and chimæras.</p>
-
-  <div class="figcenter">
-    <a id="Fig_11"><img src="images/i_079.jpg" width="623" height="619" alt="" /></a>
-    <div class="caption smcap">Fig. 11.—Car of Nadar’s Balloon.</div>
-  </div>
-
-  <p>The first ascension, made on Sunday, October 4, 1863, was one of
-    magnificent promise. In the midst of a vast holiday throng on the Champ
-    de Mars, the great globe towered aloft nearly two hundred feet, held to
-    earth by one hundred men and twice as many<span class="pagenum" id="Page_62">62</span> sand bags. In the car were
-    fifteen notable passengers including one lady, the fair young Princess
-    de la Tour d’Auvergne, in morning toilet and a pretty hat. “Lachez
-    tout!” shouts Captain Nadar, the effervescent photographer of Paris.
-    Away they soar, heading for St. Petersburg, with provisions enough to
-    sail beyond the polar sea.</p>
-
-  <p>The captain was now in supreme control, with the key to the victual
-    and liquor room in his pocket, and his twelve commandments duly signed
-    by all aboard. They had pledged themselves not to gamble, not to carry
-    inflammable materials, not to smoke unduly, not to throw bottles
-    overboard, not to quit the balloon without permission, but to descend
-    if so ordered, etc. They had sailed at five o’clock in the evening and
-    all was going merrily. But presently trouble came. The valve rope gave
-    way, the vessel was sailing in the dark, and the Godards declared she
-    was drifting to sea, whereas she was drifting in quite the opposite
-    direction. To be on the safe side they threw out the anchors by
-    permission of the commander. One anchor broke, but the other took hold
-    and checked the balloon in spite of the strong wind blowing. At last
-    after three violent bumps on the ground they landed near Meaux at nine
-    o’clock in the evening, one passenger sustaining a broken knee, the
-    others various bruises. It was a grand adventure and all were pleased.</p>
-
-  <p>Two weeks later a second voyage was begun in similar style, and again
-    from the Champ de Mars, this time in the presence of the King of
-    France and the young King George of Greece; but now Nadar took along,
-    not the Princess with the pretty hat, but Madame Nadar, his wife. To
-    entertain the crowd before starting, thirty-two persons were first sent
-    aloft 300 feet and drawn back to earth. Finally at five o’clock Sunday
-    evening, October 18th, a party of<span class="pagenum" id="Page_63">63</span> nine passengers soared proudly
-    northward, well provisioned as before, and eager for a long voyage.
-    They disappeared in the gathering night, leaving their friends much
-    concerned for their safety and ultimate destination. At half past eight
-    they were over Compiegne, seventy-eight miles away, drifting near the
-    ground to say “All goes well” and have the good tidings transmitted
-    to Paris. At nine they crossed the Belgian frontier; at midnight they
-    were over Holland; at sunrise they skirted the Zuyder Zee and entered
-    Hanover; at eight they were coursing headlong toward Nienburg and the
-    North Sea in the current of a swift west wind.</p>
-
-  <p>They were now in great peril. If they went to sea they might all be
-    drowned; if they came to earth at such horizontal speed they should
-    be terribly pounded. Choosing the latter evil, they opened the valve
-    and threw down the grappling irons. “To the ropes,” shouted the Godard
-    brothers. Assembling on deck all clung to the suspension ropes to
-    mitigate the shock of landing. Nadar put his arm about his wife to
-    protect her. The anchors snatching a tree, uprooted and dragged it
-    along; then caught and tore off the roof of a house; threshed into
-    a telegraph line pulling down the wires and poles; struck into some
-    firmer obstacle and broke off completely, leaving the huge monster
-    to sweep unchecked in the violent ground current. Owing to trouble
-    with the valve, the gas could not be liberated quickly; the great
-    vessel again and again plunged to earth and rebounded high in air,
-    its ponderous basket crashing through heavy timber, and breaking
-    down whatever opposed its course. For nine miles they pounded over
-    the plain by Nienburg toward the sea, dashing into pools, bogs and
-    thickets, their limbs sprained or broken, their bodies bruised, their
-    faces splashed with mud. Presently through loss of gas the rebounding
-    <span class="pagenum" id="Page_64">64</span>ceased, the basket dragged along the earth squeezing some of the
-    passengers beneath it, and dumping others out on the ground, leaving
-    them behind. Those remaining tried to assist Madam Nadar to land, but
-    they were tumbled out and she was caught under the basket from which
-    she was extricated with much difficulty, when the balloon was finally
-    halted. Thus their memorable voyage of seventeen hours, covering 750
-    miles, had a terrific, though not fatal ending. One had a broken femur,
-    another a dislocated thigh, others numerous scratches and contusions.
-    But no complaint was uttered; for the afflictions were regarded as
-    natural concomitants to such interesting sport. After some days tender
-    nursing by the Germans, and solicitous inquiries from the King of
-    Hanover, they returned to Paris; some indeed on their backs, but for
-    all that, none the less admired by their countrymen, as survivors of a
-    marvelous adventure.</p>
-
-  <p>Another valiant English leader in aërostation was James Glaisher,
-    member of the British Association for the Advancement of Science.
-    As one of a committee of twelve appointed by that body in 1861, to
-    explore the higher strata of the atmosphere by means of the balloon,
-    he volunteered his services as an observer, when no other capable man
-    could offer to do so. With a professional aëronaut, Mr. Coxwell, and a
-    new balloon specially constructed for the work, cubing 90,000 feet, he
-    made eleven ascensions for the society, four from Wolverhampton, seven
-    from Woolwich. Incidentally he made seventeen other ascents of various
-    altitude; not at the expense of the committee, but as a scientific
-    passenger in public balloon ascents advertised beforehand.</p>
-
-  <p>The objects of the enterprise were first to study the physical
-    conditions of the atmosphere; secondly to study the effect of the
-    higher regions upon the passengers <span class="pagenum" id="Page_65">65</span>themselves, and some pigeons,
-    which they carried along; thirdly to make some observations in
-    acoustics and magnetism, particularly to determine the period of
-    oscillation of a magnet at various altitudes. The specific study of
-    the atmosphere itself was to comprise observations at all altitudes,
-    of the temperature of the air, its pressure, and percentage of
-    moisture; observations of the velocity and direction of the wind,
-    the constitution of the clouds, their height, density and depth, the
-    constitution and electrical properties of the air. They were also to
-    collect samples of the air at different elevations, which later might
-    be examined in the laboratory. Thus the voyages were systematically
-    planned for scientific research, and were the first thorough attempts
-    in England, though similar efforts had been made previously in France.
-    It may be added that Glaisher’s observations were the most important
-    made during the first century of aëronautics, and may be found fully
-    detailed by that hardy investigator himself in the British Association
-    Reports for 1862–66.</p>
-
-  <p>Mr. Glaisher’s most interesting voyage of that memorable series
-    occurred on September 5, 1862. Starting from Wolverhampton at three
-    minutes after one o’clock, they soared swiftly upward, passing through
-    a cloud eleven hundred feet thick and emerging in a glorious field
-    of sunlight with an amethystine sky above and a boundless sea of
-    vapor beneath; a sea of rolling hills and mountain chains, with great
-    snow-white masses steaming up from their surface. They had left the
-    noisy bustle of earth in the comfortable temperature of 59°; in three
-    quarters of an hour, they were five miles aloft in a deadly silent
-    atmosphere, two degrees below zero, and approaching one third its usual
-    density, the balloon neck white with hoar frost, the men gasping for
-    breath. Here the observations became increasingly interesting but<span class="pagenum" id="Page_66">66</span>
-    immensely more difficult. They are graphically told in the following
-    extract from Mr. Glaisher’s classical report:</p>
-
-  <blockquote>
-    <p>“I asked Mr. Coxwell to help me to read the instruments, as I
-      experienced a difficulty in seeing. In consequence, however, of the
-      rotatory motion of the balloon, which had continued without ceasing
-      since the earth had been left, the valve-line had become twisted, and
-      he had to leave the car and mount into the ring above to adjust it.
-      At this time I looked at the barometer, and found it to be 10 inches,
-      still decreasing fast; its true reading therefore, was 9¾ inches,
-      implying a height of 29,000 feet. Shortly afterwards I laid my arm upon
-      the table, possessed of its full vigor, and on being desirous of using
-      it, I found it powerless; it must have lost its power momentarily. I
-      tried to move the other arm, and found it powerless also. I then tried
-      to shake myself, and succeeded in shaking my body. I seemed to have no
-      limbs. I then looked at the barometer; whilst doing so my head fell on
-      my left shoulder. I struggled and shook my body again, but could not
-      move my arms. I got my head upright, but for an instant only, when it
-      fell on my right shoulder, and then I fell backwards, my back resting
-      against the side of the car, and my head on its edge; in this position
-      my eyes were directed towards Mr. Coxwell in the ring. When I shook
-      my body I seemed to have full power over the muscles of the back and
-      considerable power over those of the neck, but none over either my
-      arms or my legs; in fact I seemed to have none. As in the case of the
-      arms, all muscular power was lost in an instant from my back and neck.
-      I dimly saw Mr. Coxwell in the ring and endeavored to speak, but could
-      not; when in an instant intense black darkness came, the optic nerve
-      finally lost power suddenly. I was still conscious, with as active a
-      brain as at the <span class="pagenum" id="Page_67">67</span>present moment whilst writing this. I thought I had
-      been seized with asphyxia, and that I should experience no more, as
-      death would come, unless we speedily descended; other thoughts were
-      actively entering my mind, when I suddenly became unconscious as in
-      going to sleep. I cannot tell anything of the sense of hearing; the
-      perfect stillness and silence of the regions six miles from the earth
-      (and at this time we were between six and seven miles high) is such
-      that no sound reaches the ear.</p>
-  </blockquote>
-
-  <hr class="page" />
-  <div id="Plate_I" class="center"><b>PLATE I.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_085a.jpg" width="500" height="663" alt="" />
-    <div class="captionp">GLAISHER AND COXWELL.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_085b.jpg" width="600" height="360" alt="" />
-    <div class="captionp">PARSEVAL KITE BALLOON.</div>
-  </div>
-
-  <blockquote>
-    <p>“My last observation was made at 1 h. and 54 m., at 29,000 feet. I
-      suppose two or three minutes fully were occupied between my eyes
-      becoming insensible to seeing fine divisions, and 1 h. 54 m., and then
-      that two or three minutes more passed till I was insensible; therefore
-      I think this took place at about 1 h. 56 m. or 1 h. and 57 m. Whilst
-      powerless I heard the words, ‘temperature’ and ‘observation,’ and I
-      knew Mr. Coxwell was in the car speaking to me, and endeavoring to
-      arouse me, therefore consciousness and hearing had returned. I then
-      heard him speak more emphatically, but I could not see, speak or move.
-      I heard him again say, ‘Do try—now do.’ Then I saw the instruments
-      dimly, then Mr. Coxwell, and very shortly saw clearly. I rose in
-      my seat and looked round, as though waking from sleep, though not
-      refreshed by sleep, and said to Mr. Coxwell, ‘I have been insensible;’
-      he said, ‘You have; and I, too, very nearly.’ I then drew up my legs,
-      which had been extended before me, and took a pencil in my hand to
-      begin observations. Mr. Coxwell told me he had lost the use of his
-      hands, which were black, and I poured brandy on them.</p>
-
-    <p>“I resumed my observations at 2 h. 7 m., recording the barometer
-      reading at 11.53 inches, and temperature −2°. I suppose three or
-      four minutes were occupied from the time of my hearing the words<span class="pagenum" id="Page_68">68</span>
-      ‘temperature’ and ‘observation’ till I began to observe; if so,
-      then returning consciousness came at 2 h. and 4 m., and this gives
-      seven minutes for total insensibility. I found the water in the
-      vessel supplying the wet-bulb thermometer, which I had by frequent
-      disturbances kept from freezing, was one solid mass of ice; and it did
-      not all melt until after we had been on the ground some time.</p>
-
-    <p>“Mr. Coxwell told me that whilst in the ring he felt it piercingly
-      cold; that hoar-frost was all round the neck of the balloon. On
-      attempting to leave the ring he found his hands frozen, and he had to
-      place his arms on the ring and drop down; that he thought for a moment
-      I had laid back to rest myself; that he spoke to me without eliciting
-      a reply; that he then noticed my legs projected and my arms hung down
-      by my side; that my countenance was serene and placid, without the
-      earnestness and anxiety he had noticed before going into the ring,
-      and then it struck him I was insensible. He wished to approach me,
-      but could not, and he felt insensibility coming over himself; that he
-      became anxious to open the valve, but in consequence of having lost the
-      use of his hands he could not, and ultimately did so by seizing the
-      cord with his teeth and dipping his head two or three times until the
-      balloon took a decided turn downwards. This act is quite characteristic
-      of Mr. Coxwell. I have never yet seen him without a ready means of
-      meeting every difficulty, as it has arisen, with a cool self-possession
-      that has always left my mind perfectly easy, and given me every
-      confidence in his judgment in the management of so large a balloon.</p>
-
-    <p>“No inconvenience followed the insensibility; and when we dropped it
-      was in a country where no conveyance of any kind could be obtained, so
-      that I had to walk between seven or eight miles.</p>
-
-    <p><span class="pagenum" id="Page_69">69</span></p>
-
-    <p>“The descent was at first very rapid; we passed downwards three miles
-      in nine minutes; the balloon’s career was then checked, and we finally
-      descended in the center of a large grass-field belonging to Mr.
-      Kersall, at Cold Weston, seven-and-a-half miles from Ludlow.</p>
-
-    <p>“I have already said that my last observation was made at a height of
-      29,000 feet; at this time (1 h. 45 m.) we were ascending at the rate
-      of 1,000 feet per minute; and when I resumed observations we were
-      descending at the rate of 2,000 feet per minute. These two positions
-      must be connected, taking into account the interval of time between,
-      viz. 13 minutes, and on those considerations the balloon must have
-      attained the altitude of 36,000 or 37,000 feet. Again, a very delicate
-      minimum thermometer read—12, and this would give a height of 37,000
-      feet. Mr. Coxwell, on coming from the ring, noticed that the center
-      of the aneroid barometer, its blue hand, and a rope attached to the
-      car, were all in the same straight line, and this gave a reading of 7
-      inches, and leads to the same result. Therefore these independent means
-      all lead to about the same elevation, viz. fully SEVEN MILES.</p>
-
-    <p>“In this ascent six pigeons were taken up. One was thrown out at the
-      height of three miles, when it extended its wings and dropped as a
-      piece of paper; a second, at four and five miles, and it fell downward
-      as a stone. A fourth was thrown out at four miles on descending. It
-      flew in a circle, and shortly alighted on the top of the balloon. The
-      two remaining pigeons were brought down to the ground. One was found to
-      be dead, and the other, a ‘carrier,’ was still living, but would not
-      leave the hand when I attempted to throw it off, till after a quarter
-      of an hour it began to peck a piece of ribbon which encircled its neck,
-      and was then jerked off the finger, and flew<span class="pagenum" id="Page_70">70</span> with some vigor toward
-      Wolverhampton. One of the pigeons returned to Wolverhampton on Sunday
-      the 7th, and it is the only one that has been heard of.”</p>
-  </blockquote>
-
-  <p>This was the loftiest ascent ever made up to that time; and thus
-    Glaisher, or rather Coxwell, who was in the ring above him, could be
-    called the “highest man” of the first century of aëronautics. Their
-    greatest elevation, however, is now generally estimated at much less
-    than seven miles, and probably below six miles, due allowance being
-    made for inaccuracies of estimate made by Mr. Glaisher. His results,
-    nevertheless, were considered valuable, revealing as they did, that the
-    balloon may be used safely up to the neighborhood of five miles; that
-    the temperature of the atmosphere does not, as previously supposed,
-    decline one degree for each 300 feet of ascent, but often declines
-    more rapidly, and sometimes even increases with the elevation for
-    considerable stretches; that the moisture percentage is extremely
-    slight at an altitude beyond five miles; that at all elevations
-    attainable by man the dry- and wet-bulb thermometers can be used
-    effectively, etc.</p>
-
-  <p>A still loftier ascent was made by Professor Berson of Germany,
-    aided by the respiration of oxygen. On July 31, 1901, accompanied by
-    Dr. Süring, he ascended from Berlin in the balloon <i>Preussen</i> to an
-    elevation of 10,800 meters, which at present constitutes the world’s
-    record for altitude. The balloon had a capacity of 300,000 cubic feet,
-    and left the ground two thirds filled with hydrogen, and carrying 8,000
-    pounds of ballast in the form of sand bags attached to the sides of the
-    basket, so that they could be cut loose with the slightest physical
-    effort.</p>
-
-  <p>The <i>Preussen</i> was one of the largest passive balloons ever
-    constructed. In cubic capacity it was comparable with the colossal
-    <i>Montgolfière</i>, <i>La Flesselle</i>, already described, and the huge free
-    balloon<span class="pagenum" id="Page_71">71</span> <i>Le Geant</i>, constructed by Nadar in 1863. But all were
-    eclipsed by the great balloon of Henri Giffard. This latter measured
-    450,000 cubic feet, and even to-day ranks as the largest captive
-    balloon ever constructed. It was a familiar object at the Paris
-    Exposition of 1878, where it was installed by the famous inventor
-    Henri Giffard, to give sightseers a bird’s-eye view of Paris. It could
-    take up forty persons at one time, or eight more than once ascended in
-    Nadar’s <i>Geant</i>.</p>
-
-  <p>No serious attempt has been made to surpass the altitude flight of
-    Professor Berson and Dr. Süring; for though it is easily possible to
-    carry human beings to a greater height than seven miles, the results
-    seem hardly to justify the cost. To ascend very much higher would
-    require an enormous and costly balloon, and to ensure the comfort
-    of the passenger might require an air-tight car, or armor supplied
-    continuously with fresh air, or oxygen. Such a suit, or car, however,
-    can be made very light, since its pressure must naturally be internal;
-    and it would admit of an extremely rapid change of elevation without
-    discomfort to the passenger. A steel bottle weighing fifty pounds,
-    and filled with compressed air, or oxygen, would supply a passenger
-    several hours, and allow him to breathe under normal pressure. The
-    total weight of a bottle and air-tight car, or suit, need not exceed
-    the weight of a man. Moreover, the ballast could be largely dispensed
-    with, thus admitting of a very rapid ascent from the earth. A celluloid
-    car would have the advantage of transparency, though it might become
-    too brittle at very low temperatures. A suit, or car, with glass
-    portholes would serve in lieu of a celluloid car for transparency. The
-    usual balloon and basket, carrying a steel bottle, furnishing air at
-    normal pressure to a man in a rubberized silk suit is a sufficiently
-    simple and<span class="pagenum" id="Page_72">72</span> practicable device; the air entering the suit near his
-    mouth and leaving below through a check valve regulated to maintain the
-    desired internal pressure. An air-tight silk fabric capable of enduring
-    safely a tensile stress of 150 pounds per running inch would answer the
-    purposes. But at present there seems to be no incentive to attempt a
-    balloon trip exceeding the heights already attained, unless it be that
-    of notoriety or sentiment.</p>
-
-  <p>The French meteorologists have devised a much simpler and cheaper
-    method of exploring the upper atmosphere, by use of small balloons
-    carrying recording instruments. An ordinary silk or gold-beater
-    skin balloon, partly inflated, ascends to a great height with the
-    instruments, drifts away losing gas, and on landing is found by some
-    one who returns it according to written directions accompanying the
-    craft. Another method, introduced by Professor Assman, is to employ
-    closed rubber balloons which at great altitudes burst by the expansion
-    of the hydrogen within them, and allow the instruments to descend
-    in parachutes softly to the ground. Instrument-carrying balloons of
-    the above type are called “sounding balloons,” or <i xml:lang="fr">balloons sondes</i>,
-    whereas if they carry no instruments, but merely show the course of the
-    wind, they may be called “pilot balloons.” Such sounding balloons have
-    been used to explore the temperature of the atmosphere to an altitude
-    of 18 miles.</p>
-
-  <p>In the preceding pages some extended balloon voyages have been
-    described. These were considered very long in their day, but in recent
-    years have been surpassed frequently, first by the professional
-    aëronauts, then by the amateurs and members of various aëronautic
-    clubs practicing aërostation as a sport, and stimulated by attractive
-    prizes. But the man who achieved the longest balloon flight<span class="pagenum" id="Page_73">73</span> during the
-    first century of the art, seems to have been Mr. John Wise, America’s
-    foremost pioneer balloonist.</p>
-
-  <p>Mr. Wise was a rare composite of showman, scientist, sport and
-    dare-devil, who during the four decades succeeding his first ascension
-    at Philadelphia in 1835, made no fewer than 440 voyages. At first the
-    aërial art captivated him by the beauty and sublimity of the natural
-    panoramas witnessed from on high; then he amused himself by dropping
-    things from the basket and hearing them whistle through space; and
-    finally he coquetted with the balloon itself, in various ways to
-    observe the result. On one occasion the neck was choked and the
-    valve could not be operated, so that when the hydrogen expanded with
-    increasing altitude, it overstretched the cover and started a rent in
-    the side of the bag. The balloon descended rapidly, but landed without
-    injurious shock.</p>
-
-  <p>The audacious aëronaut then decided to make an ascension and
-    deliberately burst the balloon, by confining the gas in it and throwing
-    out ballast. But first he tried the experiment on a dog, taking him up
-    4,000 feet, dropping him in a small collapsed balloon and watching him
-    settle slowly to earth. Then rising to an altitude of 13,000 feet he
-    stood debating whether to follow the example of the dog. The balloon
-    quickly ended the question by exploding at the top. The hydrogen rushed
-    out with a tempestuous sound, and the great vessel sank swiftly with a
-    moaning noise of the wind in her rigging. In a few seconds the bag was
-    empty and collapsed on the top of the net thus forming an effective
-    parachute. After an exciting fall of more than two miles, Mr. Wise
-    landed on a farm, with a lively thump, which overturned the basket, and
-    threw him sprawling on the ground. It was fine sport; he decided at
-    once<span class="pagenum" id="Page_74">74</span> to advertise a repetition of it, and thus was led by degrees to
-    the invention of the ripping panel.<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">[7]</a></p>
-
-  <p>Mr. Wise firmly believed that a steady wind from west to east prevails
-    at a height of two miles. He wished to use this for long voyages, and
-    even contemplated crossing the Atlantic; for he trusted his varnish to
-    hold hydrogen a fortnight if need be. Accordingly in 1873 the New York
-    <cite>Daily Graphic</cite> paid the cost of a balloon to carry him and two others
-    on that hazardous voyage. The bag had a capacity of 400,000 cubic feet,
-    but was too frail in construction to receive Mr. Wise’s approval, and
-    actually burst during inflation when slightly more than three fourths
-    full. Fortunately, perhaps, for Mr. Wise, he never had an opportunity
-    to attempt the trans-Atlantic voyage; but on one occasion he enjoyed a
-    memorable cruise in the great west wind which so took his fancy. Rising
-    from St. Louis on June 23, 1859, he sailed northeastwardly for twenty
-    hours, and landed at Henderson, N. Y., having traversed a distance of
-    809 miles, measured directly. But in attempting another long voyage
-    with two companions, in September, 1879, he passed over Lake Michigan,
-    where all were drowned.</p>
-
-  <p>In recent years Mr. Wise’s long voyage has been exceeded several
-    times. In 1897 M. Godard sailed from Leipsic to Wilna, a distance of
-    1,032 miles in 24½ hours; but this was not an official flight nor in a
-    direct course as the crow flies. In October, 1900, M. Balsan voyaged
-    from Vincennes, France, to Rodom, Russia, a distance of 843 miles in
-    27 hours and 25 minutes, and De la Vaulx starting from the same point
-    landed at Korosticheff, Russia, having traversed 1,193 miles in 35¾
-    hours. This latter is the <span class="pagenum" id="Page_75">75</span>longest balloon flight thus far recorded. A
-    close second to this record was made by A. R. Hawley in his spherical
-    balloon <i>America</i>, aided by Augustus Post, in the Gordon Bennett
-    International Balloon Race of 1910. Sailing from St. Louis, October
-    17th, they drifted 1,172.9 miles from their starting point, and landed
-    in a great forest at Peribonka River, North Lake Chilogoma, Canada,
-    where they were lost for several days.</p>
-
-  <div class="figcenter">
-    <a id="Fig_12"><img src="images/i_095.jpg" width="410" height="658" alt="" /></a>
-    <div class="caption smcap">Fig. 12.—Diagram of a Modern Spherical Balloon with
-      Ripping Panel.</div>
-  </div>
-
-  <p>Quite as eventful was the ocean voyage of Walter<span class="pagenum" id="Page_76">76</span> Wellman, who left
-    Atlantic City October 15, 1910, for Europe in a motor balloon with a
-    drag rope, or equilibrator, voyaged with favorable wind to a point
-    140 miles northeast of Nantucket Island, then was driven by adverse
-    wind toward Bermuda, and finally rescued by a passing steamer, after
-    69 hours in the air and a journey of about one thousand miles. A full
-    account of this strange voyage is given in the New York <cite>Times</cite> of
-    October 19, 1910, and in the <cite>Scientific American</cite> of subsequent date.</p>
-
-  <p>The recent advances in aërostation, though not radically changing the
-    balloon itself, contribute much to its usefulness and convenience.
-    Improvements have occurred in the means of inflation and deflation,
-    in devices for making topographical and meteorological observations,
-    as also for transmitting and receiving signals. Hydrogen shipped in
-    steel tubes is now available for easy and rapid inflation, the process
-    of obtaining it on a large scale making it practically as cheap as
-    illuminating gas. The ripping panel, invented in 1844 by America’s
-    foremost pioneer aëronaut, John Wise, is a simple and an excellent
-    practical device. This is a long patch running longitudinally above the
-    equator<a id="FNanchor_8" href="#Footnote_8" class="fnanchor">[8]</a> of the balloon, feebly sewed to the envelope, and having a
-    cord, called the “ripping cord,” extending down to the car along the
-    outside or inside of the bag, so that the pilot on coming to earth
-    can let out the gas quickly by tearing a rent in the balloon, thus
-    flattening it promptly on the earth’s surface, so as to avoid dragging
-    and bumping if any wind prevails. During an ascension the rise or fall
-    of the vessel may be instantly noted on the dial of the statoscope,
-    the temperature, pressure and moisture of the atmosphere may be read
-    on recording instruments, messages may be sent by tele<span class="pagenum" id="Page_77">77</span>graph and
-    telephone either by wire or through space, and sky or landscape may
-    be photographed if there be sufficient light. The bag itself has been
-    improved by making it of special fabrics formed of several layers of
-    silk, or cotton, with thin layers of rubber vulcanized between them
-    to render the cloth impermeable, also the bag, when not designed to
-    cleave the wind, is usually given a spherical form which is the figure
-    of greatest volume for a given surface, the figure originally used by
-    the inventor of the gas balloon; but when designed to be tethered in
-    a wind, it is given a longish shape and a tail so that it may ride
-    the wind like a kite. This type of balloon, though first proposed by
-    Douglass Archibald about 1845, was first made a practical invention by
-    Captain von Sigsfeld and Major von Parseval. In a certain sense it is a
-    tethered motor-balloon, just as a kite is a tethered aëroplane.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_III">
-    <span class="pagenum" id="Page_78">78</span>
-    <h3>CHAPTER III</h3>
-    <span class="small">EARLY HISTORY OF POWER BALLOONS</span>
-  </div>
-
-  <p><span class="smcap">Directly</span> after the first launching of human passengers in a crude
-    aërostat, numerous schemes for controlling the course of a balloon were
-    evolved. Apparently mere flotation afforded less contentment to the
-    early pioneer aëronauts than to the free balloonists of the present
-    hour. Many were eager to apply propelling mechanism to their gas bags,
-    expecting thus to achieve practical locomotion through the air, even a
-    generation before the advent of practical steam navigation. Magnificent
-    dreams they had, indeed, but none the less futile. Few suspected the
-    enormous power required to propel swift balloons of the very best shape
-    and size; still fewer realized the impossibility of driving spherical
-    bags at a practicable velocity.</p>
-
-  <p>On the other hand, it must be said, to the credit of that era of
-    investigators, that certain noted scientists, after computing the power
-    required to drive a balloon at high speed, promptly recognized the
-    inadequacy to that task, of any motors then available. In conjunction
-    with favorable aërial currents something might be effected; that they
-    fully grasped; for they knew that the wind frequently has different
-    directions at different levels. They believed, therefore, that by
-    causing the craft to rise or fall to a suitable stratum, by use of
-    various then known devices, it could be made to travel in any direction
-    at the will of the pilot. Likewise<span class="pagenum" id="Page_79">79</span> they deemed that the rise and fall
-    of a balloon, due to change of buoyancy, could be used to propel it, if
-    sails attached to the vessel were set obliquely to the motion, so as to
-    receive fair pressure; or if the balloon were made flat, or longish, so
-    as to glide horizontally, like a kite or parachute.</p>
-
-  <p>Several devices for changing the altitude of the balloon were proposed
-    or tried. If the vessel were a <i>Montgolfière</i>, the mere increase or
-    lessening of the fire would promptly cause it to rise or fall. If a gas
-    bag were employed it could be sent up or down by casting out ballast
-    or opening the valve; or again, as proposed by Pilâtre de Roziere, by
-    having a <i>Montgolfière</i> underneath the gas balloon, and lifting or
-    depressing the whole by altering the intensity of the flame. Finally,
-    an air balloon within a gas balloon was proposed by the Roberts, and a
-    gas balloon within an air balloon was proposed by General Meusnier, in
-    either of which combinations, a change of level could be effected by
-    pumping air into, or letting it escape from, the air bag. All of these
-    devices can be effected and practically operated by a competent balloon
-    maker and pilot; and yet they have not enabled man to realize his dream
-    of navigating the air in all directions without motive power.</p>
-
-  <p>The first attempts at balloon propulsion could not be seriously
-    regarded by trained engineers, even at the inception of aëronautics;
-    but still, as infantile steps in the new art, they may deserve passing
-    notice.</p>
-
-  <p>Blanchard, on March 2, 1784, made the first real effort to steer a
-    balloon, using for that purpose a spherical gas bag and car provided
-    with aërial oars and a rudder. As he was about to ascend, however,
-    from the Champs de Mars, a young officer with drawn sword persisted in
-    accompanying the pilot, thus compelling Blanchard to leave his wings
-    on earth to allow sufficient buoyancy for himself and his obtrusive
-    guest. His first trial was, therefore, frustrated; but subsequent ones
-    made with that inadequate contrivance also proved futile under the best
-    circumstances; for the scheme was evidently puerile, though tried by
-    various grown-up men besides M. Blanchard.</p>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_80">80</span>
-    <a id="Fig_13"><img src="images/i_100.jpg" width="440" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 13.—Blanchard’s Dirigible Balloon, 1784.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_81">81</span>A no less simple and quaint device for propulsion was that of the
-    two physicists, the Abbé Miolan and Janinet. The balloon was a
-    <i>Montgolfière</i> with a large hole in one side, through which the hot air
-    was to escape with such strong reaction as to drive the bag forward, on
-    the principle of a lawn sprinkler, or of Newton’s reaction wagon. The
-    projectors failed, however, to make an ascent, and the crowd becoming
-    furious destroyed the balloon.</p>
-
-  <p>A more reasonable plan for practical navigation was devised and tried
-    by the Robert brothers. A melon-shaped balloon, fifty-two feet long by
-    thirty-two feet in diameter, was made of silk and inflated with pure
-    hydrogen. Beneath was suspended a longish car of light wood covered
-    with sky-blue silk. This elegant ship was to be rowed through heaven by
-    means of six silken oars actuated by sturdy sailors. A silken rudder
-    should guide her at pleasure when the winds were asleep, or softly
-    playing in the placid sky. She was a fairy bark, indeed, a soaring
-    castle lovely to behold.</p>
-
-  <p>After a preliminary trial, accompanied by their patron, the Duke de
-    Chartres, they were ready for a substantial journey. On September 19,
-    1784, the vessel was inflated and taken to the Garden of the Tuileries,
-    in front of the palace, where its cords were held by Marshall Richelieu
-    and three other noblemen. At eleven forty-five the two Roberts and
-    their brother-in-law arose and drifted beyond the<span class="pagenum" id="Page_82">82</span> horizon on a seven
-    hours’ cruise. Before coming to earth, they plied the oars vigorously,
-    and described a curve of one kilometer radius, thus deviating 22° from
-    the feeble wind then prevailing. In a lighter wind they could deviate
-    still more. They considered, therefore, that the experiment was a
-    complete success. They had constructed the first elongated balloon,
-    and had “solved the problem of aërial navigation.” In very happy mood,
-    therefore, they landed at dusk among the delighted inhabitants of
-    Artois, where they were graciously met and hospitably entertained by
-    the Prince de Ghistelles-Richbourg.</p>
-
-  <div class="figcenter">
-    <a id="Fig_14"><img src="images/i_102.jpg" width="491" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 14.—Robert Brothers’ Dirigible, 1784.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_83">83</span>The Robert brothers were the first to employ in practice an air bag
-    inside a gas bag. This was held within the balloon by ropes and
-    connected with the outer atmosphere by a tube, the idea being to
-    regulate the internal pressure of the balloon by introducing air into,
-    or withdrawing it from, the smaller bag. But during an ascension with
-    their patron, the Duke de Chartres, they entered a violent eddy which
-    tore away the oars and rudder, at the same time agitating the balloon
-    so violently that the internal air bag broke its sustaining cords and
-    fell upon the bottom of the gas bag, thus throttling the connection
-    with the external atmosphere. The vessel rose swiftly and the gas
-    expanded dangerously near to the bursting pressure. At a height of
-    16,000 feet the Duke de Chartres, perceiving the imminent danger of
-    an explosion of the envelope, drew his sword and cut a rent ten feet
-    long in its lower part. A part of the gas immediately rushed forth,
-    and the balloon sank rapidly, but after the discharge of the ballast,
-    landed safely without further mishap. The Duke acted wisely enough,
-    but he was afterwards ridiculed for his apparent lack of courage. If
-    he had possessed more bravery and less caution he might have allowed
-    the balloon to burst and descend as a parachute, thus anticipating the
-    spectacular performance of John Wise, in 1838.</p>
-
-  <p>Simultaneously other inventors were evolving designs of no less
-    importance in the ultimate perfection <span class="pagenum" id="Page_84">84</span>of the dirigible. In a letter
-    written to Benjamin Franklin on May 24, 1784, Francis Hopkinson of
-    Philadelphia proposed to build a balloon of spindle shape and to drive
-    it by means of a wheel-like propeller at the stern, consisting of vanes
-    set at an angle to the line of progression, like the common smokejack.
-    This proposed craft, the harbinger of the modern screw-driven motor
-    balloon, far antedated the screw-driven boat and the submarine torpedo
-    which it most resembles.<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">[9]</a></p>
-
-  <p>While Blanchard and other aëronauts were paddling their globose bags
-    in search of favorable winds, vainly hoping thereby to direct their
-    course in the air, General Meusnier of the French army, and member of
-    the Academy of Sciences, made a systematic study of the requirements
-    for practical air navigation. After some research on forms suitable
-    for aëronautic hulls, he designed a power balloon having a pointed
-    car suspended from a bag of goose-egg form, this latter embodying his
-    idea of the best shape for a balloon that must cleave the air swiftly
-    and resist deformation. The propulsion was to be effected by means of
-    three coaxial screw propellers, supported on the rigging between car
-    and bag, and actuated by eighty men, for lack of a <span class="pagenum" id="Page_85">85</span>light artificial
-    motor. He thus hoped to obtain a moderate velocity which, combined with
-    skillfully selected air currents, would enable the ship to reach her
-    destination in ordinary weather.</p>
-
-  <div class="figcenter">
-    <a id="Fig_15"><img src="images/i_105.jpg" width="547" height="614" alt="" /></a>
-    <div class="caption smcap">Fig. 15.—Gen. Meusnier’s Proposed Dirigible, 1784.</div>
-  </div>
-
-  <p>General Meusnier introduced important special features in the design of
-    dirigibles for preserving their form and poise. He insisted that the
-    bag and boat should be so rigidly connected that one could not swerve
-    from alignment and relative position with the other. He also emphasized
-    the necessity of preserving the vessel from deformation during flight,
-    in order to diminish its resistance. To that end he proposed to provide
-    the hull with a double<span class="pagenum" id="Page_86">86</span> envelope, the inner one thin and light but
-    impermeable to hydrogen; the outer one strong and air-tight; the space
-    between the two envelopes to be pumped full of air under pressure
-    sufficient to preserve the form of the bag when beating its way swiftly
-    against a buffeting wind. This was an important invention which in
-    later years was adopted in many of the most powerful motor balloons—for
-    all, indeed, except those of the rigid type. He also proposed the
-    use of stabilizing planes to control the poise of the vessel, thus
-    anticipating the Lebaudy brothers by more than a century. Like the
-    Robert brothers he proposed to raise or lower the vessel in search of
-    suitable currents, by altering the quantity of air in the space between
-    the inner and outer envelope, by use of hand bellows.</p>
-
-  <p>Apparently General Meusnier and his colleagues were endowed with
-    constructive genius sufficient to have developed a practical motor
-    balloon, had they been able to secure a light engine. Lacking this the
-    early aëronauts could do little more than describe their projects, and
-    await the growth of the collateral arts and sciences. Accordingly no
-    substantial advance in motor balloons beyond Meusnier’s designs was
-    effected till after the middle of the nineteenth century; and until
-    then the art of aëronautics remained in the hands of showmen. Hundreds
-    of projects, indeed, were advanced, some exciting considerable interest
-    and expectation, but nevertheless of such paltry value as hardly to
-    deserve comment. One notable exception to these was the invention of
-    Porter in America.</p>
-
-  <p>In 1820 Rufus Porter, a Yankee inventor, and later the original
-    founder of the <cite>Scientific American</cite>, patented an air ship of very
-    promising appearance for that early day. Its hull was a long, finely
-    tapering symmetrical spindle, suspending a car of<span class="pagenum" id="Page_87">87</span> similar shape by
-    means of cords, which were vertical at its middle but more and more
-    slanting toward its ends. Midway between the hull and car was a large
-    screw propeller actuated by a steam engine in the car. A model of
-    this dirigible exhibited in Boston and New York, some years later, is
-    reported to have carried its own power, at fair speed, and to have
-    obeyed its helm satisfactorily.</p>
-
-  <div class="figcenter">
-    <a id="Fig_16"><img src="images/i_107.jpg" width="534" height="151" alt="" /></a>
-    <div class="caption smcap">Fig. 16.—Rufus Porter’s Dirigible, 1820.</div>
-  </div>
-
-  <p>The inventor, being too poor to develop his air ship alone, did
-    little with the patent during its life; but in 1850 he organized
-    a stock company to realize the needed funds. From the sale of 300
-    five-dollar shares he expected to raise $1,500, and with this sum
-    build an “aëroport,” 150 feet long, capable of carrying five persons
-    sixty miles an hour, the whole to be completed in six weeks. Once
-    this was in operation he would easily command funds sufficient to
-    build a full-sized vessel adapted to regular passenger service. For,
-    after careful calculation, he reported that: “It appears certain that
-    a safe and durable aërial ship (or aëroport) capable of carrying 150
-    passengers at a speed of ninety miles an hour, with more perfect safety
-    than either steamboat or railroad cars, may be constructed for $15,000,
-    and that the expense of running it would not exceed $25 per day.”</p>
-
-  <p>The language and project seem very modern, even at the present
-    time, and might well be copied now by a promoter of that identical
-    project. But<span class="pagenum" id="Page_88">88</span> it must be observed that the most successful European
-    experimenters, after spending hundreds of thousands of dollars on giant
-    air ships, have not yet attained one half the speed contemplated by
-    that ambitious and chimerical Yankee. The picture was handsome and
-    alluring, none the less. It may even be said to excel in outward design
-    any of the air-ship plans produced in either hemisphere before the
-    middle of the nineteenth century.</p>
-
-  <p>In 1850 a clockmaker and skillful workman, Jullien by name, exhibited
-    in the Hippodrome, at Paris, a torpedo-shaped model balloon of
-    gold-beater’s skin, provided with a screw propeller at either side
-    of its bow, and a double rudder at its stern. It measured 23 feet in
-    length and weighed 1,100 grammes complete. The propellers were actuated
-    by spring power, and proved able to drive the tiny vessel against a
-    moderate wind. The most suitable form for the bag was determined by
-    towing models through water.</p>
-
-  <div class="figcenter">
-    <a id="Fig_17"><img src="images/i_108.jpg" width="553" height="91" alt="" /></a>
-    <div class="caption smcap">Fig. 17.—Jullien’s Model Dirigible, 1850.</div>
-  </div>
-
-  <p>Aërodynamically considered, this tiny motor balloon was by far the best
-    in design of any that appeared during the first century of aëronautics.
-    It may be regarded as the harbinger of the swiftest modern French
-    balloons. It was also an inspiration to Henri Giffard who assisted
-    Jullien in constructing his clever model, and shortly afterwards built
-    the first dirigible ever driven by a heat engine.</p>
-
-  <p>The illustrious Henri Giffard was perhaps the first aëronautical
-    engineer adequately endowed and<span class="pagenum" id="Page_89">89</span> circumstanced to realize, on a
-    practical scale, General Meusnier’s well pondered and truly scientific
-    plans for a motor balloon. He had studied in the college of Bourbon,
-    and had worked in the railroad shops of the Paris and St. Germain
-    railway. He had further equipped himself by making free balloon
-    ascensions, under the auspices of Eugene Godard, for the purpose of
-    studying the atmosphere; and by building light engines, one of which
-    weighed 100 pounds, and developed three horse power. Finally in 1851 he
-    patented an air ship, consisting of an elongated bag and car, propelled
-    by a screw driven by a steam engine. He had not the means to build such
-    a vessel, but he had the genius and training necessary to construct it,
-    and at the same time enough enthusiasm and persuasive power to induce
-    his friends, David and Sciama, to loan him the requisite funds.</p>
-
-  <div class="figcenter">
-    <a id="Fig_18"><img src="images/i_109.jpg" width="565" height="400" alt="" /></a>
-    <div class="caption smcap">Fig. 18.—Giffard’s Steam Dirigible, 1852.</div>
-  </div>
-
-  <p>Giffard’s first dirigible was successful in both design and operation.
-    It consisted of a spindle-shaped <span class="pagenum" id="Page_90">90</span>bag covered with a net whose cords
-    were drawn down and attached to a horizontal pole, from which the car
-    and motor were suspended, and at the end of which was a triangular
-    sail serving as a rudder. To guard against fire, the furnace of the
-    vertical coke-burning boiler was shielded by wire gauze, like a miner’s
-    lamp, and the draft, taken from its top through a downward pointing
-    smoke pipe, was ejected below the car by force of exhaust steam, from
-    the engine, thus obviating, as Giffard asserted, all danger from the
-    use of fire near an inflammable gas. The car hung twenty feet below
-    the suspension pole, and carried a three horse-power engine driving a
-    three-blade propeller 11 feet in diameter, making 110 turns a minute.
-    The motor complete, including the engine and boiler without supplies,
-    weighed 110 pounds per horse power. The bag measured 143 feet long, 39
-    feet in diameter, and 75,000 cubic feet in volume. Giffard reports of
-    his first voyage, made from the Hippodrome in Paris at five fifteen
-    o’clock, September 23, 1852, that although he could not sail directly
-    against the strong wind then blowing, he could attain a speed of six
-    to ten feet per second relatively to the air, and he could easily
-    guide the vessel by turning her rudder. He continued his journey till
-    nightfall, then made a good landing, near Trappes, and by ten o’clock
-    was back in Paris.</p>
-
-  <p>This vessel was but a prelude to mightier projects. After some further
-    experience with dirigibles of moderate size, Giffard designed a
-    colossal air ship calculated for a speed of forty-four miles an hour.
-    Its hull was to be of torpedo shape, measuring 2,000 feet in length,
-    100 feet in diameter, and 7,000,000 cubic feet in volume. It was a
-    most audacious project, one worthy of the genius and energy of that
-    illustrious engineer, the most original and<span class="pagenum" id="Page_91">91</span> daring inventor known in
-    the aëronautical world during the nineteenth century.</p>
-
-  <p>Stimulated by this huge enterprise, Giffard’s first step was to pay his
-    debts and make a fortune. He soon acquired a hundred thousand francs
-    from the sale of small high-speed engines of his own construction, and
-    with this, settled his account with David and Sciama. Next he realized
-    several million francs from his world-famous injector, a device by
-    which steam flowing from a boiler is made to drive in feed-water
-    against the same pressure.</p>
-
-  <p>He now made definite plans to build a motor balloon of one and a half
-    million cubic feet capacity, driven by a condensing engine drawing
-    steam from two boilers, one fired with oil, the other with gas from
-    the balloon, so as to keep the vessel from rising with loss of weight.
-    His designs were complete, and everything was provided for. He had
-    deposited a million francs in the Bank of Paris to defray the estimated
-    cost. But, in the words of Tissandier,<a id="FNanchor_10" href="#Footnote_10" class="fnanchor">[10]</a> “above the human will and
-    foresight are the fatal laws of destiny to which the strongest must
-    submit.” The great inventor was visited with a painful affliction
-    of the eyes; his sight waned, unfitting him for work; he became
-    disconsolate, pined away with pain and grief, and in 1882 ended his
-    life by taking chloroform.</p>
-
-  <p>Giffard was succeeded in France, first by Dupuy de Lome; then by
-    Gaston Tissandier, well-meaning projectors of steerable balloons, but
-    too cautious to effect an important advance in the art. The first of
-    these gentlemen, an eminent marine engineer, in 1872, completed a gas
-    balloon for the French government, resembling the one designed by
-    General Meusnier in 1784, and like that also driven by mus<span class="pagenum" id="Page_92">92</span>cular power
-    actuating a screw, and kept rigidly inflated by use of an internal
-    balloon, or ballonet. The car was suspended from the bag by a close
-    fitting cover instead of a net, in order to lessen the resistance, and
-    it was kept in alignment by use of crossed suspension cords. A speed
-    of but six miles an hour was attained by the industrious work of eight
-    men operating an ample screw propeller. A decade later Tissandier, with
-    a balloon of like design, but driven by the power of an electric motor
-    and bichromate of potash battery, attained a speed of six to eight
-    miles an hour.</p>
-
-  <div class="figcenter">
-    <a id="Fig_19"><img src="images/i_112.jpg" width="537" height="408" alt="" /></a>
-    <div class="caption smcap">Fig. 19.—Dupuy de Lome’s Dirigible, 1872.</div>
-  </div>
-
-  <p>The two vessels were safe but of no practical value, for lack of
-    sufficient power to cope with the wind. Their motors were fundamentally
-    unadapted to the purpose of swift propulsion, and incapable of
-    development to very great lightness and strength. Furthermore, the
-    vessels themselves were unsuitably designed for speed; their shape
-    being one of too much resistance, and their dynamic balance<span class="pagenum" id="Page_93">93</span> being
-    that of a pendulum, or clumsy parachute, rather than that of a vessel
-    adapted to cleave the air with celerity, grace and steadiness. If there
-    had been danger of fire from placing the motor and screw near the gas
-    bag, that might justify or excuse the clumsiness of design in the craft
-    of De Lome and of Gaston Tissandier; but, having perfectly safe motors,
-    it is astonishing that they did not place the center of mass and the
-    line of thrust more nearly in the line of resistance. This obvious
-    requirement was duly recognized by several of their contemporaries,
-    notably by Hänlein in Germany, and by Captain Renard of the French War
-    Department, and had been observed by Jullien.</p>
-
-  <p>Captain Charles Renard proved to be a worthy inheritor of the dreams,
-    experience and inventions of the first century of aëronautical
-    votaries. He did not, indeed, have the picturesque madness displayed
-    by some of his predecessors; he did not project schemes of marvelous
-    originality or boldness; but he manifested uncommonly good judgment
-    and excellent scientific method in combining the researches and
-    contrivances of others with those of himself and his collaborator,
-    Captain Krebs. As a consequence they produced the first man-carrying
-    dirigible that ever returned against the wind to its starting point,
-    and the first aërial vessel whose shape and dynamic adjustment even
-    approximated the requirements of steady and swift navigation in a
-    surrounding medium presenting various conditions of turbulence or calm.
-    Captain Renard had been studying and designing dirigibles since 1878
-    in coöperation with Captain La Haye and Colonel Laussedat, president
-    of an aëronautic commission appointed by the Minister of War; and had
-    endeavored to secure from the latter an appropriation sufficient to
-    construct a dirigible; but his request<span class="pagenum" id="Page_94">94</span> was at first denied, owing
-    to the waste of funds on similar projects in 1870. However, with the
-    help of Gambetta, who promised a sum of $40,000, Renard was enabled to
-    proceed. In the meantime he had been made director of the laboratory at
-    Chalais Meudon, seconded by Captain Krebs.</p>
-
-  <div class="figcenter">
-    <a id="Fig_20"><img src="images/i_114.jpg" width="588" height="423" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 20.—Renard’s Dirigible</span>, <i>La France</i>, 1884.</div>
-  </div>
-
-  <p>These officers first worked out the separate elements in the design of
-    their motor balloon before proceeding to build on a practical scale.
-    They chose the torpedo form for their gas bag, thereby ensuring in
-    the hull itself, projectile stability, and diminution of resistance.
-    They placed the car near the envelope, thus minimizing the disturbing
-    moment of the screw thrust, and the resistance of the suspension cords.
-    They employed an extraordinarily powerful electric motor actuating a
-    large screw so as to obtain a strong thrust with the least effort.
-    In addition they adopted the best ideas of their predecessors in
-    aëronautical design; the internal<span class="pagenum" id="Page_95">95</span> ballonet of Meusnier, and the
-    close fitting cover of De Lome, with crossed suspension cords. But
-    unfortunately they used an electric motor instead of some light engine.
-    Finally, having carefully computed its requisite dimensions, they
-    proceeded to construct the elegant air ship, <i>La France</i>, which was
-    tested in 1884 and aroused anew the hope of ultimately conquering the
-    air.</p>
-
-  <p>Further details of this successful ship are of interest. Its hull
-    was 165 feet long, 27.5 feet in greatest diameter, at one fourth the
-    distance from its front end, and cubed 66,000 feet, thus having a
-    buoyancy of two long tons. It was kept rigid under varying conditions,
-    by means of a ballonet filled with air driven in by a common fan blower
-    coupled to the motor. Beneath the envelope, a long narrow rectangular
-    car made of bamboo, covered with silk, was suspended from the cords
-    of the balloon cover which embraced the hull throughout nearly its
-    entire length. The car was 108 feet long and 6 to 7 feet across,
-    carried at its forward end the propeller, at its rear a rectangular
-    rudder, and between them the aëronauts and the batteries and electric
-    motor. A sliding weight was used to alter the poise of the ship, and a
-    guide-rope to soften its descent.</p>
-
-  <p>The electric motor and battery which furnished the propulsive power
-    were designed expressly for such use, and were considered at the time
-    to be remarkably light and effective. The motor, which was designed
-    with the assistance of M. Gramme, weighed 220.5 pounds, and developed
-    nine horse power. The battery, composed of chlorochromic cells, was the
-    result of the researches of Renard himself. Having made a careful study
-    of the best geometrical arrangement of the parts of the cell, Renard
-    found that this battery would deliver to the shaft one horse power for
-    each eighty-eight pounds<span class="pagenum" id="Page_96">96</span> of its weight. Thus the power plant rivaled
-    in lightness the steam engine of Giffard, and at the same time was free
-    from danger; but apparently it could not be much reduced in weight,
-    whereas Giffard’s steam-power plant could be reduced tenfold, as shown
-    by Renard’s contemporaries.</p>
-
-  <p>The trials of <i>La France</i> in 1884–85 were most successful and
-    encouraging; not that they represented or pointed to the complete
-    mastery of aërial navigation, but because they so far surpassed all
-    previous achievements. The vessel moved through the air as steadily as
-    a boat on the water, and obeyed her rudder perfectly, heading against
-    the wind, or at any angle to it, or turning entirely about, at the will
-    of the aëronauts. On her first voyage from Chalais, August 9, 1884, she
-    traversed a distance of four and one half miles in twenty minutes, made
-    various evolutions in the air with the greatest ease, and returned to
-    her point of departure. The following account of this voyage is given
-    by Renard:</p>
-
-  <blockquote>
-    <p>“As soon as we had reached the top of the wooded plateaus which
-      surround the valley of Chalais, we started the screw, and had the
-      satisfaction of seeing the balloon immediately obey it and readily
-      follow every turn of the rudder. We felt that we were absolutely
-      masters of our own movements, and that we could traverse the atmosphere
-      in any direction as easily as a steam launch could make its evolutions
-      on a calm lake. After having accomplished our purpose, we turned our
-      head toward the point of departure and we soon saw it approaching it.
-      The walls of the park of Chalais were passed anew, and our landing
-      appeared at our feet, about 1,000 feet below the car. The screw was
-      then slowed down, and a pull at the safety-valve started the descent,
-      during which, by means of the propeller and rudder, the balloon was
-      maintained<span class="pagenum" id="Page_97">97</span> directly over the point where our assistants awaited us.
-      Everything occurred according to our plan, and the car was soon resting
-      quietly on the lawn.”</p>
-  </blockquote>
-
-  <p>Six other similar voyages were made within the two years following,
-    and we have as a result, that in five out of the seven trials, the
-    balloon returned to its point of departure. Its failure to return in
-    the other two trials was due, in the one case, to the breaking down of
-    the motor; in the other, to the resistance of a strong wind which made
-    it necessary to land at a distance from the starting point. The last of
-    these remarkable voyages was performed in presence of the Minister of
-    War, on September 23, 1885. The balloon started from Calais and sailed
-    against the wind directly to Paris, passed over the fortifications,
-    described a graceful curve and returned to its place of departure,
-    recording an average speed of 14.5 miles an hour.</p>
-
-  <p>The torpedo form of hull, chosen by Renard and Krebs, has two important
-    advantages; one is projectile stability, the other is economy of
-    propulsive power. Owing to the blunt bow and long tapering stern, the
-    center of mass is well forward, while the center of side wind pressure
-    is more to the rear. As a consequence, if the vessel should encounter a
-    quartering wind-gust, or have her nose slightly turned from the course,
-    she would promptly right herself like a dart or an arrow. If on the
-    contrary, the hull were a symmetrical spindle, the vessel would move
-    forward in unstable equilibrium, and, once slightly diverted from her
-    course, would tend to deviate further, like an arrow with unloaded head.</p>
-
-  <p>The second advantage mentioned is also worth attention, viz.: that at
-    ordinary transportation speeds a longish spindle has less resistance
-    with a blunt bow than with a very sharp one. Renard and Krebs did
-    not account for this fact; but the present writer,<span class="pagenum" id="Page_98">98</span> by determining
-    separately the skin friction and the impactual resistance of the air,
-    proved that in sharpening the bow beyond a certain best form, its
-    friction increases faster than its head resistance diminishes, the
-    most suitable shape being that of a torpedo whose nose has a radius
-    of curvature of about two diameters, and its stern a radius of about
-    twelve diameters.</p>
-
-  <p>While the successors of Giffard in France were thus engaged in
-    developing dirigibles driven by muscular or electric power, a few
-    German experimenters were applying gas and benzine engines to such
-    vessels, with better promise of ultimate practical success and
-    usefulness. The first of these was Hänlein, who in 1872 advanced the
-    meritorious project of driving a well shaped balloon by means of a gas
-    engine taking its fuel from inside the balloon, and making good the
-    loss by pumping air into the ballonet. This balloon was of far better
-    design for swiftness and kinetic stability than the contemporary one of
-    Dupuy de Lome. Its hull was a well pointed cylinder 164 feet long, 30
-    feet in diameter and of 85,000 cubic feet capacity, made air-tight by
-    a thick coating of rubber inside, and a thin one outside. The car was
-    rigidly suspended near the envelope and carried a 6 horse-power Lenoir
-    gas engine actuating a large screw. Notwithstanding that the buoyancy
-    was small, owing to the use of coal gas, this air ship attained a speed
-    of 15 feet per second. By employing hydrogen, a much larger engine
-    could have been carried, entailing a much swifter speed. During its
-    trial the balloon was kept near the earth’s surface, held loosely by
-    ropes in the hands of soldiers. The air ship was remarkably successful
-    for that early date, and had the potency of greater achievement
-    than its contemporaries in France; but owing to lack of funds its
-    capabilities were not fully <span class="pagenum" id="Page_99">99</span>developed. If it had been inflated with
-    hydrogen, and propelled by use of gas and petrol, so that the loss
-    of weight would compensate for the loss of buoyancy, it might have
-    anticipated the speed and endurance of the best air ships built toward
-    the close of the nineteenth century, or later.</p>
-
-  <hr class="page" />
-  <div id="Plate_II" class="center"><b>PLATE II.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_119a.jpg" width="600" height="316" alt="" />
-    <div class="captionp">HAENLEIN’S GAS-DRIVEN DIRIGIBLE.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_119b.jpg" width="600" height="324" alt="" />
-    <div class="captionp">WÖLFERT’S BENZINE-DRIVEN DIRIGIBLE.</div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_119c.jpg" width="600" height="315" alt="" />
-    <div class="captionp">SANTOS-DUMONT’S DIRIGIBLE, <i>NO. 16</i>.</div>
-    <div class="right small"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <p>In 1879, Baumgarten and Wölfert in Germany built a dirigible equipped
-    with a Daimler benzine motor, but otherwise not possessing any special
-    merit. An ascension was made at Leipsic in 1880, but owing to improper
-    load distribution the vessel reared on end and crashed to earth. After
-    further experiments, an ascension was made on the Templehofer field,
-    near Berlin, in 1897, but this ended disastrously; for the benzine
-    vapor ignited; the fire spread to the balloon, and the vessel fell
-    flaming to the earth, killing Wölfert and his assistant. Baumgarten had
-    died some years before.</p>
-
-  <p>In 1897, an aluminum air ship invented by an Austrian engineer, named
-    Schwartz, was launched on the Templehofer field. Its hull was of
-    cylindrical form with conical ends, made of sheets 0.008 thick, and
-    stiffened with an internal frame of aluminum tubes. Being leaky and
-    inadequately driven, it voyaged but four miles, drifting with the wind,
-    then fell to earth with considerable shock. The pilot, a soldier of the
-    Balloon Corps, escaped by jumping, before the vessel struck ground, but
-    the frail unbending hull was soon demolished by the buffeting of the
-    winds as it lay stranded on the unyielding earth. This was the second
-    air ship built after the plans of poor Schwartz, the first having
-    collapsed on inflation. He had, however, the credit of being the first
-    to drive a rigid air ship with a petrol motor, and thus to inaugurate
-    a system of aërial navigation capable of immense development, in
-    the hands of sufficient capital and constructive skill. Thus the
-    rigid type,<span class="pagenum" id="Page_100">100</span> conceived and crudely tried by Marey Monge and Dupuis
-    Delcourt in the early part of the century, began to approach practical
-    realization toward the end of the century.</p>
-
-  <p>The process of inflating with hydrogen such a rigid hull is
-    interesting. Schwartz’s plan, carried out by Captain Von Sigsfeld,
-    was to place the hydrogen in one or more sacs inside the hull, thus
-    expelling the air and filling the space, then withdrawing the sacs and
-    leaving the hydrogen within. A better plan is to have a single sac
-    inflated with air just filling the hull like the lining of an egg, then
-    to force the gas between the lining and metal wall of the hull, thus
-    expelling the air from the sac, which when completely collapsed can be
-    removed. Practically the same result can be obtained by use of a thin
-    fabric covering one half the inner wall, like the lining of an egg.
-    Further provision can easily be made for manipulating the ballonet in
-    such a case.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_IV">
-    <span class="pagenum" id="Page_101">101</span>
-    <h3>CHAPTER IV</h3>
-    <span class="small">INTRODUCTION OF GASOLINE-DRIVEN DIRIGIBLES</span>
-  </div>
-
-  <p><span class="smcap">We</span> have now traced the art of balloon guidance and propulsion from its
-    earliest inception to the close of the nineteenth century. It was a
-    period of extravagant hope and chimerical scheming, but withal a period
-    fruitful in devices of fundamental value. The best experiments paid no
-    dividends, but they prepared the way for really useful vessels. The
-    methods of manipulation and control had been sufficiently developed
-    to answer immediate needs. The air ship was at least dirigible, if
-    not practical. It kept its shape, obeyed its rudder, rose and fell
-    according to the operator’s will. It was, however, a fair-weather
-    machine, beautiful in appearance, but helpless in any considerable
-    wind. Speed was now the desideratum, and the attainment of this
-    involved new difficulties. The storm-proof balloon was still a dream.</p>
-
-  <p>Naturally one inquires what velocity makes a dirigible air ship really
-    practical, assuming all other requirements satisfied. The minimum
-    allowable speed depends largely upon the locality and season. On Long
-    Island an assured velocity of forty to fifty miles an hour would
-    seem desirable; for there the winds are swift and the water near. In
-    Washington, or Berlin, thirty miles an hour is enough, though each
-    additional mile per hour must be regarded as a considerable gain on
-    a small margin of progress in facing a stiff breeze. Colonel Renard
-    has estimated, <span class="pagenum" id="Page_102">102</span>from a study of the wind records near Paris, that a
-    dirigible is practically useful in that locality if it can maintain a
-    speed of twenty-eight miles an hour for ten or twelve hours; since in
-    that case it can maneuver 81 days in 100.</p>
-
-  <p>Renard’s own graceful ship attained a speed of but half that much. In
-    order, therefore, to give his vessel the desired usefulness its speed
-    must be doubled. This would require an eightfold<a id="FNanchor_11" href="#Footnote_11" class="fnanchor">[11]</a> increase of motive
-    power without increase of weight. Evidently then the cardinal requisite
-    was a light durable motor of extraordinary output. Such motors
-    fortunately were now coming into the market, owing to the development
-    of gasoline engines for automobile racing.</p>
-
-  <p>The year 1898 witnessed the commencement of two famous systems of
-    navigation by the lighter than air, one in France, the other in
-    Germany, destined quickly to revolutionize the art, and to establish
-    it on a practical basis. The leading exponents of these two systems
-    were Señor Don Alberto Santos-Dumont, a rich young Brazilian living in
-    Paris, and Count Ferdinand von Zeppelin, Germany’s stanch old admiral
-    of the air. Both achieved success by applying the gasoline engine to
-    the propulsion of elongated balloons, but by very different methods.
-    Santos-Dumont, apparently ignoring, or fearing to adopt, the excellent
-    hull and car designed and used by Renard, began where Tissandier left
-    off, with a symmetrical hull and low-hung car, thus producing a safe
-    aërial pendulum, if not a racing machine; then by degrees he gradually
-    felt his way to something more efficient. Zeppelin began with a long
-    cylindrical hull pointed at the ends, rigidly framed <span class="pagenum" id="Page_103">103</span>like that of
-    Schwartz, and supporting its car and propellers well aloft near the
-    line of resistance. His was a bold and effective design but difficult
-    to execute. Santos-Dumont scored the first success, and startled the
-    world by his spectacular flights; but ere long he was surpassed by
-    other builders of non-rigid balloons. Zeppelin won his success slowly
-    and by heroic perseverance in the face of enormous obstacles, finally
-    emerging as the most successful and illustrious figure in the history
-    of aëronautics. The achievements of these two pioneers and colleagues
-    make the first decade of the twentieth century memorable in the annals
-    of aërial navigation.</p>
-
-  <p>Santos-Dumont, who spent his early years on his father’s large coffee
-    plantation in Brazil, had, during boyhood, dreamed of navigating the
-    air, and in 1897, at the age of twenty-four, made in France his first
-    ascension in a spherical balloon. While living at Paris during that
-    year he gave much time to motorcycling, automobiling and operating
-    spherical balloons, of which he possessed two constructed after his own
-    ideas; one, the smallest in the world, designed for solitary voyages,
-    the other large enough for more than one person, intended for social
-    excursions. Thus by way of amusement, and probably by impulse rather
-    than deliberate purpose, he was equipping himself to become both the
-    designer and the pilot of his future dirigibles.</p>
-
-  <p>Having acquired experience and skill in operating both balloons and
-    engines, the young enthusiast set about realizing his boyhood dream
-    of navigating the air independently of the course of the wind. His
-    first dirigible was designed to carry his weight of 110 pounds and a
-    3½ horse-power petroleum engine taken from his tricycle, and reduced
-    in weight to 66 pounds. The hull was a cylinder of varnished Japanese
-    silk, 82½ feet long including its pointed ends,<span class="pagenum" id="Page_104">104</span> 11½ feet in diameter
-    and 6,354 cubic feet in gas capacity. A ballonet, or air pocket,
-    occupied the lower middle of the envelope. The basket for the little
-    pilot, engine, and two-blade propeller was suspended far below the
-    hull, to which its cords were attached by means of small wooden rods
-    inserted into hems along each side of the envelope, for a great part of
-    its length. The poise of the vessel was controlled by shifting weights
-    fore and aft, while the turning right and left was effected by means
-    of a silk rudder stretched over a steel frame. On the whole it was a
-    crude and primitive affair, but of considerable interest as the first
-    dirigible of a young man destined to give a strong impulse to the
-    development of motor balloons of the non-rigid type.</p>
-
-  <p>After some preliminary tests, the little air ship and pilot soared away
-    from the Zoölogical Garden in Paris, on September 20, 1898, rising in
-    the face of a gentle wind, to the wonder and delight of a large crowd
-    of witnesses, some of them professional aëronauts and very skeptical
-    as to the outcome of this venturesome experiment. The ship maneuvered
-    round and round overhead of the applauding throng, steering readily in
-    all directions. Then the green navigator ascended a quarter of a mile
-    and merrily continued his evolutions in the direction of the Longchamps
-    race course. But when he wished to descend he observed the envelope
-    contracting in volume, and was appalled to find that he could not
-    pump air into the ballonet fast enough to keep the hull distended. It
-    became swaybacked, and “all at once began to fold in the middle like a
-    pocket-knife; the tension cords became unequal and the balloon envelope
-    was on the point of being torn by them.” As he was falling swiftly
-    toward the grassy turf at Bagatelle, he called to some boys who were
-    flying kites, to grasp his guide-rope and run against the wind.<span class="pagenum" id="Page_105">105</span> They
-    understood and ran so swiftly with the canted balloon that it played
-    kite, and descended with a moderated fall, landing the frightened
-    aëronaut safely on the turf.</p>
-
-  <p>Except for the doubling of his long balloon, Santos-Dumont’s first
-    voyage was satisfactory, and he returned to Paris elated. He had found
-    it easy to steer in all directions. He could change his level hundreds
-    of feet without discharge of gas or ballast, by merely canting his
-    balloon, and allowing it to run obliquely up or down grade. He had
-    stemmed the wind and gone whither he pleased, at such speed as to make
-    his clothes flutter. And best of all he had found no danger in using a
-    gasoline motor near an inflammable gas bag. The mere buckling of the
-    long bag was a trifle, to be remedied by using an air pump adequate to
-    maintain the flabby thing well inflated. He felt, therefore, that he
-    had the conquest of the air well in hand, and that he was drifting into
-    air ship construction as a life work. Small wonder that he continued
-    his conquests till he had built, in less than one decade, fourteen
-    motor balloons.</p>
-
-  <p><i>Santos-Dumont No. 2</i> was closely patterned after its predecessor,
-    but was a little larger and carried a rotary fan worked by the motor,
-    to keep the balloon plump by filling the air pocket, or ballonet. On
-    May 11, 1899, an ascension was made from the old starting place, but
-    in rainy weather. As the vessel rose its hull contracted faster than
-    air could be pumped into the ballonet, the long bag doubled worse than
-    before, and dropped into the trees with its chagrined but fearless
-    rider.</p>
-
-  <p>The <i>No. 3</i>, which followed, was a short, thick vessel, 66 feet long
-    by 25 feet in diameter, having in outward appearance the features of
-    Dupuy de Lome’s very stable and very slow dirigible. It was apparently
-    a safety ship for a scared young man<span class="pagenum" id="Page_106">106</span> who had not yet learned fully to
-    appreciate Renard’s elegant design. It served for a few pleasant trips,
-    while the inventor was screwing up courage to build another cylindrical
-    vessel, and gradually realizing the advantage of an elongated car such
-    as Renard had employed in <i>La France</i>. Not only was the hull short
-    and thick, but it was further secured from buckling by a horizontal
-    stiffening pole placed between it and the basket, and from which the
-    latter was hung. After some voyages in <i>No. 3</i>, which the captain found
-    very tractable, and probably capable of fifteen miles per hour, he was
-    ready to begin a new vessel.</p>
-
-  <p>The <i>No. 4</i> was a compromise between the better features of <i>No. 3</i>
-    and its predecessors. The elongated hull and ballonet were resumed,
-    and the stiffening pole was elaborated into a longish car resembling
-    Renard’s, but of triangular cross section. On this long trussed frame
-    were placed the motor, propeller, rudder and the rider in his basket.
-    A seven horse-power engine turning, at one hundred revolutions per
-    minute, a screw propeller having two blades, each 13 feet across, gave
-    a thrust of 66 pounds. Frequent trials of the ship during the summer
-    of 1900, in presence of the Exposition crowds, brought the inventor
-    into extraordinary prominence, and secured for him the “Encouragement
-    Prize” of the Paris Aëro Club, consisting of the yearly interest on
-    one hundred thousand francs, this being one of M. Deutsch’s numerous
-    foundations for the promotion of aëronautics.</p>
-
-  <p>In the spring of 1900, M. Deutsch de la Meurthe had established another
-    prize which Santos-Dumont now greatly coveted, and hoped ere long to
-    win. This was a cash sum of one hundred thousand francs to be awarded
-    by the Scientific Commission of the Aëro Club of France to the first
-    dirigible that, between <span class="pagenum" id="Page_107">107</span>May 1 and October 1, 1900, 1901, 1902, 1903,
-    1904, should voyage from Saint Cloud to and around the Eiffel tower,
-    and return within half an hour. The distance to the tower and back,
-    not counting the turn, was nearly seven miles, and the estimated speed
-    required to fulfill the conditions for winning the prize, even in calm
-    weather, was 15½ miles per hour.</p>
-
-  <p>As Santos-Dumont thought his <i>No. 4</i> scarcely swift enough to win
-    the Deutsch prize, he enlarged it by inserting an additional length
-    of sixteen feet at its middle, supplied it with a stronger car, and
-    applied a larger engine, naming the new vessel so formed, his <i>No.
-    5</i>. Its hull was 109 feet long, 17 feet in largest diameter and cubed
-    nearly 20,000 feet. A four cylinder air-cooled petroleum motor driving
-    a screw propeller having two blades, each 13 feet across, gave a thrust
-    of 120 pounds, at 140 revolutions per minute, and produced such draft
-    as to give the inventor pneumonia. Among other novelties water ballast
-    was used, and piano wires replaced the old-time suspension cords.</p>
-
-  <p>The <i>No. 5</i> proved so powerful and swift that on July 13, 1901,
-    Santos-Dumont attempted to win the Deutsch prize. Starting from the
-    Aëro Club grounds at Saint-Cloud in presence of official witnesses,
-    at half past six in the morning, when the air is usually stillest,
-    he turned the Eiffel Tower in the tenth minute, thus gaining twenty
-    minutes for the home stretch. But on his return he encountered an
-    unexpected head wind, and after a terrific struggle reached the
-    timekeepers at Saint-Cloud in the fortieth minute.</p>
-
-  <p>To add to the romance of this voyage, the genii of the upper elements
-    stopped his motor, shortly after his return, and the bold sailor in his
-    shining ship landed in a stately chestnut tree very near the<span class="pagenum" id="Page_108">108</span> house
-    of the Princess Isabel, daughter of Dom Pedro. She very thoughtfully
-    arranged a breakfast for him and sent it up in a basket, where he was
-    at work disengaging the balloon, at the same time inviting him to call
-    and relate to her the story of his voyage. A few days later she sent
-    him a medal of St. Benedict “that protects against accidents.” He wore
-    the medal, and on his very next trial escaped without a scratch from an
-    appalling accident which might have terminated fatally. He continued to
-    wear the gift of that gracious princess, on a thin gold chain circling
-    his wrist, and many a time thereafter endured unscathed the most
-    dreadful accidents, as if he possessed a charmed life.</p>
-
-  <p>On August 8, 1901, the dauntless aëronaut again sailed for the coveted
-    prize, at the same still morning hour, sacred to duels and aërial
-    contests. In nine minutes he turned the tower and headed bravely for
-    home. But soon a leaky valve let the balloon shrink and the wires
-    sag into the whirring propeller, which therefore had to be stopped.
-    Santos-Dumont now had the choice of drifting back against the tower
-    and destroying his vessel high in air, or of descending at once, by
-    allowing the balloon to sink without discharge of ballast. He chose
-    the latter course, hoping to land on the Seine embankment; but instead
-    his balloon struck the top of the Trocadero hotel, exploded and fell
-    in fluttering shreds into the courtyard. Some firemen who had been
-    watching the flight from a distance, came with a rope and found
-    the long car leaning like a ladder against the wall of the court,
-    the balloon shreds hanging from it in graceful folds, and Captain
-    Santos-Dumont perched aloft in his wicker basket wearily waiting for
-    St. Benedict’s further aid. As usual, he was rescued intact.</p>
-
-  <p>On the evening of his fall on the roof of the hotel<span class="pagenum" id="Page_109">109</span> Santos-Dumont
-    issued specifications for his famous <i>No. 6</i>, which surpassed
-    all its predecessors in safety and speed. It had the shape of an
-    elongated ellipsoid with pointed ends, measured 110 feet in length,
-    20 feet in major diameter, 22,239 cubic feet in volume, and had an
-    absolute ascensional force of 1,518 pounds. It was driven by a twelve
-    horse-power four-cylinder water-cooled engine which gave the propeller
-    a thrust of 145 pounds. To insure against buckling of the gas bag, an
-    air pump connected with the motor, kept the ballonet under constant
-    pressure, regulated by an escape valve through which the excess of
-    air passed outward. To secure the envelope against rupture, due to
-    the expansion of the hydrogen at unusual elevations, a stronger valve
-    was used to let the gas escape from the envelope into the atmosphere.
-    Thus the air escape valve kept the pressure constant in the partially
-    distended ballonet, and consequently also in the surrounding gas
-    envelope itself; while the stronger gas valve in the envelope opened
-    only in an emergency, when the gas pressure had fully collapsed the
-    internal air pocket and was threatening to explode the envelope. With
-    all its improvements this new vessel was finished and inflated by
-    August 4, being a work of twenty-two days, and after some preliminary
-    trials was ready to try for the Deutsch prize.</p>
-
-  <p>The day of triumph followed quickly. On October 19, 1901, at 2.45
-    <span class="smcap">P. M.</span>, Santos-Dumont again headed for the Eiffel Tower in
-    presence of the official witnesses. In spite of a wind of six meters
-    per second striking him sidewise, he held his course straight for the
-    goal, and turned it in the ninth minute, as in his preceding attempt.
-    On the return he had to struggle against a quartering wind and the
-    caprice of his motor, which sometimes threatened to stop, and again
-    spurted so actively as to turn the ship upward<span class="pagenum" id="Page_110">110</span> at a steep angle.
-    The mighty throng below, in the Auteuil race track and the Bois de
-    Boulogne, sent up immense applause, then suddenly held its breath in
-    alarm, as the vessel pitched violently. But the hardy little rider was
-    self-possessed and at home on his vaulting Pegasus. Alert to every
-    prank he held his course straight for the timekeepers and passed over
-    their heads at exactly twenty-nine and one-half minutes after starting.</p>
-
-  <p>His unmercenary disposal of the two rich awards which he had won seemed
-    no less commendable than the dauntless industry which achieved such
-    rapid success. The Deutsch prize amounting in all to one hundred and
-    twenty-five thousand francs he divided into two unequal parts. The
-    greater sum of seventy-five thousand francs he gave to the prefect
-    of police of Paris, to be used for the deserving poor; the remainder
-    he distributed among his employés. The Encouragement Prize of four
-    thousand francs a year, mentioned before, he also declined to retain,
-    but instead he founded with the money a new prize at the disposal of
-    the Aëro Club. As a second reward for his triumphal voyage around the
-    Eiffel Tower, he received from the Brazilian government one hundred
-    and twenty-five thousand francs and a beautiful gold medal bearing
-    appropriate and very complimentary inscriptions.</p>
-
-  <p>Now that the stimulus and excitement of striving for the Deutsch prize
-    was over, the ardent inventor was free to develop and test his air
-    ships in a deliberate and scientific manner. He therefore set about
-    building specialized types of motor balloons, and practicing with them
-    over all kinds of territory, smooth and rough. Within the next six
-    years he constructed eight more air ships making altogether fourteen,
-    besides his various free balloons, to say nothing of the aëroplanes and
-    hydroplanes which he<span class="pagenum" id="Page_111">111</span> found time to develop. But before indulging in
-    these new luxuries he would have more experience with his <i>No. 6</i>.</p>
-
-  <p>When the cold weather set in, following his victorious flight about
-    the Eiffel Tower, Santos-Dumont went with his <i>No. 6</i> to Monaco, to
-    practice air cruising over the Mediterranean. The Prince of Monaco
-    had erected for him an “aërodrome,” or balloon shed, facing the sea
-    and very near shore. On pleasant days the daring pilot would cruise
-    up and down the bay, not far from shore, trailing his guide-rope over
-    the waves with the greatest ease, and to the applause of thousands of
-    spectators. But on February 14, 1902, he set forth on a pleasure cruise
-    over the bay with insufficient gas pressure, and thus came to grief.
-    The bag grew flabby; the hydrogen poured to its higher end; the vessel
-    reared up so steeply that the propeller had to be stopped to avoid
-    its cutting the envelope. Rather than drift at the mercy of the wind,
-    the pilot opened the valve and sank slowly to the water where he was
-    rescued by a boat. On the following day the parts of his <i>No. 6</i> were
-    fished out of the sea and sent back to Paris. His few days’ practice
-    had taught him the delights of guide-roping over the waters, and his
-    accident induced him in future to sew unvarnished silk partitions
-    across his balloons, to prevent the hydrogen passing too suddenly from
-    one end to the other.</p>
-
-  <p>Returning to Paris he built for himself an “aërodrome,” provided
-    with great sliding doors like the one at Monaco, and equipped with a
-    hydrogen plant, constructive appliances, and everything needed for
-    the rapid rebuilding or repair of air ships. It stood in a vacant lot
-    surrounded by a high stone wall and was made of posts covered with red
-    and white canvas, so that it looked like a great striped tent. Inside,
-    the central stalls were 31 feet wide, 165 feet long, and<span class="pagenum" id="Page_112">112</span> 44½ feet
-    high,<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">[12]</a> the whole enclosure having accommodation for seven dirigibles
-    all inflated and ready for instant service. When completed, in the
-    spring of 1903, it was at once used to harbor three new air ships.
-    These were the <i>No. 7</i>, designed for racing contests; the <i>No. 9</i>,
-    called the Runabout, a minim air ship used for calls and short pleasure
-    trips; and the <i>No. 10</i>, called the Omnibus, intended for several
-    persons, with ample supplies for a considerable journey.</p>
-
-  <p>The <i>No. 7</i>, which excelled its predecessors in length and bulk, was
-    intended greatly to outstrip the best of them in velocity. The first
-    air ship had attained fourteen miles per hour, the <i>No. 6</i>, nearly
-    twenty miles an hour in winning the Deutsch prize, and over twenty
-    miles per hour on subsequent occasions, though provided with a motor
-    rated at only 12 horse power. The new vessel which had little greater
-    resistance than <i>No. 6</i>, was to carry four times the internal pressure,
-    or about 12 centimeters of water, and to be propelled by an engine of
-    60 horse power. The inventor expected therefore to attain a speed of
-    between forty and fifty miles per hour. A very lofty expectation for
-    that day, and one still unrealized for many years.</p>
-
-  <p>The racing air ship, or <i>No. 7</i>, was of cigar form, supporting a long
-    car beneath, and generally resembling the <i>No. 6</i>, but slightly more
-    tapering. Her length was six times her major diameter, and her volume
-    45,000 cubic feet. The envelope was made of two layers of the strongest
-    French silk, four times varnished, and was built exceptionally thick
-    at the stern, where the differential outward pressure is greatest in
-    flight. The propulsion was effected by a 60 horse-power water-cooled
-    four-cylinder Clément engine actuating two screw propellers 16½ feet
-    in <span class="pagenum" id="Page_113">113</span>diameter, one in front the other at the rear of the car. The poise
-    and maneuvering were to be controlled in the usual way, by means of the
-    rudder and shifting weight. The inventor seemed not to realize that
-    the bow of his vessel was too sharp to cleave the air with minimum
-    resistance, though his predecessor, Jullien, in 1850, had discovered
-    experimentally that a torpedo form is better for speed than the
-    symmetrical spindle form used by Santos-Dumont in his racing vessel. He
-    did, however, in time, learn that the torpedo form of hull is better
-    for stability of forward motion, and hence adopted that form in his
-    little <i>Runabout</i>.</p>
-
-  <p>The <i>No. 9</i> was a thick torpedo-shaped air ship originally cubing only
-    7,770 feet, though later enlarged to 9,218 feet. It was so thick as
-    to appear nearly egg-shaped. In order to make it respond promptly to
-    the rudder Santos-Dumont drove it through the air blunt end foremost,
-    but with apparent regrets, thinking that it would cleave the air
-    more easily than sharp end foremost. In this he was mistaken; for
-    the writer has shown that a body of such shape encounters much more
-    resistance—roughly one hundred per cent more—when driven sharp end
-    foremost than when driven blunt end forward. This fact furnishes one
-    reason why most whales and swift fishes have blunt bows and long
-    tapering sterns. However this be, the practical man felt his way to
-    success, whether right or wrong in his theory of resistance. When
-    actuated by a three horse-power Clément motor, weighing 26½ pounds, the
-    little air ship carried its jaunty pilot twelve to fifteen miles an
-    hour on many a merry trip about Paris and its environs.</p>
-
-  <p>The <i>No. 10</i>, or <i>Omnibus</i>, was a well shaped vessel of nearly eighty
-    thousand cubic feet capacity, and amply provided with steering
-    devices. Its hull<span class="pagenum" id="Page_114">114</span> tapered slightly from front to rear, terminating
-    in projectile-shaped ends, and had a length of nearly six times its
-    major diameter. Underneath was suspended a long car provided with
-    aëroplane surfaces, in addition to the usual rudder, for controlling
-    its movements.</p>
-
-  <p>Its arrow-like appearance was suggestive of some of the greatest German
-    balloons of the decade. Indeed, the <i>Omnibus</i>, if well powered, might
-    have proved a very swift vessel, in addition to a powerful carrier.
-    But she was designed merely for easy going passenger service, for the
-    purpose of popularizing aëronautics and stimulating its growth.</p>
-
-  <p>Santos-Dumont now had three typical air ships, a spacious and well
-    equipped “aërodrome,” and ample facilities for advancing the science
-    of motor balloons on a moderate scale. He could not, however, maintain
-    the ascendency in this branch of science in France; for he encountered
-    the rivalry of great wealth employing highly trained engineering and
-    constructive talent. He could, however, still promote the art as a
-    pioneer and a popularizer. This he continued to do. With his little
-    <i>Runabout</i> he would one day guide-rope along the boulevard, another
-    day take up a little boy, another day send up a beautiful young lady
-    to navigate the air alone for a short distance, another day voyage
-    over the military parade grounds and with his revolver fire a salute
-    of twenty-one shots to the President of France, and give exhibitions
-    to arouse the interest of the War Department. But he could not keep
-    pace with the new giants in aëronautics, and he did not attempt
-    it. Nor did he ever build a vessel of sufficient power, speed and
-    durability to be purchased by the French nation. That honor went to his
-    opulent contemporaries who had not failed to take cognizance of his
-    contributions to the aërial art.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_V">
-    <span class="pagenum" id="Page_115">115</span>
-    <h3>CHAPTER V</h3>
-    <span class="small">PRACTICAL DEVELOPMENT OF NON-RIGID DIRIGIBLES</span>
-  </div>
-
-  <p><span class="smcap">In</span> 1899 the Lebaudy brothers, wealthy sugar refiners in Paris,
-    commissioned their able engineer, Julliot, to make investigations
-    and develop plans for a large and swift air ship. This he did with
-    the assistance of Surcouf, a well-known manufacturer of balloons at
-    Billancourt, Paris. Emulating the example of Santos-Dumont and certain
-    German aëronauts in making their plan, they adopted the light petroleum
-    engine for motive power, but experimented on a larger scale, thus
-    creating a new era in military aëronautics in France. Their first
-    vessel was the <i>Jaune</i> whose bag was built at Surcouf’s place, and
-    its mechanical part at the Lebaudy Sugar Refinery. When launched,
-    in 1902, it so pleased the owners that they determined to continue
-    the experiments on a larger scale. Their second air ship, called the
-    <i>Lebaudy</i>, after fulfilling various tests, was accepted by the French
-    government and formed the beginning of its modern aërial fleet.</p>
-
-  <p>Moisson, near Paris, where the balloons were kept, now became quite an
-    aëronautical center. Here, under military supervision and the skillful
-    management of the aëronaut Juchmes, other dirigibles were built in
-    rapid succession. Of these the <i>Patrie</i> was launched in 1906, and the
-    <i>République</i> in 1908, both fine swift vessels capable of voyaging many
-    hours and carrying many passengers. The Lebaudy vessels were the first
-    air ships of the<span class="pagenum" id="Page_116">116</span> “semi-rigid type,” in which the long and flexible
-    envelope, or hull, is provided with a rigid keel or floor, from which
-    the car is suspended with its machinery and passengers. They are,
-    therefore, of unusual interest both for their scientific design and for
-    the stimulus they imparted to the growth of aërial fleets. For this
-    reason they may well be studied in some detail.</p>
-
-  <p>The first Lebaudy air ship, called the <i>Yellow</i>, because of its color,
-    had an envelope constructed of a rubber-treated cotton fabric, made in
-    Hanover and covered with a yellow coating of lead chromate, to ward off
-    the sun’s actinic rays from the rubber, and thus prevent deterioration.
-    Her hull, which was cigar shaped and inflated with hydrogen, measured
-    183 feet in length, 32 feet in diameter, and 80,000 cubic feet in
-    volume. She was propelled by a 40-horse-power Daimler motor actuating
-    twin screws, and attained a maximum speed of twenty-six miles an hour.
-    During her first year’s service she made many ascensions, returning to
-    her starting point twenty-eight times out of twenty-nine. Her longest
-    voyage, made at Moisson, June 24, 1904, was sixty-two miles in two
-    hours and three quarters, with an average speed of twenty-two miles
-    an hours. But in November, 1902, while landing in a high wind at the
-    end of her voyage from Paris to Chalais-Meudon, she was wrecked by
-    colliding with a tree. Her motor, however, was uninjured, and a new
-    envelope was at once prepared.</p>
-
-  <p>The second vessel, called the <i>Lebaudy</i>, and brought out in 1904,
-    though resembling her predecessor, had a number of improvements in
-    detail. Her hull was somewhat larger than the <i>Jaune</i>, and no longer
-    pointed at the stern, but rounded off to an ellipsoidal shape, and
-    provided, like the rear of an arrow, with guiding, or steadying planes.
-    It meas<span class="pagenum" id="Page_117">117</span>ured 190 feet in length and 94,000 cubic feet in volume. It
-    was provided with two windows for internal inspection, and had an air
-    bag of 17,650 cubic feet, divided into three parts. This air bag was
-    inflated by a rotary fan near the main body, driven by the motor during
-    flight, and by a storage battery when at rest. Suitable horizontal
-    and vertical sails were used to steady and guide the vessel; also a
-    guide-rope and anchor were carried. The car, suspended by steel ropes,
-    ten feet below the hull, carried the passengers and supplies; also
-    the motor actuating twin propellers, one on either side. At night an
-    abundance of light was available, each passenger carrying a small lamp
-    fastened to his clothes, the car itself bearing a powerful acetylene
-    projector in its front, and two other lamps of 100 candle power each,
-    to illumine the vessel. It was an elaborate affair, costing fifty to
-    sixty thousand dollars, and was the outcome of experiments costing ten
-    times that sum.</p>
-
-  <hr class="page" />
-  <div id="Plate_III" class="center"><b>PLATE III.</b></div>
-
-  <div class="figcenter w600">
-    <img src="images/i_139a.jpg" width="600" height="309" alt="" />
-    <div class="captionp">THE <i>LEBAUDY</i>.</div>
-    <div class="right small"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_139b.jpg" width="600" height="297" alt="" />
-    <div class="captionp"><i>LA PATRIE.</i></div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_139c.jpg" width="600" height="297" alt="" />
-    <div class="captionp">LEBAUDY’S <i>MORNING POST</i>.</div>
-  </div>
-
-  <p>The <i>Lebaudy</i>, with these various improvements, gave much satisfaction
-    to her owners, and received favorable recognition from the French War
-    Department. During the thirty ascensions and voyages of her first
-    year’s service, she proved herself a swift vessel, easy to control,
-    very stable, and safe to land on solid ground. The Minister of War,
-    who had followed her developments with much interest, appointed a
-    commission to test her value for military service, with a view to her
-    adoption by the government. The test required that the balloon remain
-    in active service three months, always being anchored in the open, and
-    that it perform certain prescribed maneuvers and voyages. In one of
-    these it sailed with three persons on July 3, 1905, from Moisson to
-    Meaux, an air-line distance of 57 miles in two hours and thirty-five
-    minutes, at an average speed of 22<span class="pagenum" id="Page_118">118</span> miles an hour, thence to Chalons,
-    61 miles in three hours and twenty minutes. Here it was anchored to
-    some trees, but presently was caught in a strong wind, lifted high in
-    the air, then dashed violently against other trees, with the complete
-    destruction of its envelope. Within eleven weeks it was repaired
-    in the military riding school at Toul, nearby; then, after some
-    evolutions, returned to its harbor at Moisson. Other maneuvers were
-    made subsequently, in which five officers were carried at one time,
-    and interesting experiments were tried, such as dropping a sand bag
-    upon a given spot, photographing fortifications, etc. The Minister of
-    War, accompanied by two officers and other passengers, made a trip on
-    October 24th, which was the seventy-sixth voyage of this stanch vessel.
-    On November 10th, the hard-worked and successful air ship went into
-    winter quarters, being now the property of the French government, and
-    the first of her modern aërial cruisers.</p>
-
-  <p>The <i>Patrie</i> and the <i>République</i>, planned on the general lines
-    of the <i>Lebaudy</i>, but in ascending scale of magnitude, were built
-    expressly for the French government, and experienced brilliant if
-    ill-fated careers. Both vessels had whale-shaped hulls, with rather
-    sharp-pointed noses and rounding sterns. The original volume of the
-    <i>Patrie</i> was 111,250 cubic feet, which was later increased to 128,910,
-    by the insertion of a cylindrical section at the major diameter of the
-    hull. The <i>République</i> had a volume of 2,000 cubic feet more than the
-    <i>Patrie</i>, and a length of 200 feet, or a little less than the enlarged
-    <i>Patrie</i>. She also had a diameter of 35½ feet as against 33¾ in the
-    sister vessel. As the technical reader may like more complete details
-    of these two noted air ships, a fuller account is given in <a href="#appendix_III">Appendix III</a>.</p>
-
-  <p>The <i>Patrie</i> was a swift and graceful ship which,<span class="pagenum" id="Page_119">119</span> during its brief
-    activities in 1906–7, made many remarkable trips at an altitude of
-    about half a mile, and frequently maneuvered with the troops. She
-    sailed with excellent stability, had a speed of about 28 miles an hour,
-    and, with four men, had a radius of action of 280 miles. In November,
-    1907, carrying four passengers, she voyaged from Paris to Verdun,
-    on the German frontier, where she was to be stationed. In spite of
-    a quartering wind, the total distance of 175 miles was traversed in
-    seven hours and three quarters, or at an average overground speed of
-    25 miles an hour. But while at Verdun, after some maneuvers, she was
-    too insecurely anchored to the ground by means of iron stakes. A strong
-    wind came, tore out the pickets, and overpowered the soldiers, some
-    two hundred in number, who were trying to hold the vessel. As she was
-    pulling them along the ground, they were ordered to let go. The huge
-    ship bounded high into the air, soared across France, England, Wales,
-    and part of Ireland, then far out over the Atlantic where she vanished,
-    leaving no trace behind.</p>
-
-  <p>The <i>République</i> also had a brilliant but ephemeral career, from July,
-    1908, to September, 1909. She surpassed the <i>Patrie</i> not only in bulk
-    and buoyancy, but also in power and speed. She had an 80-horse-power
-    motor as against the <i>Patrie’s</i> motor of 60 to 70 horse power. She
-    could carry eight to nine men, had a speed of about thirty miles an
-    hour, and a radius of action of 500 miles. She made a number of long
-    flights and manifested satisfactory steadiness and stability. But on
-    September 25, 1909, while maneuvering near Paris, one of her propellers
-    broke and tore a great gash in her envelope. At once, with outrushing
-    gas and collapsing hull, the great ship fell 500 feet crashing to the
-    earth, a total wreck, and killing her crew of four officers.
-    <span class="pagenum" id="Page_120">120</span> This
-    disaster illustrated forcibly the advantage of the cellular system of
-    balloon construction, and drew more favorable attention to the rigid
-    type of air ship cultivated in Germany.</p>
-
-  <p>The famous firm that produced the <i>République</i> brought forth, in
-    1909, two other fine vessels patterned after it, the <i>Russie</i> and <i>La
-    Liberté</i>, built respectively for Russia and France. The <i>Russie</i> made
-    her first voyage on May 29th, ascending 600 feet with eight passengers,
-    and maneuvering under perfect control. After her official trial,
-    in June, she was sent to St. Petersburg, being the first dirigible
-    furnished to a foreign government by a private concern. The <i>Liberté</i>
-    was launched the last week in August and, after various practice and
-    official tests, was accepted by the French government two months later.
-    On a notable voyage, made on September 20th, she sailed ten hours with
-    her Panhard motor constantly working.</p>
-
-  <p>The escape of the <i>Patrie</i> was a loss keenly felt by the French people,
-    but soon compensated by the generosity of M. Deutsch de la Meurthe.
-    This liberal patron of aëronautics had a dirigible of excellent design,
-    whose hull, based on the plans of Colonel Renard, was contrived and
-    built by E. Surcouf, director of the Astra aëronautic establishment,
-    along with H. Kapferer, while its other parts were built by Voisin,
-    both of Billancourt. In September preceding the accident to the
-    <i>Patrie</i>, he had offered the use of his air ship, the <i>Ville de Paris</i>,
-    to his government, which accepted the gift with the understanding that
-    it was not to be delivered except in case of war or emergency. When,
-    therefore, in November, 1907, the disaster occurred to the <i>Patrie</i>,
-    M. Deutsch at once placed his dirigible in the hands of the military
-    authorities.</p>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_121">121</span>
-    <a id="Fig_21"><img src="images/i_145.jpg" width="700" height="350" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 21.</span>—<i>La Ville de Paris.</i></div>
-  </div>
-
-  <p><span class="pagenum" id="Page_122">122</span>
-    The <i>Ville de Paris</i> showed considerable resemblance to her prototype,
-    the <i>France</i> of 1884, but differed from that elegant vessel in various
-    important features. Her hull was shaped like a wine bottle with its
-    thickest end, or bow, brought to a sharp projectile point, and its
-    other end furnished, like an arrow, with four fixed guiding surfaces
-    to steady its flight. These guiding surfaces were elongated, finlike,
-    cylindrical sacs, inflated as shown in the illustration. The hull
-    measured 200 feet long, 34½ feet in major diameter, 112,847 cubic feet
-    in volume. Heavy bands of canvas with their edges sewed along the
-    sides of the balloon served as flaps for the attachment of the cords
-    suspending the long car beneath. With this long suspension the weight
-    of the car was more evenly distributed over the envelope than in the
-    Lebaudy balloons. An interesting improvement in this air ship was the
-    stabilizing planes, placed above the car, fore and aft, to lift or
-    depress aëroplanelike, thus enabling the pilot to raise or lower the
-    vessel, also to alter her trim, or to check her pitching. As might be
-    expected, her flight was very steady, but as the motor developed only
-    70 to 75 horse power, her velocity did not exceed twenty-five miles per
-    hour. In January, 1908, she made a run of 147 miles in seven hours, six
-    minutes, with an average speed of 21 miles an hour. Further details of
-    construction are given in <a href="#appendix_III">Appendix III</a>.</p>
-
-  <p>We now have had examples of the three leading types of motor balloons;
-    the rigid, the semirigid, the flexible. The rigid type, as exemplified
-    in the Schwartz and Zeppelin air ships, is characterized by its
-    solidly trussed hull of invariable size and form to which all other
-    parts are directly attached. The semirigid type, exemplified in the
-    Lebaudy vessels, has a flexible hull, generally of woven fabric, with
-    a trussed floor or platform for its ventral part, from<span class="pagenum" id="Page_123">123</span> which the car
-    is suspended. The flexible type, as seen in the <i>Ville de Paris</i>, the
-    <i>France</i>, and its predecessors, consists of a flexible hull entirely
-    devoid of stiffening framework, together with a car, usually quite
-    long, suspended from the bag directly. These are all of the important
-    kinds in use at present. A combination of balloon and aëroplane has
-    been tried by Santos-Dumont, Malecot, and others, but thus far has
-    not resulted in a very successful and distinct type. Of the many
-    powerful, swift, and elegant balloons which sprang into being after
-    the success of the Lebaudy vessels, all could be classified under the
-    above three types. Neither kind proved preëminently the fittest for
-    all service, but the semi-rigid and flexible balloons multiplied most
-    rapidly; partly, no doubt, because of their cheapness and convenience
-    of management. We may review briefly this new crop of air ships, before
-    turning to the novel and huge rigid vessels of Count von Zeppelin.</p>
-
-  <p>The <i>Ville de Paris</i> was followed, in 1909, by the <i>Clément-Bayard</i>,
-    a slightly larger vessel of very similar pattern, constructed for the
-    Russian government for $40,000. It also, like the <i>Ville de Paris</i>,
-    was built by the Astra Society. The most striking feature of this new
-    balloon was its curious stern with its bulblike steadying surfaces.
-    These fin surfaces were not flat, as in the <i>Patrie</i>, nor cylindrical,
-    as in the <i>Ville de Paris</i>, but of pear form, with the blunt ends
-    pointing rearward and inflated like the rest of the hull. Apparently
-    these tail bags were not economical of power, since, as is well
-    known, a pear shape encounters greater resistance when moving sharp
-    end forward than when moving blunt end forward. However this be, the
-    stabilizing force proved very effective. The vessel was driven by a
-    Clément-Bayard motor of 100 horse power actuating a wooden screw placed
-    in front of the long car,<span class="pagenum" id="Page_124">124</span> as in the <i>France</i>. A speed of 30 miles an
-    hour was attainable, and the ship could accommodate eight passengers.
-    On one occasion it made a round trip from Sartrouville, traversing 125
-    miles at an average speed of 27 miles an hour. It was acquired by the
-    Russian government on August 23, 1909, having on that day completed
-    its third official test, and satisfied the requirement of rising 1,550
-    meters and voyaging two hours at a height of 1,200 meters. Two notable
-    incidents of that voyage were that the air ship made a new record for
-    altitude, and on landing was caught by a squall which tore it from the
-    hands of thirty men, after which, owing to motor failure, it drifted
-    freely across country, tripped on a willow, and fell into the Seine,
-    whence it was rescued after considerable pains and labor.</p>
-
-  <p>Other vessels presently built by the Astra Society may be listed,
-    together with their size in cubic meters, as follows: <i>Ville de
-    Bordeaux</i>, 3,300 m<sup>3</sup>;<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">[13]</a> <i>Ville de Nancy</i>, 3,300 m<sup>3</sup>; <i>Colonel
-    Renard</i>, 4,000 m<sup>3</sup>; <i>España</i>, 4,000 m<sup>3</sup>; <i>Clément-Bayard II</i>, 6,500
-    m<sup>3</sup>; <i>Transaerienne I</i>, 6,500 m<sup>3</sup>; <i>Flandre</i>, 6,500 m<sup>3</sup> (228,579
-    cubic feet). These were among the most noted air ships produced in
-    France toward the close of the first decade of the twentieth century.
-    On the whole they proved to be swift and stable ships adapted either
-    for military use, or for exhibitions and sport, and even for regular
-    transportation of passengers.</p>
-
-  <p>The <i>Ville de Nancy</i> was one of the conspicuous dirigibles of the
-    summer of 1909. It was constructed primarily for use at the Exposition
-    at Nancy, and was owned by the Compagnie Générale Transaerienne, an
-    aërial passenger transportation <span class="pagenum" id="Page_125">125</span>society organized at Paris, in
-    March, 1909, with a capital of one million francs. This society planned
-    to inaugurate an aërial line from Paris to Bordeaux, in 1910, equipped
-    with other vessels of the Astra construction, more powerful than the
-    <i>Ville de Nancy</i>, and capable of transporting a dozen passengers.</p>
-
-  <hr class="page" />
-  <div id="Plate_IV" class="center"><b>PLATE IV.</b></div>
-
-  <div class="figcenter w600">
-    <img src="images/i_149a.jpg" width="600" height="410" alt="" />
-    <div class="captionp"><i>LA VILLE DE PARIS.</i></div>
-    <div class="right small"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_149b.jpg" width="600" height="411" alt="" />
-    <div class="captionp"><i>COLONEL RENARD.</i></div>
-    <div class="right small"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <p>The <i>Ville de Nancy</i> was slightly smaller and slightly more powerful
-    than the <i>Clément-Bayard I</i>, besides differing in minor details. It
-    measured 55 meters in length, 10 meters in greatest diameter, and
-    cubed 33,000 meters, as against the 35,000 meters of its predecessor.
-    It was driven by a 100-horse-power Bayard-Clément motor actuating a
-    Chauvière screw propeller at the front of the car. The car itself was
-    made of steel tubes covered with fabric, and near the engine with
-    sheet aluminum. The tail bags were an evident improvement on those of
-    the previous air ships, being less blunt at the rear, and therefore
-    less adapted to generate a retarding suction. They were still rather
-    bulbous, however.</p>
-
-  <p>This splendid vessel made various interesting voyages during the
-    summer of 1909, the first on June 27th, piloted by Surcouf and
-    Kapferer, directors of the Astra Society. On July 14th, she maneuvered
-    at Longchamps, side by side with the <i>République</i>, thus contrasting
-    nicely with the ship designed by Julliot. It was the first time two
-    dirigibles navigated together in regular maneuver. The <i>Ville de Nancy</i>
-    was naturally the swifter, having greater power and less bulk than
-    the other. About the middle of July she sailed from Sartrouville to
-    Nancy, where she was to sail about the Exposition grounds and make
-    daily excursions, carrying passengers for 100 francs per trip. These
-    voyages proved very popular, being the first of their kind,<span class="pagenum" id="Page_126">126</span> and in
-    themselves quite attractive. As the vessel was endowed with excellent
-    stability and had manifested high speed, she was well suited to be the
-    first regular passenger air ship, and the herald of the aërial liners
-    projected to cruise between Paris and Bordeaux.</p>
-
-  <p>The <i>Colonel Renard</i> was closely patterned after the <i>Ville de Nancy</i>,
-    but was larger and more powerful. She measured 212 feet in length,
-    140,000 cubic feet in volume and carried an engine of 120 horse power,
-    driving a Chauvière propeller. On July 13th she made her first trip,
-    cruising one hour with notable facility, then reëntered the hangar<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">[14]</a>
-    of the Astra Society, at Beauval near Meaux. Thence, on August 23d, she
-    sailed for Rheims to compete in the aëronautical races, arriving after
-    a very successful cruise. On August 29th, she circled the ten kilometer
-    rectangular course at Betheny, near Rheims, five times in 1 hour, 19
-    minutes, 40 seconds, thus winning the Prix des Aëronats,<a id="FNanchor_15" href="#Footnote_15" class="fnanchor">[15]</a> of 10,000
-    francs offered for the vessel that should accomplish, in the least
-    time, those five rounds, aggregating 50 kilometers. The showing was not
-    remarkable, but the vessel could sail much faster in a straightaway
-    voyage.</p>
-
-  <p>The prize-winning <i>Renard</i> was quickly followed by the <i>España</i>, a
-    vessel of the same size and pattern, built for the Spanish government
-    by the same capable firm. During October this fine air ship made
-    several trial trips, carrying seven men. On November 2d she made
-    a splendid official test voyage of five hours, sailing from the
-    Astra aërodrome, at Beauval, to Paris and return, a distance of 250
-    kilometers in 5 hours and 10 minutes, or at the <span class="pagenum" id="Page_127">127</span>average rate of 31
-    miles an hour for the entire course. On November 5th, she started on a
-    ten-hour voyage, with five men and fuel for fifteen hours; but after
-    five hours, stopped her engine, and came to earth, owing to the bending
-    of the main shaft of the motor.</p>
-
-  <p>Besides the great auto balloons designed by Julliot and Surcouf, of
-    which the <i>République</i> and <i>Colonel Renard</i> are examples, a number of
-    convenient cruisers were brought forth in 1909 by the Zodiac Company.
-    One of the leading spirits in this enterprise was the famous Count de
-    la Vaulx, well known for his auto balloon designs and his long voyages
-    in sphericles. The chief merit of these modest air ships, which ranged
-    in volume from 25,000 cubic feet upwards, was cheapness and facility of
-    demounting and shipment. They were intended to popularize the art among
-    the masses, by giving everyone a chance to make a voyage at no great
-    expense. Besides their applicability to sport, touring, and public
-    uses, some were designed for considerable speed and endurance; which
-    qualities, together with their demountability and partial independence
-    of hangars, were expected to give them military value. They were of
-    the flexible type, so arranged that the various parts were easily
-    detachable, so as to be packed for transportation, by wagon or car.
-    The smaller ones might be called semi-navigables, since they had the
-    organs of a swift motor balloon, but, like the common sphericles,
-    could easily be demounted and hauled home—a likely issue on a day of
-    any considerable wind. The first one cost $5,000, cubed 25,000 feet
-    and, with its 16-horse-power engine, traveled 13 miles per hour. Its
-    hull had the form of a whale with docked and rounded tail. From this
-    body hung an elongated car with a screw at the rear and elevating
-    planes<span class="pagenum" id="Page_128">128</span> in front. Others of similar make, but larger, followed in rapid
-    order, their common mission being that advocated by Santos-Dumont, in
-    the early part of the decade, when he produced his <i>Runabout</i> and
-    <i>Omnibus</i>—to give everybody a ride.</p>
-
-  <div class="figcenter">
-    <a id="Fig_22"><img src="images/i_154.jpg" width="700" height="309" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 22.</span>—<i>Le Petit Journal</i>, <span class="smcap">Zodiac
-      Type</span>.</div>
-  </div>
-
-  <hr class="page" />
-  <div id="Plate_V" class="center"><b>PLATE V.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_155a.jpg" width="600" height="456" alt="" />
-    <div class="captionp"><i>ZODIAC III.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_155b.jpg" width="600" height="375" alt="" />
-    <div class="captionp"><i>ZODIAC IV.</i></div>
-  </div>
-
-  <p><span class="pagenum" id="Page_129">129</span>The <i>Zodiac I</i> was quickly followed by vessels <i>II</i> and <i>III</i>, cubing
-    respectively 1,200 and 1,400 meters. The <i>No. II</i> had a speed of
-    twenty, or more, miles per hour, and carried two passengers when
-    inflated with coal gas, three with hydrogen. The <i>No. III</i>, of torpedo
-    form, measured 133 feet long, 28 feet in major diameter, carried four
-    persons, and sailed 25 miles an hour with her 40-horse-power Ballot
-    engine. On August 29th, piloted by Count de la Vaulx, she competed with
-    the <i>Colonel Renard</i>, at Rheims, for the <i>Prix des Aëronats</i>, making
-    five rounds of the ten kilometer course in one hour and twenty-five
-    minutes, this being at the average speed of 22 miles an hour. On
-    October 30th, again piloted by the same renowned aëronaut, she sailed
-    from Brussels to Anvers, rounded the lofty Cathedral spire, and
-    returned to her aërodrome, traversing a distance of sixty kilometers in
-    one hour and twelve minutes, or with an average speed of 31 miles an
-    hour, a good showing for so small an air ship.</p>
-
-  <p>A very handsome dirigible, named the <i>Belgique</i>, was constructed early
-    in 1909, by the skillful aëronautical engineer, Louis Godard, of Paris,
-    in collaboration with the prominent Belgian engineer and sportsman,
-    Robert Goldschmidt. It was a flexible balloon of elegant torpedo form,
-    measuring 175 feet long, 30 feet in major diameter, and 106,000 cubic
-    feet in volume. It was propelled by two 60-horse-power Vivinus engines
-    actuating two screws, made of fabric stretched over radial sticks,
-    and placed at either end of the spindle-shaped car. The control was
-    provided for by ample keel surface, an elevating plane in front,
-    and ingeniously designed fins on the rear of the hull to steady the
-    motion. The entire structure showed much originality and skill. When<span class="pagenum" id="Page_130">130</span>
-    the dirigible was tested near Brussels, on June 28th, it was piloted
-    by Louis Godard, the famous expert in sphericals, accompanied by
-    Goldschmidt. Godard’s début in this capacity was reported as excellent.</p>
-
-  <p>The Italian government brought forth, in the summer of 1909, a swift
-    and elegant auto balloon showing considerable originality of design.
-    It has a porpoise-shaped hull of 2,500 cubic meters capacity, divided
-    into seven compartments, so as to obviate the accident which wrecked
-    the <i>République</i>. An ample keel along the rear bottom, and large
-    aëroplane surfaces at the stern, serve to guide and steady the vessel.
-    Propelled by twin screws well above a short car, she readily attained
-    thirty miles an hour, carrying four persons. On October 31st, starting
-    on her seventeenth voyage, she cruised from the aëronautic park, Vigna
-    de Vale, near Rome, to Naples and back to Rome by ten o’clock at
-    night, having sailed over the edge of the Mediterranean Sea and over
-    the French squadron in the bay, remaining fourteen hours in the air
-    and traversing 520 kilometers, or 323 miles. It was one of the finest
-    voyages of the year. Further details of this Italian military dirigible
-    <i>No. I bis</i>, together with illustrations, are given in <cite>Aërophile</cite> for
-    January 15, 1910, together with its prototype the dirigible <i>No. I</i>,
-    which maneuvered so successfully in 1908.</p>
-
-  <p>England and America all along had pursued an oriental, or
-    semicivilized, policy toward the auto balloon, languidly watching
-    the progress elsewhere, and hoping some time to enjoy the fruition,
-    if not the glory, of the costly and successful experiments made in
-    other countries. In 1909, however, the British government appropriated
-    nearly $400,000 for aëronautics, and the United States House of
-    Representatives voted $500,000, but promptly re<span class="pagenum" id="Page_131">131</span>versed its action,
-    and gave nothing, though it may be said that even then there was a
-    growing sentiment in favor of a more liberal policy. The movement to
-    secure the beginning of an aërial fleet in England is summarized in the
-    following paragraph.<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">[16]</a></p>
-
-  <hr class="page" />
-  <div id="Plate_VI" class="center"><b>PLATE VI.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_159a.jpg" width="600" height="415" alt="" />
-    <div class="captionp"><i>LA BELGIQUE.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_159b.jpg" width="600" height="416" alt="" />
-    <div class="captionp">ITALIAN MILITARY DIRIGIBLE <i>NO. I BIS</i>.</div>
-  </div>
-
-  <blockquote>
-    <p>“The naval authorities were entrusted with the building of a rigid
-      ship, whilst to the military department was delegated the work of
-      building non-rigid and semi-rigid ships. A national air-ship fund
-      was organized by the <cite>Morning Post</cite> with the object of purchasing
-      a French Lebaudy semi-rigid dirigible which would be presented to
-      the War Office; whilst Mr. Arthur du Cros and other members of the
-      Parliamentary Aërial Committee arranged for a <i>Clément</i> non-rigid air
-      ship of new design, to sail from Paris to London, and also to qualify
-      for purchase as a unit of the British aërial fleet.”</p>
-  </blockquote>
-
-  <p>The non-rigid auto balloon ordered from Clément, and afterwards known
-    as the <i>Clément-Bayard II</i>, was the masterpiece of that skilful
-    designer, and occupied his best thought and energy for eighteen
-    months, aided by his devoted and capable engineer, Sabathier. She
-    was completed in the Clément-Bayard factory at Lamotte-Breuil in
-    April, 1910, and during the next five months made thirty-two test
-    ascensions and practice voyages. In particular she took a conspicuous
-    part in the military maneuvers at Picardie during the early half of
-    September, where with wonderful precision and airworthiness she made
-    forced voyages in fair weather and foul, remaining, when so desired,
-    in continuous communication with the land office by means of wireless
-    telegraphy. Finally, on a fair day, September 16th, the tried and
-    perfected vessel was brought forth from her hangar for the long
-    contemplated voyage <span class="pagenum" id="Page_132">132</span>to London, her machinery and rigging in trimmest
-    order, and her car furnished with supplies for twenty hours, or thrice
-    the anticipated time of transit.</p>
-
-  <p>The voyage was a glorious achievement for aëronautics, and for the
-    enthusiastic constructor and his devoted aids. Starting at seven
-    o’clock in the morning, with seven men aboard, including happy Clément,
-    Sabathier, and an English delegate, the whalelike cruiser sailed
-    directly to London with admirable regularity, covering the entire
-    distance of 242 miles in six hours, or at the rate of forty miles
-    an hour, which is better time than could be made by land and water.
-    Enthusiastic cheers from the English spectators greeted the arrival of
-    this French dirigible, built for the English government. Then quietly
-    the English soldiers took the vessel in hand, as if performing a
-    familiar duty, and housed her in the <cite>Daily Mail</cite> hangar, at Wormwood
-    Scrubs. Thus simply and without unusual incident terminated the first
-    motor-balloon cruise between the two countries, and one of the finest
-    voyages in the history of aëronautics.</p>
-
-  <p>In outward appearance the <i>Clément-Bayard II</i> closely resembled her
-    predecessor, except for the absence of empennage on her envelope. In
-    the whalelike elegance of her hull she was, in fact, a reversion to the
-    trim and efficient model of Renard’s dirigible of 1884, which in turn
-    was a fair copy of Jullien’s model of 1850, all having excellent forms
-    for speed and stability. But the new vessel was of greater size and
-    power than her predecessor. Her net buoyancy was sufficient to carry
-    twenty passengers. Her average speed tested in a round-trip voyage was
-    about 50 kilometers or 31 miles per hour when her two motors developed
-    200 horse power, and 55 kilometers or 34 miles per hour when <span class="pagenum" id="Page_133">133</span>the
-    engines developed their maximum effort of 260 horse power. The details
-    of construction were so elaborate and important, and so representative
-    of the best aëronautical workmanship of the time that a full account of
-    their chief features is presented in <a href="#appendix_III">Appendix III</a>. In passing it may be
-    added that some time before sailing to England the <i>Clément-Bayard II</i>,
-    because of her excellent workmanship and maneuvers, received the first
-    prize at the review of dirigibles by the French Minister of War.</p>
-
-  <hr class="page" />
-  <div id="Plate_VII" class="center"><b>PLATE VII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_163a.jpg" width="600" height="409" alt="" />
-    <div class="captionp"><i>CLÉMENT-BAYARD I.</i></div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_163b.jpg" width="600" height="412" alt="" />
-    <div class="captionp"><i>CLÉMENT-BAYARD II.</i></div>
-    <div class="right small"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <a id="Fig_23"><img src="images/i_165.jpg" width="700" height="395" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 23.</span>—<i>Clément-Bayard II</i>, 1910.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_134">134</span>
-    The dirigible to be purchased with the money secured by the popular
-    subscription organized by the <cite>Morning Post</cite> was ordered from the
-    Lebaudy factory at Moisson in July, 1909, to be delivered directly
-    through the air to Farnborough before November 6, 1910. This
-    stipulation was severe enough, but furthermore the vessel was to
-    be a considerable departure from any thus far built at that famous
-    factory, and was to be the largest air ship yet constructed in France.
-    As usual the general design of the huge balloon was entrusted to the
-    distinguished aëronautical engineer, Henri Julliot, and this was a
-    certain guarantee of its successful operation.</p>
-
-  <p>The general features of this great military dirigible resemble those
-    of her prototype, the <i>Patrie</i>, differing chiefly in the shape of her
-    hull and the method of stiffening. The hull itself was more longish
-    than the <i>Patrie’s</i>, but had the same sharp prow and blunt stern; for
-    a blunt stern offers better support to the empennage planes, though
-    it increases the resistance more than a tapering stern. The trussed
-    framing to stiffen the ship was no longer a platform inserted in the
-    base of the hull, but a long trussed beam of cruciform cross section,
-    made of steel tubing and suspended intermediately between the hull and
-    car.</p>
-
-  <p>The hull was of excellent workmanship and bold design. The envelope
-    was of rubberized tissue, measured 338 feet in length, 39.4 feet in
-    diameter<span class="pagenum" id="Page_135">135</span> and cubed 353,000 feet. Its length was, therefore, 8.5 times
-    its diameter, an extraordinary proportion for a balloon of the flexible
-    type. The hull was provided with three ballonets, two ripping panels,
-    and various valves, as shown in the scale drawing.</p>
-
-  <div class="figcenter">
-    <a id="Fig_24"><img src="images/i_167.jpg" width="700" height="404" alt="" /></a>
-    <div class="caption smcap">Fig. 24.—Morning Post Dirigible, 1910.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_136">136</span>The car, made of steel tubing and large enough for twenty persons,
-    carried two Panhard-Levassor motors of 135 horse power each, actuating
-    two Chauvière wooden screws, sixteen feet in diameter, placed on either
-    side, well outward and upward, the transmission gear permitting either
-    engine, or both, to drive the screws at one time. Below the car and
-    well forward was a ground keel, or post, on which the whole vessel
-    could pivot with the wind, when riding at anchor, while a shorter
-    ground post was placed at the rear of the car.</p>
-
-  <p>The controlling surfaces were adequate and skillfully arranged. To
-    maintain steadiness and directness of flight, fixed empennage planes,
-    both horizontal and vertical, were provided, some attached to the stern
-    of the hull, others at the rear of the trussed suspension beam. To
-    direct the up and down movement, ailerons placed well to the front and
-    rear of the long framing, were turned about conjunctively in opposite
-    directions, thus causing the vessel to raise or lower her bow. Needless
-    to say, all these navigation appliances worked with ample force and
-    effectiveness from the beginning of the earliest tests.</p>
-
-  <p>After four preliminary ascensions the great air ship started from
-    Moisson to her destination at Farnborough, having on board Henri
-    Julliot, Louis Capazza, the pilot, Alexander Bannerman, director of
-    the aëronautic military school at Aldershot, and five other men. It
-    was a triumphant and glorious voyage, one of the most splendid in
-    the history of aërostation. Piloted by aid of chart and compass, and
-    by signal fires and captive balloons arranged along her route, the
-    vessel followed a direct course, without check or hindrance, crossing
-    a wide part of<span class="pagenum" id="Page_137">137</span> the English Channel and arriving before the hangar at
-    Aldershot, where the British soldiers awaited her, and where she was
-    safely landed, having made the whole voyage of 230 miles in 5.5 hours,
-    at a level varying between five hundred and two thousand feet. As
-    shown by the accompanying map, about one third of the route lay over
-    the Channel, or, more accurately, 78 miles, which was traversed in two
-    hours. Thus the whole journey was accomplished at an average speed
-    of nearly forty-two miles an hour, or in less time than it could be
-    effected in any other way than through the air.</p>
-
-  <div class="figcenter">
-    <div class="caption">15 Novembre 1910</div>
-    <a id="Fig_25"><img src="images/i_169.jpg" width="585" height="620" alt="" /></a>
-    <div class="caption smcap">Fig. 25.—Route of British Military Dirigibles from
-      France to England, 1910.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_138">138</span>The United States War Department, in 1908, started an aërial squadron
-    by purchasing from Thomas S. Baldwin, for $10,000, a tiny air ship of
-    the flexible type, a trifle larger than Santos-Dumont’s <i>Runabout</i>, but
-    in fact the smallest military dirigible then in existence. It had a
-    rubberized gray silk cylindrical hull slightly tapering toward the rear
-    and terminating in ogival ends, its length being 96 feet, its major
-    diameter 19½ feet. From this was suspended, by means of netting and
-    steel cables, a longish car having at the rear a double rudder working
-    about a vertical hinge, at the front an elevating plane and an 11-foot
-    wooden screw driven by a Curtiss 20-horse-power water-cooled engine.
-    With two men aboard, this vessel readily attained over twenty miles an
-    hour in a straightaway course, and at times more nearly thirty miles an
-    hour. Its total ascensional force was 1,350 pounds, of which 500 were
-    available for men, ballast and supplies.</p>
-
-  <p>Santos-Dumont’s most strenuous disciples outside of France were found
-    among the German military officers. These advocated and promoted both
-    the semirigid and the flexible types of auto balloon, with such ability
-    as to match the best productions of the foremost French designers.
-    The most successful pioneers of these two types in Germany were
-    respectively, Major von Gross, commander of the balloon battalion at
-    Tegel, near Berlin, and Major Von Parseval of the Bavarian army, and
-    director of the Society for the Study of Motor Air Ships.</p>
-
-  <p>Beginning in 1907, a number of Gross auto balloons were built in
-    succession, for the German Aëronautical Battalion, by Master Engineer
-    Basenach, under the supervision of its commander, Major Gross. The
-    first was intended only as a model, <span class="pagenum" id="Page_139">139</span>though it was large enough for
-    two passengers. It cubed 63,000 feet, but having an engine of hardly
-    more than 20 horse power, was necessarily slow. It was succeeded by
-    the <i>Gross I</i>, and others, all having rigid ventral parts, like the
-    <i>Patrie</i>, but with hulls of rather better form for speed and bulk
-    combined, having blunter bow and longer stern.</p>
-
-  <hr class="page" />
-  <div id="Plate_VIII" class="center"><b>PLATE VIII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_171a.jpg" width="600" height="409" alt="" />
-    <div class="captionp"><i>U. S. SIGNAL CORPS DIRIGIBLE I.</i></div>
-    <div class="small">(Courtesy U. S. Signal Corps.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_171b.jpg" width="600" height="409" alt="" />
-    <div class="captionp"><i>GROSS II.</i></div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <p>The second Gross air ship, built in 1908, cubed 176,000 feet, and
-    attained a speed of 27 miles per hour, driven by two 75-horse-power
-    Daimler motors. On September 11th of that year, with four persons
-    aboard, she made a round trip from Berlin lasting 13 hours, covering
-    176 miles, and attaining altitudes up to 4,000 feet. This was one of
-    the finest voyages known at the time. This air ship was purchased by
-    the German government, named <i>Gross I</i>, and sent to Metz. A detailed
-    description is given in <a href="#appendix_III">Appendix III</a>.</p>
-
-  <p>The <i>Gross II</i>, brought forth in April, 1909, resembled her predecessor
-    in build, but had greater power and speed. Her hull cubed 176,000
-    cubic feet, had a blunt bow, full body and sharp stern, was provided
-    with horizontal and vertical keels, a sliding weight, and a ballonet
-    at either end. She was propelled by two Körting engines of 75 horse
-    power each, actuating two three-blade propellers. Under the action of
-    her keels and stabilizing planes and rudder, her motion was steady and
-    precise. A special feature of this air ship was the wireless telegraph
-    equipment by which she could send messages in all directions over a
-    range of 300 miles or more. She made many practice voyages during the
-    season of 1909, sometimes alone, again in concert with other auto
-    balloons and with troops. In August she made a fine voyage of sixteen
-    hours, from Tegel to Apolda and return, traversing 470 kilometers.</p>
-
-  <p>The above described vessel was followed by<span class="pagenum" id="Page_140">140</span> others, large and small.
-    The <i>Gross III</i> measured 70 meters long, cubed 7,500 meters, and was
-    propelled by four Körting motors aggregating 300 horse power. This was
-    a splendid vessel, and one of extraordinary speed.</p>
-
-  <p>Various auto balloons of the Parseval type were designed by Major Von
-    Parseval of the Bavarian army, who also was one of the inventors of the
-    kite balloon. Satisfactory experiments with his air ship were made as
-    early as 1906. These formed the basis of larger vessels, subsequently
-    constructed in the same factory of August Riedinger of Augsburg,
-    for the Motor Air Ship Study Society, of which Parseval was general
-    manager. This society, organized practically at the command of the
-    Emperor, purchased the Parseval patents and began the development of
-    auto balloons as a business enterprise, soon furnishing a series of its
-    flexible air ships to the German army.</p>
-
-  <p>After the experiments of 1906, the Parseval air ship was enlarged from
-    2,500 to 2,800 cubic meters, its length becoming 52 meters and its
-    major diameter 8.7 meters. Its hull was of cylindric form, with rounded
-    bow and egg-shaped stern; had two air bags—one fore, the other aft—and
-    at the stern carried two fixed horizontal planes and a vertical rudder.
-    From this envelope the car, made largely of aluminum, was hung by steel
-    cables, and on its bottom had trolley wheels resting on suspension
-    cables joining the front and rear parts of the hull. The vessel was
-    propelled by a 50-horse-power Mercedes motor actuating a four-blade
-    screw propeller 13 feet in diameter, mounted between the car and hull.
-    This screw was made of thin steel tubes covered with shirting. Among
-    the merits of Parseval’s air ship may be mentioned its lightness and
-    demountability, and its kite-like effect on the air, got by canting
-    the <span class="pagenum" id="Page_141">141</span>hull while the car, rolling on the suspension cables, allowed
-    the screw mounted above it to thrust horizontally. The canting was
-    effected by giving one ballonet more air than the other, thus causing
-    its end of the hull to sink. The speed was about twenty-five miles per
-    hour.</p>
-
-  <hr class="page" />
-  <div id="Plate_IX" class="center"><b>PLATE IX.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_175a.jpg" width="600" height="413" alt="" />
-    <div class="captionp"><i>PARSEVAL I.</i></div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_175b.jpg" width="600" height="349" alt="" />
-    <div class="captionp"><i>PARSEVAL II.</i></div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <p>The second <i>Parseval</i> was of greater bulk and power than her
-    predecessor. Her hull which was of cylindric form, with round prow
-    and pointed stern, measured 190 feet long, 30.5 feet in diameter, and
-    113,000 cubic feet in volume. She resembled her predecessor in the
-    arrangement of the two ballonets, and in the “loose,” or trolley,
-    system of suspension of the car. The propeller was a unique patented
-    device of Von Parseval’s. It had four cloth blades so weighted with
-    lead as to stand out firmly under centrifugal force, assuming an
-    effective shape for propulsion, though limp and deformed when at rest.
-    Various interesting evolutions were performed by this vessel in the
-    autumn of 1908, including tests imposed by the military authorities,
-    as a condition of purchase by the government, one requirement being a
-    voyage of one hour at an altitude of 1,500 meters; another requirement
-    being a continuous cruise of twelve hours. These tests completed,
-    the Motor-Luftschiff-Studien-Gesellschaft sold its proud ship to the
-    Vaterland for 210,000 marks.</p>
-
-  <p>About the same time the War Department purchased the <i>Gross I</i>, already
-    described, and Zeppelin’s third great ship, naming it <i>Zeppelin I</i>.
-    Germany thus began her program of developing a great aërial fleet,
-    by acquiring three powerful and well tried ships, each capable of
-    remaining all day in the air, and having a radius of action of several
-    hundred miles. They were frequently called upon to make test voyages in
-    all kinds of weather, to maneuver with the troops, to pass in review
-    before the Emperor, <span class="pagenum" id="Page_142">142</span>at times conveying prominent officers and members
-    of the noblest families, including Prince Henry and the Crown Prince,
-    who manifested a fondness for navigating about their newly opened
-    empire of the sky. But sometimes the tests were crucial. On September
-    11, 1908, both the <i>Gross</i> and <i>Parseval</i> were summoned to Potsdam by
-    His Majesty. They set forth from their sheds, at Tegel, in face of a
-    strong wind. After journeying some distance they each had to abandon
-    the voyage, the <i>Gross</i> returning home, and the <i>Parseval</i> falling to
-    the ground owing to an accident.</p>
-
-  <p>The third Parseval air ship was brought forth on February 18, 1909, by
-    the Luftfahrzeug-Gesellschaft, an aëronautical firm founded by merging
-    the Motor-Luftschiff-Studien-Gesellschaft with the A. E. G. This vessel
-    closely resembled her predecessor, but possessed greater size, power,
-    and perfection of detail. Her hull at first measured 224 feet long,
-    47 feet in diameter, and 198,000 cubic feet in volume, but later was
-    enlarged to 235,000 cubic feet by increasing its diameter.</p>
-
-  <p>Her car, which could accommodate twelve passengers, was framed of steel
-    tubing covered with canvas, and was divided into two parts, separated
-    by the big gasoline cylinder running athwart ship, the passenger cabin
-    being to the fore, the engine room aft. Here were stationed the two
-    engines, of 120 horse power each, actuating reversible right and left
-    <i>Parseval</i> screws 13 feet in diameter, located to the rear, well aloft
-    and outward on either side. In the forepart of the passenger cabin was
-    space for the pilot and his navigating appliances; his chart desk, his
-    valve controls, his statoscope, manometers, etc.</p>
-
-  <p>The great ship with her nine tons burden was to have sailed from
-    Bitterfeld to Frankfort, for the Aëronautical Exposition, but owing
-    to excessive<span class="pagenum" id="Page_143">143</span> gales, she was sent by rail. Once there, she made many
-    excursions, at times carrying passengers at a schedule rate, reported
-    to be 200 marks for a voyage of one to two hours. In October she made
-    an inter-city excursion covering a distance of nearly 500 miles, during
-    which she passed four nights in the open air, finally returning in
-    good form to Frankfort. On October 27th she made a farewell tour about
-    Frankfort, then voyaged along the Main and down the Rhine valley to
-    Cologne, there to participate in the aëronautic military maneuvers,
-    together with the <i>Parseval I</i>, the <i>Gross II</i> and the <i>Zeppelin
-    II</i>. Having passed creditably through these and other operations in
-    the autumn, she was eventually stationed at Tegel, as a part of the
-    national fleet.</p>
-
-  <p>The fourth <i>Parseval</i>, a smaller vessel, was built for the Deutscher
-    Aëro Club early in 1909. Her hull cubed 113,000 feet, and her framing
-    was made of the strongest materials, carefully hollowed, to eliminate
-    undue weight. At the rear of the car, on either side, were two
-    100-horse engines, driving two <i>Parseval</i> propellers at a common speed,
-    whether both engines were in operation, or only one. In many respects
-    she resembled her immediate predecessors, and her little successor
-    <i>Parseval V</i> of 1,200 cubic meters capacity and 30 meters length, built
-    for the Imperial Automobile Club.</p>
-
-  <p>The maneuvers at Cologne constituted the first grand demonstration of
-    the new fleet of military dirigibles, and proved a severe test of the
-    powers of the air ships, even when manned by experienced crews and
-    commanded by regular military officers. Two companies of the balloon
-    corps battalion were in attendance. Large provisions of hydrogen loaded
-    on wagons, each carrying 100,000 cubic feet, were kept in readiness to
-    be attached to an express train and rushed at the first alarm to any
-    balloon in need of<span class="pagenum" id="Page_144">144</span> replenishing. On Sunday, October 31, three of the
-    dirigibles representing each type, <i>Zeppelin IV</i>, <i>Parseval I</i>, <i>Gross
-    II</i>, left Cologne together, by official order, and returned after
-    flights of 7, 10 and 11 hours respectively, covering in the aggregate
-    930 miles. Again, leaving Cologne shortly before noon on November 3d,
-    they went down the Rhine, simulated a concerted attack on the great
-    fortress of Eherenbreitstein, and returned in the evening, each having
-    covered 155 miles. And so on for many days they continued to execute
-    maneuvers under military orders and in severe forced marches.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_VI">
-    <span class="pagenum" id="Page_145">145</span>
-    <h3>CHAPTER VI</h3>
-    <span class="small">DEVELOPMENT OF RIGID DIRIGIBLES</span>
-  </div>
-
-  <p><span class="smcap">Count Ferdinand von Zeppelin</span>, the famous cavalry general of Würtemburg,
-    and hero of the Franco-Prussian war, after retiring from the army,
-    organized, in 1898, a limited liability company for the purpose of
-    developing a new type of dirigible which he had long contemplated.
-    It was to be a vessel far larger and swifter than any the world had
-    yet seen. In the summer of 1900, after two years of industrious
-    experimental research and active construction, he brought forth from
-    his floating laboratory on Lake Constance, near Manzell, the first
-    of those wonderful air ships which have aroused such expectation and
-    enthusiasm in Germany. In outward appearance and in its chief features
-    of design it typified the whole series of motor balloons thus far
-    developed and navigated by that illustrious inventor. Many valuable
-    improvements were added, as a result of trial and the advance of the
-    collateral sciences; but the fundamental plans seem to have proved as
-    practical as they were bold and original. One by one were surmounted
-    the greatest obstacles, physical, financial and finally political; for
-    the Prussian Ministry did not favor his project at first, and many
-    aëronautical adepts were adverse to it. Those huge ships faced the fury
-    of many a tempest; their dauntless builder endured the storm of hostile
-    criticism; but in the end, builder and ships alike won the<span class="pagenum" id="Page_146">146</span> plaudits of
-    a proud empire and of an astonished world.</p>
-
-  <p>Outwardly a Zeppelin balloon may be described as a long cylinder with
-    ogival ends and a V-shaped keel running the length of its bottom. From
-    afar the cylinder and pointed ends appear circular in cross section,
-    but they are sixteen-sided. About one-third the distance from either
-    end of the great ship a small boat is suspended from the hull so
-    closely that at those places the keel is omitted to make room. These
-    two boats are rigidly connected with the hull and support it when the
-    vessel rests on, or is towed along the water. Within them are the crew
-    and petroleum engines, while above them and outward on each side of
-    the hull, and fastened to it by outriggers, are two pairs of screw
-    propellers, so placed as to exert their united thrust along the line
-    of resistance. In some cases the crew can walk through the V-shaped
-    keel from one boat to another, the passageway being illuminated here
-    and there, by transparent covering, or windows of celluloid, along the
-    sides and floor. Again an observer may climb up through the hull and
-    take observations of the sky from above. Telephones, electric bells,
-    and speaking tubes serve to transmit intelligence from one part of the
-    vessel to another.</p>
-
-  <p>The frame of the hull is formed of sixteen longitudinal beams, or
-    girders, of trellised metal work running from prow to stern and
-    riveted at regular intervals to cross bridges of similar trellised
-    metal work, each cross bridge being a sixteen-sided wheel with
-    trellised rims strengthened by radial rods running inward to a
-    central flange of sheet aluminum. Thus the body of the vessel is
-    divided into many compartments, each bounded by two wheels, and the
-    surrounding longitudinal beams. Each compartment contains a hydrogen
-    balloon, or sac, which <span class="pagenum" id="Page_147">147</span>fairly fills it and exerts a lift against
-    the longitudinal beams and against a netting formed of ramie cords
-    stretched from wheel to wheel, diagonally between beams at their
-    inner corners. Similarly the outward corners of the beams are joined
-    by strong diagonal wires for the purpose of rigidity, and the whole
-    external frame is covered with a heavy fabric which forms the outer
-    skin, or wall of the hull. Between this skin and the hydrogen bags
-    are air spaces, as also between bag and bag. Thus the whole vessel is
-    buoyed up by numerous thin hydrogen sacs, protected by the frame and
-    outer skin from the direct sun, from foul weather, and from external
-    shocks. The gas bags are also separated from each other by the bridge
-    work and flanges of aluminum.</p>
-
-  <hr class="page" />
-  <div id="Plate_X" class="center"><b>PLATE X.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_183a.jpg" width="600" height="266" alt="" />
-    <div class="captionp"><i>GROSS III.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_183b.jpg" width="600" height="154" alt="" />
-    <div class="captionp">ZEPPELIN AIRSHIP STRUCTURE.</div>
-  </div>
-
-  <p>Obviously there is a material advantage in having many gas cells and
-    two propelling plants; for if one fails it may not prevent navigation.
-    The tandem arrangement of bags separated by the wheel-like cross
-    bridges also allows the balloon to rear any amount without material
-    displacement of the gas, or dangerous increase of pressure; for it must
-    be remembered that a single hydrogen sac extending the full length of
-    an up-ended balloon of such length, would have an outward pressure of
-    about thirty pounds per square foot greater at the top than at the
-    bottom. The poise of the vessel is maintained by shifting weights, and
-    also by use of fins, or rudders, when driving through the air; but
-    those arrangements vary in the different machines. So much for the
-    general features of these wonderful ships, of which four were built
-    during the decade from 1898 to 1908, and several more since that period.</p>
-
-  <p>The construction and trial of Count Zeppelin’s first air ship proved a
-    formidable task, requiring all his resources of money and mechanical
-    skill. As it<span class="pagenum" id="Page_148">148</span> rivaled in size and fluid displacement a large ocean
-    liner, it could not well be launched and landed, except on the water.
-    It was therefore housed in a wooden shed 472 feet long, floating on 95
-    pontoons, and so anchored as to swing freely with the wind and assume
-    its direction. This shed, as well as the ship, was very costly, and
-    in an unfortunate hour was torn from its moorings by a tempest, which
-    did other damage entailing great expense and time for repairs. The
-    inventor’s resources were becoming strained; for, as reported, the shed
-    cost $50,000, while the first balloon cost more than twice that sum.</p>
-
-  <p>Finally, the first launching was officially set for June 30, 1900. The
-    lake was thronged with people massed along the shores, and dotting
-    its surface with every kind of craft, from the fisherman’s primitive
-    boat to the handsomest private yacht, or launch. All day the expectant
-    multitude waited, only to learn at dusk, that the inflation was not
-    completed. Next day they tarried again till evening, and merely saw
-    the raft on which the balloon rested, towed out of the floating house.
-    On the third day, July 2d, those who waited were rewarded with an
-    interesting spectacle. The long stiff air ship was drawn forth from
-    its shed, like a ram rod from a gun. Count Zeppelin, with two men,
-    occupied the front boat, while two others took the rear one. After
-    careful adjustment the vessel was liberated, at eight o’clock, rose
-    slowly and advanced over the water, accompanied by the droning of its
-    propellers and the shouts of the delighted spectators, who realized
-    that they might be witnessing the commencement of a new epoch in
-    aërial navigation. But the voyage was not an unqualified success.
-    The controlling mechanism became deranged, the framework was bent,
-    and the propellers could not be worked properly. A gentle wind was
-    blowing and the vessel drifted<span class="pagenum" id="Page_149">149</span> with it, having an independent speed
-    of only thirteen feet per second, at best. At eight-twenty she reached
-    Immenstadt and landed on the water, having voyaged three and one half
-    miles, and having attained a height of thirteen hundred feet on a part
-    of the journey.</p>
-
-  <p>At that date the <i>Zeppelin I</i> was by far the largest and most
-    elaborate air ship ever constructed. Her hull measured 416 feet long,
-    38 feet across, cubed nearly 400,000 feet, weighed 9 tons, and had a
-    displacement of 10 tons. The trellised frame was made of aluminum, and
-    its body comprised seventeen compartments, of which fifteen were 26
-    feet long, and the other two 13 feet long. The outer cover was of linen
-    treated with pegamoid and tightly stretched. The hydrogen sacs were of
-    thin fabric. The propulsion was effected by two benzine motors, one in
-    either boat, which together developed 32 horse power, each driving,
-    by means of bevel gears and shafting, a pair of four-blade propellers
-    3.77 feet in diameter, at 1,100 revolutions per minute. Steering
-    sidewise was effected by means of vertical rudders, while the trim was
-    controlled by horizontal rudders at either side of the vessel, as also
-    by means of a sliding weight which could be drawn fore and aft by means
-    of a winch. Naturally some of these details were superseded ere long by
-    better devices suggested by subsequent experience.</p>
-
-  <p>On October 17, 1900, <i>Zeppelin I</i> made her second voyage, and with much
-    better result. Starting from the same balloon house at Manzell, at
-    four-forty-five, she promptly rose a thousand feet, and maneuvered in
-    a seven-mile wind, steering in great curves at the will of the pilot.
-    At times the speed was nearly twenty miles an hour, as determined by
-    continuous observations of the balloon’s position, taken from three
-    points of a triangle, together with the<span class="pagenum" id="Page_150">150</span> velocity of the wind on its
-    course, duly recorded by an anemometer. Finally a landing on the water
-    was made at six o’clock, without mishap.</p>
-
-  <p>This last demonstration left the Count triumphant in other respects,
-    but without sufficient funds to bring his invention into practical
-    use. He must, therefore, look for additional money for the proper
-    continuation of his great work. The financial task thus ensuing
-    occupied much of his time during the next five years, but he finally
-    secured capital enough to continue his experiments and to build a
-    second airship. This was completed and ready for trial in the latter
-    part of 1905.</p>
-
-  <p><i>Zeppelin II</i> resembled its predecessor in appearance, but embodied
-    many improvements suggested by the former trials. Its hull was 414
-    feet long, 38 feet in diameter, held 367,000 cubic feet of hydrogen
-    in its sixteen gas bags, and weighed with all appliances and cargo,
-    about nine tons. It was, therefore, about ten per cent smaller than
-    its predecessor; but at the same time it was far better powered than
-    the earlier one, and more effectively controlled. Each boat carried
-    an 85-horse-power Daimler benzine motor, actuating two enlarged
-    propellers. Ample steering surfaces, operated by the helmsman in the
-    front boat, served to turn the great ship about either of three axes
-    and, at the same time, to displace her bodily up and down in the air,
-    either by direct lift or by canting her hull so that her screw thrust
-    and the pressure on her sides would produce the desired translation.</p>
-
-  <p>Two trials of Zeppelin’s second air ship were made on the Borden-See,
-    one on November 30, 1906, the other on January 17, 1907; but both
-    met with serious accident. In the first trial the balloon was towed
-    by a motor boat some distance, then cut loose in the wind, which
-    was carrying it forward faster<span class="pagenum" id="Page_151">151</span> than the boat. But it soon became
-    unmanageable and plunged into the water, suffering considerable damage.
-    In the second trial it flew for a short time at a speed of thirty
-    feet per second, when the engines were developing 36 horse power.
-    Some maneuvering was effected in a strong wind, but presently the
-    propellers stopped, the vessel dropped to the shore and was anchored on
-    the ground. During the night it was so badly damaged by the wind that
-    Count Zeppelin ordered it to be taken to pieces to furnish material for
-    further construction.</p>
-
-  <p>The loss of two mammoth air ships after such brief trial seemed
-    enough to appall even a sturdy general of the Prussian army; but
-    Count Zeppelin was too resolute to waste time in futile tears and
-    hopeless dejection. Strong natures are usually stimulated by disaster,
-    and aroused to fuller energy, to grimmer determination, if not to
-    desperate hazard. However, not desperation, but buoyant hope and high
-    expectation, based on ample experience, were now his ruling motive. Had
-    not his ship attained thirty feet per second with less than one fourth
-    her motive power? The year began with disaster indeed, but he intended
-    it to terminate in glorious victory. And such, indeed, was the happy
-    issue.</p>
-
-  <p>October, 1907, witnessed the launching of <i>Zeppelin III</i>. She had the
-    same length as her immediate predecessor, but she was a luckier vessel
-    and better powered. On her official trial she voyaged at the height of
-    half a mile, carrying eleven persons sixty-seven miles in two hours
-    and seventeen minutes, or at more than twenty-nine miles per hour.
-    This was a record velocity exceeding that of the best military balloon
-    in France. At times she attained a velocity of fifty feet per second,
-    thus considerably outspeeding the swiftest ocean liner. Moreover, her
-    stability and steering qualities were<span class="pagenum" id="Page_152">152</span> excellent. With pardonable
-    elation, therefore, the illustrious inventor could report to the
-    Minister of War the complete success of his experiments. And with good
-    reason the German government now granted financial aid to test more
-    fully the merits of the rigid system of construction.</p>
-
-  <p>With this assistance the industrious aëronaut erected a new floating
-    house on the Borden-See at Friedrichshafen, and began the construction
-    of a still larger air ship embodying further improvements in various
-    details. <i>Zeppelin IV</i> was 446 feet long, 42.5 in diameter, held
-    460,000 cubic feet of hydrogen in her sixteen compartments, and had a
-    total buoyancy of sixteen tons. She had a surplus buoyancy of over two
-    tons, carried a crew of 18 men, and had an estimated range of action
-    of eighteen hundred miles. When drawn from her shed in the autumn of
-    1907, her great buoyant hull resting lightly on the water supported by
-    her two floating cars, she had all the appearance of a royal passenger
-    express ready for important service. In general features the vessel
-    was like her three predecessors, but in the center of the keel, with
-    transparent floors and windowed sides, was a special stateroom designed
-    for passengers only. This seemed very suggestive, if not prophetic,
-    of the future trend of aërial navigation. Moreover, the mechanism of
-    propulsion and control were increased in power and effectiveness.
-    In each boat-like car was a 110-horse-power Daimler benzine engine,
-    actuating a pair of three-blade propellers about 15 feet in diameter.
-    A large vertical rudder, mounted on the extreme end of the stern, and
-    supplemented by a pair of smaller vertical rudders at either side of
-    the stern, served to steer the vessel right and left. For steering
-    up and down, as also for exerting a direct lift up or down, four
-    superposed planes like a Venetian blind were placed at either side of
-    the<span class="pagenum" id="Page_153">153</span> hull fore and aft, at about the same level as the propellers. In
-    addition the hull was provided, like a feathered arrow, with fixed
-    fin-like planes at the stern, both vertical and horizontal, for
-    securing steadiness of flight.</p>
-
-  <p>Several trials of this leviathan were made preliminary to her official
-    government test which, if satisfactory, assured her purchase by the
-    German government for $500,000. At the builder’s suggestion this test
-    should include a voyage of 24 hours duration, a safe descent on land or
-    water, an ascent to 4,000 feet, and the fulfillment of various secret
-    requirements. In the autumn of 1907 a successful voyage of eight hours
-    was easily accomplished. In the early part of the next summer, 1908, a
-    series of voyages were made which aroused intense interest throughout
-    the civilized world. On June 13th the great ship, starting from her
-    harbor at Friedrichshafen, sailed over the Alps to Lucerne, steering
-    in among the mountains; here buffeted by eddies, and cross currents,
-    there stemming such stiff head winds that her shadow could hardly
-    creep forward over the ground, again driving through a dark lowering
-    hailstorm which pelted with ominous thunder on her resounding hull; but
-    at length reaching Lucerne safely, then returning in triumph to her
-    harbor at Friedrichshafen. For twelve hours the stanch vessel endured
-    the elements, by no means hospitable, and in that period voyaged 270
-    miles at an average speed of 22 miles an hour. It was a record journey
-    and a triumph in the art.</p>
-
-  <p>The following picturesque account of a flight in Count von Zeppelin’s
-    gigantic air ship, written by Emil Sandt, appeared in the <cite>Scientific
-    American Supplement</cite> of August 15, 1908:</p>
-
-  <blockquote>
-    <p>“Early in the morning Professor Hergesell, Freiherr von Bassus, Dr.
-      Stalberg, Herr Uhland, and<span class="pagenum" id="Page_154">154</span> myself set out in Count Zeppelin’s launch
-      for the shed in which the great air ship is housed. When we arrived
-      everything was in readiness for us. Count Zeppelin is proud of the fact
-      that his colossal craft can be drawn in and out of the shed with very
-      little help. In seven minutes the huge gas bag had emerged, and a few
-      minutes later we were floating up to the sky. I took my station in the
-      central car or cabin, a comfortable room flooded with the yellow light
-      that filters through the translucent balloon fabric of which the walls,
-      the floor and the ceiling are constituted. Comfortable seats suspended
-      from fine chains provide a seating capacity for a dozen passengers.</p>
-
-    <p>“For a great portion of their length the walls are provided with
-      celluloid panes. The floor is also transparent wherever it is not used
-      as a footway. Seated comfortably in the central car, I could look
-      down through my knees and see the green earth, water, people, cities
-      and castles far below. I could also see birds circling around and
-      fluttering anxiously, evidently frightened by the strange giant of the
-      air.</p>
-
-    <p>“We crossed over to the Ueberlinger See, traversed the intermediate
-      neck of land, and turned into the valley of the Rhine at Konstanz.
-      Here I left the central car and walked toward the rear car along the
-      keelway, which is flanked with balloon cloth, and which is closed at
-      the end of the keelway by a celluloid door. I opened the door and
-      stepped out on the narrow aluminum gangway, which runs down sharply
-      to the rear car. The gangway has no protecting handrail. It is merely
-      ribbed to give a better foothold. That apparently flimsy structure
-      bridges a chasm of twenty feet between the end of the keelway and the
-      car. From below, the passage from the keelway and the car must seem
-      perilous<span class="pagenum" id="Page_155">155</span> indeed, but up in the air ship itself no fear is felt. I
-      stood on this narrow bridge and gazed on the landscape. To the north
-      I could see the Hohendtwiel. Behind us lay the Swabian See glistening
-      in the morning’s sun. In the southeast I saw Thurgau wrapped in violet
-      light. On the horizon the lofty peak of the Saentis rose broad and
-      jagged, capped with ice and snow. Below us writhed the Rhine. I looked
-      across at the propellers. Count von Zeppelin had signaled full speed
-      ahead. The giant air ship trembled. The propellers seemed like disks,
-      revolving with furious speed and yet as transparent as a locust’s
-      wings. They gave out a note like that of a deep organ, so loud that the
-      human voice, even when lifted to a shriek, could hardly be heard.</p>
-
-    <p>“I walked down to the rear car to obtain a better view. Here the
-      gigantic craft could be seen in a wonderful perspective. The sensation
-      was strange. The giant ship obediently sank and rose. Obediently moved
-      to the right or to the left, slavishly following the slightest pressure
-      of the human hand. Sometimes its angle was such that the entire fabric
-      seemed inclined like a kite. At times the forward car lay below us; at
-      times we had to look up at it.</p>
-
-    <p>“As we neared the splendid falls of the Rhine at Schaffhausen, the
-      Count brought the air ship down, in order to ascertain whether the
-      eddies occasioned by the waterfall would have any effect.</p>
-
-    <p>“We turned into the Reusstal, but were buffeted by the wind all the way
-      up the valley. To the south the sharp jutting peak of Mount Pilatus
-      hove in sight. Soon Lucerne appeared, a jewel among cities. The lake
-      itself shimmered brightly where it was struck by the sun; its darker
-      portions lay like an emerald, held in a setting of heliotrope. It was
-      like a melody in colors. Below us in Lucerne itself there was a hubbub
-      and a great jubilation. The streets<span class="pagenum" id="Page_156">156</span> were crowded with gayly clad
-      people. The roads were a-swarm. Zeppelin guided his air ship down, and
-      allowed it to glide full speed over the city at the height of a church
-      steeple.</p>
-
-    <p>“We traveled over the Vierwaldstaetter See, and crossed to Knessnacht,
-      to Zug Lake, and up northward to Zug itself. Then came the most
-      difficult task which Professor Hergesell had assigned to the air ship.
-      The craft was to carry us straight across to Lake Zurich, through
-      a narrow pass where it would be caught in a veritable cyclone. The
-      motors groaned and rattled. The propellers howled a deep groaning
-      song. The air ship did all that it could. The wind was dead against
-      us, traveling with a velocity of nearly thirty-one miles an hour. The
-      Count could easily have arisen and escaped the fury of the blast, but
-      it was his purpose not to avoid obstacles, but to court them. Whenever
-      the great air ship showed signs of swerving, it was brought back to
-      its course. Far below us in the valley the sharply marked shadow of
-      the air ship, crawling slowly from tree to tree, showed us how hard it
-      was struggling. There were minutes when it seemed as if we stood stock
-      still, despite the infernal music of the propellers. Gradually the nose
-      of the craft was thrust forward; once more the air ship mastered the
-      winds. We had forced our way through the pass, and were dashing on at
-      full speed. The vast shadow below us traveled with the velocity of a
-      bird over the mountain, valleys, cliffs and rocky points, over railway
-      embankments and road, over water and land.”</p>
-  </blockquote>
-
-  <p>Two attempts were made in July, 1908, to complete the government test;
-    but they proved abortive, and in the second one the hull was damaged by
-    the wind pushing it sidewise against the shed, as it was being towed
-    out by motor boat. This accident caused a delay of two weeks, much
-    to the disappointment <span class="pagenum" id="Page_157">157</span>of the expectant populace. As a consequence
-    Zeppelin resolved to begin the next attempt unheralded. He had the
-    repairs made quickly and all was ready early in August.</p>
-
-  <p>On Tuesday, August 4th, at six forty-five in the morning, the great
-    twenty-four hour test for the government began, without previous
-    announcement, but with fairest prospect of success. Sailing from
-    Friedrichshafen, Zeppelin purposed to follow the Rhine as far down
-    as Mayence, then return in a direct line to his starting point. All
-    went splendidly at first. He passed Constance at seven o’clock in
-    the morning, Basle at nine-thirty, Strassburg about noon, then with
-    slower speed passed Mannheim at two-fifty and Darmstadt at four-thirty.
-    At about six o’clock a descent was made at Oppenheim, eleven and a
-    quarter hours after starting. The air ship had voyaged 270 miles at the
-    average speed of 22 miles an hour. A wonderful demonstration it was
-    for the inhabitants of that historic valley, and a glorious tour for
-    the brave old sailor and his crew. Resuming the voyage, Mayence, the
-    turning point, was reached at eleven o’clock at night, and the vessel
-    was headed for home. But now the engines, being overworked, could
-    not maintain the usual speed, which therefore was lowered to twelve
-    miles an hour. Next morning at eight o’clock, after Stuttgart had been
-    passed, a descent had to be made at the village of Echterdingen, to
-    adjust and overhaul the machinery. Ninety-five miles of the return had
-    been made in nine hours.</p>
-
-  <p>It was most unfortunate that a landing had to be made without a harbor,
-    particularly as a gale was in pursuit of the vessel. Ere long she was
-    torn from her moorings by a squall, carried into the air, and set on
-    fire, probably by an electric discharge. Immediately the great hull was
-    enveloped in flame and completely <span class="pagenum" id="Page_158">158</span>destroyed, leaving a tangled network
-    of distorted framing. It was a dismal termination to the greatest motor
-    balloon voyage in the world’s history up to that date; for the vessel
-    had been in the air continuously for twenty and three-fourths hours and
-    had traveled 378 miles.</p>
-
-  <p>The hardy and venerable hero of so many voyages and long continued
-    experiments quite broke down at the sight of his grandest vessel in
-    ruin. But an unlooked for and a sudden turn of events brought him the
-    greatest triumph in his darkest hour. While the world expressed its
-    grief and sympathy his loyal countrymen hastened to his relief in an
-    admirable burst of enthusiasm. Within twenty-four hours the government
-    had made him a grant of $125,000, and subscriptions offered in all
-    parts of Germany brought the sum to over $500,000. By October, 1908,
-    the total gift amounted to $1,500,000, which was paid to the Zeppelin
-    Air Ship Company, formed for developing and building air ships on a
-    large scale. A tract of 300 acres was secured at Friedrichshafen for
-    an air ship factory. Here was erected the necessary shops, hydrogen
-    plant, balloon harbor, and everything necessary to enable the company
-    to construct several mammoth air ships each year. To these new grounds
-    the Count’s former interests were gradually conveyed, while his old
-    station, with its air ship dock on Lake Constance, was converted into a
-    military post by the German government.</p>
-
-  <p>After the destruction of <i>Zeppelin IV</i>, its predecessor, the Count’s
-    third air ship, was again prepared for service and for new triumphs.
-    Her hull was lengthened by the addition of a cylindrical section having
-    the length of one compartment, or about 26 feet. This alteration gave
-    a considerable increase of net buoyancy with but slight increase of
-    resistance. <span class="pagenum" id="Page_159">159</span>The dimensions now were: length 446 feet, diameter 38
-    feet, volume 423,768 cubic feet. The gas was contained in sixteen
-    sacs, twelve in the cylindrical part and two at each end. The ship
-    was propelled by two 85-horse-power engines, supplied with sufficient
-    gasoline for a forty-one hour voyage at 25 miles per hour. The loss of
-    gas by leakage was less by weight than the loss of fuel. The famous old
-    cruiser, thus remodeled, was operated in the autumn of 1908 with her
-    usual precision and grace; thus winning new distinction and renown. On
-    one occasion she had as passengers the Crown Prince and the Kaiser’s
-    brother, Prince Henry. The Emperor himself witnessed the demonstration,
-    and decorated the Count, referring to him as “the greatest German of
-    the century.” Soon afterward the ship was taken over by the government
-    and assigned to the Prussian Battalion of Aëronauts, being christened
-    <i>Zeppelin I</i>, since it was the first vessel of the kind taken into the
-    military service.</p>
-
-  <p>Beginning with March 9, 1909, the military <i>Zeppelin I</i> was kept in
-    active operation by the officers, and subjected to a wide variety of
-    tests day by day. She was driven through rain and snowstorms, at all
-    elevations up to a mile; she was anchored over land and over water,
-    sometimes exposed for hours to a gale; she was steered in and out of
-    her shed without the aid of her floating raft; she was sent on long
-    trips, landed in the open country, by day and by night, and returned to
-    harbor in safety. On one occasion she carried twenty-six passengers for
-    over an hour and a half; again she made an endurance flight of thirteen
-    hours. These maneuvers exhibited for the first time many capabilities
-    of the ship, which all along had been stoutly affirmed by the inventor,
-    but questioned by his critics.</p>
-
-  <p>On April 1, 1909, at four o’clock in the morning,<span class="pagenum" id="Page_160">160</span> the renowned
-    <i>Zeppelin I</i>, with the Count as helmsman, started through the rain
-    and wind on a voyage from Friedrichshafen to Munich, a hundred miles
-    distant. The ship followed the railway as far as Ulm, guided by the
-    station lights, which were kept burning all night to mark the route. As
-    she approached Munich, at the appointed hour of nine next morning, her
-    approach was announced from afar by the droning of her machinery and
-    propellers, whereupon she was welcomed by loud music from many bands
-    and the joyous ringing of all the bells in the city. The Prince Regent
-    of Bavaria and a great throng of applauding citizens awaited her at the
-    Teresenhohe park. Presently the swift cruiser approached, sailing over
-    the steeple tops like a monstrous arrow. She halted before the Regent
-    and dipped her bow three times, in graceful salute. Then she circled
-    widely over the city, intending to land at the Oberwiesenfeld Parade
-    Grounds, where part of the garrison troops were drawn up to receive
-    her. But now, while so near the goal, she found it difficult to stem
-    the increasing gale, and unsafe to land; so, with her bow pointed to
-    the city, and propellers humming furiously, she gradually yielded to
-    the storm, and drifted slowly backward toward the northeast.</p>
-
-  <p>The crucial hour had come for this stanch vessel and her audacious
-    captain. They wrestled with the storm bravely and obstinately, but
-    were beaten back steadily, with no port in view. The Count determined
-    to weather the gale till it should spend its fury. He coolly sent an
-    aërogram to Munich, saying that all was well and that he might reach
-    the city late in the day. Observing a suitable place to land, near
-    the village of Loiching, he pointed the prow of his ship downward,
-    approached the earth and cast anchor. As the front car touched the
-    ground it was grasped by the willing hands of thronging peasants and
-    vil<span class="pagenum" id="Page_161">161</span>lagers. Presently the ship was taken in charge by a military
-    relief party which the Count had hailed on the way, at Guendelkoven,
-    and which had hastened to his aid in automobiles. Fifty soldiers, in
-    regular shifts, that night held the bow of the vessel by a short leash.
-    The anchor was firmly fastened, and additional ropes secured the bow
-    to an unwheeled wagon loaded with stones. Thus all night long that
-    mighty hull swayed to and fro in the passing storm, securely as a ship
-    anchored at sea.</p>
-
-  <hr class="page" />
-  <div id="Plate_XI" class="center"><b>PLATE XI.</b></div>
-
-  <div class="figcenter w600">
-    <img src="images/i_199a.jpg" width="600" height="339" alt="" />
-    <div class="captionp">ZEPPELIN DIRIGIBLE RESTING ON THE WATER.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_199b.jpg" width="600" height="477" alt="" />
-    <div class="captionp">ZEPPELIN DIRIGIBLE OVER ZÜRICH.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <p>Next morning the vessel was well replenished and headed for home, by
-    way of Munich. The return was easy, for the wind had nearly reversed
-    its course. Sailing at 32 miles an hour, with a quartering current,
-    the stormbeaten ship soon reached Munich, where she was hailed with
-    boundless enthusiasm. The Prince Regent entertained the Count during
-    his sojourn of three hours, and decorated him with a gold medal. The
-    ship then sailed for Friedrichshafen, with the full speed of the wind
-    and of her propellers, at one time attaining 68 miles an hour. At
-    nightfall she landed gently on the lake near Manzell, having weathered
-    that tempestuous voyage without serious mishap.</p>
-
-  <p>This was a splendid proof of her stanchness; but a few days later
-    she was put through other tests quite as severe, one being a night
-    voyage of thirteen and a third hours, after a day of busy maneuvering.
-    Following this came her still longer voyage, to Metz, where she was
-    stationed as a frontier war vessel, and one of a considerable fleet
-    contemplated by the German government.</p>
-
-  <p>In the meantime the energetic Count had started his fifth vessel, or
-    military <i>Zeppelin II</i>, which now was nearing completion at the works
-    of the Zeppelin Air Ship Construction Company. Her hull measured 446
-    feet in length, had a diameter of 42½ feet,<span class="pagenum" id="Page_162">162</span> and a volume of over
-    half a million cubic feet. It also had a ladder running through one
-    of the compartments to a platform on its top. Her motors of 220 horse
-    power were taken uninjured from the wreck of the old <i>Zeppelin IV</i> at
-    Echterdingen.</p>
-
-  <p>Without previous notice this new air ship set forth in a rain on the
-    evening of May 29, 1909, headed toward Berlin, having on board the
-    Count and seven other men. The purpose of the voyage was merely to
-    exercise the ship; not to reach any definite goal; but by mistake she
-    was reported on her way to Berlin, so that the Kaiser and his retinue
-    waited some hours in vain to receive her. She voyaged bravely past
-    Nuremberg and Leipsic to Bitterfeld, within 85 miles of the capital;
-    then turned for home, the Count being unaware of the hopes he was
-    disappointing. She returned successfully past Weimar and Stuttgart,
-    then, near Goeppingen, descended on an open plain to take on gasoline
-    from a neighboring petroleum refinery. As they were nearing the ground
-    in a heavy rain, Count Zeppelin, who was acting as pilot, suddenly
-    beheld, just before them, a half dead pear tree, with gaunt bare limbs.
-    He gave a sharp order to starboard the helm; but his aëronaut, worn by
-    too long service, thrust the helm to port, and the ship, impelled by a
-    sudden gust, plunged head on against the tree. Her prow was wrecked,
-    the frame and envelope being wrenched and torn for a distance of 100
-    feet.</p>
-
-  <p>The disaster seemed complete, but the dauntless Count was equal to the
-    emergency. Twenty workmen were summoned from Friedrichshafen, sixty
-    miles away, and sped to the rescue in automobiles. Electric wires from
-    a nearby plant were stretched to furnish light for night repairs. The
-    grounds were guarded by police and troops. The hull was detached from
-    the tree; furnished with a temporary<span class="pagenum" id="Page_163">163</span> prow of young firs covered with
-    balloon cloth; relieved of the forward motors and other impedimenta;
-    furnished with fresh supplies; and, in exactly 28 hours from the
-    mishap, was ready for the homeward voyage.</p>
-
-  <p>Slowly the crippled air ship sailed for Friedrichshafen, followed by
-    the white-haired inventor in an automobile, unmoved and triumphant.
-    A mighty shout ascended from the immense crowd of witnesses who had
-    assembled from many quarters. All Germany was elated and jubilant. The
-    great voyage and the prompt recovery from apparent disaster were a
-    triumph of the whole people, for they had helped their hero to build
-    this ship, and now participated in his victory over the spite of
-    fortune and the elements. The Emperor telegraphed his congratulations,
-    affirming his renewed confidence in the rigid system. Without further
-    difficulty the vessel reached her port at an easy gait of ten miles an
-    hour, thus completing a memorable voyage of seven hundred miles—one of
-    the most glorious in the history of aëronautics.</p>
-
-  <p>If the citizens of Berlin were disappointed on this occasion,
-    they had not long to wait for an aërial visit from the wizard of
-    Friedrichshafen. On August 27th, at 4.45 <span class="smcap">a.m.</span>, his crew of
-    five men sailed for Berlin via Nuremberg and Leipsic in his sixth air
-    ship, his latest and largest, hurriedly finished for the Berlin voyage.
-    It cubed 533,000 feet, and was driven by two Daimler engines of 150
-    nominal horse power each. In the afternoon they reached Nuremberg,
-    circled over the city and landed for the night. Starting at 2.15 next
-    morning they battled their way toward Leipsic against a strong wind,
-    and at 6.45 <span class="smcap">p.m.</span> landed for the night at Bitterfeld, where
-    they arrived with a broken propeller. Here Count Zeppelin joined
-    them. The next morning,<span class="pagenum" id="Page_164">164</span> after a good night’s rest and some repairs,
-    they started at half past seven, in a dense fog, which, however, soon
-    cleared. Finally they arrived at Berlin at half past twelve o’clock,
-    as the people were returning from church. They circled over the city,
-    to the delight of the multitude of spectators who thronged the house
-    tops, parks, and thoroughfares, finally reaching the parade ground at
-    Tegel. Here, after saluting the Emperor, the happy navigator maneuvered
-    before the imperial tribune, greeted by the thunderous Hoch! Hoch! of
-    a hundred thousand throats, and the ringing of all the church bells of
-    the nation’s capital. The venerable Count was graciously received by
-    the Emperor and members of the royal family. After spending the day at
-    Berlin, the crew sailed for Friedrichshafen, about midnight, where,
-    after various accidents and delays, they arrived in safety on September
-    6th.</p>
-
-  <p>In some respects this was Von Zeppelin’s crowning voyage of the year,
-    though effected with a hurriedly finished vessel, not yet thoroughly
-    adjusted. In mechanical execution this journey was equaled on many
-    other occasions; for those great air ships were kept in active service
-    and were everywhere hailed with enthusiasm. Both the Emperor and his
-    people were proud to number those grand cruisers among the nation’s
-    aërial warships. With general commendation, therefore, was received
-    the announcement that four large <i>Zeppelins</i> were ordered for the use
-    of the German navy. And not surprising was the announcement that other
-    inventors were at work on designs for dirigibles of the rigid type.
-    The projects of these new rivals, who began to appear in 1909, are set
-    forth in the following account:<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">[17]</a></p>
-
-  <p><span class="pagenum" id="Page_165">165</span></p>
-
-  <blockquote>
-    <p>“Count Zeppelin, who proved that air ships have a practical future,
-      is no longer undisputed ‘king of the air.’ His rivals have taken his
-      pattern, and improved it until soon air ships will be able to keep
-      afloat for many days and in that case to cross oceans. A type of this
-      modern ship is the first Schütte leviathan of wood and steel bracing,
-      now nearly finished at Mannheim. It is expected to lift its twenty-four
-      and one-fifth tons one and a quarter miles, because its beam is sixty
-      feet as compared with the forty-four feet of the <i>Zeppelin II</i>. The car
-      is one hundred and thirty feet long, with a cabin to accommodate thirty
-      passengers. The new ship displaces nineteen thousand cubic meters,
-      as against fifteen thousand in the <i>Zeppelin III</i>. It is expected to
-      carry a cargo of five to six tons supported by ten spherical sustaining
-      chambers, and eight ring-shape reservoir chambers connected by a secret
-      apparatus. These eight reservoirs automatically receive all expanding
-      gas that escapes from the sustaining chambers, thus conserving the
-      entire supporting power. Four motors of combined five hundred and forty
-      horse power will drive the propellers. Expert opinion predicts a speed
-      of thirty-seven to forty-three miles an hour, three miles faster than
-      the <i>Gross III</i>, at this writing the fastest air ship in the world. The
-      whole enterprise is backed by Mr. Lanz, a rich manufacturer, who is
-      president of the German Air-Navy League. A wooden-braced ship of equal
-      equipment and size, designed by the Engineer Rettich, is well under way.</p>
-
-    <p>“Another rival of the <i>Zeppelin</i>, so far only projected, has been
-      designed by the Engineers Radinger and Wagner, and is intended to
-      be an advance in endurance. It should float for fifty days without
-      replenishing gas. It is planned to have a rigid hull of hollow
-      paper tubes and steel bracing and to be<span class="pagenum" id="Page_166">166</span> thirty per cent lighter
-      than a <i>Zeppelin</i> built of aluminum, in any equal size. Drum-shape
-      compartments are to hold the sustaining hydrogen, none of which is to
-      be lost through expansion by the sun, as any surplus will be compressed
-      by automatic pumps into the hollow tubes.<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">[18]</a> Having six thousand
-      meters less displacement than the <i>Zeppelin III</i>, it will carry a
-      reserve of seven hundred cubic meters of gas. Thirty-two per cent of
-      its weight-carrying capacity will be given up to passengers, fuel, and
-      baggage. Engines of two hundred and forty-two combined horse power are
-      expected to develop a speed of forty to fifty miles an hour. Larger
-      craft of the same type would, of course, carry much heavier cargoes
-      and have higher speed. This type of ship, soon to be placed in the
-      construction cradle, is expected to cross the ocean easily with fifteen
-      passengers.”</p>
-  </blockquote>
-
-  <p>In keeping with the lively growth of these great ships was the
-    formation of the German aërial transportation company, with a capital
-    stock of $750,000, reported in <cite>l’Aérophile</cite> for December, 1909. A line
-    of large <i>Zeppelins</i> was to connect Baden-Baden, Mannheim, Munich,
-    Leipsic, Cologne, Düsseldorf, Berlin, Dresden, Essen and Frankfort.
-    The first two auto balloons of this line were to be the <i>Zeppelin
-      IV</i> and <i>Zeppelin V</i>, to be put in commission in the spring of 1910.
-    The <i>Zeppelin IV</i> was to cube 706,000 cubic feet, and carry twenty
-    passengers in three cars, each containing a motor. The <i>Zeppelin V</i> was
-    to be constructed of a remarkably light rigid alloy “electrometal,”
-    and was to carry at least thirty passengers. This enterprise certainly
-    formed an appropriate termination to the first decade of practical auto
-    ballooning.</p>
-
-  <p><span class="pagenum" id="Page_167">167</span></p>
-
-  <p>The projected passenger line of the German Air Ship Society was
-    inaugurated the following summer with serene audacity and fairy-like
-    magnificence. The first ship employed, <i>Zeppelin VII</i>, was a huge
-    vessel of unusual power, speed and elegance of appointment. She was
-    485 feet long by 46 in diameter, cubed 690,000 feet, and carried three
-    engines totaling 420 horse power and competent to drive her 35 miles
-    per hour. Midway beneath her hull and rigidly joined to it, was a
-    passenger car thirty-five feet long, having a vestibule at one end, a
-    lavatory at the other, and five compartments between them, with seats
-    for twenty persons. Beyond the ends of the car were open decks leading
-    to the boats fore and aft containing the machinery.</p>
-
-  <p>At three o’clock on the morning of June 22, 1910, with Count Zeppelin
-    in charge, and a dozen passengers aboard, this majestic auto balloon
-    sailed from Friedrichshafen up the Rhine Valley for Düsseldorf, three
-    hundred miles, and after a prosperous voyage of nine hours, made an
-    easy landing. Next morning at eight thirty she voyaged from Düsseldorf
-    to Dortmund, thirty-seven miles north, sailing at a general height of
-    one thousand feet, over some of the finest industrial parts of Germany.
-    Then she returned to Düsseldorf with her delighted passengers who were
-    all enthusiasm for the new mode of travel so auspiciously begun. Of the
-    thirty-two persons aboard, the majority were regular public passengers
-    who had paid fifty dollars each for the trip, several of them tourists
-    from various countries, and ten of them women.</p>
-
-  <p>The maiden voyage of this first air liner was a marvel and dream
-    of delight to the fortunate few traveling in such celestial style.
-    The comforts and splendors of the service quite surpassed their
-    expectations. Seated in that fairy car of aluminum framing <span class="pagenum" id="Page_168">168</span>lined with
-    mahogany and rosewood inlaid with pearl, they looked from spacious
-    windows over the beautiful German landscape gliding beneath them, and
-    enjoyed visions fit for itinerating gods. Along the shining waters of
-    the Rhine, and over its castellated crags, and among its rolling hills
-    terraced with luxuriant vineyards, now lapped in the glory of summer,
-    and above stately cities murmuring with multitudinous life, they sailed
-    in serenest comfort and security, marveling at their own strange
-    career through the sky, and equally regarded with wonder by all the
-    inhabitants below, not to say written and read about by millions in all
-    parts of the civilized world. The delights of land and sea travel were
-    happily mingled, without their inconvenience. Neither dust nor smoke
-    was here, nor rattle of iron rails, nor lurching and rolling from heavy
-    seas. Quite otherwise. The senses were charmed with the fanning of
-    fragrant winds forever and uniformly blowing, with the melodious drone
-    of the swift propeller wheels, with the green glories of the earth and
-    purple splendors of the sky. When the tourist was sated with these he
-    could turn to his book; when tired of his chair he could stroll to and
-    fro in the car on a soft carpet, or along the trellised deck beyond;
-    when his appetite called, he could answer with the choicest food and
-    wine; for every convenience of an ample buffet was available. It was
-    all so enchanting if only practical.</p>
-
-  <p>Encouraged by these trials the company announced, and hoped to make,
-    voyages at frequent intervals. But in this they promptly encountered
-    difficulties. On June 28th the <i>Deutschland</i> started from Düsseldorf on
-    a four-hour cruise, with nearly a score of passengers, mostly newspaper
-    representatives. But she remained in the air longer than intended.
-    Passing Solingen she tried to reach Eberfeld, but<span class="pagenum" id="Page_169">169</span> ineffectually; nor
-    could she find a landing place. Toward five o’clock she was caught in
-    a great rising wind and carried one mile aloft like a passive balloon
-    in a vortex or thunderhead. Here much gas was lost by expansion, and
-    presently, as the ship emerged from a snow cloud in the upper vortex,
-    with cooled gas and hull laden with precipitation, she descended at a
-    terrible velocity. With crippled motive power, the vessel could not be
-    supported dynamically by the impact of the air against her sustaining
-    planes and against her canted hull, for lack of forward speed. At
-    length with a terrific crash she struck upon the forest of Teutoberg,
-    80 miles from Dusseldorf, a great tree trunk piercing the rear boat and
-    projecting among the terrified crew. Here the vessel lodged with her
-    stern and controlling gear badly wrecked, and here she was abandoned
-    by the passengers, with her huge hull resting on the branches forty
-    feet from earth. Ere long she was retrieved by a company of infantry
-    who sawed down the trees, dismantled the ship, and returned the parts
-    on railway trucks to Friedrichshafen, to be used in building another
-    vessel.</p>
-
-  <p>Thus in both civil and military aëronautics the pioneers had to endure
-    many losses and grievous hardships; but the direst disasters often mark
-    the way to the greatest victories.</p>
-
-  <hr class="page" />
-  <div class="chapter" >
-    <span class="pagenum" id="Page_171">171</span>
-    <h2>PART II<br />
-      <span class="xlarge">GROWTH OF AVIATION</span></h2>
-  </div>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_VII">
-    <span class="pagenum" id="Page_173">173</span>
-    <h3>CHAPTER VII</h3>
-    <span class="small">MODEL FLYING MACHINES</span>
-  </div>
-
-  <p><span class="smcap">From</span> time immemorial man has admired the aërial evolutions of
-    wing-gifted creatures, and aspired to imitate them. But which
-    evolutions should he attempt first? Which if any are practicable for
-    the ponderous lord of creation? The question is still pertinent.</p>
-
-  <p>Nature in her bounty bewilders us with wondrous models. All about
-    and overhead, with exquisite art, they challenge us to float or fly.
-    Before the flower-bell drifts the ruby-throat, his long bill in the
-    honey-hearted bloom; now bulletlike he leaps through boundless space.
-    Why not adopt that style of locomotion? Call your rainbow equipage to
-    the door, and take the family forth in purple state, to the music of
-    melodious wheels.</p>
-
-  <p>If the humming bird will not serve, look above you. There rides
-    the dark-winged master of aërial motion, throned like a god on the
-    impetuous wind. Mark his majestic sweep as all day long, with unbeating
-    pinion, he scours the wide plain and rugged regions of the hills,
-    unwearied, reposeful, deliberate; now skimming the fragrant forest, or
-    meadow; now scaling the precipice, or swinging above the abyss; now
-    soaring cloudward beyond the range of human vision. There is a model
-    for the ambitious and the brave!</p>
-
-  <p>Or turn to mid ocean when the hurricane, shearing the tops of the
-    arched billows, scatters them in<span class="pagenum" id="Page_174">174</span> foam and spray over the watery chaos,
-    and the big ship strains in the storm. See the long-winged albatross,
-    white vision of joy in the darkness, careering all playfully round
-    the imperiled vessel, and above the monstrous waves; wheeling in glad
-    curves, frolicking in the face of the tempest, riding, without toil or
-    trepidation, the rudest<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">[19]</a> winds a thousand miles over the sea. What a
-    jocund pace for man!</p>
-
-  <p>Of all the charming modes of flight now possible to us it is certain
-    that our ancestors could copy but one with any hope of success. Minus
-    motive power they could not imitate the direct flight of the homing
-    pigeon, much less the mid-air pause of the bumblebee floating round a
-    daisy. Hence there remained to them only passive flight on nonvibrant
-    wings. The gliding of vultures, of gulls, and of certain quadrupeds and
-    fishes, they could imitate with profit; but when they essayed power
-    flight they invariably and egregiously failed.</p>
-
-  <p>The art of aviation presents two main groups of fliers. The first
-    comprises the various man kites, parachutes, gliding machines, soaring
-    machines. These may be called passive flyers, because they carry no
-    motive power, but ride passively on the air by the force of gravity or
-    a towline.</p>
-
-  <p>The second group comprises the bird-like flap-wing machines, called
-    orthopters by technical people; the screw-lift flyers, called
-    helicopters; the aëroplanes, also called monoplanes, biplanes,
-    triplanes, according to the number of superposed main lifting surfaces;
-    and lastly the gyroplanes, whose sustaining surfaces may turn over and
-    over, like a falling lath, or whirl round and round, like a boomerang.
-    These all may be called dynamic, or power, <span class="pagenum" id="Page_175">175</span>flyers. The technical
-    names, however, are not so important, as they are numerous; for the
-    whole aëronautic nomenclature is in a formative, not to say chaotic,
-    state. We may, therefore, like Adam, name the creatures as they pass
-    before us for review or discussion.</p>
-
-  <p>Disregarding the crude essays at human flight, recorded in the early
-    literature and history of many peoples, we may notice first the well
-    authenticated sketches of Leonardo da Vinci. His fertile mind conceived
-    three distinct devices for carrying a man in the air. But he and his
-    successors for nearly four centuries could do little more than invent.
-    For lack of motive power they could not navigate dynamic flyers,
-    however ingeniously contrived.</p>
-
-  <div class="figcenter">
-    <a id="Fig_26"><img src="images/i_215.jpg" width="447" height="307" alt="" /></a>
-    <div class="caption smcap">Fig. 26.—Da Vinci’s Helicopter.</div>
-  </div>
-
-  <p>Da Vinci’s first design, as shown in Fig. 26, provides the operator
-    with two wings to be actuated by the power of both arms and legs,
-    through the agency of very ingenious harness. With this device
-    an acrobat could fly forward and downward, to the delectation of
-    a multitude; but he would have to be caught on something soft to
-    escape injury. Since Leonardo’s day the experiment has been tried
-    occasionally, <span class="pagenum" id="Page_176">176</span>with varied results, sometimes grotesque, sometimes
-    tragic. He doubtless realized the impracticability of an orthopter
-    actuated by human muscle, and yet he has had many followers. The
-    orthopter is still a favorite device cultivated by a few persons who
-    propose to work its wings by means of a gasoline motor. Doubtless the
-    feat is physically possible, and may be accomplished in time.</p>
-
-  <div class="figleft">
-    <a id="Fig_27"><img src="images/i_216.jpg" width="206" height="343" alt="" /></a>
-    <div class="caption smcap">Fig. 27.—Da Vinci’s<br />Parachute.</div>
-  </div>
-
-  <p>Da Vinci’s second flyer was a helicopter, as shown in Fig. 26. An
-    aërial screw 96 feet in diameter was to be turned by a strong and
-    nimble artist who might, by prodigious effort, lift himself for a short
-    time. Though various small paper screws were made to ascend in the air,
-    the larger enterprise was never seriously undertaken. Many subsequent
-    inventors developed the same project; but the fellow turning the screw
-    always found it dreadful toil and a hopelessly futile task. Of late
-    the man-driven helicopter has been abandoned, but the motor-driven one
-    is very much cultivated. Scores of inventors in recent years, aided by
-    light motors, have been trying to screw boldly skyward, and some have
-    succeeded in rising on a helicopter carrying one man.</p>
-
-  <p>Da Vinci’s third scheme for human flight, as shown in Fig. 27, was a
-    framed sail on which a man could ride downward, if not upward. This
-    device never fails to navigate with its confiding sailor. Sometimes
-    he lands in one posture, again in another; but voyage he must, with
-    the certainty of gravitation. Leonardo is, therefore, the father
-    of the parachute. This, in turn, has had a varied offspring. <span class="pagenum" id="Page_177">177</span>The
-    common parachute, the aërial glider, the soaring machine, or passive
-    aëroplane, that rides the wind without motive power and without loss of
-    energy.</p>
-
-  <p>The foregoing sketches by the great artist were made toward the year
-    1500, and there the science stood for nearly three centuries. Much
-    speculation followed, but no substantial progress. Mathematicians
-    proved by figures the inadequacy of the human muscle to achieve human
-    flight. Dreamers demonstrated the same by launching themselves from
-    high places, and breaking their bones on the unfeeling earth, before
-    unpitying crowds. Finally came the balloon, giving a new impetus to an
-    embryo art.</p>
-
-  <p>The earliest of Da Vinci’s aëronautic ideas to be practically realized
-    was the parachute. The exact date of its first employment is not
-    exactly known. In the year 1617 Fauste Veranzio published in Venice
-    a good technical description of the construction and operation of
-    the parachute, accompanied by a clear illustration, as shown in
-    Fig. 28. But the first authentic account of a parachute descent of
-    a human being is that given by Sebastien Lenormand. This dauntless
-    inventor, on December 26, 1783, descended from the tower of the
-    Montpelier Observatory, holding in either hand an umbrella sixty inches
-    in diameter. A few days later he sent to the Academy of Lyons the
-    following description of his improved parachute, illustrated in Fig. 29:</p>
-
-  <blockquote>
-    <p>“I make a circle 14 feet in diameter with a heavy cord; I attach firmly
-      all around, a cone of linen whose height is 6 feet; I double this
-      cone with paper laid on the linen to render it impermeable to air; or
-      better, instead of linen, taffeta covered with gum elastic. I place
-      all about the cone small cords, which are attached below to a wicker
-      frame, and<span class="pagenum" id="Page_178">178</span> forming with this frame an inverse truncated cone. Upon
-      this frame I place myself. By this means I avoid the ribs and handle
-      of the umbrella, which would add considerable weight. I am sure to
-      risk so little that I offer to make the experiment myself, after once
-      having tried the parachute with different weights to make sure of its
-      solidity.”</p>
-  </blockquote>
-
-  <div class="figcenter">
-    <a id="Fig_28"><img src="images/i_218.jpg" width="450" height="689" alt="" /></a>
-    <div class="caption smcap">Fig. 28.—Veranzio’s Parachute.</div>
-  </div>
-
-  <p>Previous to Lenormand’s experiments, Blanchard, the aëronaut, had
-    dropped small parachutes from his balloon, sometimes carrying animals,
-    but never a human being. For unaccountable reasons<span class="pagenum" id="Page_179">179</span> the world had to
-    wait fourteen years longer to see a man make the new familiar parachute
-    descent from a balloon. On October 22, 1797, in presence of a large
-    crowd Jacques Garnerin ascended in a closed parachute to a height of
-    3,000 feet, then cut loose. The people were astonished and appalled;
-    but they soon saw the umbrella-shaped canvas spread open and oscillate
-    in the sky with its human freight. As it was but eight yards in
-    diameter, it descended rapidly and struck the ground with violence,
-    throwing Garnerin from his seat. He escaped with a bruised foot,
-    mounted a horse, and returned to the starting point, where he received
-    a lively ovation.</p>
-
-  <div class="figleft">
-    <a id="Fig_29"><img src="images/i_219.jpg" width="360" height="434" alt="" /></a>
-    <div class="caption smcap">Fig. 29.—Lenormand’s Parachute, 1784.</div>
-  </div>
-
-  <p>After this experiment, parachute descents became popular the world
-    over, and have been repeated up to the present time substantially
-    without change. A slight improvement in the construction was made by
-    cutting away the top of the canvas, thus allowing the air to escape
-    sufficiently to check the oscillations; but no radical change in
-    the design has come into general use. It would seem easy to have
-    transformed the craft into a traveling parachute gliding down the sky
-    like a great bird on out-stretched wings. Such a device would enable
-    the aëronaut to sail some miles and direct his course in<span class="pagenum" id="Page_180">180</span> the air. If
-    fair skill had been acquired it might have hastened the advent of human
-    flight twenty years, so far as it is practicable without the aid of
-    the internal combustion motor. For two decades ago Maxim produced an
-    abundantly powerful steam engine; but could find no one to furnish him
-    a manageable glider on which to mount it. Now, indeed, such gliders are
-    available; but they were developed by aviators, not by balloonists, or
-    parachutists, who should have effected that advance many years ago.</p>
-
-  <p>Curiously enough, Nature has furnished a traveling parachute which
-    seems never to have been imitated by man, though not difficult to
-    copy. It is a large two-winged seed, which when dropped in any poise,
-    immediately rights itself, and glides gracefully through the air. The
-    seeds grow on a tree in India, bearing the name <i>Zanonia Macrocarpa</i>,
-    and when shaken from its branches look like so many sparrows sailing
-    earthward in wide curves. Artificial gliders of this type are easy to
-    construct, and would make interesting toys. However, if man has not
-    copied such natural models, he has done much better, by making his
-    gliders concave below instead of concave upward, as are the beautiful
-    Indian seeds.</p>
-
-  <p>An interesting model of a traveling parachute, quite as efficient as
-    the gauzy-winged seed, is shown in the accompanying figure. It is a
-    sheet of paper twenty inches long by four inches wide, having a quarter
-    inch strip of tin folded in its forward margin, and having its rear
-    margin turned upward slightly, to steer the little craft from a too
-    steep descent. In order to improve the stability of the paper plane,
-    its sides may be bent upward. The model when dropped in any attitude
-    quickly rights itself, and sails down a gently sloping course, the rear
-    margin functioning as a rudder or tail.</p>
-
-  <p><span class="pagenum" id="Page_181">181</span></p>
-
-  <div class="figright">
-    <a id="Fig_30"><img src="images/i_221.jpg" width="430" height="349" alt="" /></a>
-    <div class="caption smcap">Fig. 30.—Paper Traveling Parachute.</div>
-  </div>
-
-  <p>One of the earliest trustworthy and scientific accounts of
-    experimentation with an aërial glider was given by Sir George Cayley in
-    <cite>Nicholson’s Journal</cite>, in 1809 and 1810. After a careful study of the
-    principles of stability, he, in 1808, constructed a glider spreading
-    300 square feet of surface and weighing with its load 140 pounds. It
-    had wing surfaces slightly inclined to each other, and a tail inclined
-    enough to determine a gentle downward course. “When any persons,” says
-    Cayley, “ran forward in it with his full speed, taking advantage of a
-    gentle breeze in front, it would bear him up so strongly as scarcely
-    to allow him to touch the ground, and would frequently lift him up and
-    carry him several yards together. It was beautiful to see this noble
-    white bird sail majestically from a hill to any given point of the
-    plain below it, with perfect steadiness and safety, according to the
-    set of the rudder, merely by its own weight, descending in an angle of
-    about 18° with the horizon.”</p>
-
-  <p>Sir George Cayley made a brave start in the science of dynamic
-    flight, marshaling to it all the mechanical resources of his day. He
-    applied the most reliable data of fluid resistance then available. He
-    formulated the laws of equilibrium and control of a flying machine
-    quite as well as any of his successors for two generations. He
-    estimated the<span class="pagenum" id="Page_182">182</span> propulsive power required to carry a man, and computed
-    the weight of the newly invented Bolton and Watt steam engine capable
-    of supplying that power. He even conceived the idea of burning a gas
-    or inflammable vapor behind a piston, thus anticipating the modern
-    aëronautical motor. But the project as a whole was too formidable at
-    that time for the genius of this one man, or of his generation of
-    colleagues. Sailing flight they could have practiced with profit to the
-    advancement of aviation, but power flight on a practicable scale had to
-    await the long evolution of the internal combustion engine.</p>
-
-  <p>The next great advancement in the devices and principles of aviation
-    was made by another Englishman, and a worthy successor to Sir George
-    Cayley. In 1842 Mr. Henson patented the aërial equipage shown in
-    the accompanying illustration. It was what in present-day parlance
-    is called a monoplane, being in fact the first commercially planned
-    aëroplane known to history. As seen at a glance it consisted of a large
-    sustaining surface rigidly trussed and driven through the air by two
-    propellers actuated by a steam engine. It was to be guided up and down
-    by means of a horizontal rudder, and guided to the right and left by
-    means of a vertical rudder, seconded by a keel cloth; both rudders
-    being at the rear of the large plane. The machine was designed to be
-    launched by running down an inclined plane or track. Fuller details
-    of this first patent aëroplane are given in the following official
-    description in the South Kensington Museum of a model aëroplane
-    constructed by Henson and Stringfellow:</p>
-
-  <blockquote>
-    <p>“The model consists of an extended surface, or aëroplane, of oiled
-      silk or canvas, stretched upon a bamboo frame made rigid by trussing
-      both above <span class="pagenum" id="Page_183">183</span>and below. A car is attached to the underside of the
-      aëroplane to contain the steam engine, passengers, etc. It has three
-      wheels to run freely upon when it reaches earth. Two propellers, three
-      feet in diameter, are shown with their blades set at 45°. They are
-      operated by endless cords from the engine. Behind these is a fan-shaped
-      tail stretched upon a triangular frame capable of being opened out,
-      closed, or moved up and down by means of cords and pulleys. By this
-      latter arrangement ascent or descent was to be accomplished. A rudder
-      for steering sideways is placed under the tail, and above the main
-      aëroplane a sail was to be stretched between two masts rising from the
-      car, to assist in maintaining the course. When in motion the front edge
-      of the machine was to be raised in order to obtain the required air
-      support. To start the model it was proposed to allow it to run down
-      an incline—e.g., the side of a hill, the propellers being first set
-      in motion. The velocity gained in the descent was expected to sustain
-      it in its further progress, the engine overcoming the head resistance
-      when in full flight. Experiments were eventually made on the Downs
-      near Chard, in Somerset, and the night trials were abandoned, as the
-      silk became saturated from a deposit of dew. After many day trials,
-      down wide inclined rails, the model was found to be deficient in
-      stable equilibrium for open-air experiments, little puffs of wind or
-      ground currents being sufficient to destroy the balance. The actual
-      machine was never constructed, but in 1847–48 F. Stringfellow built a
-      model which is supposed to be the first flying machine to perform a
-      successful flight.”</p>
-  </blockquote>
-
-  <hr class="page" />
-  <div id="Plate_XII" class="center"><b>PLATE XII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_223a.jpg" width="600" height="347" alt="" />
-    <div class="captionp">HENSON’S AËROPLANE.</div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_223b.jpg" width="600" height="388" alt="" />
-    <div class="captionp">ADER’S AËROPLANE.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <p>The creation of Henson’s flying machine at that early period is one
-    of the most original and fruitful achievements in the century-long
-    development of the modern aëroplane. Barring the torsional wing-tips<span class="pagenum" id="Page_184">184</span>
-    invented more recently, it hardly differs in principle from the
-    successful monoplane of to-day. The same mode of propulsion, the same
-    mode of sustention, the same mode of launching and lighting, the same
-    mode of steering and control. What has been added since is not so much
-    original invention as perfection of detail through the combined efforts
-    of many designers. After Cayley, Henson, as nearly as any one person
-    was the inventor of the flying machine. He did not bring his conception
-    to practical maturity, nor was that to be expected; but he did lay
-    down the broad lines which have led others to success. His ideas still
-    feature every practical aëroplane, and particularly every successful
-    monoplane. Indeed, it is now possible to construct an aëroplane from
-    Henson’s description that will fly, even in breezy weather, with
-    a stability practically as good as that of the early Voisin and
-    Antoinette machines before the use of the aileron or torsional wing was
-    practiced. It is all a question of wise proportioning and sufficient
-    motive power.</p>
-
-  <p>So much for Henson’s contrivance as an abstract invention. The
-    concrete, full scale machine was to spread 6,000 square feet of
-    surface, weigh 3,000 pounds, and be propelled by a high pressure steam
-    engine of 25 or 30 horse power. The machine was not completed on a
-    large scale, and wisely so; for it was inadequately powered, and,
-    moreover, required many refinements of detail to make it entirely
-    practical. These improvements had to be left to succeeding inventors
-    with accumulated experience and resources.</p>
-
-  <p>In 1844 Mr. Henson began the construction of a steam-driven model,
-    in partnership with his friend, Mr. Stringfellow, who designed the
-    motor for it. They experimented together for some weeks with only
-    meager success, but gaining valuable experience.<span class="pagenum" id="Page_185">185</span> A model of the
-    Henson-Stringfellow machine is on exhibition at the South Kensington
-    Museum.</p>
-
-  <p>In 1846 Stringfellow built a steam model aëroplane about the size of a
-    large soaring bird, and weighing all together, with fuel and water, 6½
-    pounds. A special feature of this model was that its main surfaces were
-    sloped like the wings of a bird, <em>slightly concave below and feathered
-    toward the back</em>; thus making it more efficient and stable in flight.
-    With a good head of steam, and propellers whirling, the model ran down
-    a stretched wire, leaped into the air “and darted off in as fair a
-    flight as it was possible to make, to a distance of about 40 yards.”
-    Thus the first power-driven aëroplane to fly successfully was the
-    little steam model constructed by Stringfellow in 1846.</p>
-
-  <div class="figcenter">
-    <a id="Fig_31"><img src="images/i_227.jpg" width="500" height="369" alt="" /></a>
-    <div class="caption smcap">Fig. 31.—Wenham’s Aëroplane, 1866.</div>
-  </div>
-
-  <p>In 1866, two decades after the flight of Stringfellow’s monoplane,
-    Mr. F. H. Wenham, another Englishman illustrious in the annals of
-    aëronautics, patented the multiplane; that is, an aëroplane comprising
-    two or more superposed surfaces. This<span class="pagenum" id="Page_186">186</span> proved to be a valuable
-    contribution to the art of aviation, and continues in use at the
-    present time. The device furnished an increase of sustaining surface
-    without enlargement of the ground plan. It moreover lends itself
-    conveniently to a strong and simple trussing of the surfaces. Some
-    designers protest that superposed surfaces blanket one another; but the
-    advantages just named seem amply to compensate for this objectionable
-    feature. If the surfaces be properly spaced, very little interference
-    is found; moreover, any blanketing that may occur diminishes the drift
-    as well as the lift,<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">[20]</a> though not necessarily in the same proportion.</p>
-
-  <p>Wenham’s aëroplane is illustrated in Fig. 31. The rider lies underneath
-    the multiple wings, so as to diminish the resistance to progression
-    through the air. The apparatus could thus be used as an aërial toboggan
-    for coasting down the atmosphere. To prolong the flights two flappers
-    actuated by a treadle were to be employed, their ends being hinged at
-    a point above the operator’s back. Though the device was patented, no
-    very serious efforts were made to operate it practically. Once, indeed,
-    the inventor took his glider to a meadow and mounted it, during a lull
-    in the evening wind, but soon a gust caught him up, carried him some
-    distance from the ground and toppled him over sidewise, breaking some
-    of the surfaces. The machine disclosed some good working principles;
-    but it was inadequately ruddered, and too feebly constructed, to
-    weather the buffets of the prevailing ground currents.</p>
-
-  <hr class="page" />
-  <div id="Plate_XIII" class="center"><b>PLATE XIII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_229a.jpg" width="600" height="298" alt="" />
-    <div class="captionp">STRINGFELLOW’S AËROPLANE (FRONT).</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_229b.jpg" width="600" height="316" alt="" />
-    <div class="captionp">STRINGFELLOW’S AËROPLANE (SIDE).</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <p>Adopting the scheme of superposed surfaces then recently devised
-    by Wenham, Mr. Stringfellow in 1868 constructed the interesting
-    steam-driven model <span class="pagenum" id="Page_187">187</span>shown in Plate XIII. This consists essentially of
-    three superposed planes, rigidly connected by rods and diagonal wires,
-    propelled by a pair of screws actuated by a high pressure steam engine,
-    and guided by a tail. The three planes aggregated 21 feet in length and
-    28 square feet in surface; totaling, with the tail, 36 square feet.
-    The engine was rated at one third of one horse power. Its weight is
-    not known, but may be roughly surmised from the fact that a separate
-    engine exhibited simultaneously by Stringfellow weighed thirteen pounds
-    per horse power. The model was entered for competition in the London
-    Aëronautical Exhibition of 1868. In actual operation, however, it seems
-    not to have excelled the monoplane of 1846; but still it is of much
-    interest as being the prototype of the multiple-wing aëroplane now in
-    common use. It seems to have been the first aëroplane having two or
-    more sustaining surfaces joined by rods and stayed by diagonal cords
-    after the manner of a Pratt truss. This historic little model was
-    purchased by Professor Langley for the Smithsonian Institution, and
-    is now to be seen suspended from the ceiling of the National Museum,
-    beside Langley’s own models and Lilienthal’s epoch-making glider.</p>
-
-  <div class="figcenter">
-    <a id="Fig_32"><img src="images/i_231.jpg" width="500" height="272" alt="" /></a>
-    <div class="caption smcap">Fig. 32.—Penaud’s Aëroplane Toy, 1871.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_188">188</span></p>
-
-  <p>In 1871 M. A. Penaud produced the interesting toy aëroplane shown in
-    Fig. 32. The model is propelled horizontally forward by a single screw,
-    actuated by twisted rubber, and is fastened, as shown, to the middle of
-    a long stick or backbone. The center of mass of the machine is well to
-    the front, tending to plunge the model earthward like a heavy-headed
-    arrow; but this down-diving is promptly checked by the tiny rudder
-    which is so inclined as to counteract the diving proclivity. That is
-    to say the rudder dips so as to receive the aërial impact on its upper
-    surface; which impact increases with the speed of flight and causes
-    the bow to rise, until the weight before the wings just balances the
-    impact on the rudder at the rear. The equilibrium is thus automatic, on
-    the principle expounded by Sir George Cayley sixty years earlier. This
-    quaint little bird when liberated in the Garden of the Tuileries flew
-    a distance of 131 feet in eleven seconds, much to the delight of some
-    members of the French Society for Aërial Navigation. It may be added
-    that Penaud, who was a most promising and clever aëronautical inventor,
-    contemplated a twin-screw monoplane large enough to carry<span class="pagenum" id="Page_189">189</span> two men, but
-    died in his early manhood, before the project could be realized.</p>
-
-  <div class="figcenter">
-    <a id="Fig_33"><img src="images/i_232.jpg" width="600" height="305" alt="" /></a>
-    <div class="caption smcap">Fig. 33.—Tatin’s Aëroplane Model, 1879.</div>
-  </div>
-
-  <p>In 1879 M. Victor Tatin made some very promising tests with the model
-    shown in Fig. 33, so promising, in fact, as to convince many that human
-    flight was even then practicable. This little flyer was a twin-screw
-    monoplane mounted on wheels, and actuated by an oscillating compressed
-    air engine, the whole machine weighing 3.85 pounds, and supported by a
-    silk plane measuring 16 by 75 inches. The central body of the aëroplane
-    was a thin steel tube three feet long by four inches in diameter
-    containing the compressed air, and weighing only one pound and a half,
-    though strong enough to endure a pressure of twenty atmospheres. When
-    the model was allowed to run round a board walk 46 feet in diameter,
-    tethered to a stake at the center, it quickly acquired a speed of 18
-    miles an hour, rose in the air, and flew a distance of fifty feet.</p>
-
-  <p>A remarkable deduction from the very careful measurements made with
-    this machine was that it carried at the rate of 110 pounds per tow line
-    horse power, when flying at an angle of 8 to 10 degrees. Mr. Tatin
-    concluded: “These experiments seem to demonstrate that there is no
-    impracticability in the construction of a large apparatus for aviation,
-    and that perhaps even now such machines could be practically used in
-    aërial navigation. Such practical experiments being necessarily very
-    costly, I must to my great regret, forego their undertaking, and I
-    shall be satisfied if my own labors shall induce others to take up such
-    an enterprise.”</p>
-
-  <p>Tatin’s faith in the practicability of a large aëroplane was later
-    voiced by Mr. Chanute in his valuable book, <cite>Progress in Flying
-    Machines</cite>, published in 1894, but now unfortunately out of print.
-    Recalling that Maxim had recently produced a large motor<span class="pagenum" id="Page_190">190</span> weighing
-    complete only ten pounds per horse power, he says: “Aviation seems to
-    be practicably possible, if only the stability can be secured, and an
-    adequate method of alighting be devised.” Since the above quoted facts
-    and opinions were published, no competent man well informed in the
-    science of aviation has for one moment doubted the feasibility of human
-    flight.</p>
-
-  <div class="figcenter">
-    <a id="Fig_34"><img src="images/i_234.jpg" width="450" height="287" alt="" /></a>
-    <div class="caption smcap">Fig. 34.—Hargrave’s Model Screw Monoplane, 1891.</div>
-  </div>
-
-  <p>In 1891, twelve years after Tatin’s experiment, Lawrence Hargrave, of
-    Sydney, Australia, made a similar compressed air monoplane, with a
-    single-screw propeller, but without wheels for launching and lighting.
-    The model, which is shown in Fig. 34, had a wing-spread of 20 square
-    feet, weighed about three pounds, and flew 128 feet in eight seconds.
-    The weight carried was at the rate of 90 pounds per horse power, a very
-    encouraging result. Two years later he described a small steam engine
-    which he had developed, weighing 10.7 pounds per horse power, and
-    capable of driving the model about two miles, though he did not use it
-    for that purpose, being engrossed with other researches.</p>
-
-  <p>One interesting outcome of his numerous experiments was the Hargrave
-    Kite, now more familiarly<span class="pagenum" id="Page_191">191</span> known as the box kite. A good example of
-    his kites is the type shown in Fig. 35. This consists of two arched
-    biplanes mounted tandem on a backbone, or connecting framework. The
-    kite floats steadily, and was thought suitable for the body of a flying
-    machine to be driven by an engine and propeller. Thus meteorology is
-    indebted to aëronautics for its most useful kite.</p>
-
-  <div class="figcenter">
-    <a id="Fig_35"><img src="images/i_235.jpg" width="450" height="114" alt="" /></a>
-    <div class="caption smcap">Fig. 35.—Hargrave’s Kite.</div>
-  </div>
-
-  <p>A very novel and interesting type of aëroplane model was tested by
-    Mr. Horatio Phillips in 1893. After careful preliminary experiments
-    with various forms of curved “sustainers,” or lifting surfaces, tested
-    in a wind tunnel, to determine which were most suitable wing forms,
-    he finally constructed the flying apparatus shown in <a href="#Plate_XIV">Plate XIV</a>. This
-    consisted of a compound aëroplane composed of many superposed narrow
-    curved slats, the whole resembling an open Venetian blind. These
-    curved blades, or sustainers, measured 12 feet long, 1.5 inches wide,
-    2 inches apart, and were held in a frame sharpened to cleave the air
-    with slight resistance. The entire aëroplane spread 136 square feet
-    of lifting surface, and was mounted on a truck as shown, carrying a
-    steam engine and boiler, to actuate a two blade propeller 6 feet in
-    diameter. The whole apparatus weighed 330 pounds, to which a dead load
-    was usually added, and ran around a circular wooden track 628 feet in
-    circumference, being tethered at the center, as in Tatin’s experiment.
-    The apparatus readily lifted itself, when running at a speed of 28
-    miles an hour,<span class="pagenum" id="Page_192">192</span> and carried at the rate of 72 pounds per horse power,
-    the added load weighing at times nearly one fourth that of the machine
-    itself. The ultimate purpose of the experiment was to prepare the
-    way for a one-man aëroplane like that shown in the lower part of the
-    figure. This latter model actually carried a man across a field in
-    1904, but was found defective in longitudinal balance, because perhaps
-    of its inadequate horizontal rudder. Apparently Mr. Phillips had in
-    1904 a machine capable of well-balanced flight, if he had made the
-    rudders large enough, and provided a mechanism for rotating the slats
-    at either wing end, so as to control the lateral poise, as proposed by
-    the present writer in 1893, for practically that same flier (see <a href="#Page_229">page
-    229</a>).</p>
-
-  <p>Phillips’s aëroplane shows a distinct advance over its predecessors,
-    even Wenham’s multiplane, because of the careful curving of the
-    sustainers. Tatin’s flat wing machine had, indeed, shown a greater
-    efficiency as a whole, but that was likely due to less proportionate
-    body resistance. To Phillips we owe the introduction of superposed
-    arched surfaces, now so commonly used in mechanical flight. Whether he
-    was wise in using so many narrow wings, instead of a few broad ones,
-    was a question to be answered by precise measurement.</p>
-
-  <p>Prof. S. P. Langley, like Mr. Hargrave, made numerous flying models,
-    trying, in turn, the power of twisted rubber, compressed air and
-    steam. He constructed scores of gauzy winged contrivances which
-    flitted about like huge butterflies or birds, till their mission
-    was accomplished—that of illustrating a scientific principle to his
-    inquiring mind. One by one they came into existence, enjoyed an
-    ephemeral life, and then were consigned to the aëronautical attic of
-    the Smithsonian Institution, a storehouse of quaint flying creatures.
-    It was a most interesting <span class="pagenum" id="Page_193">193</span>collection which well merited preservation
-    as the “juvenile” creations of an illustrious man. But the first
-    experiments of Langley, like the similar ones of Hargrave, were of
-    value chiefly as training to the inventor himself; they were not
-    important advances in the art of aviation. Such advances were to follow
-    the long preliminary training.</p>
-
-  <hr class="page" />
-  <div id="Plate_XIV" class="center"><b>PLATE XIV.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_237a.jpg" width="600" height="364" alt="" />
-    <div class="captionp">PHILLIPS’ TETHERED AËROPLANE.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_237b.jpg" width="600" height="494" alt="" />
-    <div class="captionp">PHILLIPS’ AËROPLANE.</div>
-  </div>
-
-  <p>On May 6, 1896, Dr. Langley launched the picturesque steam model,
-    which, to his mind, first proved conclusively the practicability of
-    mechanical flight. It was the crowning success, and, as he thought
-    then, probably the termination of his aëronautic labors. “I have
-    brought to a close,” says he, “the portion of the work which seemed
-    to be peculiarly mine—the demonstration of the practicability of
-    mechanical flight—and for the next stage, which is the commercial
-    and practical development of the idea, it is probable that the world
-    may look to others. The world, indeed, will be supine if it does not
-    realize that a new possibility has come to it, and that the great
-    universal highway overhead is now soon to be opened.”</p>
-
-<p>As shown in <a href="#Plate_XV">Plate XV</a>, Langley’s first successful steam flying machine
-    is a tandem monoplane<a id="FNanchor_21" href="#Footnote_21" class="fnanchor">[21]</a> with twin screws amidships. It measures
-    nearly 13 feet from tip to tip of its wings, about 16 feet along its
-    entire length, and weighs with motor and propellers 30 pounds. The
-    boiler weighs 5 pounds, the engine 26 ounces, and the power developed
-    was between 1 and 1.5 horse power. The model is therefore somewhat
-    larger than a large condor, and very much more powerful.</p>
-
-  <p>Being too small to carry a pilot, it was launched <span class="pagenum" id="Page_194">194</span>over water, to
-    obviate wreckage on landing. The machine was capable of flying several
-    miles continuously, but in the actual test on the Potomac River the
-    flight was limited, in order to prevent the model passing beyond
-    the shore. The flyer was placed on launching ways on the top of a
-    houseboat, hurled rapidly forward by force of a spring, and liberated
-    in space, with engine and propellers running at full speed. Its
-    subsequent behavior has been graphically described by an eyewitness,
-    Dr. Alexander Graham Bell, in the following passage, published in
-    <cite>Nature</cite>, May 28, 1896:</p>
-
-  <blockquote>
-    <p>“On the occasion referred to, the aërodrome, at a given signal, started
-      from a platform about 20 feet above the water, and rose at first
-      directly in the face of the wind, moving at all times with remarkable
-      steadiness, and subsequently swung around in large curves of perhaps a
-      hundred yards in diameter, and continuously ascending till its steam
-      was exhausted, when at a lapse of about a minute and a half, and at a
-      height which I judged to be between 80 and 100 feet in the air, the
-      whole ceased turning, and the machine, deprived of the aid of its
-      propellers, to my surprise did not fall, but settled down so softly and
-      gently that it touched the water without the least shock, and was in
-      fact immediately ready for another trial.</p>
-
-    <p>“In the second trial, which followed directly, it repeated in nearly
-      every respect the actions of the first, except that the direction of
-      its course was different. It ascended again in the face of the wind,
-      afterward moving steadily and continually in large curves, accompanied
-      with a rising motion and a lateral advance. Its motion was, in fact, so
-      steady that I think a glass of water on its surface would have remained
-      unspilled. When the steam gave out again it repeated for a second
-      time the experience of the first trial when the steam had ceased, and
-      settled <span class="pagenum" id="Page_195">195</span>gently and easily down. What height it reached at this trial
-      I can not say, as I was not so favorably placed as in the first, but I
-      had occasion to notice that this time its course took it over a wooded
-      promontory, and I was relieved of some apprehension in seeing that
-      it was already so high as to pass the tree tops by 20 or 30 feet. It
-      reached the water in one minute and thirty-one seconds from the time
-      it started, at a measured distance of over 900 feet from the point at
-      which it rose.</p>
-  </blockquote>
-
-  <hr class="page" />
-  <div id="Plate_XV" class="center"><b>PLATE XV.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_241a.jpg" width="600" height="303" alt="" />
-    <div class="captionp">LANGLEY’S STEAM MODEL.</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_241b.jpg" width="600" height="257" alt="" />
-    <div class="captionp">LANGLEY’S GASOLENE MODEL.</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_241c.jpg" width="600" height="236" alt="" />
-    <div class="captionp">LANGLEY’S TWO SURFACE GASOLENE MODEL.</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <blockquote>
-    <p>“This, however, was by no means the length of its flight. I estimated
-      from the diameter of the curve described, from the number of turns of
-      the propellers, as given by the automatic counter, after due allowance
-      for slip, and from other measures, that the actual length of flight on
-      each occasion was slightly over 3,000 feet. It is at least safe to say
-      that each exceeded half an English mile.</p>
-
-    <p>“From the time and distance, it will be noticed that the velocity was
-      between 20 and 25 miles an hour, in a course which was constantly
-      taking it ‘up hill.’ I may add that on a previous occasion, I have seen
-      a far higher velocity attained by the same aërodrome when its course
-      was horizontal.</p>
-
-    <p>“I have no desire to enter into detail further than I have done, but
-      I can not but add that it seems to me that no one who was present on
-      this interesting occasion, could have failed to recognize that the
-      practicability of mechanical flight had been demonstrated.”</p>
-  </blockquote>
-
-  <p>In passing it may be added that in 1899 this model was again flown
-    successfully, having superposed surfaces; for its inventor all along
-    recognized the structural advantage of the bridge trussing in biplanes.
-    If he preferred the monoplane, or single-tier arrangement, it was
-    because the best flights were obtained with such models.</p>
-
-  <p><span class="pagenum" id="Page_196">196</span></p>
-
-  <p>Many persons now thought that Langley would do well to rest on his
-    laurels, leaving to others the “commercial and practical development”
-    of his ideas. But he had caught the aëronautic fever. Like many another
-    poor son of fancy, he was haunted by magnificent dreams. Now, perhaps,
-    was stirring in his mind that vision of his childhood when he lay on
-    his back in the New England pasture and “watched a hawk soaring far
-    up in the blue, and sailing for a long time without any motion of its
-    wings, as though it needed no work to sustain it, but was kept up there
-    by some miracle.” Mr. Andrew D. White declares that Professor Langley
-    was a poet by nature. Whatever the dominant impulse, he followed his
-    “aërodrome” like one possessed. It was the all engrossing pursuit of
-    the latter years of his life, entailing how much vexation, toil and
-    unjust censure!</p>
-
-  <p>In 1898 the Board of Ordinance and Fortification, after carefully
-    studying the flights of 1896, appropriated $50,000 to enable Professor
-    Langley to build a one-man flyer. He first tested a gasoline driven
-    aëroplane having one fourth the linear dimensions of the man-carrying
-    one. In external appearance this model resembled the steam “aërodrome,”
-    described above, but was considerably larger. It spread 66 square feet
-    of surface, weighed 58 pounds, and developed 2½ to 3 horse power.
-    When ready for the test, August 8, 1903, this beautiful white-winged
-    creature was taken to the middle of the Potomac, 40 miles below
-    Washington, mounted on the launching ways, swiveled into the eye of
-    the wind and shot forth like a stone from a catapult, her engine and
-    propellers humming merrily.</p>
-
-  <p>The flight must have been very graceful and dignified, for it
-    elicited commendation even from the squad of reporters present, men
-    who customarily<span class="pagenum" id="Page_197">197</span> recorded such events with uncontrollable mirth and
-    ridicule. Dr. Langley merely remarks: “This was the first time in
-    history, so far as I know, that a successful flight of a mechanically
-    sustained flying machine was seen in public.” It was also the first
-    successful gasoline<a id="FNanchor_22" href="#Footnote_22" class="fnanchor">[22]</a> aëroplane, and the forerunner of the host
-    of flyers presently to spring up in all parts of the world. Its
-    flight though very brief, owing to a surcharge of gasoline, was so
-    satisfactory in all its dynamic features, that it seemed to justify an
-    immediate launching of the one-man machine, with which like maneuvers
-    were anticipated. As will appear in the sequel this prospect of fair
-    sailing was beset with unsuspected shoals.</p>
-
-  <p>We have now traced the growth of the aëroplane from its earliest
-    conception to the present time, as exemplified by working models. First
-    came the parachute of da Vinci and others, whose sole function was
-    to carry a weight softly to earth, with no provision for steadiness
-    of motion, or control of direction. Then, in the beginning of the
-    nineteenth century, arrived the gliders adjusted for steadiness,
-    equilibrium and a predetermined slanting course in the air; beautiful
-    passive birds, actuated by gravity, but riderless and awaiting the
-    advent of artificial motive power. Then suddenly appeared Mr. Henson’s
-    wonderful <em>project</em>; a large man-carrying aëroplane, provided with
-    a motor, propellers, rudders, wheels for launching and landing—an
-    impossible scheme for that day, but destined to be realized in
-    the course of two generations. Henson’s idea was doubtless the
-    most prolific in the history of aviation. After this followed the
-    numerous instructive models, actuated by twisted rubber, steam,
-    gasoline, compressed air—economic <span class="pagenum" id="Page_198">198</span>contrivances for ascertaining the
-    secrets of propulsion, equilibrium and control, of the prospective
-    man-flyer. These may be said to have demonstrated the practicability
-    of man-flight, though many contemporaneous and allied experiments, to
-    be noticed presently, all contributed to the triumphs subsequently
-    achieved by the race of sanguine, daring and tireless inventors.</p>
-
-  <div class="figleft">
-    <a id="Fig_36"><img src="images/i_246.jpg" width="200" height="383" alt="" /></a>
-    <div class="caption smcap">Fig. 36.—Launoy<br />and Bienvenu’s<br />Helicopter, 1784.</div>
-  </div>
-
-  <p>In this brief outline, the two other main types of flyers, the
-    orthopters and helicopters, have been omitted. The orthopters, or wing
-    flapping machines, have been very numerous, but have not yet approached
-    practical success in use. Though a man-carrying orthopter has not yet
-    been produced, an elegant pigeon-like model operated by rubber has been
-    made by Pichancourt, which flies and balances nicely. The helicopters,
-    or direct-lifting screws, have more than once raised their weight and
-    that of the helicoptrist, or navigator. These latter, therefore, seem
-    to be of sufficient interest to merit a short historical review.</p>
-
-  <p>Leonardo da Vinci, the fertile pioneer in aviation, missed one novel
-    device worthy even of his genius. He constructed aërial screws of
-    paper, but he did not endow them with motive force. Such an achievement
-    was in his power, and would have ranked him with Archytas of Tarentum,
-    who 400 <span class="smcap">b. c.</span> invented the kite, and an artificial dove said
-    to have flown, no one knows how. Having escaped da Vinci’s ingenuity,
-    the power helicopter failed to materialize for three centuries, but
-    finally appeared in France.</p>
-
-  <p><span class="pagenum" id="Page_199">199</span></p>
-
-  <p>In 1784 Launoy and Bienvenu, the first a naturalist, the second a
-    mechanician, exhibited before the French Academy the interesting toy
-    shown in Fig. 36. This was the first power-driven helicopter, and is
-    said to have lifted itself in the air quite readily. As may be observed
-    it consists of two coaxial screws rotating in opposite directions
-    actuated by the power of an elastic stick, like a bow. The screws were
-    each about one foot in diameter and made of four feathers; one screw
-    being fastened to the top of the rotating shaft, the other fastened
-    to the bow, which rotated in the contrary direction. The little model
-    excited much interest, particularly as its inventors expected to build
-    a man-carrying helicopter on the same plan. The larger project was
-    obviously without merit; for no combination of springs can maintain
-    flight for more than a few seconds even on the most favorable scale.</p>
-
-  <p>A more powerful toy helicopter was produced by Mr. Horatio Phillips in
-    England in 1842. This was a single aërial screw emitting jets of steam
-    which compelled it to spin, on the principle of a lawn sprinkler, or
-    a Hero engine. The whole apparatus weighed two pounds, and had screw
-    blades inclined 20° to the horizon. The steam was generated by the
-    combustion of charcoal, niter and gypsum, as in the fire extinguisher
-    previously invented by the same ingenious man. The performance of this
-    curious helicopter, is thus described by Mr. Phillips: “All being
-    arranged, the steam was up in a few seconds, then the whole apparatus
-    spun around like a top, and mounted into the air faster than any
-    bird; to what height it ascended I have no means of ascertaining. The
-    distance traveled was across two fields, where, after a long search, I
-    found the machine minus the wings, which had been torn off from contact
-    with the ground.”</p>
-
-  <p><span class="pagenum" id="Page_200">200</span></p>
-
-  <p>“The distance traveled was across two fields.” For vagueness this
-    surpasses the poet’s measure—“as far as oxen draw the plow in a day.”
-    It would be most interesting to have an exact description of this
-    classical experiment, when for the first time a flying machine rose
-    in the air propelled by a heat motor. It would be desirable also
-    to know the possibilities of such a helicopter, particularly since
-    Prof. Cleveland Abbe has proposed to employ a like agent to carry
-    meteorological instruments into the higher atmosphere.<a id="FNanchor_23" href="#Footnote_23" class="fnanchor">[23]</a></p>
-
-  <div class="figcenter">
-    <a id="Fig_37"><img src="images/i_248.jpg" width="560" height="276" alt="" /></a>
-    <div class="caption smcap">Fig. 37.—Forlanini’s Helicopter, 1878.</div>
-  </div>
-
-  <p>A still more ambitious helicopter was that shown in Fig. 37 invented by
-    Professor Forlanini, an Italian Civil Engineer, and launched in 1878.
-    The lower screw was fastened to the frame of a steam engine, the upper
-    screw was attached to the crank shaft. Steam was supplied from the
-    globe shown beneath, which was two thirds filled with water, and well
-    heated over a separate fire just before an ascension. As the globe was
-    merely a reservoir of hot water and steam, carrying neither fuel nor
-    furnace, its power waned rapidly. The best flight lasted about twenty
-    <span class="pagenum" id="Page_201">201</span>seconds, attaining a height of 42 feet. The apparatus weighed 77
-    pounds, spread 21.5 square feet of screw surface, and lifted about 26.4
-    pounds per horse power.</p>
-
-  <p>Many other helicopter models have been tried from time to time, with
-    various sources of power, without, however, yielding any important
-    results beyond those already given. But these were sufficiently
-    encouraging. If a large machine could be made to lift as many pounds
-    per horse power, it would be easy to build one competent to carry
-    a man. That, indeed, has been done on several occasions. Of the
-    various inventors who have built man-lifting helicopters M. Cornu and
-    M. Bréguet, in France, seem to have been first to attain a measure
-    of success. While their machines have raised a passenger directly
-    from the ground, they have not yet maneuvered in horizontal flight
-    with sufficient speed to be of practical service. However, a few
-    helicoptrists in various countries are still industriously at work, and
-    hope eventually to rival the aëroplanists in the mastery of flight.
-    There will doubtless be room in the sky for both. Perhaps also there
-    will be occupation and a mission for both.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_VIII">
-    <span class="pagenum" id="Page_202">202</span>
-    <h3>CHAPTER VIII</h3>
-    <span class="small">NINETEENTH CENTURY MAN-FLYERS</span>
-  </div>
-
-  <p><span class="smcap">Having</span> traced the growth of winged models from their earliest beginning
-    to the time when they proved the possibility of mechanical flight, we
-    may now study the evolution of larger machines, designed to carry human
-    beings. Considering first the aëroplane, we may follow the two general
-    methods advocated by various inventors for launching a man safely in
-    the air, both of which led to success. The first of these may be called
-    Henson’s method, the second Lilienthal’s, coupling them with the names
-    of their distinguished pioneer exponents. Henson in 1842 proposed
-    that the pilot should mount a full-power machine, run along a smooth
-    course, and glide into the air without previous experience in the art
-    of navigating. Lilienthal recommended careful preliminary training on a
-    glider, by which the novice should acquire sufficient skill in parrying
-    the wind to qualify him to manage a dynamic machine, under its more
-    complex conditions of control. Others, more cautious still, contended
-    that automatic equilibrium should be secured before a rider risked his
-    bones on the aërial bronco; while still others thought the uncertain
-    beast should be tethered to some point in the sky, say a balloon or
-    taut wire, or the end of a pole; so that however he bucked, or reared,
-    he should not fall over on his rider.</p>
-
-  <p>We have noticed in the first chapter some picturesque man-flights,
-    usually deplorable or tragic;<span class="pagenum" id="Page_203">203</span> and always fruitless for lack of
-    scientific method in experimentation and report to the world. There can
-    be no doubt that such flights were accomplished, mainly, of course,
-    by the aid of gravity; but the difficulty is to ascertain the exact
-    nature of any given performance, the specifications of the apparatus,
-    and the principles of equilibrium and control. Gradually, however, the
-    experimenters improved both in the construction of man-carrying devices
-    and in the manner of imparting their results to their colleagues, or
-    successors; and so the flying enterprise began to assume a progressive
-    aspect, attended with that scientific dignity which invests secure
-    and continuous advance in any branch of knowledge. Little of value,
-    however, can be gleaned from any such flights made prior to the middle
-    of the nineteenth century. From that time forward observers and
-    inventors made definite and fairly methodical efforts to develop the
-    art of gliding and soaring in the air, the first fruit of which was to
-    hasten the advent of the modern aëroplane.</p>
-
-  <p>A French novelist and aëronautic writer, G. de la Landelle, relates
-    an amazing adventure in the art of soaring, which may have some
-    foundation in fact, though savoring strongly of fiction. An experienced
-    sailor, Captain Le Bris, having observed the albatross soaring without
-    wing-beat, determined to imitate the fascinating flight of that
-    limber-winged spirit of the sea. To such end he built the bird shown in
-    Fig. 38, a ninety-pound albatross, with arched wings fifty feet across
-    and articulated to the boat-like body. In this the brave aviator would
-    stand upright, turn the wings and tail to maintain his balance, and
-    steer grandly through the sky. Placing this long-winged creature across
-    a cart driven by a peasant, he stood erect and headed against a breeze;
-    the wings set low to prevent lifting<span class="pagenum" id="Page_204">204</span> till an opportune moment, and the
-    bird held down to the car by a rope which the captain could quickly
-    release. When the horse was a-trot, and the wind blowing freshly, Le
-    Bris raised the front edges of the wings. Thereupon the albatross
-    tugged upward, and the mooring rope was slipped, but accidentally
-    whipped around the driver’s waist. The horse galloped away with the
-    cart; the bird, with the exultant sailor on its back, soared 300 feet
-    into the air, and incidentally carried up the peasant, dangling at
-    the end of the rope and howling with fright. Noting the distress of
-    his passenger, the kindly captain sailed close to earth, so that the
-    peasant might disembark and run to his horse, meaning then to hie away
-    for a long cruise in the clouds. But with this change of weight the
-    vessel seemed not to navigate well; so she was brought skimming to
-    land, with no mishap save a slight damage to the advancing wing, which
-    broke as it touched the ground.</p>
-
-  <div class="figcenter">
-    <a id="Fig_38"><img src="images/i_252.jpg" width="460" height="128" alt="" /></a>
-    <div class="caption smcap">Fig. 38.—Le Bris’ Aëroplane, 1855.</div>
-  </div>
-
-  <p>Having repaired the great bird’s wing, Captain Le Bris next made
-    a launching from the arm of a derrick, 30 feet above the ground,
-    overlooking a quarry 70 feet deep. The attendant swains stood
-    open-mouthed, wondering whether this madman would overleap the clouds,
-    or promptly butt out his brains on a jagged rock. When the wind blowing
-    from the quarry seemed to float him in perfect poise, he tripped the
-    suspension hook, and headed for the precipice on even keel. He was now
-    happily<span class="pagenum" id="Page_205">205</span> launched, and keen for an aërial journey; but after passing
-    the brink, he seemed to encounter an eddy which tilted his craft
-    forward. The vessel dipped and rose; the captain plied his levers,
-    turning now the tail, now the pinions. He crossed safely over the
-    invisible breakers, and reached the quiet air of the quarry on level
-    wing. But now his forward speed was lost, the great bird sank rapidly
-    and crashed upon the rocky bed below. The wary seaman anticipating a
-    bump, sprang upward to soften his fall; but a lever rebounding from the
-    shock, hit one of his legs and broke it.</p>
-
-  <p>Some twelve or thirteen years later, in 1867, Le Bris, aided by a
-    public subscription at Brest, built a second albatross, with which
-    he made a number of small flights, sometimes riding it himself, and
-    sometimes replacing his weight by ballast. On one occasion the loaded
-    bird, held by a light line, rose 150 feet and advanced against the
-    wind. Suddenly the sailors holding the line observed it slacken, and
-    saw with amazement the long-winged creature soar forward 600 feet, as
-    stately and serene as its living prototype. Presently encountering a
-    sheltered and quiet region of air before some rising ground, it settled
-    softly to earth in perfect equipoise. But on a subsequent launching
-    from the same favorable ground, the dumb creature pitched forward and
-    plunged to the earth where it lay shattered and torn in a hopeless
-    tangle. Le Bris looked on the wreck in despair, surveying sadly the
-    remains of his once cherished bird; then sat upon the débris a long
-    time, his head between his hands, his heart broken, his mind tortured
-    with anguish. Impoverished, chagrined, derided, he now must abandon
-    the albatross business. Five years later this intrepid sailor of sea
-    and air was killed by some ruffians, in 1872, while a constable in his
-    native place, and after a period of<span class="pagenum" id="Page_206">206</span> honorable service to the state in
-    the Franco-Prussian War.</p>
-
-  <p>The story is more romantic than instructive, for want of exact data.
-    To give the experiments their proper value to others, fuller details
-    of the mechanism should be furnished, and adequate measurements of the
-    speed and direction of the aërial currents. At one time the sailing
-    was even, at another, rough, though outwardly the conditions appeared
-    the same. Apparently the successful flights occurred when the bird was
-    launched to windward from rising ground, that is, when the current had
-    an upward slant, to exert a propulsive effort. This species of soaring
-    has been observed frequently in nature, and has been imitated both with
-    models and with man-carrying gliders. Nevertheless Le Bris’ experiments
-    were very remarkable for the time, and, if adequately reported, might
-    have proved to be of much interest and value to aëronautical science.</p>
-
-  <p>Another Frenchman alert to the glory of aërial motion was L. P.
-    Mouillard, the poet-farmer of Algeria. From boyhood he studied the
-    birds with unabated interest and pleasure. He would journey miles to
-    attend the “morning prayer” of the starlings in the forest of Baba-Ali;
-    noting, just before sunrise, how their melodies suddenly hushed, and
-    the forest seemed to bound upward, and heaven filled with the music of
-    innumerable wings. He would time the shadow of the high bird of passage
-    riding the hurricane from continent to continent. He saw the tyrant
-    eagle fold his wings in mid air and plunge a thousand feet in ferocious
-    swoop after the swift-fleeing duck or rabbit. He loved to watch the
-    great tawny vulture on the mountain top shake the dew from his vast
-    plumes, straddle the morning wind, and all day long, with never a beat
-    of those grand pinions, soar godlike through immensity, the marvel<span class="pagenum" id="Page_207">207</span>
-    and delight of the nether world. When the electric wind of the desert,
-    blowing from Central Africa, brought the big scavengers and noble birds
-    of prey, he sat on the ground scrutinizing their majestic flight and
-    planning to imitate it. He would lie in ambush where the silent-rowing
-    owl darted at dusk through the timber, fierce and swift as the eagle;
-    a dreadful thing, with its night piercing eyes, its big ears and beak,
-    its horrid talons, its sudden shriek startling the forest with ominous
-    echoes. No feature escaped him, and least of all an aërodynamic one.</p>
-
-  <p>For thirty years he continued these studies. He would bring home
-    the birds, lay them on their backs and mark their contour on paper,
-    measure their projected area, weigh and compare them. He formulated
-    curious conclusions about sailors and rowers, the functions of tail and
-    quill feathers, weight and wing-spread, bulk, agglomeration of mass,
-    resistance and velocity. He notes that only massive birds soar well,
-    the broad-winged ones requiring a moderate wind, the narrow-winged ones
-    requiring a gale, and sailing with perfect ease in a tempest; and he
-    concludes that man may imitate both types. His book<a id="FNanchor_24" href="#Footnote_24" class="fnanchor">[24]</a> is replete with
-    charming anecdotes, observations and quaint theories, interesting alike
-    to ornithology and aviation.</p>
-
-  <p>But Mouillard did more than theorize; he built soaring machines and
-    soared a little. His third and best glider, illustrated in Fig. 39, was
-    a tailless monoplane made of curved agave sticks screwed to boards,
-    and covered with muslin. The aviator, standing in the open space C,
-    harnessed the plane on with straps looped round his legs and shoulders,
-    and fastened to the points D D. His forearms, passing under straps,
-    rested on the board, enabling <span class="pagenum" id="Page_208">208</span>him to tilt the whole by shifting his
-    weight. In order to vary the dihedral angle between the wings, they
-    were hinged together and actuated by rods running from the man’s feet
-    to the ends of the boards, hardly as far out as the center of wind
-    pressure, thus apparently stressing his legs like a wishbone.</p>
-
-  <div class="figcenter">
-    <a id="Fig_39"><img src="images/i_256.jpg" width="510" height="105" alt="" /></a>
-    <div class="caption smcap">Fig. 39.—Mouillard’s Aëroplane.</div>
-  </div>
-
-  <p>He now sent the home folks away from the farm, buckled on his wings and
-    walked along the prairie road waiting for a breeze. The road was raised
-    five feet above the plain and bordered by ditches ten feet wide. His
-    wings felt light; he ran forward to test their lift, and he thought to
-    amuse himself by jumping the ditch. The result is thus expressed in his
-    own words:<a id="FNanchor_25" href="#Footnote_25" class="fnanchor">[25]</a></p>
-
-  <blockquote>
-    <p>“So I took a good run across the road and jumped at the ditch. But,
-      oh, horrors; once across the ditch my feet did not come down to earth;
-      I was gliding on the air, and making vain efforts to land; for my
-      aëroplane had set out on a cruise. I dangled only one foot from the
-      soil, but, do what I would, I could not reach it, and I was skimming
-      along without the power to stop. At last my feet touched the earth;
-      I fell forward on my hands; broke one of my wings, and all was over;
-      but goodness, how frightened I had been! I was saying to myself that
-      if even a light wind-gust occurred, it would toss me up 30 to 40 feet
-      into the air, and then surely upset me backward, so that I would fall
-      on <span class="pagenum" id="Page_209">209</span>my back. This I knew perfectly, for I understood the defects of my
-      machine. I was poor, and I had not been able to provide myself with a
-      more complete aëroplane. All’s well that ends well. I then measured the
-      distance between my toe marks, and found it to be 138 feet.</p>
-
-    <p>“Here is the rationale of the thing. In making my jump I acquired a
-      speed of 11 to 14 miles per hour, and just as I crossed the ditch I
-      must have met a puff of rising wind. It probably was traveling some 8
-      to 11 miles per hour, and the two speeds added together produced enough
-      pressure to carry my weight.”</p>
-  </blockquote>
-
-  <p>He repaired his wing and repeated the test a few days later. A violent
-    wind gust came; picked him up from the earth, and whelmed him over. In
-    his alarm he allowed his “wish-bone” to spread, and the wings to fold
-    up like those of a butterfly at rest, pinching him between them like
-    a nut in a nutcracker. One wonders whether the overwheeling vultures
-    witnessed this gentleman’s flight with any sense of humor.</p>
-
-  <p>After mature reflection, Mouillard concluded that he should give his
-    aëroplane a rudder, and flex the wings, in order to insure adequate
-    control. But here he halted, being a poor man unskilled in the art
-    of construction. He had reached the limit of his endowments. He had
-    observed faithfully and described charmingly the wonderful flights
-    of various birds; but he must leave to his technical successors the
-    pleasure of imitating or excelling those extraordinary maneuvers—leave
-    them the pleasure, the sacrifice, the long years of toil and danger,
-    accompanied perhaps by indiscriminate applause or derision.</p>
-
-  <p>In the meantime another distinguished disciple of the birds was
-    energetically at work in Germany.<span class="pagenum" id="Page_210">210</span> No less ardent than Le Bris, or
-    Mouillard, Otto Lilienthal was far better equipped and circumstanced.
-    He was a graduate of the Potsdam Technical School, and a student
-    for three years in the Berlin Technical Academy. He was engaged in
-    practical construction ten years in various machine shops at Berlin.
-    After 1880 he operated a flourishing machine factory of his own. From
-    boyhood he with his brother Gustavus had carefully studied the flight
-    of birds, and had made numerous experiments in aviation. On moonlight
-    nights in their little home place of Anclam, in Pomerania, the boys
-    would run downhill, flapping their home-made wings, like Dædalus and
-    Icarus, but with no other danger than discovery and teasing by their
-    neighbors. At Potsdam and Berlin they continued to experiment and to
-    construct wings of increasing size and power. Thus Otto Lilienthal
-    reached early manhood thoroughly trained by his long courses in the
-    technical schools and shops, brimming with well pondered ideas,
-    strengthened by continuous observation and experiment, and in financial
-    circumstances which permitted him to devote time and money to the
-    unremunerative pursuit of aviation. To this may be added that his
-    mature years were cast in a time when the allied sciences could aid
-    him far more than they had aided his predecessors of the preceding
-    generation.</p>
-
-  <p>After careful research for the most efficient form of alar surface,
-    Lilienthal resolved to imitate the birds. First he would build a pair
-    of arched wings, and learn to coast down the atmosphere, balancing
-    and steering like a stork in the gusty and treacherous current. He
-    would thus acquire the pilot’s skill, and ascertain the towline power
-    required to sustain a given weight. Then he would add a suitable
-    propelling mechanism, test it cautiously, <span class="pagenum" id="Page_211">211</span>and acquire the mastery of
-    dynamic flight. Incidentally, perhaps, he would learn to ride all over
-    creation without motive power; for he was convinced that certain great
-    birds soar without muscular effort, and that man could acquire this
-    delightful art in favorable weather. To strengthen the plausibility
-    of that doctrine, he announced his discovery that the general trend
-    of the wind is three and a half degrees upward, a fact inexplicable
-    and almost incredible to his illustrious confrère of the Smithsonian
-    Institution.<a id="FNanchor_26" href="#Footnote_26" class="fnanchor">[26]</a> Such was Lilienthal’s ample program; more, indeed,
-    than he would live to accomplish, though possibly not beyond his power
-    of achievement, if he could have lived to enjoy the hale long years of
-    his illustrious countryman aëronaut, Count Von Zeppelin.</p>
-
-  <p>In the year 1891 Lilienthal made his first series of trials in sailing
-    flight. His glider was the bird-shaped apparatus shown in <a href="#Plate_XVI">Plate XVI</a>,
-    made of willow wood covered with waxed sheeting. It weighed about 40
-    pounds, and spread 107 square feet of surface. Taking this in his arms
-    he first ran 24 feet along a raised board and jumped off, gliding
-    through still air. Then, elevating the board to a height of six feet,
-    he repeated the run, jump and glide, always landing very softly. Thus
-    he became “king of the air in calm weather,” a title still creditably
-    sustained by his numerous successors of the present day; for as yet no
-    one “mounts the whirlwind and directs the storm.”</p>
-
-  <p>Next he went to some little mounds in a field beyond Werder, and jumped
-    from these, gradually lengthening his flights till he attained a range
-    of nearly 80 feet. As he was now gliding in light <span class="pagenum" id="Page_212">212</span>winds, he found it
-    necessary to add a vertical rudder, in order to preserve his balance
-    easily, and keep his bow toward the direction of the wind. His complete
-    apparatus was, therefore, a birdlike affair, with two rigid wings and
-    a double tail for steering vertically and horizontally. He found also
-    that he could fly longer and alight more softly when the wind was
-    blowing—an obvious possibility.</p>
-
-  <p>Encouraged by this experience Lilienthal explored the country about
-    Berlin for sailing ground where he could make long glides, whatever
-    the direction of the wind. Such a region he found near Rathenow, where
-    the Rhinow hills, covered with grass and heather, slope gently upward
-    from the flat plowland to a height of over 200 feet. This he thought
-    an ideal coasting ground; for he felt the aërial currents very smooth,
-    and he could always select clear land sloping ten to twenty degrees
-    toward the wind. Here in the summer of 1893, with a new and improved
-    glider, he made many flights, finally ranging from 200 to 300 yards,
-    steering up and down, or to right and left at will; sometimes pausing
-    in mid air, and several times returning to the starting point. This was
-    more than coasting; for a mere coaster never maintains, nor returns
-    to, his original level. It was a fair start at true soaring, the ideal
-    locomotion. A glorious sport it was, sailing like an eagle high over
-    the landscape and over the heads of the astonished spectators.</p>
-
-  <p>The new machine resembled its predecessors in form and maneuver; but
-    differed in dimensions. It was a birdlike craft with parabolically
-    arched wings and a double tail. It measured 7 meters across, spread
-    14 square meters of surface, weighed with the rider 200 pounds, and
-    in calm air could sail down a slope of 9°, at a speed of 9 meters
-    per second. This was very efficient sailing, the work of <span class="pagenum" id="Page_213">213</span>gravity
-    being hardly two horse power. With the man lying prone, as eventually
-    planned, the economy would be still greater.</p>
-
-  <hr class="page" />
-  <div id="Plate_XVI" class="center"><b>PLATE XVI.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_261a.jpg" width="600" height="298" alt="" />
-    <div class="captionp">LILIENTHAL’S MONOPLANE GLIDER.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_261b.jpg" width="600" height="299" alt="" />
-    <div class="captionp">LILIENTHAL’S BIPLANE GLIDER.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_261c.jpg" width="600" height="297" alt="" />
-    <div class="captionp">PILCHER’S MONOPLANE GLIDER.</div>
-  </div>
-
-  <p>The craft was thought also to possess stability; and this it had, in a
-    measure, about those two axes corresponding to the two rudders; but the
-    control about the third axis, effected by dangling the legs to right
-    or left, was extremely crude and primitive. It was in keeping with his
-    adage: “to contrive is nothing; to construct is something; to operate
-    is everything.” If he had contrived more intelligently, he would have
-    operated more easily, and avoided those wild and dangerous dancings in
-    space. A more scientific adage would read: “To design effectually is
-    everything, to construct is routine, to operate is play.”</p>
-
-  <p>The marvel is that Lilienthal, the observant, the technically trained,
-    the practically skilled, should operate for three years, then patent,
-    an aërial glider having two rudders, but lacking the third rudder,
-    or torsional wing, now so commonly used throughout the world. But
-    doubtless he contemplated a device for preserving the lateral balance
-    without shifting his weight; for he acknowledged the economic advantage
-    of lying prone on the machine, and stated that this might be done after
-    some important improvements in the apparatus had been made.</p>
-
-  <p>Having executed nearly two thousand flights with his monoplane,
-    Lilienthal in 1895 built a two-surface glider. He found this still
-    easier to control, and now thought he had sufficiently acquired the
-    art of sailing to justify his undertaking the next and more difficult
-    art of imitating the rowing flight of birds. He had constructed a
-    ninety-pound engine, of two and a half horse power, to actuate the
-    wings of his glider; but, before applying this motor, he went to the
-    Rhinow Hills for a little further experience <span class="pagenum" id="Page_214">214</span>in sailing. Previously
-    he had remained in the air twelve to fifteen seconds; but he wished to
-    exceed this record.</p>
-
-  <p>On the 9th of August, 1896, he made a long glide to prove the
-    effectiveness of the horizontal rudder, and then wished to undertake
-    a second flight of the greatest duration feasible. No intimation had
-    he that this sail would prove disastrous. Giving the timepiece to his
-    assistant, he set forth on a level course, but suddenly dipped forward
-    and plunged headlong to earth through a height of fifty feet. He was
-    dragged out from the débris with a broken spine, from which he died the
-    following day.</p>
-
-  <p>The machine on which the father of aërial gliding made his last flight
-    is shown in <a href="#Plate_XVI">Plate XVI</a>. Of the hazardous nature of its construction Mr.
-    Chanute thus writes: “The two surfaces were kept apart by two struts,
-    or vertical posts, with a few guy wires, but the connecting joints were
-    weak, and there was nothing like trussing. This eventually cost his
-    most useful life. Two weeks before that distressing loss to science,
-    Herr Wilhelm Kress, the distinguished and veteran aviator of Vienna,
-    witnessed a number of glides by Lilienthal with his double-decked
-    apparatus. He noticed that it was much wracked and wabbly, and wrote to
-    me after the accident: ‘The connection of the wings and the steering
-    arrangement were very bad and unreliable. I warned Herr Lilienthal very
-    seriously. He promised me that he would soon put it in order, but I
-    fear that he did not attend to it immediately.’”</p>
-
-  <p>It will be observed that Lilienthal gave fair attention to the merits
-    of both the monoplane and the biplane, the two familiar types in
-    lively competition at the present hour. The first he found in Nature;
-    the second he could have found in England, as the developments
-    principally of Wenham and of Phillips. <span class="pagenum" id="Page_215">215</span>His example and prestige did
-    much to promote the biplane; but he seems to have had no very decided
-    preference for either. Though he found his biplane very satisfactory,
-    he thought of returning to the monoplane.</p>
-
-  <p>In April, 1896, he wrote:<a id="FNanchor_27" href="#Footnote_27" class="fnanchor">[27]</a> “I am now engaged in constructing an
-    apparatus in which the position of the wings can be changed during
-    flight in such a way that the balancing is not effected by changing
-    the position of the center of gravity of the body. In my opinion this
-    means considerable progress, as it will increase the safety. This will
-    probably cause me to give up again the double sailing surfaces, as it
-    will do away with the necessity which led me to adopt them.” He thus
-    seems to have studied the two types impartially, and to have invented a
-    means for balancing the machine without shifting the center of mass.</p>
-
-  <p>Lilienthal had given a powerful and permanent impulse to aviation,
-    both by his writings and by his practical experience in the air. He
-    first showed quantitatively the advantage of arched wings, by carefully
-    derived tables of wind pressure; then he mounted the wings himself
-    and taught the world, by bold and frequent flight, the art of aërial
-    gravity sailing. The two remaining achievements, dynamic and soaring
-    flight, he was to undertake as promptly as possible. If his life had
-    been spared, no doubt he would have contributed much to the advancement
-    of these arts, both by example and by direct effort; for he was in the
-    prime of life, full of energy and daring, highly equipped, and ardently
-    devoted to his favorite science. He began his studies in aviation at
-    the age of thirteen and died at the age of forty-eight years.</p>
-
-  <p>Among the admirable traits of the father of sailing<span class="pagenum" id="Page_216">216</span> flight must be
-    mentioned his scientific liberality and <i xml:lang="fr">esprit de corps</i>. Though he
-    patented his invention he did not conceal, or withhold, his discoveries
-    when he could publish them properly. These discoveries were made at
-    a great sacrifice of time and means, and must have appeared to him
-    valuable trade secrets; yet he published all his scientific data, his
-    theories, and observations; he encouraged his confrères in various
-    countries to witness and emulate his experiments, to share intimately
-    his laboriously developed knowledge of aviation, to join hands with
-    him in hastening the advent of practical flight. Such is the <i xml:lang="fr">esprit
-    de corps</i> which has ever prevailed among truly scientific men, as
-    distinguished from the mercenary and commercial; such are the unselfish
-    investigators whom the world delights to honor, both for their genius
-    and for their liberal contributions to the common and permanent
-    possessions of humanity.</p>
-
-  <p>Before his death Lilienthal had the pleasure of knowing that competent
-    disciples were emulating him in doctrine and practice. One of the
-    earliest and cleverest of these was Percy S. Pilcher, Assistant
-    Lecturer in Naval Architecture and Marine Engineering at the University
-    of Glasgow. In the summer of 1895 he built the glider shown in <a href="#Plate_XVI">Plate
-    XVI</a>. This, like Lilienthal’s, was a double-tailed monoplane arched fore
-    and aft; but, better than his for manual control, it was straight from
-    tip to tip, like the designs of Henson, Penaud, and other predecessors.
-    This improvement was introduced to prevent side gusts from rocking the
-    craft so readily as they do the V-shaped gliders. His best sailer, the
-    <i>Hawk</i>, shown in the figure, had wings curved one in twenty, about one
-    third from their front edge.<a id="FNanchor_28" href="#Footnote_28" class="fnanchor">[28]</a> Sometimes <span class="pagenum" id="Page_217">217</span>he sailed downhill; again
-    he was towed or launched, like a kite, by means of a cord, running
-    through five-fold multiplying gear, and drawn by running boys, or a
-    horse. In both cases he controlled the machine to his own satisfaction,
-    making in 1897 smooth downhill glides of 700 feet length, from an
-    elevation of 70 feet.<a id="FNanchor_29" href="#Footnote_29" class="fnanchor">[29]</a> He had also visited Lilienthal, but only
-    after achieving success at home.</p>
-
-  <p>Having acquired some skill in sailing, Mr. Pilcher began work on a
-    power machine. This was to be propelled by a screw actuated by an
-    oil engine, and was to be mounted on wheels backed by stiff springs.
-    Having observed his speed of descent in gliding, he computed that
-    two tow-line horse power would float him and his machine, weighing
-    together 220 pounds. A like result was obtained when he was flown as
-    a kite. He was, therefore, on the straight road to achieving human
-    flight on a screw-propelled, wheel-mounted monoplane. If he had been
-    more cautious he might have been the first person to achieve human
-    flight in a practicable type of dynamic machine; for he seems to have
-    equaled, if not excelled, his German master in aëroplane design. But
-    like the master he provided inadequately for the structural strength
-    of his glider, and braved too far the dangers of gusty weather. One
-    stormy day, September 30, 1899, wishing to please several persons who
-    had come a long distance to see him, he made two trial flights in a
-    gentleman’s park near Rugby. The second of these proved fatal. The
-    spectators heard a cracking noise, saw the tail break, and the whole
-    craft plunge headlong to the ground. Poor Pilcher was mortally hurt and
-    died thirty-four hours later, without ever regaining consciousness. He
-    was then in his thirty-third year.</p>
-
-  <p><span class="pagenum" id="Page_218">218</span></p>
-
-  <p>Had this talented young Briton and his German tutor both lived, there
-    would doubtless have been a pleasant race and rivalry between them;
-    for the pupil was forming opinions and plans sufficiently divergent
-    from those of his master and friend. He did not approve Lilienthal’s
-    high wings and low center of gravity, nor his V-shape for lateral
-    equilibrium, nor his flapping wing tips for propulsion, nor his method
-    of launching the dynamic machine. Fortunately both published their
-    ideas and experiments, leaving to their successors the task of judging
-    the merits of their designs, and of adding any improvements that might
-    still be required in order to achieve final success.</p>
-
-  <p>Contemporary with Pilcher, Mr. Octave Chanute and Mr. A. M. Herring,
-    in America, were emulating the work of Lilienthal. Mr. Chanute was an
-    experienced civil engineer, who had previously written a history of
-    aviation, and experimented with numerous flying models; Mr. Herring,
-    his employee for the time, was a mechanical engineer who had assisted
-    in Langley’s experiments, and previously had flown a Lilienthal glider,
-    and had made researches in the science of mechanical flight. On June
-    22, 1896, accompanied by two assistants, they went into camp among the
-    sand dunes, on the southern shore of Lake Michigan, to study the art of
-    navigating an aëroplane without artificial motive power. Mr. Chanute
-    thought that the maintenance of equilibrium under all circumstances
-    was at that time the most important problem of aviation; and that
-    until automatic stability was secured, it would be premature and
-    dangerous to apply a motor. He wished to evade, for he did not relish,
-    Lilienthal’s way of balancing by shifting the body and kicking wildly
-    at the stars. His main purpose, therefore, was to acquire the pilot’s
-    science; but secondarily he would <span class="pagenum" id="Page_219">219</span>learn much about the architecture
-    of gliders, the behavior of air currents, the elements of propulsion
-    and sustentation.</p>
-
-  <hr class="page" />
-  <div id="Plate_XVII" class="center"><b>PLATE XVII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_269a.jpg" width="600" height="300" alt="" />
-    <div class="captionp">CHANUTE’S FIVE DECK GLIDER.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_269b.jpg" width="600" height="301" alt="" />
-    <div class="captionp">HERRING IN CHANUTE BIPLANE.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_269c.jpg" width="600" height="297" alt="" />
-    <div class="captionp">HERRING’S COMPRESSED-AIR BIPLANE.</div>
-    <div class="small">(Courtesy Carl Dientsbach.)</div>
-  </div>
-
-  <p>They made some flights with a Lilienthal monoplane; but, finding this
-    unsafe and treacherous, they discarded it in favor of a multiple-wing
-    glider designed by Chanute, which after many empirical modifications
-    in the placement of the sustaining surfaces, assumed the form shown in
-    Plate XVII. This glider resembled the Lilienthal biplane in having the
-    surfaces vertically superposed, the rider below them, and the rudder in
-    the rear; but it was a five-decker whose wings, on either side, could
-    swerve fore and aft, so as to bring the center of lift always over the
-    center of gravity, in order to prevent excessive rearing or plunging.
-    This glider was found very tractable in a twenty-mile wind, and in a
-    thirteen-mile breeze would sail down a slope of one in four.</p>
-
-  <p>After further study, the five-decker was replaced by a three-decker;
-    which presently was deprived of its obtrusive and unessential lower
-    surface, thus assuming the familiar form shown in Plate XVII. As will
-    be observed, this was a radically new and elegant design, consisting
-    of two superposed arched surfaces held together by vertical posts and
-    diagonal wires, like a Pratt truss. It was, in fact, the renowned
-    “Chanute glider” which has been copied by so many succeeding designers
-    of biplanes.</p>
-
-  <p>The Chanute glider weighed 23 pounds, spread 135 square feet, and
-    readily carried a total weight of 178 pounds at 23 miles an hour. It
-    was provided, as shown, with side planes and a double rudder, and
-    this latter was elastically connected to the main body to insure
-    steadiness of flight, on the principle of the elastic wing margins used
-    by D. S. Brown in 1874. This craft was found easy to manipulate<span class="pagenum" id="Page_220">220</span> in
-    launching, sailing and landing, a two-inch shift of the pilot’s weight
-    equivalencing a five-inch shift on the Lilienthal monoplane. It was
-    steady at a speed of twenty to forty miles an hour through the air,
-    even when the wind was blowing seventeen miles an hour overground. The
-    angle of descent was 7.5° to 11°, depending on the speed and trend of
-    the wind. The work of gravity expended in maintaining steady flight was
-    at the rate of two horse power for the 178 pounds, a good showing with
-    the rider vertical.</p>
-
-  <p>Summer passed before Mr. Chanute could perfect the invention for
-    automatic stability by means of swerving wings; but otherwise the
-    gliding experiments were very satisfactory. The strong and simple
-    biplane evolved during those few weeks of fruitful study, though not
-    an original creation, having been foreshadowed theoretically and
-    experimentally, in the work of Wenham,<a id="FNanchor_30" href="#Footnote_30" class="fnanchor">[30]</a> Stringfellow, Lilienthal,
-    Phillips, and Hargrave, was nevertheless an important contribution to
-    the science of aviation, by reason of its strength and simplicity of
-    design, its efficiency, its stability, and, best of all for that day,
-    its record for good flights and safety. All who could appreciate it
-    understood that the addition of a light motor would transform it to
-    a dynamic flyer, navigable at least in mild weather. The most eager,
-    perhaps, was Mr. Herring; for he had not only mastered this glider,
-    but some years previously had flown successfully rubber-driven models
-    very much resembling it in design. These two aviators, therefore, came
-    to a parting of the ways, Chanute still pursuing automatic stability,
-    <span class="pagenum" id="Page_221">221</span>Herring impatiently heading for dynamic flight by the shortest route
-    available. Had they continued together on a practical course, they
-    might, ere the close of the century, have anticipated at least the
-    early flights of the French aviators, if they could have constructed or
-    purchased an adequate motor.</p>
-
-  <p>After some further development of the aërial glider to adapt it
-    to power flight, Mr. Herring began the construction of a dynamic
-    aëroplane. He had previously built very light steam and gasoline
-    engines,<a id="FNanchor_31" href="#Footnote_31" class="fnanchor">[31]</a> and deemed the latter best for a perfected flyer, though
-    preferring steam or compressed air in a first experimental test.</p>
-
-  <p>When seen by the present writer in October, 1898, at St. Joseph,
-    Mich., Mr. Herring was about to launch himself in the compressed-air
-    driven biplane shown in <a href="#Plate_XVII">Plate XVII</a>. It was essentially a powered
-    Chanute-Herring glider, steadied by a double tail, and controlled by
-    shift of the pilot’s weight, the tail being elastically attached.
-    The writer then suggested that both a glider and a dynamic aëroplane
-    should be controlled entirely by steering and balancing surfaces, on
-    the principle set forth in his paper of 1893; and, in particular,
-    indicated that the lateral balance should be controlled by changing the
-    inclination of the wings on either side, while the double tail should
-    be used to steer and steady the aëroplane sidewise and vertically; in
-    other words, that a torque about each of the three rectangular axes of
-    the machine should be secured from impactual pressure, thus obviating
-    the need for shifting the pilot’s weight. Mr. Herring, while making no
-    objection to this proposal, intimated that he had a device for insuring
-    control without shifting the pilot’s weight, but believed the most
-    important ef<span class="pagenum" id="Page_222">222</span>fort for the moment should be to make a short flight with
-    the machine as it stood, for the purpose of enlisting capital, then
-    to add the controlling devices at leisure. He expected to remove the
-    wheels shown in the figure, hold the aëroplane against a stiff breeze
-    from Lake Michigan, start the propellers, strike a soaring attitude,
-    and fly forward for a few seconds against the wind.</p>
-
-  <p>The successful accomplishment of such a flight covering an overland
-    distance of seventy-three feet in eight or ten seconds, against a wind
-    of thirty miles an hour, was reported in the Chicago <cite>Evening News</cite>,
-    of November 17th of that year; but the present writer has not been
-    able to ascertain the reporter’s name, or that of any other witness to
-    the event, which, if true, is well worthy of verification and detailed
-    record.</p>
-
-  <p>In following the votaries of passive flight, as represented by
-    Lilienthal and his school, we have overlooked the great man-carrying
-    bird of Clément Ader, one of the most prominent and successful aviators
-    of that active period. If the reports be true, Ader may justly claim to
-    be the first person to navigate the air in a dynamic flying machine.
-    However, it must be observed that his achievements did not at first
-    arouse in France a great pitch of exultation and enthusiasm. There
-    seemed at the time to be some skepticism as to the practicability of
-    his device. But later cordial reparation was made by placing it on the
-    Stand of Honor at the Aëronautical Salon, held in the Grand Palais, at
-    Paris, in December, 1908.</p>
-
-  <p>Clément Ader set out in life with the fixed determination to make
-    a fortune, then to build a practical flying machine. Adopting the
-    profession of electrical engineer, he quickly accumulated enough
-    capital, as he thought, to realize his early ambition. He<span class="pagenum" id="Page_223">223</span> next visited
-    Africa to study at close range the great soaring birds that Mouillard
-    had described with so much admiration and vivacity. Going to Algeria
-    he disguised himself as an Arab, and, with two Arab guides, journeyed
-    to the interior where he watched the great soaring vultures, which
-    he enticed with bits of meat to perform before him their marvelous
-    maneuvers, wheeling in wide circles, and without wing beat, from earth
-    to sky.</p>
-
-  <p>After several years of study of the anatomy and flight of birds, Ader
-    began, at the age of forty-two years, to construct an aëroplane. His
-    first machine was a birdlike monoplane mounted on skids, or wheels,
-    and driven by a 40-horse-power steam engine actuating a screw, placed
-    forward. The total weight was 1,100 pounds, the spread 46 feet, the
-    length 21 feet. The <i>Eole</i>, as he called it, received its first
-    open-air test on the morning of October 9, 1890, in the grounds
-    surrounding the Chateau d’Armainvilliers, near Gretz, a portion of the
-    course being so prepared that the trace of the wheels would be visible.
-    When everything was ready for the trial, Ader mounted the machine, in
-    presence of a few friends, ran quickly over the ground, urged by the
-    propeller thrust, then rose into the air and sailed 150 feet. Such is
-    the report of the witnesses to what is claimed as the first flight of a
-    human being in a power-driven flying machine.</p>
-
-  <p>Subsequently this bold inventor built <i>Eole No. 2</i>, which, by special
-    permission of the War Department, he tested on a prepared track, 2,400
-    feet long, on the Satory Camp. Over this course he ran his machine
-    several times, and on one occasion flew 300 feet; but on alighting
-    broke one of the wings.</p>
-
-  <p>Ader, now having spent one and a half million francs on his
-    experiments, placed the <i>Eole</i> on exhibition in order to raise money
-    for their continuation. <span class="pagenum" id="Page_224">224</span>In this venture also he was successful,
-    being presently subventioned by the French War Department to build an
-    aëroplane for its use. His subsequent labors are concisely set forth in
-    <cite>Automobilia and Flight</cite> for February, 1909, as follows:</p>
-
-  <blockquote>
-    <p>“Under these new conditions the workshop in the Rue Pajou was abandoned
-      for larger premises in the Rue Jasmin, where the construction of the
-      <i>Avion</i> was commenced in May, 1892, all persons engaged with the
-      construction being under a military vow of secrecy. The motor was built
-      first, and tested before a commission composed of army officers and
-      some of the leading technicians of France. It was found to develop 30
-      horse power for a total weight of 32 kilogrammes; and even now, though
-      seventeen years old, is regarded as a <i xml:lang="fr">chef d’œuvre</i>. In the spring of
-      1897 the <i>Avion</i> was ready to make flights. Like its predecessors it
-      was modeled on the form of a bat; but, although the wings could not
-      be flapped, they could be folded, and could be advanced or retarded
-      horizontally.</p>
-
-    <p>“Everything appearing satisfactory, Ader informed the military
-      commission that he was ready to undergo tests; the committee met at
-      the workshops in the Rue Jasmin on August 18, 1897; were pleased with
-      the machine, and ordered flights to be made immediately at Satory. It
-      was not, however, until October 12th that a flight was attempted on
-      the carefully guarded military ground, and in the presence of General
-      Mesnier. The apparatus covered a distance of 1,600 yards, and although
-      it did not fly, for this distance it is certain that on several
-      occasions it completely left the ground. Ader declared that according
-      to whether the wings were carried forward or to the rear, it was the
-      front or the rear wheels only which left the ground. The pressure in
-      the generator at this moment varied between<span class="pagenum" id="Page_225">225</span> 3 and 4 atmospheres. On
-      increasing it to 6 or 7 atmospheres none of the wheels touched.</p>
-
-    <p>“Satisfied with the results of the test, General Mesnier called the
-      commission together for further trials on the following day, October
-      14, 1897. Unfortunately it was a rough, squally morning, that would
-      have prevented many a modern aviator from bringing a machine into the
-      open. But as the officers had been brought together specially for this
-      purpose, a flight was attempted.</p>
-
-    <p>“‘After several revolutions of the propellers, and a few yards covered
-      at a moderate speed, we were off at a high rate of travel,’ wrote
-      Ader, who was at the wheel on this memorable occasion. ‘The pressure
-      was about 7 atmospheres. Almost immediately the vibrations of the
-      rear wheel ceased, and, directly after, those of the front wheels
-      were no longer felt, showing that we had entirely left the ground.
-      Unfortunately the wind had increased in strength, and I had some
-      difficulty in keeping to the line that had been marked out. I increased
-      the pressure to 9 atmospheres, and immediately the speed increased
-      considerably, the vibrations ceased again, showing that we had once
-      more left the ground. Under the influence of the wind the aëroplane
-      had a constant tendency to drift to the right, away from the circular
-      track that had been marked for it. Finally, with the wind broadside on,
-      the machine was in a rather dangerous position, for it was being still
-      more rapidly driven out of its course. I increased the pressure still
-      more and put the rudder hard over to the left, with the result that
-      for a few seconds the machine worked back towards the track and still
-      maintained itself in the air. But it was impossible to struggle against
-      the wind, and finding that the machine was being carried towards some
-      artillery sheds, and somewhat unnerved by the<span class="pagenum" id="Page_226">226</span> speed at which the
-      ground appeared to be rushing past, I stopped the engine; there was a
-      shock, and I was on the ground.’</p>
-
-    <p>“Ader was uninjured, but his machine was rather badly smashed. It had
-      certainly flown, but with such difficulty in the face of the wind that
-      the army commission was evidently little inclined to report favorably
-      upon it. Several weeks passed without any communication being received
-      from the War Department; then it became apparent to Ader that the
-      Government had no longer faith in his invention. This was proved early
-      in the following year by an official communication to the effect that
-      no further funds could be allotted to this work. Discouraged at the
-      abandonment after forty years’ labor and the expenditure of about
-      two million francs, Ader commenced the destruction of his machines.
-      The earlier ones were destroyed, but the <i>Avion</i>, the one which had
-      appeared before the army commission, was saved and sent to the Museum
-      of the Arts et Métiers in Paris.”</p>
-  </blockquote>
-
-  <p>The last aëroplane, or <i>Avion</i>, weighed 1,100 pounds, spread 270 square
-    feet, and was driven by a 40-horse-power steam engine actuating twin
-    screws projecting before the bird-shaped flyer. The engine weighed but
-    7 pounds per horse power—quite a remarkable achievement for that day.</p>
-
-  <p>In following the votaries of passive flight, as represented by
-    Lilienthal and his school, we have overlooked the great dynamic
-    aëroplane of Mr. Maxim, one of the most prominent aëroplane builders of
-    that active period. Having in 1889 made elaborate experiments on the
-    atmospheric resistance of sustaining surfaces, and on the thrust of
-    screw propellers, he proceeded to build the gigantic aëroplane shown
-    in <a href="#Plate_XVIII">Plate XVIII</a>, the greatest flyer thus far known to history. It was a
-    twin-screw multiplane <span class="pagenum" id="Page_227">227</span>mounted on a platform forty feet long by eight
-    feet wide, and having four wheels running along a track eight feet
-    wide and half a mile long. Above the rails of this track were guard
-    rails to prevent the flyer from rising more than three inches during
-    the tests. The whole machine weighed 3.5 tons, spread 5,500 square
-    feet of surface, and, at a speed of 40 miles an hour, lifted more than
-    a ton, in addition to the weight of the three men and 600 pounds of
-    water. Its propelling plant comprised a naphtha tubular boiler, and a
-    compound steam engine of 350 horse power actuating twin screws 17 feet
-    10 inches in diameter which gave a thrust approximating 2,000 pounds.
-    These screws were made of American yellow pine, covered with canvas and
-    painted, then smoothly sandpapered to reduce the friction; for Maxim,
-    like certain French aviators, erroneously imagined that a polished
-    surface has less air friction than a dead even surface. The framework
-    was composed of seamless steel tubing stayed with steel wire. The
-    aëroplane was to be steered right and left by a rudder, and up and down
-    by horizontal planes, one fore, another aft, and its lateral stability
-    was to be secured by side planes set at a dihedral angle. A meritorious
-    feature for that day were the superposed arched surfaces whose framing
-    was smoothly covered below and above by skillfully stretched fabric,
-    causing the air to flow evenly without wasteful eddies.</p>
-
-  <hr class="page" />
-  <div id="Plate_XVIII" class="center"><b>PLATE XVIII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_279a.jpg" width="600" height="411" alt="" />
-    <div class="captionp">MAXIM’S AËROPLANE.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_279b.jpg" width="600" height="409" alt="" />
-    <div class="captionp">LANGLEY’S LARGE AËROPLANE.</div>
-    <div class="small">(Courtesy Smithsonian Institution.)</div>
-  </div>
-
-  <p>Many runs along the track were made to test the working of this
-    great apparatus before trusting it to launch forth in free flight.
-    Dynamometers gave independently the thrust of the screws, and the lift
-    of the wings on the front and rear axles. The ascensional planes for
-    controlling the fore and aft equilibrium were tested during the run,
-    as also the practical operation of the propelling plant. During<span class="pagenum" id="Page_228">228</span> the
-    trials of 1893 the machine frequently lifted clear of the lower track,
-    and flew forward resting against the guard rails above the wheels.
-    Finally, on a gusty day, the lift against the upper track caused this
-    to give way, whereupon the machine rose into the air with Mr. Maxim
-    and his assistant, then toppled over on the soft earth, suffering
-    some damage to its framework. Here the experiments were discontinued
-    for lack of funds, having indeed demonstrated that a large weight
-    can be carried in dynamic flight, but having proved little as to the
-    feasibility of controlling an aëroplane in launching, in free flight,
-    and in landing.</p>
-
-  <p>Compared with the work of his contemporaries this achievement of Mr.
-    Maxim was herculean, both in construction and expenditure, the cost
-    being reported as nearly one hundred thousand dollars. It raised high
-    hopes for aviation. It proved conclusively not only that a flying
-    machine could be made to lift a pilot, but that it could carry hundreds
-    of pounds additional weight. It still holds the world’s record for
-    magnitude of machine and cargo. But it had two great defects; it was
-    improperly balanced and it was inadequately powered; for, as Mr. Maxim
-    says, “the quantity of water consumed was so large that the machine
-    could not have remained in the air but a few minutes, even if I had had
-    room to maneuver and learned the knack of balancing in the air.”<a id="FNanchor_32" href="#Footnote_32" class="fnanchor">[32]</a>
-    These defects, however, would soon be remedied by the work of others,
-    and particularly by the costly experiments of the automobilists, who
-    were rapidly developing a light gasoline motor suitable for aviation.</p>
-
-  <p>The inventors thus far noticed had developed most of the important
-    features of the present-day <span class="pagenum" id="Page_229">229</span>flying machines, but had not provided
-    adequate mechanism for preserving a steady lateral balance. The present
-    writer had proposed the combination of a double rudder and torsional
-    wings to steer and control a flyer, and had published a paper setting
-    forth its general principle and describing a specific device; but
-    inventors had little need for a third rudder till they encountered
-    the dangers of dynamic flight in gusty weather. The paper referred
-    to was presented to the Third International Conference on Aërial
-    Navigation, in August, 1893, under the title, <cite>Stability of Aëroplanes
-    and Flying Machines</cite>, and was published with the proceedings of the
-    conference.<a id="FNanchor_33" href="#Footnote_33" class="fnanchor">[33]</a> It discusses mainly the question of automatic stability
-    and steadiness; but recommends personal control during the experimental
-    period. It concludes as follows:</p>
-
-  <blockquote>
-    <p>“We have been considering the question of automatic stability, in so
-      far as it may be secured in the construction of the craft itself,<a id="FNanchor_34" href="#Footnote_34" class="fnanchor">[34]</a>
-      apart from a pilot, or special equilibrating devices. The application
-      of the latter would give exercise to an infinite amount of ingenuity,
-      and would, perhaps, best be left to the fancy of the individual
-      inventor. One curious design, however, occurs to me, which, since I
-      have not seen it described elsewhere, may be worth a moment’s notice.</p>
-
-    <p>“Suppose a Phillips’s machine (see <a href="#Plate_XIV">Plate XIV</a>) to be provided with a
-      double tail, and to have a vertical fin extending longitudinally along
-      its entire length, well above the center of gravity. These would steady
-      its flight and promote stability. <em>Suppose also that its sustaining
-      slats were pivoted, so that a pilot could at pleasure change their
-      inclina<span class="pagenum" id="Page_230">230</span>tion on the right and left side independently. He could then
-      set the engine for a desired speed, sweep forward along the earth
-      with the sustainer slats horizontal, and at will mount into the air,
-      by giving the slats an upward inclination. Once in the air he could
-      raise or lower the machine by slightly changing the angle of the slats;
-      he could wheel to right or left by giving one set of slats a little
-      different slope from the other; he could arrest all pitching, rocking
-      and wheeling by a slight counter movement of the sustainers.</em> It would
-      be necessary, of course, to preserve a rapid forward motion, for it
-      is a peculiarity of the compound aëroplane that, if it comes to a
-      standstill in the air, it will drop plumb down with a frightful plunge
-      until it acquires headway.”</p>
-  </blockquote>
-
-  <p>The succeeding paragraph disclosed a specific contrivance embodying
-    the principle just given. This showed two levers rotating drum shafts
-    for actuating wires adapted to change the impact angles of the wing
-    surfaces. Accordingly this much of the mechanism of control, together
-    with the broad device of the torsion wings, has been the common
-    property of inventors since the publication of that paper. Furthermore,
-    the combination of torsional wings and a double rudder, either fixed or
-    movable, has been public property since that date.<a id="FNanchor_35" href="#Footnote_35" class="fnanchor">[35]</a></p>
-
-  <p>Little was said about the manner of manipulating the double rudder and
-    torsional wings; for the rules of manipulation would vary in different
-    machines, depending upon structural design and external conditions.
-    For example, if the proposed fin and vertical rudder were ample and
-    suitably placed, the lateral balance could be controlled by merely
-    <span class="pagenum" id="Page_231">231</span>twisting the wings, without touching the vertical rudder; but if the
-    fin and rudder were not adequate, the lateral poise would be controlled
-    by twisting the wings and working the vertical rudder conjunctively.
-    A novice might prefer leaving the rudders fixed and controlling the
-    poise in short flights by twisting the wings by means of a single lever
-    having two independent movements, one to rotate the wings oppositely,
-    the other to rotate them identically.</p>
-
-  <p>The principle of control expressed in italics had been set forth also
-    in a preceding paragraph. Having proposed means for securing both
-    stability and steadiness about each of the three axes of an aëroplane,
-    the text continued:</p>
-
-  <blockquote>
-    <p>“These ends could probably be attained very well by mounting two
-      compound aëroplanes on a long backbone,<a id="FNanchor_36" href="#Footnote_36" class="fnanchor">[36]</a> somewhat after the manner
-      of the Hargrave cellular kites, and adding a compound rudder to the
-      whole.” ... “<em>If the inclination of the sustainers, front and back,
-      could be altered independently, it might be feasible for a pilot to
-      preserve the equilibrium of the machine even when its center of gravity
-      was frequently shifted, as by the moving of passengers to and fro.</em>”<a id="FNanchor_37" href="#Footnote_37" class="fnanchor">[37]</a></p>
-  </blockquote>
-
-  <p>At that date, 1893, an inventor doubtless could have secured a broad
-    claim on a mechanism embodying the torsion-wing-and-double-rudder
-    mechanism of control. But in those days aviation was pursued largely
-    as a liberal study by scientific men who wished to hasten the advent
-    of practical flight, by presenting important physical measurements
-    and principles which could be freely employed by all. Accordingly the
-    three-rudder system of control <span class="pagenum" id="Page_232">232</span>seems not to have been claimed by an
-    inventor much before the close of the nineteenth century. Since then it
-    has been patented in one form or other by many practical aviators, some
-    endeavoring to claim the whole broad contrivance, others claiming more
-    restricted devices.</p>
-
-  <p>The static principle of the torsion wing is a familiar one in
-    elementary mechanics. It is this: a torque of given magnitude and
-    direction has the same effect on a rigid body whatever its point of
-    application. The longitudinal torque, or moment, may therefore be
-    exerted by the wings, by suitable rudders, by forward planes, by any
-    auxiliary planes, or fins, however placed or moved for the purpose.
-    Accordingly there seems to be an unlimited variety of concrete
-    patentable devices available to the inventor for securing impactual
-    torque about the longitudinal axis, or either of the other two axes.
-    But in planning such devices it is well to remember that the moment of
-    a couple increases with its arm, so that in a wide aëroplane the wing
-    tips may best furnish the torque; while in a high short-winged machine,
-    vertical planes, fins, or rudders may give the desired longitudinal
-    moment. Obviously such vertical guiding or controlling surfaces may be
-    so placed as to tilt the machine toward the center of curvature of its
-    path, at the same time opposing the centrifugal force, and exerting a
-    torque about the vertical axis tending to steer the flyer along its
-    path.<a id="FNanchor_38" href="#Footnote_38" class="fnanchor">[38]</a></p>
-
-  <p><span class="pagenum" id="Page_233">233</span></p>
-
-  <p>The principle of projectile stability is another consideration of
-    some importance in aviation, or more generally in all submerged
-    navigation, whether of air or water. A submerged body has projectile
-    stability if its nose tends always to forerun its centroid, and follow
-    a steady course. A dart is a good example; a fish, a torpedo. Thus if
-    a torpedo-shaped homogeneous solid be hurled in any manner through a
-    fluid, obliquely or even tail foremost, it promptly turns its nose to
-    the front and proceeds steadily along an even course; but if the body
-    has not true dynamical balance, it may oscillate or gyrate, or flit
-    about in the most erratic manner.</p>
-
-  <p>Projectile stability in a flyer, as in an arrow, may be attained by
-    playing the centroid in or near the line of forward resistance, and
-    well ahead of the side resistance. The reasons for this are manifest.
-    If, however, this arrangement be neglected, a special damping, or
-    controlling, device is required to preserve headlong and steady motion.
-    In particular, the objections to placing the centroid too low were
-    emphasized in the above quoted paper as follows:</p>
-
-  <blockquote>
-    <p>“I have mentioned the advantage of placing the center of mass below the
-      center of surface; this has also its objections. While the stability
-      against inversion is increased, the stability against rocking is
-      sacrificed. The aëroplane so constructed may not easily overturn; but
-      it will sway to and fro with a pendular motion. This, when lateral, is
-      very objectionable, when fore and aft it is fatal to uniform progress,
-      as we shall see in studying the longitudinal stability of flying
-      machines. We shall then see that the center of mass cannot be lowered
-      with impunity.”</p>
-  </blockquote>
-
-  <p>Of the various flyers and models thus far studied, some manifest fairly
-    good, others very imperfect projectile stability. Many inventors have
-    been more<span class="pagenum" id="Page_234">234</span> alert to the gravitational stability and safety of the
-    parachute than to the kinetic stability and keen, direct flight of the
-    arrow. Some of the most pretentious machines imitated the thistle down
-    more nearly than the dart or swallow. But the exigencies of actual
-    flight would easily rectify such imperfections of design.</p>
-
-  <p>Tractional balance also is a property of some importance in fluid
-    navigation. This requires that the line of propulsive thrust coincide
-    with the line of fluid resistance. It is a property, however, that
-    inventors readily apprehend, and usually provide for.</p>
-
-  <p>In general a flyer is subject to four forces: weight, thrust, air
-    pressure and inertia. When these balance about any axis the craft has
-    equilibrium about that axis; when they balance about the three axes
-    the craft is completely balanced, and preserves its orientation in
-    flight. Devices for preserving this complete balance have already been
-    described; as also provision for propulsion and sustentation, launching
-    and landing safely.</p>
-
-  <p>Thus at the close of the nineteenth century all the essential
-    principles and contrivances of pioneer flight were worked out, except
-    one—a suitable motor. This was the real problem of the ages. The rest
-    was easy by comparison. A light enduring motor, if available to the
-    old time inventors, would have brought dynamic flight centuries ago.
-    That only could have baffled Da Vinci, Cayley, Henson, Wenham and the
-    long line of pioneer aviators. Eventually, of course, steam engines had
-    come, endowed with ample power; but costly to build and wasteful to
-    operate. The light automobile engine appeared in the latter nineties;
-    promptly thereafter followed the dynamic flyer, the snow-winged herald
-    of the twentieth century.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_IX">
-    <span class="pagenum" id="Page_235">235</span>
-    <h3>CHAPTER IX</h3>
-    <span class="small">AËROPLANES OF ADEQUATE STABILITY AND POWER</span>
-  </div>
-
-  <p><span class="smcap">The</span> dawn of the twentieth century found several votaries contriving
-    aëroplanes for one or more passengers. The epoch of models had
-    virtually closed, bequeathing a rich heritage. The essential elements
-    of aviation, barring the motor, had been clearly worked out. The age
-    of practical flight was at hand. No further need to prove feasible
-    the heavier than air; for that had been done repeatedly. Scientific
-    design and patient trial, not invention and physical research, were now
-    the chief demand. Further research would improve the aëroplane, but
-    not bring it into practical operation. Capital, constructive skill,
-    judgment in adapting principles and devices already known, energy,
-    persistence, caution, imperturbability in danger and derision; these
-    were requisites. Science had led the way, with uplifted torch; let the
-    craftsmen follow her with kit and apron. The aëroplane was sufficiently
-    invented; it now wanted, not fastidious novelty, but concrete and
-    skillful design, careful construction, exercise in the open field.</p>
-
-  <p>Of the group of aëroplanists in the beginning of the nineteenth century
-    Mr. Hugo Mattullath, of New York, was one of the most original, daring
-    and resourceful. He had been a successful inventor, manufacturer and
-    business man, accustomed to large enterprises. In the latter nineties,
-    deeming the time opportune for practical aviation, he determined to<span class="pagenum" id="Page_236">236</span>
-    build a commercial flying machine. He would begin where Maxim had
-    stopped. A larger and swifter craft appeared to him most desirable.
-    In his judgment any clever mechanic could make a one-man flyer. “Take
-    that for granted and waste no time on toys!” Professor Langley’s
-    “aërodrome,” with every spare ounce filed away, should lift itself,
-    of course. It might navigate a calm; possibly even a zephyr, if no
-    one sneezed; but never could it carry passengers on schedule time. He
-    therefore would jump the little flyers, and build at once a commercial
-    aëroplane strong enough to defy the storm, powerful enough for regular
-    traffic on a business scale. That meant a ship for numerous passengers,
-    equipped to fly fifty miles an hour against the prevailing wind. A
-    glorious project indeed; an enterprise suited to a gentleman of first
-    rate ability.</p>
-
-  <p>Mattullath’s aim was aërial transportation, not exhibition at county
-    fairs and crowded carnivals. Regular interurban routes were projected,
-    terminating in ample landing floors. Broad-winged aëroplanes, huge
-    catamarans with shining hulls, sumptuously furnished in gold and
-    crimson, should convey happy crews, in all seasons, from metropolis to
-    metropolis. Six great engines and propellers to drive the ship, with
-    abundant reserve power. Melodious strains of music rising incessantly,
-    to soften the thunder of motors and the demoniacal howl of the wind.
-    Then transcontinental voyages, outsailing the nimbus, how lovely to
-    the anointed of fortune! Jocund savannas nestling by the sea, or in
-    the bosom of orchid-crested hills, should welcome to earth the silken
-    sojourners of the north migrating, gay-plumed and potent, to their
-    winter homes in tropic paradise. All the isles of ocean, all the merry
-    mountains, earth, sea and air, one shining empire, blissful and secure
-    as Olympus. Chimborazo, girt<span class="pagenum" id="Page_237">237</span> with every clime, from torrid base to
-    snowy peak should glow</p>
-
-  <div class="center-container">
-    <div class="poetry">
-      <div class="stanza">
-        <div class="i0">With alabaster domes and silver spires,</div>
-        <div class="i0">And blazing terrace upon terrace high</div>
-        <div class="i0">Uplifted; here serene pavilions bright,</div>
-        <div class="i0">In avenues disposed; their towers begirt</div>
-        <div class="i0">With battlements that on their restless fronts</div>
-        <div class="i0">Bore stars—illumination of all gems!</div>
-      </div>
-    </div>
-  </div>
-
-  <p>Such were his holiday fancies, seldom revealed, even to his associates.
-    The public had no intimate part in his project. A few trusted
-    engineers, eminent in their profession, and a few financiers, formed
-    his advisory board. For two years he worked on the structural elements
-    of the great sails, propellers, and framing of his ship. But unhappily
-    when he was preparing to present his final plans to his council of
-    engineers, before building the large vessel, he was brought suddenly to
-    the close of his career.<a id="FNanchor_39" href="#Footnote_39" class="fnanchor">[39]</a></p>
-
-  <p>Mattullath’s proposed air ship consisted of two parallel torpedo-shaped
-    hulls sustained by superposed plane or slightly arched surfaces, and
-    propelled by feathering-paddle disk wheels embedded in the planes;
-    the engines, cargo and passengers to be placed within the hulls.<a id="FNanchor_40" href="#Footnote_40" class="fnanchor">[40]</a>
-    This arrangement would enhance the comfort of the passengers at high
-    speeds, eliminate resistance, distribute the load on the framing,
-    and increase the moment of inertia of the vessel, thereby rendering
-    it less sensitive to side gusts. To improve the projectile stability
-    and steadiness, the centroid was placed as high as practicable. Large
-    steering planes were used fore and aft on both sides of the vessel,
-    whose inclination could be changed independently, to turn the ship
-    about its longitudinal or transverse axis. A vertical rear rudder
-    steered <span class="pagenum" id="Page_238">238</span>to right or left, in conjunction with the side planes. All the
-    posts were of double wedge shape; all the planes were canvassed above
-    and below to shield the framing, after the style of Maxim. The hulls,
-    the posts, the planes, all parts, were keenly sharpened to economize
-    power. The ship was to run over its smooth launching field till it
-    acquired a rising speed of forty to fifty miles an hour, then continue
-    accelerating up to velocities sufficient for competition with passenger
-    trains in all weather.</p>
-
-  <p>While one may easily point out certain questionable features in
-    Mattullath’s project, as for example, its odd propellers, one can not
-    so easily estimate its true merits. The torsion wing device for lateral
-    control and steering, which he claimed in his patent application,
-    abandoned after his death, now constitutes a very important feature of
-    every flying machine. His planes for fore and aft control, introduced
-    by Maxim, are also in general use to-day. The principle of load
-    distribution, which he greatly prized for diminishing stress and adding
-    stability, has still to be evaluated by practical test in larger craft
-    than any now in operation. The closed hull, for comfort and economy at
-    high speed, is at present popular with many designers.</p>
-
-  <p>One tentative assumption of Mattullath’s, made on the authority of
-    Maxim and Langley, was that the friction of the air is a negligible
-    part of the entire resistance encountered by the hull, framing and sail
-    surfaces. Accepting their experimental conclusion, he designed a flyer
-    so sharp and smooth in all its parts as practically to eliminate the
-    pressural, or head resistance. With no skin friction, with scant hull
-    and frame resistance, he could afford<a id="FNanchor_41" href="#Footnote_41" class="fnanchor">[41]</a> to fly at <span class="pagenum" id="Page_239">239</span>a very slight
-    angle, thus minimizing the drift, or wing resistance, while at the same
-    time securing abundant lift by rapidity of flight. He thus arrived,
-    by cold deduction from the data of those prominent experimentalists,
-    at an aëroplane swift as the albatross, and wondrously economical of
-    power. But his financiers were loath to gamble on that assumption. He
-    therefore, at their suggestion, instigated systematic measurements
-    of air friction on smooth surfaces, which demonstrated that in a
-    sharp aëroplane flying at a very slight angle, the skin friction is
-    nearly equal to all the other resistances combined. These results were
-    obtained and published<a id="FNanchor_42" href="#Footnote_42" class="fnanchor">[42]</a> some months after his death. They were
-    unfavorable to his project, and to all projects for attaining high
-    speed through the air by excessive sharpening of the vehicle.</p>
-
-  <p>The first dynamic aëroplane of adequate stability and power to carry a
-    man in prolonged flight, was that of Professor Langley. This machine
-    was nearly a duplicate, on a four-fold scale, of the gasoline model
-    previously described, which had flown many times with good inherent
-    equilibrium. There was accordingly every reason to expect that,
-    weighted and launched like the model, it would fly with the same poise
-    and swiftness, even if left to govern itself. Having in addition
-    a living pilot, provided with rudders for steering and balancing,
-    together with adequate fuel for a long journey, it seemed to promise
-    still better results than the model. But an unfortunate accident in the
-    launching so crippled this carefully designed craft that it fell down
-    helpless, without a chance to exhibit its powers of sustentation and
-    balance, even for a moment, in normal flight.</p>
-
-  <p><span class="pagenum" id="Page_240">240</span></p>
-
-  <p>The first trial occurred on September 7, 1903, in the middle of the
-    Potomac River at Widewater, Va. The aëroplane was placed on the same
-    catapult, above the boat, that had previously started the models on
-    their smooth and rapid maneuvers. The pilot took his seat, and started
-    the 50-horse-power engine which ran the propellers without appreciable
-    vibration. Tugs and launches were placed along the course where they
-    might be of service. Photographers, on the water and along shore, were
-    ready to furnish important pictorial records of the experiment. The
-    aëroplane was released and sped along the track attaining sufficient
-    headway for normal flight; but at the end of the rails it was jerked
-    violently down at the front, and plunged headlong into the river,
-    sinking beneath the waves. Buoyed up by its floats, it quickly rose to
-    the surface, with its intrepid pilot uninjured, and with little damage
-    to the structure.</p>
-
-  <p>As revealed by an examination of the catapult and photographs, the
-    guy post that strengthened the front pair of wings had caught in the
-    launching ways, and bent so much that those wings lost all support. The
-    aëroplane, therefore, had not been set free in the air, but had been
-    wrenched and jerked downward. Thus the launching proved nothing of the
-    propulsive or sailing powers of the machine.</p>
-
-  <p>Those who understand the principles of aviation can judge the merit of
-    Langley’s “aërodrome”<a id="FNanchor_43" href="#Footnote_43" class="fnanchor">[43]</a> from its mechanical description. As shown in
-    <a href="#Plate_XVIII">Plate XVIII</a>, it was a tandem monoplane driven by twin screws amidships.
-    The pilot seated in the little boat could control the poise and course
-    by several devices; he could shift his weight longitudinally 4.5 feet,
-    lat<span class="pagenum" id="Page_241">241</span>erally 2.5 feet; he could elevate and depress the rear double
-    rudder, which when untouched ensured steady longitudinal poise, on the
-    principle introduced by Penaud; he could steer to right and left by
-    turning about its vertical axis, the wind-vane rudder shown below and
-    rearward of the boat. The lines of lift, propeller thrust and forward
-    resistance passed through the centroid, or near it, thus providing
-    for projectile and gravitational stability. In this feature Langley’s
-    “aërodrome” far surpassed those of his immediate predecessors, whose
-    machines, by reason of their low centroid, possessed the stability of a
-    pendulum, rather than that of a dart, or swallow. These various devices
-    combined should give the craft better control in free flight than that
-    possessed by any of the models, which had flown successfully many times
-    in moderate weather.</p>
-
-  <p>If the projectile and steering qualities of Langley’s machine surpassed
-    those of its predecessors, the propelling mechanism was a still
-    greater advance in the art of aviation. The gasoline engine was a
-    marvel of lightness, power, endurance and smoothness of running. It
-    weighed, without accessories, 125 pounds, and developed 52.4 horse
-    power in actual test at a speed of 930 revolutions a minute. With
-    all accessories, including radiator, cooling water, pump, tanks,
-    carburetor, spark coil and batteries, it weighed 200 pounds, or
-    scarcely five pounds per horse power—a great achievement for that time.
-    It could run many hours continuously under full load, consuming about
-    one pound of gasoline per horse power per hour. Its five cylinders,
-    arranged radially round a single crank shaft, were made of steel lined
-    with cast iron, and measured 5 inches in diameter by 5.5 inches in
-    stroke. Its running balance was excellent. By means of bevel gears it
-    drove the twin screws at 700 revolutions per minute, giving<span class="pagenum" id="Page_242">242</span> a thrust
-    of 480 pounds, the screws being very nearly true helices of unit pitch
-    ratio and 30° width of blade, carefully formed of three radial arms
-    covered with canvas.</p>
-
-  <p>The whole machine weighed 830 pounds, including the pilot; spread 1,040
-    square feet of wing surface; measured 48 feet from tip to tip, and 52
-    feet from the point of its bowsprit to the end of its tail; soared at a
-    speed of about 33 feet a second and a ten-degree angle of flight, the
-    wings arching one in eighteen at one fourth the distance from their
-    front edge. The double rudder, at the extreme rear, measured 95 square
-    feet in each of its component surfaces.</p>
-
-  <p>It is evident from these figures, very kindly furnished by Mr. Manly,
-    the mechanical engineer in charge of the experiments, that such an
-    aëroplane had every equipment needed for a steady flight of many hours
-    in fair weather. A thrust of 490 pounds on well-designed surfaces
-    should easily carry 500 pounds of gasoline in addition to the 830
-    pounds regular weight of ship and pilot. This would enable the machine
-    to fly practically all day without renewal of supplies. It appears,
-    therefore, that Professor Langley had, in 1903, a dynamic aëroplane
-    quite the peer, in many respects, of the best that were developed
-    during the first decade of aviation, and that a mere accident, which
-    should be expected in such complex experimentation, deprived him of
-    the credit of the first man-flight on an adequately controlled and
-    powered machine. Quite true, he lacked launching wheels; but how easy
-    to add these, since they were proposed many times. He omitted the
-    front steering plane, but had a rear one serving the same purpose. The
-    worst that can be said is that he needed the equivalent of torsion
-    wings for lateral control; but in moderate weather he could have flown
-    successfully without them, as Farman, Delagrange, Paulhan<a id="FNanchor_44" href="#Footnote_44" class="fnanchor">[44]</a> <span class="pagenum" id="Page_243">243</span>have so
-    fully demonstrated. Besides, Langley had already tested the torsion
-    wing device, and contemplated using it on his large machine.</p>
-
-  <p>A second launching was attempted on the Potomac River near Washington,
-    on December 8, 1903. This time the rear guy post was injured, crippling
-    the rear wings, so that the aëroplane pitched up in front and plunged
-    over backward into the water. After some repairs it was stowed away
-    in the Smithsonian Institution, where its frame and engine are still
-    intact, its wings having been injured in the wreck and discarded. The
-    experiments were now abandoned for want of funds to continue them.</p>
-
-  <p>Notwithstanding that Professor Langley had contributed much to the
-    science of aërodynamics, by his elaborate researches, and had really
-    developed a machine capable of sustained flight, if properly launched,
-    he was subjected to unmitigated censure and ridicule; for he had
-    incurred the enmity of various journalists and wiseacres, partly by
-    his official secrecy, and partly by that natural reticence which
-    avoids premature publicity in important scientific enterprises. This
-    irresponsible criticism, combined with the cessation of work which
-    should have brought success, profoundly grieved him, and doubtless
-    hastened his death. He had, however, the satisfaction of knowing that
-    a few competent specialists appreciated his labors, and would continue
-    them to abundant fruition. A few days before his death he had the
-    gratification of receiving, from the newly formed Aëro Club of America,
-    the following communication acknowledging the value of his efforts to
-    promote aërial travel.</p>
-
-  <p><span class="pagenum" id="Page_244">244</span></p>
-
-  <h4 class="smcap">Resolutions of the Aëro Club of America</h4>
-
-  <p class="center"><i>Adopted January 20, 1906.</i></p>
-
-  <blockquote>
-    <p>“<em>Whereas</em>, our esteemed colleague, Dr. S. P. Langley, Secretary of
-      the Smithsonian Institution, met with an accident in launching his
-      aërodrome, thereby missing a decisive test of the capabilities of this
-      man-carrying machine, built after his models which flew successfully
-      many times; and whereas, in that difficult experiment, he was entitled
-      to fair judgment and distinguished consideration because of his
-      important achievements in investigating the laws of dynamic flight, and
-      in the construction of successful flying models; therefore be it</p>
-
-    <p>“<em>Resolved</em>, That the Aëro Club of America, holding in high estimation
-      the contributions of Dr. Langley to the science of aërial locomotion,
-      hereby expresses to him its sincerest appreciation of his labors as a
-      pioneer in this important and complex science; and</p>
-
-    <p>“<em>Be it further resolved</em>, That a copy of these resolutions be sent to
-      the Board of Regents of the Smithsonian Institution and to Dr. Langley.”</p>
-
-    <p>This kindly message from America’s foremost aëronautic society brought
-      a moment’s pleasure to the last hours of the illustrious scientist.
-      “Professor Langley was on his deathbed when these resolutions were
-      brought to his attention, and when asked what should be done with the
-      communication, his pathetic answer was: ‘Publish it.’ To all who know
-      his extreme aversion to publicity in any form, this reply indicates how
-      keenly he felt the misrepresentation of the press.”<a id="FNanchor_45" href="#Footnote_45" class="fnanchor">[45]</a></p>
-  </blockquote>
-
-  <p><span class="pagenum" id="Page_245">245</span></p>
-
-  <p>Professor Langley’s progress with the “aërodrome” was due largely to
-    the skill, energy and devotion of his designer and superintendent of
-    construction, Mr. Charles M. Manly. This talented young graduate in
-    mechanical engineering, of Cornell University, in 1898, went directly
-    from the class room to assume the chief burden of Langley’s researches
-    in aërodynamics, and his practical experiments in mechanical flight,
-    remaining till their termination in 1904. He was the confidential
-    secretary and adviser to his chief in that whole enterprise. When
-    in 1900 Dr. Langley stood baffled before the greatest obstacle in
-    aviation, unable to find any manufacturer, in America or Europe, who
-    could furnish a practical engine of the desired power, lightness and
-    durability, Manly came to his rescue with a design which guaranteed
-    success and which resulted in the wonderful gasoline motor built in the
-    Smithsonian shops. Finally when the aëroplane was ready to be launched,
-    it was Manly who bore the long weeks of trial in the malarial region of
-    Widewater, harassed by accidents and foul weather, not to mention the
-    merry agents of the press; and it was he who twice rode the ponderous
-    aërodrome, shot forth in mid air at the imminent risk of his life.</p>
-
-  <p>While Langley was building his great tandem monoplane, Wilbur and
-    Orville Wright of Dayton, Ohio, were developing a biplane which was
-    an improvement on the aërial glider of Chanute and Herring. This was
-    to be their preliminary effort toward achieving continuous flight.
-    Their first product, tried at Kitty Hawk, North Carolina, in the
-    summer of 1900, is shown in <a href="#Plate_XIX">Plate XIX</a>. The chief points of departure
-    from Chanute and Herring’s glider were (1) to place the rider prone
-    on the lower surface, as first proposed and tried by Wenham, forty
-    years’ previously; (2) to discard the vertical rudder; (3) to<span class="pagenum" id="Page_246">246</span> place
-    the horizontal rudder forward, as done by Mattullath and Maxim; (4)
-    to control the lateral balance by changing the impact angles of the
-    wings, as recommended by the present writer in 1893. Of these four
-    modifications the first was impractical for general use, though good
-    for soaring and possibly racing; the second was unsatisfactory and
-    later abandoned; the third was effective, and has been accepted by
-    some aviators as an improvement, but rejected by others who prefer the
-    rear<a id="FNanchor_46" href="#Footnote_46" class="fnanchor">[46]</a> horizontal rudder; the fourth proved acceptable to them, as to
-    various other inventors before and after them.</p>
-
-  <p>With this glider they made a number of satisfactory flights. The front
-    rudder and the torsional wings proved adequate to control the craft
-    in sailing straight ahead down the Kill Devil sand hills, near Kitty
-    Hawk, N. C. In this, as in all their machines to the present date, sled
-    runners, fixed under the machine, as proposed by Ader and others, were
-    used for launching and landing. With a surface of 165 square feet, they
-    could glide down a slope of 9.5° at a speed of 25 to 30 miles an hour.
-    This showed only a moderate efficiency, but it was a beginning.</p>
-
-  <p>The glider used in the summer of 1901 was modeled after that of the
-    previous year, but larger. It was 22 feet wide, 14 feet long, 6 feet
-    high, spread 308 square feet, and weighed 108 pounds. With this a
-    number of glides were made, of various lengths up to 400 feet. At a
-    speed of 24 miles an hour gravity exerted on the aërial coaster 2½
-    tow line horse power, showing an efficiency nearly equal to that of
-    Pilcher’s glider of 1897.</p>
-
-  <p>In camp with the Wright brothers in 1901 was Mr. Chanute, the leading
-    aëronautic expert in Amer<span class="pagenum" id="Page_247">247</span>ica. They thus had the advantage of
-    his long experience, both as a student of aviation and a practical
-    experimenter. With them were also two other specialists, Mr. E. C.
-    Huffaker, an experienced aëronautical investigator, who had worked
-    successively with Langley and Chanute; and Dr. G. A. Spratt, who had
-    made some important investigations on the value of curved surfaces and
-    the travel of the center of pressure with the varying angles of flight.
-    The numerous animated conferences with these gentlemen were instructive
-    and profitable. When the season closed the brothers returned home and
-    experimented on curved surfaces to improve the efficiency of their
-    glider.</p>
-
-  <hr class="page" />
-  <div id="Plate_XIX" class="center"><b>PLATE XIX.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_301a.jpg" width="600" height="408" alt="" />
-    <div class="captionp">FIRST WRIGHT GLIDER.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_301b.jpg" width="600" height="409" alt="" />
-    <div class="captionp">SECOND WRIGHT GLIDER.</div>
-  </div>
-
-<p>The 1902 machine, shown in Plate XIX, had two main surfaces, measuring
-    each 32 by 15 feet, and a front rudder measuring 15 square feet. The
-    whole weight was 116 pounds. It will be noted that a vertical rudder
-    was now employed. This was a reversion to the design of Chanute and
-    Herring, but after some experience, the rudder was made adjustable,
-    as in Henson’s aëroplane of 1842. Its surface was 12 square feet,
-    but later reduced to six. With this machine they obtained between
-    700 and 1,000 glides during the season. It showed greater efficiency
-    than its predecessors, its normal angle of descent being estimated at
-    seven degrees or less. This was some improvement over the efficiency
-    of the Chanute-Herring glider, partly due, of course, to placing the
-    rider flat, instead of allowing him the more comfortable erect posture
-    adopted later.</p>
-
-  <p>Whatever improvements of efficiency and strength had been made,
-    these were of secondary importance compared with the provisions for
-    projectile stability and manual control. Here at last, after ten
-    years’ groping, was an actual glider with sufficiently high centroid
-    to minimize the pendulum effect, and with<span class="pagenum" id="Page_248">248</span> three rudders to give
-    impactual torque about the three axes. These simple provisions had
-    been previously pointed out in aëronautic writing, and, in the latter
-    nineties, had been embodied in Mattullath’s aëroplane, but not tested
-    in the large machine, owing to his death. The wonder is that, of all
-    the practical inventors of aëroplanes, Mr. Mattullath was the only
-    one of that period fully to grasp and adopt these main ideas before
-    starting to build a man-carrying machine. However, it must be added
-    that he had previously made small flying models, which may have
-    suggested the advantage of kinetic stability and the three-torque
-    system of control. If Lilienthal and his disciples, who laid so much
-    stress on gliding experience, had started like Mattullath with three
-    torque-surfaces, they would have missed indeed those acrobatic and
-    picturesque kickings at the sky, but they would have reached the
-    desired goal with less danger, time and expense. They displayed more
-    skill in riding a fractious glider than in designing a tractable
-    one, by providing for impactual torque about each of three axes. Had
-    they started with a good theory of dynamic control, they could have
-    dispensed with coasting entirely, and commenced aviating with short
-    runs over a smooth course followed by cautious leaps in the air, after
-    the style of certain ingenious French aviators. However, the knack
-    of balancing was finally acquired, and thus the glider was ready to
-    receive the propelling mechanism.</p>
-
-  <p>In 1903 a 16-horse-power engine and twin-screw propellers were applied
-    to the navigable glider at Kitty Hawk, as shown in <a href="#Plate_XX">Plate XX</a>. The power
-    machine weighed 750 pounds, and was usually started by aid of a tow
-    line and falling weight which helped the craft to acquire headway.
-    After many trials and modifications, the first successful launchings,
-    four in number, were made on December 17th. The <span class="pagenum" id="Page_249">249</span>first flight lasted
-    12 seconds, the next two a little more, the fourth lasted 59 seconds,
-    covering a distance of 852 feet over the ground in the face of a
-    twenty-mile wind. To the superficial observer these performances did
-    not seem a very remarkable advance on the flights of Ader, but they
-    had in them greater promise and potency of practical flight. They were
-    the first flutterings of a fledgling endowed with the chief essential
-    organs of aërial locomotion—an awkward but healthy creature that had
-    been evolving steadily for several generations. It would grow rapidly,
-    and ere another half decade, increase the 59 seconds to so many minutes.</p>
-
-  <hr class="page" />
-  <div id="Plate_XX" class="center"><b>PLATE XX.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_305a.jpg" width="600" height="412" alt="" />
-    <div class="captionp">FIRST WRIGHT AËROPLANE (REAR).</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_305b.jpg" width="600" height="410" alt="" />
-    <div class="captionp">FIRST WRIGHT AËROPLANE (SIDE).</div>
-  </div>
-
-  <p>The experiments were continued during the next two years with
-    increasing success. During the season of 1904, on a field near Dayton,
-    one hundred and five flights were made, some short, others covering the
-    entire circuit of the field no fewer than four times, the two largest
-    measuring each nearly three miles, each accomplished in about five
-    minutes. Various improvements were made in the propelling and steering
-    mechanism, and increased skill in maneuvering was gradually acquired.</p>
-
-  <p>In 1905 the flights were resumed with a new machine embodying some
-    changes dictated by experience, particularly in the method of control.
-    Forty-nine landings were made involving seven breakages, but no
-    personal injury. On September 26th a flight of eleven miles was
-    achieved. This was followed, within the next nine days, by flights of
-    twelve, fifteen, twenty-one and twenty-four miles, at a usual speed
-    of 38 miles an hour. After this the field practice ceased for more
-    than two years, and the machine was dismantled to preserve secret its
-    mode of construction till the patents could be disposed of. As these
-    performances and those preceding are of unusual interest, a fuller
-    account is given in <a href="#appendix_IV">Appendix IV</a>.</p>
-
-  <p><span class="pagenum" id="Page_250">250</span></p>
-
-  <p>The Wright brothers now had to assume in aviation the rôle of cautious
-    business men. The gliding experiments had been a scientific recreation,
-    and had been fairly well reported to engineers, except in those details
-    to be covered by patent claims; but the details of the power machine
-    were withheld, or sparingly disclosed. The brothers had sacrificed
-    time and money. They were making aviation a profession. They must,
-    therefore, be repaid. But if they exhibited too promptly their machine
-    and aërodynamic data, they might jeopardize their financial interests
-    by assisting or stimulating rival aviators. On the other hand, by
-    procrastination and concealment they might, in various ways, forfeit
-    priority and scientific credit. Chanute’s glider was already familiar
-    in Europe, and it was estimated to have ample efficiency for successful
-    flight with existent motors. Their own published experiments were
-    being studied and repeated. They might, therefore, expect that, at any
-    time, some rash or cunning fellow would bolt into the air and proclaim
-    to all the world that their unpublished devices, if they possessed
-    any novelty, were by no means necessary, as they fancied, to usher
-    in actual dynamic flight. The aëroplane would thus appear to be the
-    sudden outgrowth of fertile and mature conditions, rather than the
-    product of uncommon originality. Scores of aviators would immediately
-    spring into being—chauffeurs, mechanics, sporting gentlemen of every
-    dye. Light motors being now available, any intelligent artisan could
-    power a Hargrave kite, or Chanute glider, and soar aloft. Every odd
-    craft, not too absurdly designed, would navigate, with some showing.
-    Publicity and prize money would develop and perfect the various types
-    with feverish haste. But in 1905 the Wright brothers apprehended no
-    portentous or imminent invasion of the sky. The foreign bogie was<span class="pagenum" id="Page_251">251</span> five
-    years behind, being unfamiliar with sand hill practice and the torsion
-    wing. They would, therefore, chance the result of withholding their
-    data and concealing their machine. It was a curious situation; Langley
-    and Manly, who produced the first aëroplane endowed with all the
-    essential powers of prolonged flight, were bound to official secrecy;
-    the Wrights, who had a finished machine, tried and fairly ready for
-    public exhibition, were hampered by trade secrecy. These silent leaders
-    in aviation presented a gratifying contrast to the shouting fraternity
-    who, in the daily press, announced impending marvels which never
-    materialized.</p>
-
-  <p>The same year, 1905, which crowned with most success the private
-    flights of the Wright brothers, brought into unusual prominence
-    the quarter century long experiments of Prof. J. J. Montgomery of
-    Santa Clara College, Santa Clara, Cal. He had given much attention
-    to the science of aviation, particularly to passive flight, and had
-    constructed several successful gliders operated by himself or his
-    friends. The most remarkable of these machines was a glider resembling
-    in general appearance Langley’s tandem monoplane, but having means for
-    changing the wing curvature during flight, thus varying the lift on
-    such wing, and thereby enabling the operator to control the equilibrium
-    and direction during his glides in the air.</p>
-
-  <p>On April 29, 1905, a forty-five pound glider of this pattern bearing an
-    intrepid parachute jumper, Daniel Maloney, was lifted from the college
-    grounds by a hot-air balloon to an elevation of 4,000 feet, then cut
-    loose. “In the course of the descent,” writes one of his pupils, “the
-    most extraordinary and complex maneuvers were accomplished—spiral and
-    circling turns being executed with an ease and grace almost beyond
-    description, level travel accomplished<span class="pagenum" id="Page_252">252</span> with the wind and against it,
-    figure-eight evolutions performed without difficulty, and hair-raising
-    dives were terminated by abrupt checking of the movement by changing
-    the angles of the wing surfaces. At times the speed, as estimated by
-    eye-witnesses, was over sixty-eight miles an hour, and yet after a
-    flight of approximately eight miles in twenty minutes the machine was
-    brought to rest upon a previously designated spot, three-quarters of
-    a mile from where the balloon had been released, so lightly that the
-    aviator was not even jarred, despite the fact that he was compelled
-    to land on his feet, not on a special alighting gear.” This daring
-    performance amazed the world, and most of all, the specialists who all
-    along knew such a feat to be practicable. As a further description
-    of Professor Montgomery’s wonderful experiments may interest the
-    reader, the following account, written by himself, is inserted from
-    <cite>Aëronautics</cite> for January, 1909:</p>
-
-  <blockquote>
-    <p>“When I commenced practical demonstration in my work with aëroplanes
-      I had before me three points. First, equilibrium; second, complete
-      control; and third, long continued or soaring flight. In starting I
-      constructed and tested three sets of models, each in advance of the
-      other in regard to the continuance of their soaring powers, but all
-      equally perfect as to equilibrium and control. These models were tested
-      by dropping them from a cable stretched between two mountain tops, with
-      various loads, adjustments and positions. And it made no difference
-      whether the models were dropped upside down or in any other conceivable
-      position, they always found their equilibrium immediately and glided
-      safely to earth.</p>
-
-    <p>“Then I constructed a large machine patterned after the first model,
-      and with the assistance of three cowboy friends personally made a
-      number of flights <span class="pagenum" id="Page_253">253</span>in the steep mountains near San Juan (a hundred
-      miles distant). In making these flights I simply took the aëroplane and
-      made a running jump. These tests were discontinued after I put my foot
-      in a squirrel hole, in landing, and hurt my leg.</p>
-  </blockquote>
-
-  <hr class="page" />
-  <div id="Plate_XXI" class="center"><b>PLATE XXI.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_311.jpg" width="700" height="490" alt="" />
-    <div class="captionp">MONTGOMERY’S AËROPLANE.</div>
-  </div>
-
-  <blockquote>
-    <p>“The following year I commenced the work on a larger scale, by engaging
-      aëronauts to ride my aëroplane dropped from balloons. During this
-      work I used five hot-air balloons and one gas balloon, five or six
-      aëroplanes, three riders—Maloney, Wilkie and Defolco—and had sixteen
-      applicants on my list and had a training station to prepare any when I
-      needed them.</p>
-
-    <p>“Exhibitions were given in Santa Cruz, San José, Santa Clara, Oakland
-      and Sacramento. The flights that were made, instead of being haphazard
-      affairs, were in the order of safety and development. In the first
-      flight of an aëronaut the aëroplane was so arranged that the rider had
-      little liberty of action, consequently he could make only a limited
-      flight. In some of the first flights, the aëroplane did little more
-      than settle in the air. But as the rider gained experience in each
-      successive flight I changed the adjustments, giving him more liberty of
-      action, so he could obtain longer flights and more varied movements in
-      the flights. But in none of the flights did I have the adjustments so
-      that the riders had full liberty, as I did not consider that they had
-      the requisite knowledge and experience necessary for their safety; and
-      hence, none of my aëroplanes were launched so arranged that the rider
-      could make adjustments necessary for a full flight.</p>
-
-    <p>“This line of action caused a good deal of trouble with aëronauts or
-      riders who had unbounded confidence and wanted to make long flights
-      after the first few trials, but I found it necessary as they seemed
-      slow in comprehending the important elements and<span class="pagenum" id="Page_254">254</span> were too willing to
-      take risks. To give them the full knowledge in these matters I was
-      formulating plans for a large starting station on the Mount Hamilton
-      Range from which I could launch an aëroplane capable of carrying two,
-      one of my aëronauts and myself, so I could teach him by demonstration.
-      But the disasters consequent on the great earthquake, completely
-      stopped all my work on these lines. The flights that were given were
-      only the first of the series with aëroplanes patterned after the first
-      model. There were no aëroplanes constructed according to the two other
-      models, as I had not given the full demonstration of the workings of
-      the first, though some remarkable and startling work was done. On one
-      occasion, Maloney in trying to make a very short turn during rapid
-      flight pressed very hard on the stirrup which gives a screw shape
-      to the wings and made a side somersault. The course of the machine
-      was very much like one turn of a corkscrew. After this movement, the
-      machine continued on its regular course. And afterwards Wilkie, not to
-      be outdone by Maloney, told his friends he would do the same, and in a
-      subsequent flight, made two side somersaults, one in one direction and
-      the other in an opposite, then made a deep dive and a long glide, and
-      when about three hundred feet in the air, brought the aëroplane to a
-      sudden stop and settled to the earth. After these antics, I decreased
-      the extent of the possible change in the form of wing surface so as to
-      allow only straight sailing or only long curves in turning.</p>
-
-    <p>“During my work I had a few carping critics that I silenced by this
-      standing offer: If they would deposit a thousand dollars I would cover
-      it on this proposition. I would fasten a 150-pound sack of sand in the
-      rider’s seat, make the necessary adjustments, and send up an aëroplane
-      upside down with a<span class="pagenum" id="Page_255">255</span> balloon, the aëroplane to be liberated by a time
-      fuse. If the aëroplane did not immediately right itself, make a flight,
-      and come safely to the ground, the money was theirs.</p>
-
-    <p>“Now a word in regard to the fatal accident.<a id="FNanchor_47" href="#Footnote_47" class="fnanchor">[47]</a> The circumstances are
-      these: The ascension was given to entertain a military company in which
-      were many of Maloney’s friends, and he had told them he would give the
-      most sensational flight they ever heard of. As the balloon was rising
-      with the aëroplane, a guy rope dropping switched around the right wing
-      and broke the tower that braced the two rear wings and which also gave
-      control over the tail. We shouted Maloney that the machine was broken
-      but he probably did not hear us, as he was at the same time saying
-      ‘Hurrah for Montgomery’s air ship,’ and as the break was behind him,
-      he may not have detected it. Now did he know of the breakage or not,
-      and if he knew of it did he take a risk so as not to disappoint his
-      friends? At all events, when the machine started on its flight the rear
-      wings commenced to flap (thus indicating they were loose), the machine
-      turned on its back and settled a little faster than a parachute. When
-      we reached Maloney he was unconscious and lived only thirty minutes.
-      The only mark of any kind on him was a scratch from a wire on the side
-      of his neck. The six attending physicians were puzzled at the cause
-      of his death. This is remarkable for a vertical descent of over 2,000
-      feet.”</p>
-  </blockquote>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_X">
-    <span class="pagenum" id="Page_256">256</span>
-    <h3>CHAPTER X</h3>
-    <span class="small">ADVENT OF PUBLIC FLYING</span>
-  </div>
-
-  <p><span class="smcap">In</span> 1903, Mr. Ernest Archdeacon stimulated by a conference with Mr.
-    Chanute, at a meeting of the Aëro Club of France, founded a prize of
-    3,000 francs to be awarded to the first person who should sail or
-    fly 25 meters, with a maximum descent not exceeding one third of the
-    range. As yet no one in either hemisphere had flown in a practical
-    machine, but various aviators were industriously pluming their wings.
-    Captain Ferber had been a follower of Lilienthal since 1898, and a
-    pupil of Mr. Chanute since 1891. Dozens of votaries in France, not
-    to mention other countries, had entered, or were about to enter, the
-    aviation field. Archdeacon himself, Voisin, Blériot, Esnault-Pélterie,
-    Vuia, Delagrange, Tatin, Cornu, Bazin, Levavasseur and many others,
-    were stanch apostles of the heavier than air. Many of these were
-    disciples of Lilienthal, but they were destined all to be distanced
-    by an impetuous Hensonite, who could not realize the necessity for
-    spending months, or years, cautiously coasting downhill to acquire the
-    adroitness requisite to speed a flying chariot over the plain.</p>
-
-  <p>In 1906, while many aviators in Europe were developing flyers, and
-    cautiously testing them in various ways, by gliding above sand or
-    water, or swinging from a high wire or traveling arm, Señor Alberto
-    Santos-Dumont, of Brazil, brought forth in France the quaint and crude
-    biplane shown in <a href="#Plate_XXII">Plate XXII</a>.<span class="pagenum" id="Page_257">257</span> Aërodynamically this was not a great
-    improvement on the aëroplane of Sir George Cayley constructed 98 years
-    earlier; but it had a petrol motor whose power and lightness would
-    have astounded that talented pioneer in aviation. The motor was an
-    eight-cylinder Antoinette, weighing 170 pounds and developing 50 horse
-    power. The screw, formed of two aluminum blades, was of two meters
-    diameter, one meter pitch, mounted on the engine shaft, and, at 1,500
-    revolutions a minute, gave a thrust of 330 pounds. The total lifting
-    surface of the aëroplane was 650 square feet, and the weight, including
-    pilot, 645 pounds. This bird-shaped craft ran tail foremost through the
-    air, having the screw at the rear, and the rider in a small basket just
-    before the wings. By means of a pilot-wheel and lever, he could operate
-    the “tail,” i. e., the front rudder, sidewise and vertically, thus
-    steering the craft in two directions. The lateral balance was preserved
-    automatically by means of the dihedral inclination of the wings, aided
-    sometimes by the rider swaying his weight to right or left.</p>
-
-  <p>After some days of preliminary adjustment and trial, Santos-Dumont was
-    ready for a dash in his new aëromobile. On August 22d, 1906, he made
-    a brief tentative flight, the first witnessed in Europe since Ader’s
-    surreptitious experiment. On October 23d, he ran this strange machine
-    swiftly over the ground and glided boldly into the air, flying above
-    the excited spectators at a speed of 25 miles an hour, and covering
-    a distance of 200 feet, thus gaining the Archdeacon cup. Again on
-    November 12th, 1906, he made four flights, the last one covering 220
-    meters in twenty-one seconds, thus gaining the prize of 1,500 francs
-    offered by the Aëro Club of France for the first person who should fly
-    100 meters. The demonstration was made before the general public<span class="pagenum" id="Page_258">258</span> and
-    technical witnesses, including an official committee of the Aëro Club
-    of France, who reported that the aëroplane preserved good balance and a
-    true soaring speed independent of the acquired momentum.</p>
-
-  <p>Intrinsically the achievements of November 12th were crude and
-    primitive; but in moral effect they were very important. They marked
-    the inception of public aëroplaning before the professional and lay
-    world alike. There was no patent mechanism to conceal, no secret to
-    withhold from rivals, such as had shrouded the work of more circumspect
-    aviators in Europe and America. If Santos-Dumont was not the first to
-    fly, he was the first aëroplane inventor to give his art to the world,
-    and to inaugurate true public flying in presence of technical men, as
-    he had initiated modern motor ballooning. His liberal enthusiasm and
-    that of his colleagues, both aëroplanists and patrons, quickly made
-    France the world’s foremost theater of aviation, at least for the
-    moment. The contagion would of course spread swiftly, and involve the
-    entire civilized world.</p>
-
-  <p>Santos-Dumont’s unconventional dash into the air sounded the knell of
-    Lilienthalism. This slow method served to pass time profitably in the
-    nineties, while the gasoline motor was still developing. But with an
-    <i>Antoinette</i> in hand, what live man, particularly what live Frenchman,
-    could tinker long years on the sand hills? Why not mount the craft
-    on little wheels and take a cautious little run; then after some
-    adjustment, make more runs followed by innocuous saltatory flights?
-    This would be so easy, so fascinating, so instructive. How much better
-    than to make two thousand preliminary jumps down the hill slope
-    with the body dangling wildly to keep the balance, then to redesign
-    the entire frame before an engine could be successfully applied!
-    An <i>Antoinette</i><span class="pagenum" id="Page_259">259</span> motor, placed on a competently designed Henson
-    aëroplane, would have obviated the whole Lilienthal school. However,
-    they did noble and opportune work, while awaiting the growth of the
-    gasoline engine. This school achieved success by a roundabout method
-    because Henson’s method was not available till the present century,
-    for want of a cheap, light motor. When that appeared Lilienthalism
-    quickly subsided. In other words, Lilienthal’s method was a passing
-    convenience, never a necessity. It could have been employed very
-    profitably in Cayley’s time to develop the art of gliding and soaring;
-    but in the time of Santos-Dumont and his colleagues, flying by Henson’s
-    method would have burst upon the world by reason of its superior value
-    and the allied progress, even if the Lilienthal school had never
-    existed. This is illustrated by the fact that Santos-Dumont succeeded
-    without aid from the sand-hill votaries.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXII" class="center"><b>PLATE XXII.</b></div>
-
-  <div class="figcenter w600">
-    <img src="images/i_319a.jpg" width="600" height="409" alt="" />
-    <div class="captionp">SANTOS-DUMONT’S BIPLANE.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_319b.jpg" width="600" height="410" alt="" />
-    <div class="captionp">SANTOS-DUMONT’S <i>DEMOISELLE</i>.</div>
-    <div class="small">(Courtesy A. J. Moisant.)</div>
-  </div>
-
-  <p>The next daring aëroplanist to arouse the world of aviation was Henri
-    Farman, also a votary of the wheel-mounted flyer. He had been an adept
-    motorist, therefore accustomed to brisk driving. In the summer of
-    1907 he received from the Voisin brothers the aëroplane illustrated
-    in <a href="#Plate_XXIII">Plate XXIII</a>. With this he made a number of preliminary flights
-    during the autumn, proving that his aëroplane had suitable stability
-    and motive power. On October 26th, on the government drill grounds at
-    Issy-les-Moulineaux he surpassed Santos-Dumont’s record, by flying
-    771 meters. But this was to him of minor importance; he was preparing
-    to win the Deutsch-Archdeacon prize of 50,000 francs offered for the
-    first person who should fly one kilometer over a returning course.
-    On January 12th, he convoked a committee of the Aëro Club of France
-    to witness a trial on the morrow. Next morning at ten o’clock, the<span class="pagenum" id="Page_260">260</span>
-    weather being calm and clear, his great machine ran a hundred yards
-    across the course, then rose gracefully into the air, and sailed away
-    for the 500-meter post. Here, making a wide curve, it rounded safely
-    and returned, passing the home line in elegant flight, thus winning the
-    grand prize.</p>
-
-  <p>The machine with which Farman achieved his first success, and which
-    broadly resembles his subsequent triumphal flyers, seems to be a cross
-    between a Hargrave kite and a Chanute glider, having a Maxim horizontal
-    steering plane in front. As shown in the figure it was mounted on
-    four bicycle wheels; was steered up and down by the front plane, and
-    sidewise by the box rudder seen in the rear. The rider seated between
-    the large supporting surfaces, and in front of his engine, operated
-    these rudders separately, by pushing or rotating a pilot wheel, and
-    abetted the automatic lateral balance by swaying his body. The machine
-    spread 559 square feet of sustaining surface, weighed 1,100 pounds
-    and carried a 50-horse-power <i>Antoinette</i> motor actuating a single
-    two-blade aluminum propeller 6.9 feet in diameter by 3.6 feet pitch,
-    directly connected to the engine shaft. The stability in mild weather
-    was so great that Farman, during his first few weeks’ practice, made
-    over 200 flights, measuring in length from 100 to 500 yards, without
-    serious mishap. In gusty weather, however, his machine was defective
-    in steadiness, and unsafe near the ground. This objection was remedied
-    later by adding flexible wing margins for controlling the lateral
-    balance.</p>
-
-  <p>The age of prize flying was thus fairly ushered in by the feeble but
-    very important public demonstrations of Santos-Dumont and Henri Farman.
-    Other public flyers would quickly follow. Delagrange, Blériot, Curtiss
-    would soon become international figures, not to mention numerous more
-    recent avia<span class="pagenum" id="Page_261">261</span>tors. They, were men of originality, skill and energy,
-    who would shortly be in the front line contesting for world laurels,
-    and winning them gloriously.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXIII" class="center"><b>PLATE XXIII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_323a.jpg" width="600" height="302" alt="" />
-    <div class="captionp">FARMAN BIPLANE, 1908.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_323b.jpg" width="600" height="295" alt="" />
-    <div class="captionp">FARMAN BIPLANE, 1909.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_323c.jpg" width="600" height="296" alt="" />
-    <div class="captionp">HARMON IN FARMAN BIPLANE.</div>
-  </div>
-
-  <p>Leon Delagrange, the sculptor-inventor, who first had demonstrated
-    the biplane, on March 30, 1907, aspired in 1908 to outfly Farman.
-    He now practiced industriously on the military drill ground at
-    Issy-les-Moulineaux, a large field which the Minister of War permitted
-    the Aëro Club of France to use for such purpose. Here he and Farman,
-    in friendly competition, flew day by day over gradually increasing
-    courses. At times they were joined by other aviators, and thus the
-    drill grounds at Issy became famous as an aviation school.</p>
-
-  <p>Farman’s new rival made startling progress during those frequent trials
-    of March, 1908. “Just imagine,” he says, “that within a week I was
-    able to complete my education as an aviator.” On March 17th he made an
-    official flight of 269.6 meters, thus winning a prize of 200 francs
-    offered by the Aëro Club of France for a beginner who should fly over
-    200 meters. Four days later he engaged in contest with Farman. Two
-    poles were erected 500 meters apart to mark the points about which the
-    men must race. The machines were brought forth from their sheds in
-    the morning, gleaming dimly through a dense fog, and were given some
-    preliminary trials. Then Farman made a flight of 2004.8 meters, going
-    twice around the course in 3 minutes, 31 seconds. He thus trebled his
-    grand prize flight of January. Presently Delagrange took wing and flew
-    1,500 meters in 2.5 minutes. Having been beaten by Farman, he invited
-    his successful rival to take a seat behind him, and the two sailed away
-    close to the ground, covering a distance of 50 meters. This was the
-    first trip ever made by two<span class="pagenum" id="Page_262">262</span> men in one flying machine. For the first
-    time also two machines had flown in competition over a considerable
-    course.</p>
-
-  <p>Delagrange continued to pursue Farman for the championship. On April
-    11th, he flew 2,500 meters, and would have exceeded Farman’s official
-    record of 2,004 meters, had he not touched the ground. The next day
-    he summoned the official committee of the Aëro Club of France to
-    witness and time his performance. Poles were erected at the corners
-    of a triangle 350, 200, 275 feet apart respectively. Around this
-    course he flew nearly five times, covering a distance of 5,575 meters
-    in 9¼ minutes. Of this range the last 3,925 meters were covered
-    without touching the ground. Thus at last he had out-flown Farman and
-    established a new official record, the total distance actually covered
-    being about ten kilometers, or approximately six miles. This ended,
-    at least temporarily, the friendly competition at Issy; for now the
-    aviators separated, Farman going to Belgium, Delagrange to Italy.</p>
-
-  <p>Delagrange’s fortune accompanied him abroad. On May 24th, he made some
-    impressive demonstrations on the Place d’Armes at Rome in presence of
-    the Minister of War and thirty thousand people. On May 27th, he flew
-    before the King and Queen of Italy and many other court personages,
-    remaining in the air nine and one half minutes, thus surpassing all
-    previous European records for endurance and distance. But this was
-    only preliminary. On the morning of May 30th, he came forth again on
-    the Place d’Armes, a light breeze blowing. His machine rolled quickly
-    over the ground, then circled gracefully ten times around in the air
-    at a height of four to seven meters, covering an official distance of
-    12.75 kilometers, and remaining aloft 15 minutes, 26 seconds. On June
-    22d, at Milan, he flew before 15,000<span class="pagenum" id="Page_263">263</span> people in the Place d’Armes,
-    covering seventeen kilometers in 16 minutes, 30 seconds. Finally, on
-    September 6th, at Issy-les-Moulineaux, he flew 29 minutes, 54 seconds,
-    covering 14.8 miles, which proved his crowning effort for the year. As
-    the two flights just mentioned surpassed all previous official ones
-    in duration, it appears that Delagrange raised the world’s record
-    four times within five months, increasing his own time from six and a
-    half minutes in April to about thirty minutes in September, or nearly
-    fivefold.</p>
-
-  <p>In the meantime, Farman was making rapid progress, gathering prizes and
-    achieving wide renown. On May 30th, at Ghent, Belgium, taking with him
-    M. Archdeacon, he flew 1,241 meters at a height of seven meters. He
-    thus established a new record with two people, and won the 1,200 franc
-    wager made with Santos-Dumont and Archdeacon against M. Charron, who
-    contended that a flying machine would not, within the year, carry two
-    men weighing sixty kilograms each. On June 6th he flew 20 minutes, 20
-    seconds, covering 19.7 kilometers, thus again increasing the world’s
-    record, and winning the Armengaud prize of ten thousand francs for the
-    first aviator to remain aloft fifteen minutes in France. On September
-    29th and October 2d, at Chalons, he successively increased the world’s
-    record, and achieved his best results for the year. The first of these
-    trials lasted 42 minutes, covering 24.5 miles; the second lasted 44.5
-    minutes, covering 25 miles. This last flight was forty times as long as
-    the one of January, which gave him the grand prize of fifty thousand
-    francs, and is a good index of the wonderful progress in aviation
-    made in France during the year 1908. Between these two performances
-    he, on September 30th, sailed from Chalons to Rheims, a distance of
-    27 kilometers, in twenty minutes. This<span class="pagenum" id="Page_264">264</span> flight was made over trees
-    and houses, sometimes at an elevation of 200 feet, and was the first
-    town-to-town flight ever accomplished. The following day he won the 500
-    franc prize for height, passing over balloons 82 feet from the ground.
-    Such was the lively pace Farman set for the rest of the world.</p>
-
-  <p>Mr. Curtiss drifted into the business of building and operating air
-    ships and flying machines by frequent association with inventors, who
-    came to his bicycle works at Hammondsport, N. Y., for assistance in the
-    design and construction of aërial craft. He was particularly sought as
-    a constructor of propelling mechanism, for he had special skill and
-    experience in producing light gasoline engines. As a motor expert he
-    was invited to the laboratory of Dr. Alexander Graham Bell, at Beinn
-    Breagh, near Baddeck, Nova Scotia, in the summer of 1907. Dr. Bell had
-    developed his wonderfully light, strong and stable tetrahedral kites
-    to such an extent that he wished to convert them into “aërodromes” by
-    applying light propelling mechanism. He accordingly invited two young
-    Canadian engineers, F. W. Baldwin and J. A. D. McCurdy, to consult
-    with him regarding the structural details of his proposed flyer,
-    and contracted with Mr. Curtiss to supply the motive power. These
-    gentlemen with Lieutenant T. Selfridge, a guest of Dr. Bell, developed
-    so many independent ideas that Mrs. Bell suggested the advantage of
-    forming themselves into a scientific organization, at the same time
-    offering the capital required for experimentation. Acting on this
-    advice and generous offer, they formed themselves into the now famous
-    Aërial Experiment Association, whose object was the construction of a
-    practical aëroplane, driven through the air by its own motive power,
-    and carrying a man.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXIV" class="center"><b>PLATE XXIV.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_329a.jpg" width="600" height="245" alt="" />
-    <div class="captionp">THE <i>RED WING</i>.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_329b.jpg" width="600" height="281" alt="" />
-    <div class="captionp">CURTISS BIPLANE.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_329c.jpg" width="600" height="296" alt="" />
-    <div class="captionp">CURTISS BIPLANE WITH PONTOONS.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_265">265</span></p>
-
-  <p>After some preliminary downhill glides<a id="FNanchor_48" href="#Footnote_48" class="fnanchor">[48]</a> and studies with a motorless
-    aëroplane, the association, on March 12, 1908, brought forth their
-    first dynamic machine, the <i>Red Wing</i>, shown in Plate XXIV, in order
-    to speed it along the ice of Lake Keuka, near Curtiss’s factory; the
-    purpose being, not to fly, but to test the effect of the vertical
-    rudder. To the surprise of the twenty-five onlookers, the machine,
-    after running two hundred feet along the ice, serenely rose into the
-    air and flew 319 feet. “This,” says Dr. Bell, “was the first public
-    exhibition of the flight of a heavier-than-air machine in America.”
-    It is noteworthy also that this machine was completed and ready for
-    trial in less than seven weeks from the time of starting. Its design,
-    while embodying suggestions from each member of the association, was
-    attributed chiefly to Lieutenant Selfridge, who took the leading part
-    in evolving the plans, and who gave them his final approval, it being
-    the intention of the association to offer each man a chance to produce
-    a flying machine after his own notions, aided by the experience and
-    liberal advice of his fellows.</p>
-
-  <p>As the advantage of flying from the ice had been suggested some years
-    before the death of Lilienthal, it seems remarkable that this method
-    did not yield important results earlier in the development of aviation.
-    A smooth ice field is such an ideal place for testing a dynamic
-    aëroplane, that previous gliding experience would seem unnecessary,
-    providing the machines were designed with a fair knowledge of the
-    elementary principles of stability and control. Even glider practice
-    could be effectively conducted over a smooth ice field after momentum
-    had been acquired by aid of gravity, or a tow line. Having sufficient
-    momentum the aviator could test his rud<span class="pagenum" id="Page_266">266</span>ders cautiously without rising,
-    then, after a little experience, make short glides in the air, and so
-    be prepared to install the motor. Landing or falling on smooth ice at
-    great horizontal speed, from a low elevation, is much less hurtful than
-    tumbling on the ground, as every bold skater knows from experience.</p>
-
-  <p>The aëroplane II, designed by Mr. Baldwin, aided by his associates
-    and their combined experience, resembled that of Lieutenant Selfridge
-    in the trussing of its body surfaces, but was mounted on wheels, and
-    provided with torsional wing tips for lateral control. When tested, it
-    was found easy to launch and land, besides responding very promptly to
-    the three-rudder control. In the hands of Mr. Curtiss, on May 22d, this
-    aëroplane, called the <i>White Wing</i>, flew 1,017 feet in 19 seconds, and
-    landed smoothly on a plowed field. This at the time was the longest
-    flight ever made by an aviator in his first trip on a heavier-than-air
-    machine.</p>
-
-  <p>It was now Mr. Curtiss’ turn to be captain of design and construction.
-    Under his supervision aëroplane III, called the <i>June Bug</i>, was ushered
-    forth, in the month of honeymoons. It differed from the two preceding
-    in having a box tail; also in having a nainsook cover, instead of the
-    red and white silk that characterized the <i>Red Wing</i> and the <i>White
-    Wing</i>.</p>
-
-  <p>After some practice, this flyer behaved so well that it seemed
-    competent to win the Scientific American Cup offered for a public
-    flight of one kilometer straight away. Accordingly an official trial
-    was arranged with a committee of the Aëro Club of America, for the
-    fourth of July, 1908. It was the first official flight in the western
-    hemisphere, and proved in every way most satisfactory. The machine
-    flew 2,000 yards over an S-shaped course at a speed of 39 miles an
-    hour, displayed admirable control, and<span class="pagenum" id="Page_267">267</span> had abundant motive power. The
-    performance was an intimation and augury of the victorious flights to
-    come the following year. As the Association now repaired to Dr. Bell’s
-    summer home, the Hammondsport experiments terminated for the season.</p>
-
-  <p>The year 1908 also brought to happy fruition the long and persistent
-    experiments of Louis Blériot, the most illustrious pioneer and
-    champion of the monoplane. Beginning in 1900, he had tried one type
-    after another, of flying machine, till he became world renowned for
-    his fertility of invention, his daring, his picturesque accidents and
-    hairbreadth escapes. So long as he was not killed he was certain to
-    make progress; for he had every endowment that ensures success. He
-    possessed the energy of early manhood, having been born in 1872; he
-    had the thorough technical training of the Central School of Arts and
-    Manufactures, where he graduated in 1895; he possessed extraordinary
-    talent for invention and constructional detail; he had the prowess,
-    courage and coolness requisite for testing intractable and dangerous
-    flyers; he was in the world’s most active center of aviation; he
-    also had sufficient means. If he was late in achieving success, it
-    was because he preferred to develop original ideas, and could not be
-    content with merely copying his predecessors.</p>
-
-  <p>Like many other novices in aviation, Blériot began by trying to build
-    a machine with flapping wings that should fly like a bird. This was to
-    be actuated by a carbonic acid motor. In 1904 he abandoned his first
-    machine, of bird type, and turned to aëroplanes, beginning with a
-    biplane of the Farman, or Voisin type. His second machine was built by
-    Gabriel Voisin, one of the most experienced of the pioneer aëroplane
-    manufacturers. This biplane, unprovided with an engine, was mounted
-    on floats, towed along the Seine by a motor boat, and rose from the<span class="pagenum" id="Page_268">268</span>
-    surface carrying Voisin as pilot. <i>Blériot III</i>, composed of elliptical
-    cells, or sustaining surfaces, and powered with two <i>Antoinette</i>
-    motors of 25 horse power each, was tested without success on Lake
-    Enghien during the year 1905–6. <i>Blériot IV</i> was made of quadrangular
-    cells, and launched at Bagatelle in 1906, carrying a soldier, Peyret;
-    but crashed to earth in its first trial. Finally in 1907, <i>Blériot
-    V</i>, mounted by the inventor himself, rose into the air and flew
-    successfully, but was lacking in stability. His sixth aëroplane was
-    of the Langley type, provided with a 24-horse-power motor, then with
-    a 50-horse-power <i>Antoinette</i>; but it was unstable fore and aft. One
-    day it traversed 184 meters, then fell from a height of 25 meters and
-    was shattered on the ground. His seventh was one of the swiftest yet
-    constructed, attaining a speed of nearly 80 kilometers an hour, and, in
-    two private trials, covering a distance of 500 meters. Thus seven years
-    had slipped away, leaving Blériot still in the tentative period of his
-    work. But now he was at the threshold of a career of brilliant success,
-    which soon brought him the highest honors at home and throughout the
-    world.</p>
-
-  <p>After various minor flights in the spring and summer of 1908, Blériot,
-    on October 31st of that eventful year in aviation, determined to
-    attempt a cross country voyage, as Farman had done the day before. As
-    will be remembered, Farman had flown from Chalons to Rheims, above
-    trees and houses, a distance of nearly 17 miles, thus achieving the
-    first town-to-town flight in history. Blériot would improve that record
-    at once, by flying in a closed circuit embracing several villages.</p>
-
-  <p>His renowned cross-country flight was directed from Toury to Artenay, a
-    village nine miles distant. Mounting his aëroplane <i>VIII-ter</i>, at mid
-    afternoon, <span class="pagenum" id="Page_269">269</span>in presence of a large gathering, Blériot followed the
-    course shown in Fig. 40. In the neighborhood of Artenay he landed for a
-    few minutes. After some slight repairs to his magneto, he reascended,
-    turned about and headed for home. Half way on his return course he
-    stopped again for a few minutes, at the Village of Santilly; then
-    readily reascended and flew to the neighborhood of his starting point.
-    He thus traveled about 17 miles in a closed circuit. This performance,
-    with that of Farman the day before, inaugurated the period of aërial
-    voyages in heavier-than-air machines. It appealed so powerfully to the
-    sentiment of the community that a monument was erected at Toury to
-    commemorate the glorious achievement.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXV" class="center"><b>PLATE XXV.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_335a.jpg" width="600" height="194" alt="" />
-    <div class="captionp">BLÉRIOT FLYING OVER TOURY-ARTENAY CIRCUIT.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_335b.jpg" width="600" height="297" alt="" />
-    <div class="captionp">BLÉRIOT MONOPLANE <i>NO. VIII</i>.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_335c.jpg" width="600" height="294" alt="" />
-    <div class="captionp">BLÉRIOT MONOPLANE <i>NO. IX</i>.</div>
-  </div>
-
-  <div class="figcenter">
-    <a id="Fig_40"><img src="images/i_337.jpg" width="550" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 40.—Blériot’s Toury-artenay Aëroplane Circuit, 1908.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_270">270</span>A fair view of the famous monoplane, in its renowned cross-country
-    voyage, is presented in <a href="#Plate_XXV">Plate XXV</a>. It consisted of a single sustaining
-    surface firmly attached to a long trussed spine mounted on three
-    wheels, and carrying at its front end the gasoline motor and propeller,
-    at its rear end two of the rudders, the third, or lateral, rudder
-    being placed at the wing terminals. A part of the trussed frame was
-    covered, to minimize the atmospheric resistance against the framing,
-    pilot and engine. The vertical rudder at the rear turned the machine
-    to right or left; the horizontal rear rudder controlled the elevation
-    and pitching of the machine; the torsional wing tips controlled the
-    lateral stability, and could be used to cant the aëroplane or check its
-    listing, as in the Wright and Curtiss machines. The craft exhibited an
-    easy poise in the air, and possessed good equilibrium, owing to its
-    arrowlike structure and its three-rudder system of control. It was a
-    strong rival of the biplanes previously noticed, and a herald of better
-    things to come.</p>
-
-  <p>In the meantime the Wright brothers had resumed their field practice.
-    During the month of May, 1908, they tested their famous aëroplane of
-    1905, provided with increased engine power, and carrying two passengers
-    upright. A few brief flights were made at speeds of 41 to 44 miles an
-    hour, showing that all the mechanism was adequate and effective. But on
-    May 14th a false push on a<span class="pagenum" id="Page_271">271</span> lever, made by Wilbur Wright, brought the
-    flyer to earth, wrecking it too badly to be repaired in the few days
-    available for experimentation. These flights were but preliminary to
-    the official trials set for the approaching summer; for the brothers
-    had contracted to furnish one machine to the United States Signal
-    Corps, another to a French syndicate.</p>
-
-  <p>The Chief Signal Officer of the United States Army in December, 1907,
-    had issued specifications, and invited bids, for a flying machine
-    apparently far in advance of the art. The flyer was to carry two men
-    aggregating 350 pounds, was to remain aloft one hour continuously, and
-    was to maintain an average speed of 40 miles an hour in a cross-country
-    flight to and fro, covering a distance of ten miles. The contractor
-    must instruct two officers to operate the flyer. Furthermore the
-    machine must be capable of flying 125 miles without stopping. The
-    requirements seemed severe, even to those well versed in aviation.
-    Nevertheless two bids were received; one from the Wright brothers for a
-    biplane to cost $25,000, another from Mr. A. M. Herring for a biplane
-    costing $20,000. Both bids were accepted for the summer of 1908; but
-    only the Wright contract was eventually carried out.</p>
-
-  <p>About the same time the Dayton inventors had sold their patent rights
-    in France to a syndicate in that country. The contract specified
-    a machine for two passengers, having a speed of 50 kilometers an
-    hour, and a range of 125 miles. Furthermore, the inventors agreed to
-    instruct three pupils to manage the aëroplane. The fulfillment of
-    these two contracts occupied some months, but presented no formidable
-    difficulties. Though neither of the brothers had ever flown an hour,
-    and though both were comparatively unskilled as operators, they had
-    such faith in their invention that they undertook to<span class="pagenum" id="Page_272">272</span> launch themselves
-    publicly in untried machines, Wilbur Wright in France, Orville in
-    America, at about the same time.</p>
-
-  <p>Of these two tests, the one conducted by Orville Wright at Fort Myer,
-    near Washington, was the most successful at first. After a few brief
-    preliminary trips, he suddenly astonished the world by phenomenal
-    flying. On the morning of September 9, 1908, he made a voyage above
-    the drill ground lasting 57 minutes, 31 seconds, and again in the
-    evening another flight lasting one hour and three minutes, this time
-    before a throng of distinguished spectators. Immediately thereafter
-    he took aboard Lieut. Frank P. Lahm for a flight of six minutes’
-    duration. These records were improved day by day, and all things
-    seemed propitious for the official tests of speed and endurance.
-    But on September 17th, while sailing with Lieutenant Selfridge at a
-    height of about 75 feet, a blade of the right-hand propeller struck
-    and loosened a stay wire of the rear rudder. Instantly the wire coiled
-    about the blade, snapping it across the middle. Thereupon the machine
-    became difficult to manage, and plunged headlong to earth, throwing the
-    men with their faces on the bare ground, fatally wounding Lieutenant
-    Selfridge, and seriously injuring Mr. Wright. Lieutenant Selfridge did
-    not recover consciousness, and died within three hours, from wounds
-    on the forehead and concussion of the base of the brain. Mr. Wright
-    suffered a fracture of the left thigh and of two ribs on the right
-    side. The aëroplane was badly shattered in its framing, but the engine
-    was practically intact. This accident terminated the tests for the
-    season; but ere long a date was set for their resumption during the
-    following year.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXVI" class="center"><b>PLATE XXVI.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_341a.jpg" width="600" height="280" alt="" />
-    <div class="captionp">WRIGHT BIPLANE OF 1908.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_341b.jpg" width="600" height="277" alt="" />
-    <div class="captionp">STANDARD WRIGHT BIPLANE OF 1910.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_341c.jpg" width="600" height="281" alt="" />
-    <div class="captionp">WRIGHT RACING BIPLANE OF 1910.</div>
-  </div>
-
-  <p>Wilbur Wright began his demonstration for the French syndicate on the
-    plain of Auvours, ten miles <span class="pagenum" id="Page_273">273</span>from Le Mans, France, on August 8,
-    1908. For some weeks his flights were very brief, owing to the balky
-    condition of his engine; but this difficulty was removed by the middle
-    of September. After the accident to his brother he remained inactive
-    for a few days; then, to reassure his supporters, he raised the world’s
-    record by flying a distance of over 52 miles, remaining aloft 1 hour,
-    31 minutes, 25 seconds. After this he continued at frequent intervals
-    to make long flights, quite usually taking a passenger with him, and on
-    several occasions a lady. His endurance, his altitude, his abandon and
-    perfect control amazed and delighted Europe. Incidentally he won some
-    valuable prizes, beating the French records for duration, distance and
-    elevation. Once he rose to a height of 380 feet. On September 21st, he
-    flew 42 miles in 1 hour and 31 minutes; on October 11th, he carried a
-    passenger an hour and ten minutes; finally on the last day of the year
-    he flew 77 miles in two hours and twenty minutes, thus winning the
-    much coveted Michelin prize, of twenty thousand francs for the longest
-    distance flown during the year. It was a triumphal close to the most
-    progressive and eventful year in aviation—the first year of exhibition
-    flying, the inaugural year of a noble art.</p>
-
-  <p>Having completed the speed and distance tests at Le Mans by the close
-    of the year 1908, Wilbur Wright went to Pau, in the South of France,
-    for the winter practice with his three pupils, Count de Lambert, Paul
-    Tissandier and Alfred Leblanc. Here on the vast trial grounds at Pont
-    Long, six miles from Pau, he had a commodious hangar with a workshop
-    on one side, and on the other, apartments for the aviator and his
-    mechanics. He arrived with his pupils, on January 14th, and next day
-    was joined by his brother and sister, who had followed him from Paris,
-    Orville being now well recovered from his<span class="pagenum" id="Page_274">274</span> injuries received at Fort
-    Myer. In a short time the machine was set up, and early in February
-    began its regular service, having a pair of levers for the teacher and
-    another pair for the passenger. The pupils quickly acquired the art of
-    steering, being first allowed to control one lever, with Mr. Wright
-    holding the other; then being entrusted to manage the whole machine,
-    with their tutor as passenger; and finally becoming themselves teachers
-    of the newly acquired art. Only a few hours’ practice was needed to
-    attain proficiency, the whole time in the air aggregating hardly half a
-    day for each pupil, though the lessons extended over many days.</p>
-
-  <p>A pleasant feature of the sojourn at Pau and Le Mans was the number
-    and character of the visitors, and the boundless enthusiasm displayed
-    toward the new art. Tens of thousands of people from the neighboring
-    places, and tourists from many parts of the earth assembled to see the
-    flights; statesmen, military officers, scientific and parliamentary
-    delegations, representatives of innumerable periodicals. Queen
-    Margherita, having missed a flight on her first visit to Le Mans,
-    came a second time, and remained three hours standing on the field,
-    fascinated by the wonderful aërial equipage. The King of Spain, Alfonso
-    XIII, who visited the aërodrome at Pau, on February 20th, manifested
-    the keenest interest and delight in examining the aëroplane and seeing
-    it fly; first with the pilot alone, then with an extra passenger. He
-    took a seat in the machine beside Mr. Wright, discussed its working,
-    and expressed his deep regret that reasons of state prevented him from
-    making an ascension. A month later the King of England, who was at
-    Biarritz, adjourned to Pau, where he remained to witness two unusually
-    fine flights. He expressed the greatest pleasure in the performance,
-    questioned the brothers about the details <span class="pagenum" id="Page_275">275</span>of the machine, and
-    complimented them on their achievement.</p>
-
-  <p>From Pau, Wilbur Wright went to Italy, about the end of March, to
-    fulfill an engagement to give demonstrations and lessons in the use of
-    the biplane. He was welcomed at Rome by the King of Italy, on April 2d,
-    and later gave a public exhibition of flying, to aid the sufferers in
-    the recent earthquake at Messina. His flights were attended with great
-    enthusiasm, and his lessons in aviation were quickly mastered; his
-    pupil, Lieutenant Calderara, soon making public flights alone. A rare
-    sight it was, this modern winged chariot soaring above the ruins of
-    that ancient campagna, bearing with it a moving-picture camera.</p>
-
-  <p>By the end of April Mr. Wright had finished his task in Italy, and was
-    journeying homeward with his sister and brother by way of London, where
-    they enjoyed the hospitalities of the Aëronautical Society of Great
-    Britain; and where, on May 3d, the brothers received the beautiful gold
-    medal of that famous society, the oldest aëronautical organization in
-    the world.</p>
-
-  <p>The return to America was primarily for the purpose of completing
-    the official tests at Fort Myer; but incidentally the brothers must
-    find time to receive new honors and ovations. While in the shop at
-    Dayton, working vigorously to complete a new aëroplane for the War
-    Department, in the hope of finishing the demonstrations by June 28th,
-    the limit of their allotted month, they were showered with attentions
-    too numerous for their comfort. They must drop their tools in order to
-    go to Washington to receive the gold medal of the Aëro Club of America
-    from President Taft, at the White House, on June 10th. On June 17th
-    they must witness an elaborate demonstration in their honor at Dayton,<span class="pagenum" id="Page_276">276</span>
-    where they received a gold medal from the city, another from the State,
-    and another from the Federal Government. Finally late in June, they
-    arrived in Washington with the rehabilitated biplane, to make good
-    their contract with the Signal Corps.</p>
-
-  <p>The early tests of this aëroplane were not an unmixed triumph for the
-    Wright brothers and their well-wishers. At first the machine failed to
-    fly completely about the drill ground. It took the air with difficulty,
-    and came to the earth on the first turn. Some lack of adjustment in the
-    frame was suspected. The motor was accused of weakness. The launching
-    weights<a id="FNanchor_49" href="#Footnote_49" class="fnanchor">[49]</a> were too light. The brothers explained that a new flyer
-    is like a new horse; the driver must learn his idiosyncrasies before
-    attempting to show him off to advantage. They intimated also that
-    they would be pleased to have the great throng of prominent people,
-    who flocked daily to the drill ground, kept away until their flying
-    instrument was properly tuned for public performances. They discouraged
-    superfluous attentions. The big legislators who ventured audaciously
-    to peep into the sacred shed containing the marvelous machine, were
-    hailed by the military guard, and unceremoniously marched across the
-    line among the plain people. It was a dreadful shock to these mighty
-    signors, and many a fat lawmaker cursed audibly, vowing never to vote
-    a cent for flying squadrons. But still they haunted the drill ground
-    daily, despite the long journey and the late dinner; for they were
-    fascinated by the untold and unconjecturable possibilities of the new
-    art.</p>
-
-  <p>June 28th came quickly, obliging the patient aviators to beg another
-    extension of time. They <span class="pagenum" id="Page_277">277</span>were granted thirty days longer, which seemed
-    to them more than necessary; but in this judgment they were mistaken.
-    One accident after another delayed the consummation of their official
-    task of flying one hour above the field, then five miles across country
-    and return. Finally, on July 27th, Orville Wright, who was making all
-    the flights, took with him Lieut. Frank P. Lahm, and sailed gloriously
-    for one hour, twelve minutes and forty seconds, before ten thousand
-    delighted spectators. It was an ideal summer evening, and all the
-    maneuvers were performed with excellent poise, security and grace. A
-    new world’s record was established. Now all the vast throng from the
-    President and his cabinet to the simplest laborer, appreciating the
-    achievement as a triumph for America and for humanity, burst forth into
-    prolonged acclamation and applause.</p>
-
-  <p>The cross-country flight was next in order. The course from Fort
-    Myer to Alexandria lay over scattered forests and a deep valley. The
-    flight seemed a difficult and hazardous enterprise; but the brothers,
-    confiding in their machine, seemed to have little apprehension of
-    failure or peril. Indeed, they seemed most concerned about the bonus
-    to be secured by flying at an average rate exceeding the contract
-    speed of 40 miles an hour; for each additional mile an hour would pay
-    them $2,500 above the normal price of the aëroplane. They accordingly
-    declined to fly in any but very calm weather, no matter how vast the
-    gathering of visitors, or how illustrious. They wished, of course, to
-    expedite the final and crucial test; but they could not always have
-    ideal conditions, and would not take undue chances. On the evening
-    after the endurance test the engine balked, owing to the clogging of a
-    rubber pipe from the gasoline tank. Dusk came on, and the disappointed
-    crowd went home to a late dinner.<span class="pagenum" id="Page_278">278</span> The Secretary of War, who was
-    present, very kindly granted a third extension of time, covering the
-    rest of the month. Next evening it was a trifle breezy. Wilbur Wright
-    announced that the flight could be made, but that the bonus would
-    be less than on a still evening; he would therefore wait for calmer
-    weather. Twelve thousand people were turned away disappointed. There
-    was muttering among the impatient and warm of blood. It was remarked
-    that the War Department could easily drop these procrastinated
-    experiments and buy a practical aëroplane in the open market for
-    $5,000. But the discommoded officers good-naturedly allowed the thrifty
-    sons of Dayton to have their way in striving for a large bonus, beyond
-    the normal price of $25,000.</p>
-
-  <p>On the following evening the weather was clear and fairly still. All
-    was in readiness for the flight to Alexandria and return. Orville
-    Wright, taking with him Lieut. B. D. Foulois, circled the drill ground
-    on easy wing, then sailed directly across country for the captive
-    balloon at Shuter’s Hill. In a few moments they vanished beyond the
-    forest, and for a while even the most optimistic were doubtful of their
-    safety. At length they reappeared sailing homeward at very great speed.
-    The machine proudly circled the drill ground amid thunders of applause,
-    and landed softly at the lower end, beyond the shed.</p>
-
-  <p>The multitude hastened to congratulate the aviators on their marvelous
-    performance. For everybody it was a scientific and national triumph;
-    for Wilbur Wright it was something more. With pencil and pad he quickly
-    computed the bonus, surrounded by a wall of reporters. “Wise old
-    Wilbur,” remarked one, “he knows the worth of coin in a crude republic.
-    While Fame blows her trumpet he counts the solid gain.” The figures
-    showed an average<span class="pagenum" id="Page_279">279</span> speed of 42.6 miles, making the bonus $5,000. The
-    voyage was one of the finest ever executed up to that date; it was
-    a glorious termination to a long and troublesome, but epoch-making
-    demonstration. Now there remained only the task of instructing two
-    officers to fly, and this was leisurely accomplished by Wilbur Wright
-    in October.</p>
-
-<p>As shown in <a href="#Plate_XXVI">Plate XXVI</a> the Wright aëroplane used at Fort Myer in
-    September, 1908, was a twin screw biplane mounted on skids and having
-    the three-rudder system of control. The rear rudder turned the machine
-    right or left, the front rudder raised or lowered it, the warping of
-    the wings controlled the lateral poise. The turning right or left
-    could be effected on level wing; but the inventors canted the machine
-    sidewise, to obviate skidding, or sidewise gliding of the craft, due
-    to centrifugal force. These three-rudder movements were performed by
-    three separate levers actuating suitable mechanism; but they could be
-    performed easily by a single lever having three separate movements, as
-    preferred by some designers. The aëroplane in launching ran along a
-    monorail, accelerated by a towrope passing over pulleys, and attached
-    to a falling weight comprising nearly a ton of iron. The dimensions of
-    the various parts are given as follows by Major George O. Squier,<a id="FNanchor_50" href="#Footnote_50" class="fnanchor">[50]</a>
-    the officer in charge of the experiments:</p>
-
-  <blockquote>
-    <p>“The aëroplane has two superposed main surfaces 6 feet apart with
-      a spread of 40 feet, and a distance of 6½ feet from front to rear.
-      The area of this double supporting surface is about 500 square feet.
-      A horizontal rudder of two superposed plane surfaces about 15 feet
-      long and 3 feet wide is placed in front of the main surfaces. Behind
-      the main <span class="pagenum" id="Page_280">280</span>planes is a vertical rudder formed of two surfaces trussed
-      together about 5½ feet long and one foot wide. The motor, which was
-      designed by the Wright brothers, has four cylinders and is water
-      cooled. It develops about 25 horse power at 1,400 r. p. m. There are
-      two wooden propellers 8½ feet in diameter which are designed to run at
-      about 400 r. p. m. The machine is supported on two runners and weighs
-      about 800 pounds.”</p>
-  </blockquote>
-
-  <p>On the whole the demonstrations at Fort Myer in 1909 did not greatly
-    enhance the prestige of aviation. They were attended by too many delays
-    and accidents, and too much waiting for ideal weather. As a consequence
-    the guardians of the national purse were not clamoring for an aërial
-    flotilla. Some few, no doubt, understood that the aëroplane could
-    brave more than a zephyr with safety; but the general public accepted
-    the demonstrations at their face value. The unthinking multitude did
-    not realize that with sufficient incentive, such as war presents,
-    the Wright brothers could repeat those brilliant flights, of the end
-    of July, under more severe weather conditions. Fortunately, events
-    were transpiring elsewhere which vastly increased the popular fame
-    and valuation of the new art. This refers more particularly to those
-    startling achievements in aviation abroad which were largely stimulated
-    by competition and prizes.</p>
-
-  <p>After the Fort Myer flights the Wright brothers separated, Orville
-    going to Germany to represent their interests and give demonstrations;
-    Wilbur exhibiting at the Hudson-Fulton celebration in New York, and
-    teaching the Signal Corps officers to manipulate the newly purchased
-    government aëroplane. As usual, both achieved distinction in their new
-    fields. At Potsdam, on October 2d, Orville Wright, after a ten-minute
-    flight with Crown Prince Frederic<span class="pagenum" id="Page_281">281</span> William, ascended alone, mounting
-    steadily in circles for fifteen minutes, and reaching an elevation
-    roughly estimated at 500 meters, after which he descended safely in
-    five minutes. On September 18th, he made a new record at Berlin by
-    carrying a passenger, Captain Englehardt, for 1 hour, 35 minutes and 47
-    seconds. Wilbur Wright, on September 9th, flew from Governor’s Island,
-    in New York harbor, to and around the Statue of Liberty, then returned
-    to the point of departure. On October 4th, starting from the same
-    point, he flew over the waters of New York Bay and above the Hudson
-    River to a point opposite Grant’s Tomb, then returned to Governor’s
-    Island, covering a distance of about 19½ miles in 33½ minutes. The
-    trip upward was made at an elevation of about 200 feet, through a
-    stratum disturbed by vortices rising from the steamer smokestacks, and
-    eddies caused by the northeast wind blowing over the tall buildings.
-    The return was made at a level of 50 feet on the Jersey side of the
-    river where the air was less turbulent. He intended later in the day
-    to make a long flight, but, owing to the bursting of a cylinder head,
-    he stopped his demonstrations and returned to Washington to finish
-    his instruction of the Signal Corps officers. This was easy routine,
-    and it afforded opportunity to try the effect of transferring one of
-    the forward steering planes to the rear and applying it there as a
-    fixed horizontal tail, as used by Voisin, Curtiss and others. The new
-    arrangement was reported to increase the longitudinal steadiness of the
-    aëroplane, and was used in subsequent Wright aëroplanes.</p>
-
-  <p>The brothers now ceased public flying for a while, to attend to the
-    business of manufacturing and selling their craft. They formed an
-    American company, enlarged their facilities for constructing machines,
-    procured grounds for training operators, and<span class="pagenum" id="Page_282">282</span> prepared generally to
-    fill orders both for aëroplanes and for public exhibitions. Not the
-    least of their labor was to defend their patent claims, which they
-    wished to be interpreted so broadly as practically to exclude all
-    flyers whose lateral poise is controlled by changing the angle of
-    incidence of the wings, or of lateral stabilizing planes. This was
-    not an easy undertaking, since the torsion wing was a well-known
-    device, having been described many times in public print, and having
-    figured in earlier patents and experiments in various countries. To
-    add to the difficulty, their patent claims apply specifically to the
-    warping of normally flat sustaining surfaces, the warping of arched
-    wings having been patented by Prof. J. J. Montgomery, whose invention
-    antedates theirs.<a id="FNanchor_51" href="#Footnote_51" class="fnanchor">[51]</a> However, if they produced no novel and radical
-    invention in aviation, they, like Santos-Dumont in aëronautics, were
-    first to achieve some measure of practical success, by applying a light
-    automobile engine to a familiar machine in which former inventions
-    and ideas were skillfully employed. On this ground of practical
-    success they strove for an interpretation broad enough to establish
-    a monopoly covering even Montgomery’s rights, which apparently they
-    were infringing. But when to this end they applied for a preliminary
-    injunction restraining Curtiss from using his system of control, and
-    Paulhan from using Farman’s system, they were unable to convince the
-    court of the justice of their petition, and the injunction suit was
-    vacated.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XI">
-    <span class="pagenum" id="Page_283">283</span>
-    <h3>CHAPTER XI</h3>
-    <span class="small">STRENUOUS COMPETITIVE FLYING</span>
-  </div>
-
-  <p><span class="smcap">The</span> cardinal allurements in aviation for 1909 were the prize offered
-    for the first flight across the English Channel, and the prizes to be
-    won at the world’s first aviation meet, scheduled for the last week
-    in August of that year, at Rheims, France. The desire to win these
-    honors stimulated to livelier effort the most noted designers and
-    operators of aëroplanes, all of whose machines were represented at the
-    great tournament. It also brought into sudden prominence several new
-    aviators. Young men, little versed in the science or literature of
-    flight, took to wing, and in a few days found themselves world-famous.
-    Aërial chauffeurs, skillful and daring, delighted vast throngs of
-    people, kept the cables warm with news, and incidentally filled their
-    purses with money. Thus the trade of aëroplane jockey was one of the
-    interesting products of this eventful year.</p>
-
-  <p>The first half of the aviation season of 1909 brought forth many
-    improvements which seemed to augur well for the public demonstrations
-    to follow. Hubert Latham, with the swallowlike <i>Antoinette</i> monoplane,
-    designed by Levavasseur, the inventor of the <i>Antoinette</i> motor, began
-    soaring grandly in the sky and into fame. Paul Tissandier, on May 20th
-    at Pau, established a new French record by flying 1 hour and 2 minutes.
-    The Voisin brothers were perfecting in detail their boxlike aëroplanes,
-    noted for inherent stability, and destined to achieve further <span class="pagenum" id="Page_284">284</span>renown
-    during the summer, under the dexterous hand of intrepid young Paulhan.
-    This new and daring young aviator, after a few practice flights, began
-    making world records. On July 15th, he flew 1 hour, 7 minutes and
-    19 seconds. On July 18th he made a new world’s record for altitude,
-    driving his Voisin aloft 150 meters at Douai. Impatient Roger Sommer,
-    rejecting his own make of biplane, purchased a machine from Farman,
-    and after a little practice, broke the world’s record for distance on
-    August 7th, by flying at Chalons, 2 hours, 27 minutes, 15 seconds. Many
-    others were advancing in skill, and would erelong achieve excellent
-    results. Most strenuous of all, perhaps, were Curtiss and Blériot, the
-    champions of high speed, respectively in the biplane and monoplane, and
-    Farman, the winner of large prizes.</p>
-
-  <p>In the latter part of April, Henri Farman tested a new biplane of
-    his own design and manufacture, which proved very satisfactory. It
-    resembled his former craft, but was provided with small balancing
-    planes hinged to the rear margins of the wings near their tips.
-    This machine, furthermore, was provided with both landing skids and
-    wheels, the latter yielding to any unusual stress by means of elastic
-    connections, so that the skids took up the shock. With this improved
-    biplane, Farman beat his former records by flying continuously 1 hour,
-    23 minutes, at Chalons, on July 19th. Four days later he made a new
-    cross-country record by flying from the Chalons parade ground to Suppe,
-    about forty miles, in 1 hour and 5 minutes. These flights were gently
-    suggestive of what might be expected at Rheims the following month.</p>
-
-  <p>During the opening period of the 1909 aëroplane season, Glenn H.
-    Curtiss brought forth a new biplane, designed for the Aëronautic
-    Society of New<span class="pagenum" id="Page_285">285</span> York, with the coöperation of his new partner, Mr. A.
-    M. Herring, and began active practice for various prizes at home and
-    abroad. After some brief trials at Hammondsport, N. Y., he shipped his
-    aëroplane to Morris Park, in order to participate in the Aëronautic
-    Society’s first flight exhibition of the year. On June 26th he flew,
-    but without official witness, far enough to win one of the $250
-    prizes offered to the Aëro Club of America by its president, Mr.
-    Cortlandt Field Bishop, for the first four persons who should fly one
-    kilometer. He now wished to make an official flight for this prize
-    and also for the Scientific American trophy, a beautiful engraved
-    silver cup—which he had won a year previously for the first public
-    flight of one kilometer, made in America, but which now should go to
-    the person making the longest official flight of the year 1909, not
-    under 25 kilometers. But the Morris Park race track proved unsuitable
-    for such contest, being too restricted. He therefore took his biplane
-    to Mineola, Long Island, where he could practice on a wide plain, and
-    possibly make some new records. Here a triangular course 1.3 miles long
-    was staked off, and some short trial flights were made. Then Mr. C. M.
-    Manly, who was official timekeeper for the Aëro Club of America, was
-    notified that a trial for the prize would be made.</p>
-
-  <p>The demonstrations near Mineola were most successful, and proved the
-    beginning of a brilliant summer for Mr. Curtiss. On July 17th he won in
-    quick succession both of the prizes mentioned above. The trial for the
-    smaller prize began at 5.15 in the morning and lasted but 2½ minutes,
-    followed 6 minutes later by the start for the coveted cup. In both
-    cases the machine took the air with ease and grace, after a 200-foot
-    run over the rough marsh land. In the cup trial the first twelve
-    turns, aggregating 25 kilometers, <span class="pagenum" id="Page_286">286</span>were accomplished in 33½ minutes,
-    but the machine continued for seven more rounds, and finally landed
-    in excellent form, just 52½ minutes after it had crossed the starting
-    line. The actual measured distance flown was 24.7 miles, but the true
-    distance traversed by the machine was probably 30 miles, making the
-    time speed between 30 and 40 miles per hour. This was slow, indeed, but
-    the control was satisfactory. Those who wished for high speed would
-    find it in the new aëroplane which Mr. Curtiss would presently take to
-    Rheims for the speed contest, in which he was to fly as sole champion
-    of the United States.</p>
-
-  <p>The type of machine used by Mr. Curtiss in 1909 was a natural outgrowth
-    of his previous ones, but very much perfected in power and finish. It
-    was a biplane mounted on a three-wheeled chassis, two wheels under the
-    main body and one well to the front, so as to prevent toppling forward.
-    It was propelled by a single screw at the rear, directly connected to
-    a water-cooled motor of the Curtiss make. Its flight was controlled
-    by three rudders exerting torque respectively about the three axes of
-    the aëroplane, supplemented by two fixed keels, a vertical one in the
-    front and a horizontal one in the rear. Of the three rudders mentioned,
-    one in the rear turned the craft right and left, like a boat, one in
-    the front raised or lowered her, while the third or lateral rudder,
-    consisting of small horizontally pivoted planes between the wing-ends,
-    and turning oppositely to each other, controlled the lateral poise.
-    These lateral rudders, or winglets, used by Curtiss, Farman and others,
-    are commonly called <i xml:lang="fr">ailerons</i>.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXVII" class="center"><b>PLATE XXVII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_357a.jpg" width="600" height="384" alt="" />
-    <div class="captionp"><i>BLÉRIOT XI</i> WITH MOISANT AVIATOR ON MEXICAN BORDER.</div>
-    <div class="small">(Courtesy A. J. Moisant.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_357b.jpg" width="600" height="298" alt="" />
-    <div class="captionp"><i>BLÉRIOT XII.</i></div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <p>Louis Blériot with his two new machines, his <i>No. XI</i> at Douay and
-    his <i>No. XII</i> at Issy-les-Moulineaux, practiced nearly every fine
-    day in June and July, making fast progress in the art, and achieving
-    some <span class="pagenum" id="Page_287">287</span>notable records. By warping the wings he could keep his
-    balance better than in former years, and dare more severe weather.
-    On June 12th, he made a straightaway flight of 820 feet in his <i>No.
-    XII</i>, taking as passengers A. Santos-Dumont and A. Fournier, the
-    entire weight being 1,232 pounds. This was the first flight of three
-    passengers in an aëroplane. On June 25th, despite a strong wind, he
-    circled in his <i>No. XII</i> eleven times about the parade ground at
-    Issy-les-Moulineaux in 15½ minutes, maintaining excellent stability.
-    Next day he made 30 circuits in 36 minutes, 55⅗ seconds, stopping
-    finally because of spark failure due to excess of oil. On July 4th,
-    at the aëronautic meet at the Juvisy Aërodrome, for sufferers from
-    the earthquake in the south of France, he flew in his <i>No. XI</i> for 50
-    minutes, 8 seconds, at a height of 50 to 80 feet, finally stopping
-    because of feed trouble in his engine. This flight was his second up to
-    that date. On July 13th, he made a new cross-country record by an early
-    morning flight in his <i>No. XI</i> from Etampes to within eight miles of
-    Orleans, stopping some minutes en route, to show the practicability of
-    his monoplane. Thirty-five minutes after landing, his machine was taken
-    apart and shipped back to his factory at Neuilly, near Paris. After
-    this record he received gold medals from the Aëro Club of Great Britain
-    and the Aëro Club of France. He was also awarded the <i>Prix de Voyage</i>
-    of 14,000 francs, of which he himself received 5,000 as pilot, 4,000 as
-    constructor, while 3,000 went to the motor manufacturer and 2,000 to
-    the propeller designer.</p>
-
-  <p>The monoplanes <i>No. XI</i> and <i>No. XII</i> represented Blériot’s most
-    successful types. They bore a family resemblance to his preceding
-    machines, but had a more vigorous lateral control due to warpage of
-    their main surfaces instead of the wing-tips, as of<span class="pagenum" id="Page_288">288</span> old. Both were
-    provided with a single-screw propeller in front, and both were mounted
-    on three-wheeled chassis with shock absorbers. The larger machine, or
-    <i>No. XII</i>, had a wing surface of 337 square feet; the smaller a surface
-    of 151 square feet. The latter, on its historic cross-Channel trip,
-    carried a three-cylinder air-cooled Anzani engine.</p>
-
-  <p>Hubert Latham, in his beautiful <i>Antoinette</i> monoplane, began to
-    achieve distinction for himself and his admirably designed long-tailed
-    flyer early in the spring, and, ere midsummer, was one of the favorite
-    idols of the thronged aërodromes. He preferred a lofty course; he
-    cut through the sky with the precision and grace of a winged-spear;
-    he fascinated the spectators by the steadiness of his sweep. The
-    French reporters declare they saw him roll and light cigarettes in
-    full flight. Not only did he delight the artist, but he surprised the
-    official measurer. Toward the end of May he established a new monoplane
-    record by a flight lasting 37 minutes and 3 seconds. On the 5th of
-    June he flew continuously 1 hour, 7 minutes and 37 seconds, at a speed
-    of 45 miles an hour. This was done in a wind and heavy rain which
-    drenched and blinded him, finally inducing him to come down. On June
-    7th he carried a passenger, something new for a monoplane. In July he
-    increased the altitude record by flying 450 feet high. Next day he
-    flew across country from Arras to Douai, 12½ miles, in 20 minutes.
-    Very reasonably, therefore, he announced, his intention of sailing for
-    England above the waters of the turbulent strait.</p>
-
-  <p>The <i>Antoinette</i> monoplane resembled, at a distance, a long-winged
-    fish with its head cut off and replaced by a screw-propeller. It had a
-    skifflike body with the screw in front, followed by the <i>Antoinette</i>
-    engine, then by the pilot’s seat, the tail part carrying fixed
-    horizontal and vertical fins and mov<span class="pagenum" id="Page_289">289</span>able horizontal and vertical
-    rudders. These rudders together with <i xml:lang="fr">ailerons</i>, or warping wings,
-    controlled the poise in flight. The body was mounted on a light chassis
-    having cushioned wheels, and a landing skid for absorbing shocks. The
-    engine employed no carburetor, and was cooled by water which turned
-    to steam in the engine jackets, condensed in tubes on the side of the
-    prow, then was pumped back to the jackets.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXVIII" class="center"><b>PLATE XXVIII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_361a.jpg" width="600" height="407" alt="" />
-    <div class="captionp"><i>ANTOINETTE</i> MONOPLANE OF 1909.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_361b.jpg" width="600" height="410" alt="" />
-    <div class="captionp"><i>ANTOINETTE</i> MONOPLANE OF 1910.</div>
-  </div>
-
-  <p>The cross-Channel prize, above mentioned, was a cash sum of one
-    thousand pounds, offered by the <cite>London Daily Mail</cite> for the first
-    successful flight from France to England. Many would fain have it,
-    though the voyage seemed dangerous, if not foolhardy. Of the various
-    aviators who coveted the prize, Latham and Blériot were the most
-    strenuous in competing for it. The bold boy tried first.</p>
-
-  <p>Housing his aëroplane on the high cliff facing the Channel near Calais,
-    Latham looked toward England, impatiently waiting for placid weather,
-    and a chance to soar. The venture was hazardous. By some it was deemed
-    rash, owing to the uncertainty of having to alight upon the water, if
-    the motor should fail. But the brave youth was less alarmed than the
-    old aviators, who had no intention of competing with him. So, with a
-    boy’s confidence, he brought forth his huge-winged <i>Antoinette</i>, on
-    July 19th, skimmed along the ground, soared grandly above the high
-    cliffs, and sped over the waters at a great elevation, as usual in his
-    aërial voyages.</p>
-
-  <p>Latham’s flight was magnificent, but brief. Owing to spark failure
-    and the stoppage of his motor six miles from the French shore, he
-    settled promptly, but skillfully, down upon the sea. When found by
-    the accompanying torpedo boat destroyer, detailed to follow him from
-    Calais, he was seated on the aëroplane, serenely smoking, buoyed up by
-    the great<span class="pagenum" id="Page_290">290</span> hollow wings. He was quickly brought to shore, undaunted and
-    eager for another trial; but in the rescue his frail flyer was roughly
-    handled and very much wrecked.</p>
-
-  <p>Louis Blériot now hurried to Calais eager to attempt the cross-Channel
-    flight. Placing his little monoplane, <i>No. XI</i>, in a tent on a farm
-    near Calais, he waited an opportune moment to sail. On Sunday, July
-    25th, he was routed from bed very early by his friend, Alfred LeBlanc,
-    and taken forth all reluctant to the field, for preliminary practice
-    before sunrise; for the weather was favorable and he should sail as
-    soon as the sun arose. Though suffering from a foot burned in a recent
-    accident, he discarded his crutches and mounted his winged machine with
-    eager courage, remarking: “If I cannot walk I will show the world that
-    I can fly.” For some minutes he circled about the ground where, even
-    at that early hour, many scores of people were assembling. All was now
-    in readiness; the flyer was in excellent trim, the pilot in buoyant
-    spirits, and the torpedo boat destroyer, <i>Escopette</i>, well out at sea
-    to escort her swift aërial charge as well as might be.</p>
-
-  <p>The moment of departure had come. Blériot, buttoned in his
-    close-fitting suit and hood, sat on his white-winged machine, headed
-    for the cliff, and surrounded by a group of well-wishers. At 4.35 the
-    light-wheeled craft with propeller whirring, sped along the ground,
-    rose gracefully in the air and shot bravely over the precipice, with
-    the hustling aviator on its back. The admiring spectators were wild
-    with excitement and joy. But there was one sad group in Calais that
-    morning. Latham and his watchers, who had been waiting for better
-    weather, rose in time to see his rival on the wing, but too late for
-    pursuit, as the wind had suddenly risen.<span class="pagenum" id="Page_291">291</span> The unwary boy remained
-    behind, weeping with disappointment.</p>
-
-  <p>Blériot was now soaring high over the sea, faring toward Dover without
-    a guide or a compass. For some time he could observe the <i>Escopette</i>
-    following him, her great column of smoke obscuring the new risen sun.
-    Presently both shores vanished, and for ten minutes he could descry
-    neither land nor signal of any kind. He was sailing over the sea at
-    forty miles an hour and drifting with the air he knew not whither; but
-    he allowed his fiery steed to follow its instinct, as a bewildered
-    horseman does sometimes. Along the horizon now appeared the white
-    cliffs of the English shore. He was headed not for Dover but for
-    Deal, carried adrift by the southwest wind. Three boats crossing his
-    course seemed plying for some port on his left, and hailed him with
-    lively greeting. He could not well inquire the way, but he followed
-    the general course of the vessels, soaring high aloft. At length he
-    saw a man on the cliff violently waving the tricolor, and strenuously
-    shouting: “Bravo! Bravo!” He plunged in the direction of the signaler,
-    whom he knew to be his friend M. Montaine. On nearing the earth he was
-    caught in a violent turmoil of air and whirled about. Wishing to land
-    at once, he stopped his power sixty feet aloft, and swooped abruptly
-    down with an awakening thud upon the old English soil, sleeping in the
-    peaceful sunlight of a Sabbath morning.<a id="FNanchor_52" href="#Footnote_52" class="fnanchor">[52]</a></p>
-
-  <p>Blériot’s landing was the greatest jolt to British insularity since the
-    birth of steam navigation. Nevertheless it was welcomed with unfeigned
-    delight as emphasizing the triumph of a new art which enriches all
-    people. Shortly afterward was erected <span class="pagenum" id="Page_292">292</span>on the spot a monument in white
-    granite having the plan and size of the renowned <i>No. XI</i> monoplane.</p>
-
-  <p>Sportsmanlike, Latham wired his congratulations to Blériot, expressing
-    the hope to follow ere long. Two days later he flew across the Channel
-    to within one mile of the English coast, where he had to land in the
-    water again because of motor failure. This time he struck the sea
-    violently and suffered a broken nose. His goggles were shattered and
-    cut his face.</p>
-
-  <p>The big competitive flyers of the world now turned toward Betheny
-    Plain near Rheims, where the first International Aviation Meet was to
-    be held August 22–29, 1909. Here was a place to make record flights,
-    to win rich prizes, and to achieve great distinction. A well-designed
-    aërodrome had been prepared for the occasion. In the midst of a broad
-    plain was marked by means of high poles, or pylons, a rectangular
-    course, measuring roughly one by two miles, or more exactly, 1,500 by
-    3,500 meters. At one end was the judges stand, the grand stand, the
-    café and the aëroplane sheds. The numerous cash prizes offered for
-    speed, for distance, for endurance, for altitude, etc., totaled in
-    value nearly forty thousand dollars. But the most coveted prize of
-    all was the James Gordon Bennett Aviation Cup, together with $5,000
-    cash, the winner of which should have the honor of placing the next
-    international contest in his own country. This should be awarded to the
-    aviator having the best speed over a two-round, or 20-kilometer course.
-    The next most desired prize was a cash sum of $10,000 for the longest
-    flight. A special charm of the tournament was that each fortunate
-    entrant should meet the distinguished aviators from all localities, and
-    should fly in presence of a world-gathering. Aëroplanes of all the most
-    successful <span class="pagenum" id="Page_293">293</span>types were there, numbering together thirty-eight machines.</p>
-
-  <p>The first day of the great aviation week, Sunday, August 22d, was
-    devoted to elimination trials to determine which aviators should
-    represent France in the race for the Bennett trophy. Of the seventeen
-    entrants in these trials the three who should cover two rounds of
-    the course in the shortest time should be selected as champions, the
-    next six, in order of speed, to act as reserve pilots. But owing to
-    the severe weather of that day, only six of the seventeen entrants
-    succeeded in flying well enough to be admitted in either capacity.
-    Of these six the cup champions were: Blériot, Lefebvre, Lambert and
-    Latham; the reserve champions being in order, Tissandier, Paulhan and
-    Sommer. These men won their places by bold flying in rough conditions;
-    for rain had fallen heavily during the previous night, and the wind
-    was still blowing in swift and gusty current over the sodden field.
-    Indeed, the weather seemed anything but propitious at the opening of
-    that great experimental tournament, on the success of which should be
-    based the estimates and forecast of so many subsequent meets. Swift
-    clouds overhead, and black flags displayed on high masts, indicated
-    that flying would be impossible. A passing storm raged at five o’clock
-    in the afternoon. But toward evening the face of Nature brightened,
-    and with it the hopes of the aviationists. The weather at last became
-    ideal. Nearly all the aëroplanes came forth, and at six o’clock no
-    fewer than seven were on the wing at one time. Some of them were
-    doing most startling feats. Lefebvre would make a threatening swoop
-    at the grand stand, then circle swiftly away. Blériot, in a moment of
-    unsteadiness, charged a wheat stack with his swift monoplane, damaging
-    his sharp-bladed propeller. Count de<span class="pagenum" id="Page_294">294</span> Lambert sailed under Paul
-    Tissandier, heedless of the aërial wake beneath. The crowds applauded
-    and cheered every novel and bold maneuver. The closing hour with its
-    sunny calm atmosphere and its vivacious well-pleased populace, presaged
-    greater joys for the morrow. Sir Henry Norman, who was present,
-    declared that those events marked the birth of a new epoch in human
-    development.</p>
-
-  <p>Monday, the second day of the meet, dawned fair and calm, with
-    promise of settled weather. It was the last qualifying day for
-    the ten-thousand-dollar long-distance prize, the Grand Prix de la
-    Champagne. No one who had not flown a reasonable space on, or before
-    Monday, could take part in the trials for that coveted honor on
-    Wednesday, Thursday and Friday. The aviators were about early, and many
-    had qualified before evening. Several of the pilots tried for speed
-    records. Blériot, with an 80-horse-power monoplane, made one round of
-    the course in 8 minutes, 42⅖ seconds. Curtiss, in his 60-horse-power
-    biplane, lowered the time to 8 minutes, 35⅗ seconds. This was an
-    achievement of the greatest concern, since Curtiss stood alone, as
-    champion of America, against the more experienced flyers of Europe.
-    He thought of nothing, engaged in nothing, except the speed trials,
-    for in these he hoped to win, with his 60-horse flyer, even against
-    renowned Blériot, in his 80-horse machine. Other interesting events
-    were designed solely to entertain or amuse the people. Lefebvre again
-    furnished merriment by sweeping over and under, and around Paulhan, who
-    was flying at an elevation of 25 feet. M. Kapferer had navigated from
-    Meaux, in the dirigible <i>Colonel Renard</i>, and sailed about the grounds,
-    with fine effect.</p>
-
-  <p>Tuesday should have brought ideal conditions and performances; for it
-    was the day set for the<span class="pagenum" id="Page_295">295</span> visit of M. Falliéres, President of France.
-    But the morning was dark, with ominous clouds gathering over the
-    aërodrome, and black flags streaming in the strong wind. When the
-    President arrived, though the clock told four, no flying had yet begun.
-    He examined the machines, held an informal reception, and at five took
-    his box in the grand stand. Presently Bunau-Varilla in his Voisin
-    biplane, rocking in the fifteen-mile wind, flew past, waving his hat to
-    the distinguished spectators. After him came dauntless young Paulhan
-    who also passed the President, shortly before the latter, with his
-    party, returned to the railway station. He flew at an elevation of 300
-    to 500 feet, his Voisin heaving and lurching in the tumultuous wind,
-    like a boat on the breakers. He had no lateral stabilizing plane, so
-    he let his box kite rock. The people were appalled, but what cared he
-    for wind gusts, so far from earth? Let the craft roll and pitch; he
-    was not uneasy. On the return lap he raced and beat a railway train.
-    These were but inklings of what he would do with increased experience.
-    Latham followed presently on his long swift monoplane, to the delight
-    of all who love the graceful in mechanism and motion. Ere long he
-    was chased and overhauled by Blériot, in his cross-Channel flyer.
-    This was exciting, but Blériot produced still greater enthusiasm by
-    beating the speed record, lowering it to 8 minutes, 4⅖ seconds, for
-    one round of the 10-kilometer (6.21 mile) course. The day was ended,
-    and the spectators were charmed again by the spectacular evolutions
-    of Lefebvre, who cavorted in the air before the grand stand, cutting
-    impressive curves and figure “8’s.”</p>
-
-  <p>Wednesday morning, the fourth of the meet, was heavy with black clouds,
-    which presaged unfavorable weather. The winds were light, but still
-    nothing transpired till late in the afternoon to break the<span class="pagenum" id="Page_296">296</span> monotony
-    of waiting. During this long interval the crowd could amuse itself
-    with gossip, refreshments and music, and with an occasional flight of
-    lesser moment. About four o’clock Paulhan set forth in a six-mile wind
-    to try for the Grand Prix de la Champagne. His lumbering Voisin had
-    a speed of hardly more than thirty miles an hour, but it was driven
-    by a very reliable 50-horse Gnome 7-cylinder motor, whose body spins
-    round a fixed crank, carrying the propeller with it. No one at first
-    expected a very long flight. The wind rose, sometimes exceeding 20
-    miles an hour, tossing the young pilot terribly, and once throwing
-    him so far within the course that he must turn a complete circle in
-    order to round the corner post, or pylon. But he kept right on, so
-    long as there remained a drop of fuel. He first broke Wilbur Wright’s
-    best record, by 23 minutes, then Sommer’s recent record, by 6 minutes,
-    finally landing, at half past six o’clock, with a new world’s record
-    of 82 miles in 2 hours, 43 minutes and 24⅘ seconds. The people were
-    frantic with excitement; they clapped their hands and waved thousands
-    of handkerchiefs; they rent the air with tremendous applause as he
-    was borne toward the grand stand on the shoulders of his clamorous
-    comrades. Others at the same time had been flying with varied fortune.
-    During Paulhan’s long demonstration, Fournier had encountered a
-    miniature whirlwind, turned over in the air, at a great height, and
-    crashed sidewise to the ground, with some injury to his nose, and with
-    much damage to the wings and tail of his machine. Latham, wishing to
-    lower his circuit time, flew thrice around the course, but without
-    improvement. During his flight, a splendid rainbow appeared, which
-    together with the <i>Antoinette</i> dragon fly soaring high aloft with
-    Latham on its back, produced an impressive spectacle.</p>
-
-  <p><span class="pagenum" id="Page_297">297</span></p>
-
-  <p>Thursday morning brought fine weather and the promise of an eventful
-    day. As a consequence serious efforts were made to excel all previous
-    records, particularly for speed, duration and distance. In the forenoon
-    Latham flew 43.5 miles in the <i>Antoinette XIII</i>. In the afternoon Count
-    de Lambert, in his Wright biplane, flew 72 miles. Blériot entertained
-    the throng by carrying Delagrange as passenger; but while sailing near
-    the ground he encountered some dragoons, turned sidewise to avoid
-    striking them, and plunged into a fence, breaking his propeller. But
-    the great sensation of the day was Latham’s afternoon flight for the
-    Grand Prix, in his <i>Antoinette No. 29</i>. Starting with plenty of fuel
-    and favorable weather, he rose to a high level and flew till his supply
-    was exhausted, at times encountering rough winds and for a while
-    plowing through a rainstorm. It was the banner flight of the week thus
-    far; for it surpassed all other long ones in distance and speed, though
-    not equaling Paulhan’s in endurance. His total range, when compelled
-    to alight through exhaustion of fuel, was 95.88 miles, in 2 hours,
-    18 minutes, 9⅗ seconds. This showed an average speed of 41.63 miles
-    an hour for the whole distance, while the speed for his first round
-    was 44.65 miles an hour. For this great achievement he could thank
-    his 50-horse, 8-cylinder <i>Antoinette</i> motor, one of the lightest in
-    existence, for that power.</p>
-
-  <p>Friday, August 27th, was the last day allotted for the distance, or
-    Grand Prix contest. After the wonderful new records of Paulhan and
-    Latham, people were marveling what might happen on the final day. Many
-    assumed, of course, that Latham’s record of 96 miles would remain
-    unsurpassed. At four-thirty, Latham started on another long flight, in
-    his <i>Antoinette</i> monoplane <i>No. 13</i>, followed presently<span class="pagenum" id="Page_298">298</span> by Farman and
-    Sommer in Farman biplanes; these flying six to twelve feet from the
-    ground, with gallant Latham soaring aloft nearly three hundred feet in
-    his swift long-winged fish, and occasionally gaining a lap on them.
-    Sommer stopped after three rounds, because of motor trouble. Latham’s
-    fuel gave out after a voyage of 68.35 miles, and he glided to earth.
-    Farman continued to plod along on his slow, low-wandering craft, with
-    little attention. Others were in the air, with biplanes and monoplanes,
-    entertaining the populace—Blériot, Curtiss, Delagrange, Tissandier,
-    Bunau-Varilla—these had the applause. Presently the spectators
-    remembered that ground-skimming Farman had been a very long time on the
-    wing. He now became the center of rapt attention. Slowly he distanced
-    Paulhan’s great world’s record of Wednesday; slowly he distanced
-    Latham’s greater world’s record of Thursday; but still he plodded away.
-    The sun sank on his flight; darkness came on the field, so that he
-    vanished from view at the far end of the course. At the close of the
-    nineteenth round he landed in the dark before the grand stand, limp
-    and exhausted, having journeyed 3¼ hours and traversed 118.06 miles.
-    For the second time he had won a $10,000 prize; nineteen months ago by
-    flying 1 kilometer, to-day by flying 190 kilometers. A searchlight was
-    thrown upon him. He was pulled from his machine and carried upon the
-    shoulders of his friends, receiving a prolonged and tremendous ovation.</p>
-
-  <p>The seventh morning of the tournament, Saturday, August 28th,
-    came with a beaming smile, promising good flights and a pleasant
-    termination of the glorious cup contest for the highest speed in two
-    rounds of the 10-kilometer course. The air was calm, mild and hazy
-    above the Betheny plain. The<span class="pagenum" id="Page_299">299</span> flyers were in fine mood for great
-    achievements. The thronging groups of well-dressed men and women
-    awaited further startling events, with varied animation and constant
-    chatter. The day was well diversified with interesting flights; but,
-    of course, not with long ones. The chief interest centered in the
-    leading cup-champions—solitary Yankee Curtiss and great Blériot with
-    his 80-horse monoplane, supported, if need be, by his allies in the
-    contest, Lefebvre and Latham.</p>
-
-  <p>Curtiss, shortly after ten o’clock, made a preliminary trial, lowering
-    his best anterior time. With this he was so pleased that he prepared
-    immediately for the one official flight allowed in that contest. He
-    filled his small gasoline tank, replenished his radiator, signed a
-    legal paper certifying this to be his trial for the cup, and at once
-    took wing, circling before the grand stand, then crossing the line at
-    full speed. The biplane pitched perceptibly at its unusual gait, but
-    turned the corner in easy curves, completing the first round in 7.57⅖,
-    the second in 7.53⅕; the total time being 15 minutes, 50⅗ seconds, and
-    showing an average speed of 47.04 miles an hour.</p>
-
-  <p>About noon Blériot came forth with his 80-horse monoplane <i>No. 22</i>,
-    which was expected to eclipse the Curtiss biplane, but in reality
-    proved exasperatingly slow. At two o’clock he tried another propeller,
-    with little encouragement. An hour later he tried again with a
-    four-blade propeller, but descended before completing the round. After
-    tinkering for an hour, aided by several mechanics, he flew to his shed,
-    shortly before five o’clock. As no start was allowed after five-thirty,
-    he hastened zealously and started his official flight at five-ten. The
-    mighty monoplane cut the air at terrific speed, without pitching, or
-    rolling, and finished the first round in<span class="pagenum" id="Page_300">300</span> 7.47⅘, or 5⅔ seconds less
-    than Curtiss’ best lap. The overjoyed French throng rent the air with
-    frantic bravos! Curtiss and Mr. Bishop were silent, appreciating the
-    skill of that fiery antagonist, with his monster engine. As the steady
-    birdlike craft turned the last pylon, and swept homeward in magnificent
-    career, the timers called out the seconds. The throng listened with
-    abated breath and then with alarm. Blériot had lost speed in the
-    second round. When he crossed the line his total time was 5⅗ seconds
-    greater than that of his only rival. The conqueror of the Channel, the
-    champion of France, was defeated and the international trophy must go
-    to America, won by a taciturn, calculating Yankee, never before seen in
-    Europe, and hardly known to fame.</p>
-
-  <p>Other official flights for the cup during the day were made by Latham
-    and Lefebvre for France, and by Mr. Cockburn, champion for England,
-    the latter bird-man sailing into a stack of wheat in the middle of
-    his first round, then wheeling to earth. Incidentally Henri Farman
-    established a new world’s three-man duration distance and speed record
-    by carrying two passengers ten kilometers in 10 minutes 39 seconds.
-    Thus ended the chief day of the tournament, leaving the contestants in
-    the following order of speed: Curtiss, Blériot, Latham, Lefebvre.</p>
-
-  <p>Of the other leading prizes, that for the fastest single round was
-    taken by Blériot; that for the fastest three-round flight was won by
-    Curtiss on Sunday, with a record of 23 minutes, 29 seconds for the
-    thirty kilometers; the Altitude Prize was won by Latham, who attained
-    an elevation of 508.5 feet; the Prix des Mecaniciens was won by
-    Bunau-Varilla in a flight of 100 kilometers; the Prix des Aëronats
-    was won, on Sunday, by the large dirigible, the <i>Colonel Renard</i>,<span class="pagenum" id="Page_301">301</span>
-    in a voyage of 50 kilometers, or 31.06 miles, at an average speed of
-    24.9 miles an hour. Along with the chief prizes, many smaller ones of
-    considerable value were awarded, thus summing up the total of $37,000.</p>
-
-  <p>The small band of men who organized the first international aviation
-    meet, with the Marquis de Polignac as president, and the great wine
-    merchants of the Champagne district as their supporters, were now
-    elated and triumphant. They had undertaken a novel and costly sporting
-    enterprise, regarded by many as hazardous, or rash, even though
-    sanctioned by the Aëro Club of France. For an enormous attendance
-    would be required to meet the expense of preparations and prize money.
-    It was doubtful whether the few available aviators could draw large
-    crowds to Betheny for a week, even in ideal weather, and there was risk
-    of sending the critical populace away displeased if abundant flights
-    were not made. The whole event might prove a painful fiasco, if rains
-    and high winds should predominate; for were not aviators notoriously
-    reluctant to fly in rough weather? Vain apprehensions, ignoring the
-    reckless and intrepid daring of the Gallic sportsmen! Nothing short of
-    a week’s continual tempest could have kept them down.</p>
-
-  <p>The great tournament was a triumph, not only to the courageous
-    promoters, but also to the aviators, the manufacturers, the whole of
-    mankind. It astonished both actors and spectators. It marked a new
-    epoch in the art of aëroplaning. It inaugurated a magical and wholly
-    novel kind of recreation and public amusement that should be demanded
-    at once in all civilized countries. It eradicated, in a measure, the
-    inveterate notion that the aëroplane is essentially a fair-weather
-    machine. With a cheap instrument capable of flying scores of miles
-    in rain and wind,<span class="pagenum" id="Page_302">302</span> what applications might not come, of the greatest
-    import to the world?</p>
-
-  <p>The fashion set at Rheims was imitated in other cities. Before the
-    close of the year 1909, aviation meets were scheduled for Brescia in
-    Italy, Berlin, Juvisy, near Paris, Blackpool and Doncaster, England.
-    The succeeding year was to have more such events than the really
-    capable aviators could attend. In both hemispheres, sums in cash,
-    equaling or exceeding those at Rheims, would be offered by many
-    prominent communities, eager to witness such novel and thrilling
-    entertainment as only dexterous aviators could furnish. But it would be
-    learned also that considerable financial risk attends an aviation meet,
-    unless good judgment mark the choice of site, season, pilots and the
-    executive agencies. Several of the meets following the one at Rheims
-    succeeded neither in defraying expenses nor in furnishing competent
-    aviators to repay the trouble of holding the tournament. The meets
-    held in England were practically failures. A most interesting flight,
-    however, was performed by Latham in a wind of 25 to 35 miles an hour.
-    This itself was a very impressive achievement. The Brescia meeting was
-    remarkable for the turbulence of its aërial currents and for Rougier’s
-    record high flight of 645 feet.</p>
-
-  <p>The two most wonderful flights in the autumn of 1909 were those of
-    Count de Lambert and Farman. During a meet at the Juvisy aërodrome,
-    Lambert, on October 18th, after circling the ground a few times on a
-    Wright biplane, attaining a height of 450 feet, started for Paris,
-    steadily ascending in the direction of the Eiffel Tower. Circling this
-    at an altitude of about 1,300 feet, he returned to Juvisy at 5.30
-    <span class="smcap">p.m.</span>, having journeyed 30 miles over that dangerous route, in
-    about 50 minutes. This indicated <span class="pagenum" id="Page_303">303</span>that lofty flying might enable one
-    to pass safely over a city, even with an unreliable motor, since, if
-    the propeller stopped, a glide of many thousands of feet could be made,
-    to choose a landing. Farman’s flight was less spectacular, but quite
-    as marvelous. On November 4th, while competing for the Michelin trophy
-    for the longest distance traversed in 1909, he flew continuously for
-    4 hours, 6 minutes, 25 seconds, voyaging in that time 144 miles, at
-    an average speed of 35.06 miles an hour. This proved to be the record
-    distance-and-endurance flight for the year. Other men spoke of sailing
-    all day in a machine carrying ample gasoline, but failed to make good
-    their words.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXIX" class="center"><b>PLATE XXIX.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_377a.jpg" width="600" height="403" alt="" />
-    <div class="captionp">ESNAULT-PELTERIE MONOPLANE, EARLY PATTERN.</div>
-    <div class="small">(Courtesy W. J. Hammer.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_377b.jpg" width="600" height="387" alt="" />
-    <div class="captionp">ESNAULT-PELTERIE MONOPLANE OF 1910.</div>
-  </div>
-
-  <p>Unheralded, but quite astonishing, were the flights of Santos-Dumont
-    in September, 1909. Though conspicuous as a pioneer in aviation, he
-    for a while had been absorbed in other affairs, and had not kept pace
-    with his brother aëroplanists in France, since his bold and brief
-    dashes into the air in the early days of the art. During the season of
-    1909, however, he developed a surprisingly small and simple monoplane,
-    spreading 102 square feet of wing surface, and weighing in complete
-    running order, 259 pounds. It was driven by a Darrac motor, mounted
-    above the main surface, carrying the propeller directly on its shaft,
-    and having radiator tubes along the inner surface of the main plane.
-    Its triangular trussed frame was wheel-mounted, and tapered rapidly
-    to the rear, terminating in horizontal and vertical rudders. With
-    this tiniest flyer he sailed across country from St. Cyr to Buc, 4¾
-    miles, in five minutes, at the unprecedented speed of 55 miles an
-    hour, repeating the performance several times, according to report. He
-    also left the ground after a run of 60 feet, in an unofficial trial.
-    Characteristically, he presented to the public the scale<span class="pagenum" id="Page_304">304</span> drawings of
-    his machine, with all rights to its use.</p>
-
-  <p>A very original type of monoplane was developed by Robert
-    Esnault-Pélterie, who began experimenting in 1903. As shown in <a href="#Plate_XXIX">Plate
-    XXIX</a>, its body frame was covered to reduce air-resistance, and was
-    provided with ample keel surface to promote directness and steadiness
-    of flight. The weight was borne on two wheels in tandem, aided by
-    wheels at the wing tips to preserve the lateral balance when the
-    machine was resting. When under way the lateral poise was controlled by
-    wing warping; the motion about the other two axes being controlled by a
-    horizontal and a vertical rudder, the latter being “compensated,” that
-    is, having its axis near the center of side pressure, when in action.
-    An air-cooled motor of 30 to 35 horse power with a direct mounted
-    four-blade screw formed the propulsion plant. Though the “R. E. P.”
-    aëroplane, as it was commonly called, did not achieve great distinction
-    at first, due, perhaps, to the inventor’s being over original, and
-    making all its parts himself, instead of buying some high-class engine
-    and propeller, as other successful aëroplanists had done, still his
-    machine was greatly admired by technicians for its excellent finish and
-    the fastidious, thorough and patient manner in which its young inventor
-    labored to make it perfect, both in design and construction. It was
-    regarded as a future record breaker, which, indeed, it was destined to
-    become on further improvement.</p>
-
-  <p>Although little was accomplished in building aëroplanes in other
-    countries than America and France, up to the beginning of 1909, that
-    year witnessed some good flights in homemade machines in Germany,
-    England and Canada. In November, 1909, Herr Grade, in Germany, made
-    a flight of <span class="pagenum" id="Page_305">305</span>55 minutes in his monoplane. Mr. S. F. Cody, who
-    constructed a biplane for the British army, flew over forty miles
-    across country on September 8th, high above trees and buildings,
-    remaining on the wing for 63 minutes. The machine spanned 52 feet,
-    weighed with the pilot, nearly a ton, and was controlled by front
-    and rear vertical rudders and two lateral rudders, well in front, so
-    geared that if worked oppositely the machine listed, while if worked
-    identically it rose or fell. In Canada Dr. Alexander Graham Bell and
-    his associates continued the experiments, already described, begun
-    in 1908 by the Aërial Experiment Association. In 1909 their fourth
-    machine, the <i>Silver Dart</i>, flew many times round a course on the
-    frozen lake, Bras d’Or, traversing, all told, about 1,000 miles in 100
-    flights.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXX" class="center"><b>PLATE XXX.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_381a.jpg" width="600" height="453" alt="" />
-    <div class="captionp">GRADE MONOPLANE.</div>
-    <div class="small">(Courtesy E. L. Jones.)</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_381b.jpg" width="600" height="384" alt="" />
-    <div class="captionp">CODY BIPLANE.</div>
-  </div>
-
-  <p>The last months of this strenuous year, 1909, and of the first decade
-    of dynamic flight, closed without further startling developments. True,
-    some records were made, but they merely pleased, not perturbed the
-    world, now accustomed to marvels. Be it recorded, however, that, with a
-    Voisin biplane, Paulhan, on November 1st, flew 96 miles in 2 hours, 20
-    minutes, and on November 20th flew 1,960 feet high in a Farman biplane;
-    on December 9th, Maurice Farman, mounted on his own type of biplane,
-    rode through the icy atmosphere from Buc to Chartres, a distance of 40
-    kilometers, in 50 minutes, the longest town-to-town flight up to that
-    date; and on December 31st he flew from Chartres to Orleans, a distance
-    of 41.6 miles, in forty-six minutes. But several fine achievements
-    which the world anticipated for that year remained unattempted. The
-    great prize flight of 183 miles from London to Manchester was still
-    untried, though several machines and pilots seemed equal to the voyage,
-    and $50,000 would be awarded by Lord Northcliffe to the brave<span class="pagenum" id="Page_306">306</span> aviator
-    who should accomplish that journey in not more than three stages and
-    within a period of twenty-four hours. Neither had anyone yet flown
-    to an elevation of one kilometer. These tasks were left over as
-    allurements for the succeeding year.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XII">
-    <span class="pagenum" id="Page_307">307</span>
-    <h3>CHAPTER XII</h3>
-    <span class="small">FORCING THE ART</span>
-  </div>
-
-  <p><span class="smcap">The</span> decade that inaugurated dynamic man-flight had closed without fully
-    demonstrating the capabilities of such aëroplanes as had been so far
-    developed. No considerable altitude record had as yet been achieved. No
-    very long cross-country flight had yet been attempted, though for many
-    months the New York <cite>World</cite> had offered $10,000 for the first aërial
-    voyage from Albany to New York, and the London <cite>Daily Mail</cite> had long
-    offered $50,000 for a flight from London to Manchester. The uses of the
-    aëroplane for scouting by land and sea had not been tested, much less
-    its probable value in aggressive warfare. Such experiments were for
-    the immediate future, as also the development of specialized types of
-    machines for racing, for climbing, for burden bearing, for distance,
-    for endurance, for landing on water, for rising from water, for
-    protection of passengers from severe weather. To air men and spectators
-    alike the future of the art promised to be quite as captivating as the
-    past.</p>
-
-  <p>The first startling achievements to usher in the new decade were the
-    great altitude flights. New world records followed in rapid succession
-    all through the year 1910, with marked persistence and wonderful
-    progress. Levels that had been regarded as the peculiar region of motor
-    balloons were passed one after another, until the aviators vanished
-    beyond the clouds, their limbs palsied with cold, and<span class="pagenum" id="Page_308">308</span> their aëroplane
-    wings whitened with frost. Though the greatest prizes were not offered
-    for this species of flight, and frequently none at all, it had an
-    abiding fascination for both the flyers and the public. At the same
-    time it proved to be as safe as it was theatrical and popular.</p>
-
-  <p>The starter in this exciting race for cloudland was Hubert Latham,
-    already the official holder of the world’s altitude record. At Bouy,
-    on January 7th, in presence of official witnesses, he rose in his
-    <i>Antoinette</i> monoplane, describing a great upward spiral till his
-    barometer recorded 1,050 meters; then returned to earth with like ease
-    and precision, landing softly near his hangar, before his assistants,
-    transported with enthusiasm. He had touched the goal of Gallic
-    ambition, having driven his aëroplane to the height of one kilometer.</p>
-
-  <p>Latham’s tenure of the world’s altitude record quickly passed to
-    his doughty rival, Louis Paulhan. At Los Angeles, on the twelfth of
-    January, Paulhan, mounted on a Farman biplane, ascended 4,165 feet, as
-    against Latham’s record of 3,444 feet. This was a great step upward,
-    due not only to Paulhan’s prowess and dexterity, but also to the
-    science and constructive skill of the less spectacular gentlemen in the
-    designing room, workshop and laboratory.</p>
-
-  <p>Latham strove again for the world’s altitude record and gained it on
-    July 7th at the second Rheims tournament, by driving his <i>Antoinette</i>
-    to a height of 4,541 feet.<a id="FNanchor_53" href="#Footnote_53" class="fnanchor">[53]</a> But again his victory was soon eclipsed;
-    for two days later, Walter Brookins at Atlantic City ascended 6,175
-    feet in a Wright biplane. An American was thus the first to fly above
-    one mile, as a Frenchman had been first to pass the <span class="pagenum" id="Page_309">309</span>1-kilometer limit.
-    The 2-kilometer and 2-mile elevations were exceeded before the close of
-    the year, as shown by the following table, which also manifests a fair
-    distribution of honors among various nations and types of machines:</p>
-
-  <table class="collapse" summary="Altitude records">
-    <tr>
-      <th class="bt bb br">Feet</th>
-      <th class="bt bb br">Aviator</th>
-      <th class="bt bb br">Aëroplane</th>
-      <th class="bt bb br">Place</th>
-      <th class="bt bb">Date</th>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>3,445</div></td>
-      <td class="br">Latham</td>
-      <td class="br">Antoinette</td>
-      <td class="br">Betheny Plain</td>
-      <td>January 7</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>4,165</div></td>
-      <td class="br">Paulhan</td>
-      <td class="br">Farman</td>
-      <td class="br">Los Angeles</td>
-      <td>January 12</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>4,541</div></td>
-      <td class="br">Latham</td>
-      <td class="br">Antoinette</td>
-      <td class="br">Rheims</td>
-      <td>July 7</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>6,175</div></td>
-      <td class="br">Brookins</td>
-      <td class="br">Wright</td>
-      <td class="br">Atlantic City</td>
-      <td>July 9</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>6,604</div></td>
-      <td class="br">Drexel</td>
-      <td class="br">Blériot</td>
-      <td class="br">Lanark, Sc.</td>
-      <td>August 11</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>8,271</div></td>
-      <td class="br">Morane</td>
-      <td class="br">Blériot</td>
-      <td class="br">Havre, France</td>
-      <td>September 3</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>8,406</div></td>
-      <td class="br">Chavez</td>
-      <td class="br">Blériot</td>
-      <td class="br">Issy</td>
-      <td>September 8</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>9,104</div></td>
-      <td class="br">Wijnmalen</td>
-      <td class="br">Farman</td>
-      <td class="br">Mourmelon</td>
-      <td>October 1</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>9,714</div></td>
-      <td class="br">Johnstone</td>
-      <td class="br">Wright</td>
-      <td class="br">Belmont Park</td>
-      <td>October 31</td>
-    </tr>
-    <tr>
-      <td class="tdr br"><div>10,499</div></td>
-      <td class="br">Leganeaux</td>
-      <td class="br">Blériot</td>
-      <td class="br">Pau</td>
-      <td>December 9</td>
-    </tr>
-    <tr>
-      <td class="tdr bb br"><div>11,474</div></td>
-      <td class="bb br"><a id="FNanchor_54" href="#Footnote_54" class="fnanchor">[54]</a>Hoxsey</td>
-      <td class="bb br">Wright</td>
-      <td class="bb br">Los Angeles</td>
-      <td class="bb">December 26</td>
-    </tr>
-  </table>
-
-  <p>Such lofty flights have proved a severe test of both the aëroplane and
-    the pilot. In the lighter atmosphere the engine must turn the propeller
-    at higher speed to secure the same thrust, and the aëroplane must sail
-    faster to support the same weight as at the lower levels. Thus more
-    power is required on high, though the explosive medium, being less
-    dense, is less capable of exerting power. The driver has, therefore, to
-    jockey his machine with assiduous care and alertness, at a time when he
-    is least fitted for exertion, owing to fatigue, cold, and it may be,
-    physical discomfort due to the great change of atmospheric pressure.
-    But still, both aëroplane and pilot are capable of ascending well above
-    any levels thus far attained.</p>
-
-  <p>After the triumphant altitude flights of 1910 the aëronautical
-    skeptics could no longer contend that <span class="pagenum" id="Page_310">310</span>the aëroplane was useless in
-    transportation and warfare, because of its inability to fly above
-    high land or the usual range of the guns of battleships and coast
-    fortifications. Most of the important mountain passes lie below 10,000
-    feet. The safe elevation for motor balloons menaced by terrene guns is
-    taken to be much less than two miles, and in military practice they
-    usually operate below the one-mile level. The aëroplanes, therefore,
-    may not only cross mountain ranges, but may also scrutinize, or
-    grievously molest, land forces, marine squadrons and perhaps even the
-    great gaseous cruisers of the atmosphere, which they can far outspeed,
-    and may even destroy.</p>
-
-  <p>The increase in speed of flight during 1910 was also quite remarkable.
-    The official record by which Mr. Curtiss won the Bennett Aviation
-    Contest at Rheims, in 1909, showed a speed of 47.04 miles an hour.
-    Still higher velocities, ranging from 50 to 60 miles an hour, were
-    reported later in that season from England and France. In 1910,
-    however, at the Rheims aviation meet, Morane, with a Blériot monoplane,
-    covered the 20-kilometer course in 12 minutes 45.2 seconds, or at an
-    average speed of 66.2 miles an hour, showing a gain of forty per cent
-    on Mr. Curtiss’s speed of the preceding year. Still better was achieved
-    at the international tournament held at Belmont Park in 1910. Le Blanc
-    in a 100-horse Blériot monoplane, especially designed for speed,
-    covered nineteen laps of the 5-kilometer course at an average rate of
-    61 miles an hour, and his fastest lap at the rate of 71.68 miles an
-    hour, thus exceeding Curtiss’s speed of the previous year by fifty per
-    cent. Other spurts during the latter part of 1910 were reported to have
-    attained nearly 80 miles an hour over a closed circuit, though perhaps
-    not a level one. The best results were<span class="pagenum" id="Page_311">311</span> achieved with machines having
-    high power engines, small surfaces and slight forward resistance.</p>
-
-  <p>The advance in long-distance flying in 1910 more than kept pace with
-    the progress in speed. The best achievement at the close of the
-    preceding year had been Farman’s flight of 144 miles at an average rate
-    of 35.06 miles an hour in a closed circuit. At the Rheims aviation meet
-    in 1910, Jan Olieslaegers, in a Blériot monoplane, driven by a Gnome
-    engine, covered 244 miles in a rectangular course, at an average speed
-    of 48.31 miles an hour. At Buc, on the 28th of October, an aviator of
-    three months’ practice, Maurice Tabuteau, in a Maurice Farman biplane,
-    driven by a Rénault engine, flew over a closed circuit, covering 288.8
-    miles at an average speed of 47.9 miles an hour. At Pau on December
-    21st, M. G. Leganeaux, in a Blériot monoplane, flew for the Michelin
-    Cup, covering 516 kilometers or 320.6 miles in six hours and one
-    minute, or at an average speed of 53¼ miles an hour—a splendid showing.
-    Finally, at Buc, on December 30th, Tabuteau, flying for the annual
-    Michelin prize, covered 362.66 miles in a Maurice Farman biplane with
-    an 8-cylinder 60-horse Rénault motor. The average speed in this very
-    long flight was 47.3 miles an hour, or practically the rate by which
-    Curtiss won the international contest of the preceding year. Of course
-    a considerably better showing of both distance and velocity could have
-    been made on a longer course.</p>
-
-  <p>The world records for cross-country flying and for endurance and load
-    illustrate both the increasing perfection of the machine and of the
-    pilot’s skill and confidence. At Los Angeles, on January 19th, Mr. and
-    Mrs. Paulhan, in a Farman biplane, flew together 21 miles overland from
-    the aviation field to Redondo and Hermosa Beach and return.<span class="pagenum" id="Page_312">312</span> On January
-    31st Van der Born made a world’s duration record with a passenger on
-    a Farman biplane, flying 1 hour 48 minutes 50 seconds. On March 5th,
-    Henri Farman, who had previously twice broken the world’s duration
-    record for a pilot with two passengers, set a new and astonishing
-    pace at Mourmelon, by carrying Mr. Hevardson and Madame Frank in
-    easy flight for 62.5 minutes on his new biplane. In France, on April
-    3d, Emile Dubonnet on his <i>Tellier</i> monoplane flew from Juvisy to La
-    Ferte-Saint Aubin, a distance of 109 kilometers or 70 miles in 1 hour
-    and 50 minutes, thus winning the ten-thousand-franc prize offered
-    by <cite>La Nature</cite> for the first straightaway flight of 100 kilometers
-    to be effected in less than two hours, over a previously indicated
-    course. This fine record voyage was achieved in a machine never before
-    thoroughly tried. At Chalons-sur-Marne, on April 8th, Daniel Kinet,
-    a Belgian, mounted with a passenger on a Farman biplane driven by
-    a 50-horse Gnome engine, broke the world’s record for duration and
-    distance for two persons by flying round a closed circuit 2 hours 19¼
-    minutes, covering a distance of 152 kilometers, or 94 miles. On April
-    17th, H. Farman, with a passenger in his biplane, voyaged from Etampes
-    to Orleans, 28 miles. Next day, Paulhan, mounting the same machine,
-    flew 108 miles, and the following day 42 miles. This tour established a
-    new cross-country record for total distance, for single stage distance
-    with one passenger, and for duration and single stage distance with two
-    passengers. During the same month Farman made a new record for four
-    passengers by carrying three gentlemen for 1 hour and 4 minutes on his
-    new biplane, spreading 47.6 feet. On June 9th, two French officers,
-    Lieutenant Fequant piloting and Captain Marconnet observing, flew
-    on a Farman biplane <span class="pagenum" id="Page_313">313</span>from Bouy to Vincennes, 145 kilometers, in two
-    hours and a half, thus breaking the world’s cross-country distance and
-    duration record for a pilot with a passenger. On June 13th, Charles K.
-    Hamilton, in a Curtiss biplane, flew from New York to Philadelphia, a
-    distance of 86 miles in 103 minutes, and returned the same day, thus
-    completing 172 miles in one day. This was an exhibition flight made for
-    <cite>The New York Times</cite> and the <cite>Philadelphia Ledger</cite>, for a sum reported
-    to be $10,000. It was a sequel to Glenn H. Curtiss’s memorable flight
-    on June 5th, down the Hudson River from Albany to New York, for the New
-    York <cite>World’s</cite> $10,000 prize. Hamilton’s average speed was 50 miles
-    an hour going and 51 miles returning. On August 29th, at Lille, Louis
-    Bréguet is reported to have carried with him on a biplane of his make,
-    five passengers, who, together with the gasoline, weighed 921 pounds.
-    It may be added that the Bréguet biplane of that date was advertised
-    and guaranteed to carry a cargo, or extra load, of 250 kilograms. It
-    thus appears that by 1910 the aëroplane had grown powerful enough for
-    an aërial cab service, and that it could carry sufficient explosive
-    gelatine to derange a battleship.</p>
-
-  <p>The contest for cross-country records continued unabated all that
-    memorable year. During the first three days of September, Jean
-    Bielovucic, a youth of twenty-one, mounted on a new type of Voisin
-    biplane, with but a few days’ practice, flew from Paris to Bordeaux,
-    covering 540 kilometers, or 336 miles, in four stages, comprising
-    altogether 6¼ hours on the wing. In spite of severe weather, at times,
-    he beat the regular express train and established a new world’s record
-    for cross-country straightaway distance flying with stops. On August
-    17th, Alfred Le Blanc, finished a six-stage tour round a hexagonal
-    circuit northeast of Paris, with the finish at Issy,<span class="pagenum" id="Page_314">314</span> near Paris,
-    covering a total distance of 785 kilometers, or 440 miles, in 12
-    hours 56.4 seconds effective time. On September 7th, Weyman flew with
-    a passenger from Paris to Clermont near the Puy de Dome, covering
-    205 miles in one day, while trying for the Michelin prize of 100,000
-    francs, for a flight to the Puy de Dome inside of six hours. On
-    December 18th, Thomas Sopwith, competing for the longest flight across
-    the Channel and into Belgium, on a British-built aëroplane, flew from
-    the Isle of Sheppy across the Channel, and landed at Beaumont, Belgium,
-    covering a distance of 174 miles in 3.5 hours. At Buc, on November
-    27th, Laurens, in a 60-horse R. E. P. monoplane, flew with his wife 53
-    miles at an average speed of nearly 50 miles an hour. On December 22d,
-    Lieutenant Cammerman, a French army officer, won the L. Weiller prize
-    by flying across country with a passenger, 147 miles in 4 hours and 2
-    minutes.</p>
-
-  <p>These are but a few of the records which serve to illustrate the
-    progress in cross-country flying during that year of strenuous and
-    world-wide popular demonstrations. But the bare numerical statement of
-    facts can give no conception of the delight and exultation aroused in
-    millions of souls who witnessed or learned of these marvelous human
-    achievements. They were the advancing triumph of a proud and fortunate
-    generation, happy in realizing one of the fondest dreams of the ages.
-    Often during one of these cross-country flights the aëroplane was
-    accompanied by a swift railway train whose passengers were delirious
-    with enthusiasm. The entire route was thronged with people assembled
-    from afar. It was a general holiday for all the fortunate cities and
-    villages along the way. Mills and factories blew their whistles and
-    forgot the serious business of life, homes were deserted, schools
-    were<span class="pagenum" id="Page_315">315</span> dismissed; the whole population for the time congregated in
-    the open; bearded mechanics in their aprons, bare-armed housewives
-    holding their children aloft, girls and boys with wondering eyes, all
-    shouting, waving banners, throwing up hats, and hailing with tumultuous
-    demonstration that strange and huge-winged creature gliding from
-    horizon to horizon with the steadiness, precision and directness of a
-    mighty projectile. But beyond stating the records of this season of
-    aërial wonders, only a passing notice can be given to some of the more
-    conspicuous events.</p>
-
-  <p>The most famous overland voyages of the season 1910 began with the
-    race for the London <cite>Daily Mail</cite> prize of $50,000, offered by Lord
-    Northcliffe for the first person who should fly from London to
-    Manchester, 183 miles within twenty-four hours, with not more than
-    two stops. An Englishman, Claude Grahame-White, comparatively new in
-    the pilot’s art, was first to undertake that difficult and perilous
-    adventure. Starting from London, without competitor, on April 24th, he
-    flew in his Farman biplane, from London to Rugby, thence to Hademore,
-    about halfway to Manchester, landing at a quarter past nine o’clock
-    at night, after a four-hour trip, and hoping to reach Manchester next
-    day. But during the night his aëroplane, which was left in the open,
-    was damaged by the wind, thus necessitating repairs and a new start. On
-    April 27th, while he was strenuously mending and adjusting his biplane
-    for a new start, Louis Paulhan, who the day previously had arrived from
-    France with a Farman biplane to enter the contest, was also vigorously
-    setting up and adjusting his machine.</p>
-
-  <p>At half past five in the afternoon, Paulhan suddenly set out for
-    Manchester. Mr. White, who was much fatigued and expecting to start on
-    the morrow<span class="pagenum" id="Page_316">316</span> at dawn, after much-needed rest, learned toward six o’clock
-    that his rival was on the wing, and hurriedly sailed from London,
-    hoping by skill and good chance to overtake the flying Frenchman.
-    The race was now the most exciting event in the world. The first
-    flyers of France and England were competing for the greatest prize
-    yet offered in the history of aviation, competing in a most modern
-    and extraordinary race, attended with abundant danger and hardship.
-    The contestants were evenly matched in mechanism and capability, but
-    the Frenchman had gotten the march on the unwary Englishman. Paulhan
-    followed the Northwestern Railway, at times outracing the special
-    pilot train carrying his mechanics and supplies. At ten minutes after
-    eight o’clock, he landed at Lichfield, having covered 115 miles. Mr.
-    White had landed five minutes before eight near Roade, after flying
-    fifty-nine miles.</p>
-
-  <p>Next morning, Paulhan sailed away at a quarter past four. Mr. White,
-    hoping to overtake him, had started at dead of night and covered
-    twenty miles before Paulhan had started. It was a heroic effort, but
-    unavailing. At twelve minutes after five, Mr. White landed at Hademore,
-    having completed two thirds of the entire journey. Twenty-five minutes
-    later Paulhan landed on the outskirts of Manchester, greeted by a
-    thousand persons. He had covered the whole distance in 4.2 hours, and
-    had fulfilled all the essential conditions for winning the great prize.</p>
-
-  <p>The next world-famous aëroplane voyage was that of Glenn H. Curtiss for
-    the New York <cite>World’s</cite> prize of $10,000 for the first aërial journey
-    from Albany to New York, allowing two stops. Aviators had been yearning
-    for this prize since the previous year, but had been too timidly shying
-    at the dangers of the route. After most careful preparations for this
-    voyage, Curtiss, bearing a letter from the<span class="pagenum" id="Page_317">317</span> Mayor of Albany to the
-    Mayor of New York, sailed away at seven o’clock on Sunday morning, May
-    29th, accompanied by a New York Central special train, bearing his wife
-    and a few friends and newspaper men. He landed an hour for supplies
-    and adjustment at Camelot, 41 miles down the river, and thence flew to
-    Spuyten Duyvil, at the northern extremity of New York, having completed
-    the required distance, 128 miles, in 2 hours and 32 minutes, or at the
-    rate of 50.52 miles per hour along the course. An hour later, he flew
-    down the river to New York Harbor and landed on Governor’s Island,
-    where he received a becoming ovation.</p>
-
-  <p>Perhaps the most exciting incident of the voyage to Mr. Curtiss was his
-    transit of the Storm King Mountain. As he was flying through the narrow
-    gap at this place he caught the down-rolling air on one side more
-    than on the other, and dropped very suddenly sidewise 30 or 40 feet.
-    By shifting his front control, he quickly gained headway and promptly
-    righted his machine.</p>
-
-  <p>Commenting on Mr. Curtiss’s average speed of 50 miles an hour and his
-    rugged course, <cite>Aëronautics</cite> makes comparison between his voyage and
-    Paulhan’s great prize flight as follows:</p>
-
-  <blockquote>
-    <p>“Paulhan took 4 hours 12 minutes elapsed time to cover 183 miles when
-      he won the <cite>London Mail’s</cite> $50,000 and made it in two stages of 117 and
-      66 miles each. The 117 miles were covered in 2.39, a rate of nearly 44
-      miles per hour. A night’s sleep intervened and the remaining 66 miles
-      were covered in 1.23, a rate of nearly 48 miles per hour. The average
-      for the above was 44.37 miles per hour. Paulhan could have landed at
-      almost any time and started again, whereas Curtiss could not have
-      started if he had had to land in the water, and for the whole distance
-      there was scarcely a suitable<span class="pagenum" id="Page_318">318</span> space for landing on the ground, as for
-      nearly the entire way rocky, wooded hills with precipitous sides line
-      the river.”</p>
-  </blockquote>
-
-  <p>The most audacious and marvelous aëronautic exploit of the year was the
-    flight of George Chavez across the Alps from Brig to Domodossola, in
-    his attempt to win the prize of 70,000 francs offered by the Italian
-    Aviation Society for the first aëroplane flight from Brig to Milan, a
-    distance of 75 miles. From the nine volunteers for this contest who
-    presented themselves to the committee in charge, five competitors
-    were selected, and these for several days made tentative efforts to
-    scale the lofty pass, but were baffled by the wind or fog. Finally at
-    one-thirty, on September 23d, the conditions being favorable, Chavez
-    rose, from Briegen-Berg, in his white-winged Blériot, spiraled upward
-    1,000 meters, circling around the vast amphitheater of the mountains,
-    and in nineteen minutes appeared in magnificent career well above the
-    Simplon Pass, probably 7,000 feet above the sea, whence he glided
-    grandly down the Italian slope, parrying the rude cross winds and
-    finally reaching Domodossola, where the enthusiasm was at its climax.
-    Here he expected to land on a level spot to replenish his supplies,
-    thence proceed over the easy remaining two thirds of his journey. But
-    though the perilous pass had been crossed so successfully, disaster
-    appeared in the valley when least expected. As the aëroplane was
-    gliding thirty feet high over the level tract chosen for landing, it
-    met a sudden gust, its wings collapsed, and it fell crashing to earth,
-    pinioning its brave pilot under the débris.</p>
-
-  <p>Poor Chavez suffered severe wounds about the face and head, had both
-    legs broken, and for some moments lay unconscious. But he was soon
-    revived by his friends and taken to a hospital, where he died<span class="pagenum" id="Page_319">319</span> four
-    days later. Thus ended the career of a brave and most promising youth
-    of twenty-three. He had taken his pilot’s license only in February,
-    1910, yet had established a new world’s record on September 8th, by
-    driving his Blériot to an elevation of 8,406 feet. He was of Peruvian
-    parentage and born in Paris.</p>
-
-  <p>The exact nature of the accident was never ascertained, but it was
-    surmised that the sudden starting of his engine preparatory to landing
-    overstressed some part of the structure already fatigued from hard
-    usage. However this be, the committee recognized that Chavez had with
-    excellent skill covered all the really difficult and dangerous part
-    of this journey. Accordingly they very generously waived the exact
-    letter of the rules, and awarded him one half the prize, though he had
-    completed but one third of the journey.</p>
-
-  <p>Quite as dangerous, spectacular and brilliant as the flight across
-    the Alps, though less arduous, was Hubert Latham’s aërial voyage over
-    Baltimore. On previous occasions cross-city flights had been made,
-    but never one of such length or one executed under such exacting
-    conditions. At various times aviators had flown above Paris, Rome,
-    Berlin, etc. On October 14th Mr. White had flown across Washington,
-    landing on a narrow street between the White House and War Department;
-    on October 15th Leganeaux had flown above Paris with a passenger; but
-    these were short flights over an uncharted course. Latham’s voyage
-    was unique; for he had to follow a long and a prescribed course over
-    the business section and closely built residence portion of the city.
-    This great exploit was an exhibition flight made on the invitation
-    of the <cite>Baltimore Sun</cite> for a sum of $5,000. It was to be made at the
-    time of the Baltimore aviation tournament at Halethorpe, Md., and<span class="pagenum" id="Page_320">320</span> was
-    calculated to be seen by half a million people; for the whole city was
-    to be notified and would cease its usual activities to witness the rare
-    and hazardous demonstration.</p>
-
-  <p>The voyage was triumphant and glorious in every feature. Starting from
-    the aviation ground, seven miles south of Baltimore, about noon on
-    November 7th, Latham drove his beautiful <i>Antoinette</i> about the field
-    in an ascending spiral, like some imperial bird taking its bearings;
-    then, chart in hand, deliberately sailed away over his elaborately
-    prescribed journey. This was a figure 8 course with its bottom at the
-    aviation field and its center at the <cite>Sun</cite> Building in the heart of
-    Baltimore, the whole length being 22 miles. As the long-winged bird
-    in majestic poise, with the intrepid rider on its back, approached
-    in the distance, soaring 1,000 feet above the gleaming waters of the
-    Chesapeake, the great bell of the City Hall sounded a mighty peal, and
-    the whole populace responded in tumultuous chorus; whistles, bells and
-    a myriad voices mingling their heartiest welcome to the bravest of
-    aviators. With arrowlike speed and directness he rounded the center of
-    the course at the <cite>Sun</cite> Building, then looped the vast northern half of
-    the city, flying a thousand to three thousand feet high, more easily
-    to parry the surging eddies of the northwest wind; rounded again the
-    center of his course and then returned to the aviation field, where he
-    landed with infinite coolness before the excited throng of applauding
-    spectators, whose acclaim was all too feeble to express their mingled
-    wonder, admiration and delight. The voyage lasted forty-two minutes and
-    fulfilled perfectly every minute requirement, including a short circle
-    and salutation before the home of Mr. Ross Winans, an invalid gentleman
-    who had solicited this unique favor, and rewarded<span class="pagenum" id="Page_321">321</span> it with a gift of
-    $500. It was the climax of the aviation week at Baltimore.</p>
-
-  <p>Among the many brilliant flights of that memorable year of strenuous
-    piloting will long be remembered the voyage of the Hon. C. S. Rolls to
-    Calais and return without landing, and that of Mr. Sopwith, already
-    recounted; the splendid flight of Mr. Clifford B. Harmon in his Farman
-    biplane from Mineola, Long Island, to a small rounded island before
-    his house on the Connecticut shore, for the trophy offered by <cite>Country
-    Life</cite> to the first person who should fly across Long Island Sound;
-    Henri Farman’s flight of December 18th, for the Michelin long-distance
-    prize, covering 288 miles, and establishing a new endurance record of
-    8 hours 23 minutes; Mlle. Helene Dutrieu’s flight of December 21st,
-    for the Coupe Femina, covering 103¾ miles in 2 hours and 35 minutes
-    in a Farman biplane. Interesting, too, were the first attempt to fly
-    from Paris to Brussels with a passenger, when Mahieu and Manihé on
-    starting were brought to bay by a vicious dog which violently attacked
-    the propeller and was cut in two; and when Loridan and Fay landed on a
-    tree, from which they descended by a ladder. After this followed the
-    glorious voyage of Henri Wijnmalen, the youthful and many-sided Dutch
-    sport, for the prize of 150,000 francs offered by the Automobile Club
-    of France for the quickest aëroplane trip not exceeding 36 hours, with
-    a passenger from Paris to Brussels and return. This voyage of some
-    320 miles was valiantly accomplished by Wijnmalen and his companion
-    Dufour, in a day and a half, of 13.2 effective hours, and in weather
-    for the most part windy or tempestuous. Finally to the foregoing list
-    of splendid achievements must be added the glorious voyage of John
-    Moisant, who in August flew with a passenger, by compass, from Paris to
-    London,<span class="pagenum" id="Page_322">322</span> though he had never been over the route before and had only
-    just learned to use an aëroplane.</p>
-
-  <p>The International Aviation Tournament of 1910, held at Belmont Park,
-    Long Island, October 22d to 31st, was the most prominent and eventful
-    meet of the year, and the second of its kind in history, as the
-    meeting of the preceding year at Rheims was the first. The present
-    meet was conducted by the Aëro Corporation, Limited, of New York,
-    under the auspices and official sanction of the Aëro Club of America,
-    representing the Federation Aëronautique Internationale.</p>
-
-  <p>This tournament was the annual aërial Olympic contest of the world, and
-    should have been indicative not only of the aviator’s skill, but also
-    of the state of national progress in the science and art of aëroplane
-    construction. Unfortunately, however, for the prestige of the most
-    deserving nations, the rules of the International Aëronautic Federation
-    did not confine the contestants to the use of home-built machines, to
-    prevent the glory of winning the international contest from passing to
-    the nation which merely furnished the operator, a person who might be
-    an illiterate jockey, and representative of a country wholly devoid of
-    science. As luck decided, however, the highest honor in 1910 was won by
-    a first-class French machine driven by a first-class English aviator.</p>
-
-  <p>In some respects the raw material and working elements of this meet
-    were most satisfactory. The site is near the wealthiest and most
-    populous center in America. The grounds are spacious and level,
-    and provided with all the equipment of a great race course; the
-    transportation facilities by carriage and by rail from the heart of
-    New York are adequate to every requirement. The personnel of the
-    meet comprised the most experienced and most devoted<span class="pagenum" id="Page_323">323</span> members of the
-    Aëro Club of America, the oldest and strongest aëronautical body in
-    the western world, and the only one representing the International
-    Aëronautic Federation. It is true the season was late and the weather
-    would probably be cold and tempestuous; the management was burdened by
-    a costly license, whether just or unjust, imposed upon it as the price
-    of immunity from patent litigation; the remaining time, after the final
-    placement of the meet, was all too short for the myriad preparations
-    to be made. But whatever the obstacles, physical or financial, the
-    personnel was paramount, and naturally made the huge tournament a
-    glorious triumph. It was the cardinal sporting event of the year.</p>
-
-  <p>The status of aviation was well represented in both pilots and
-    machines. Twenty-seven aviators were entered on the program, many of
-    them world famous. Of these Alfred Le Blanc, Hubert Latham, Emile
-    Aubrun were the formidable champions of France in the contest for the
-    James Gordon Bennett aviation trophy; Claude Grahame-White, James
-    Radley, A. Ogilvie represented England; while Walter Brookins, J. A.
-    Drexel, Charles K. Hamilton were enlisted as defenders of the coveted
-    cup and of American prestige. All told, the aviators brought with them
-    nearly two-score machines, ranging in capacity from 30 to 100 horse
-    power. Of these about half were monoplanes and half biplanes, for the
-    most part of French and American manufacture.</p>
-
-  <p>The prizes and remuneration awarded to the contestants were on a
-    scale proportionate to their skill and number. All told the winnings
-    aggregated more than $60,000. Further appropriations were made to
-    cover the expenses of the aviators, and a further sum equal to about
-    forty per cent of the winnings was paid for immunity from prosecution
-    for possible <span class="pagenum" id="Page_324">324</span>infringement of an unlitigated patent. Considering the
-    immense expenditures for buildings, for policing and other incidentals
-    of the meet, it may be readily inferred that there was an ample
-    deficit, and that the air men as a whole were much better rewarded
-    than some of the sportsmen who gave so much time and labor to the
-    organization of the tournament.</p>
-
-  <p>A conspicuous feature of the meet was the display of hardiness and
-    skill of several of the aviators in facing the cold and tempestuous
-    weather. This was particularly characteristic of Latham in his
-    <i>Antoinette</i> monoplane, and of Ralph Johnstone and Arch Hoxsey in
-    Wright biplanes. On October 27th Latham flew round the regular course
-    for an hour when it was nearly impossible to turn the pylons against
-    the fierce wind, while Johnstone and Hoxsey performed lofty altitude
-    flights in a powerful gale which carried them backward, sometimes at
-    the rate of 40 miles an hour. As a consequence they landed in the
-    open country, remained overnight and returned next day. Johnstone was
-    carried backward to Holtsville, 55 miles east of the aviation grounds,
-    and Hoxsey was blown to Brentwood, 25 miles away, both landing at dusk
-    in open fields, and both having attained great elevations: Hoxsey,
-    6,903 feet; Johnstone, 8,471 feet.</p>
-
-  <p>An interesting novelty of the aviation week, at least to Americans,
-    were the erratic Demoiselle monoplanes, invented by Santos-Dumont and
-    piloted by Garros and Audemars. These aëroplanes were notable as having
-    the pilot under the sustaining plane, and the engine above with its
-    direct mounted propeller. The lateral stability was enhanced by a low
-    placement of the center of mass, and by a slight dihedral inclination
-    of the wings. Furthermore, as there was not much leverage or surface in
-    the rear<span class="pagenum" id="Page_325">325</span> double rudder, the flight was more stable than steady, like
-    that of a propelled parachute. In fact, the little monoplanes pitched,
-    rocked, and fluttered about so like huge butterflies as to provoke
-    constant merriment. They gave a faint suggestion of how ludicrous
-    aëroplane clowns could be made by one who has genius for such things.</p>
-
-  <p>Barring the stormy voyages above mentioned, the most memorable events
-    of the tournament were the Gordon Bennett speed contest, the Statue of
-    Liberty race and Johnstone’s great altitude flight. Of the numerous
-    other performances little need be said, except that they contributed
-    to the general success of an elaborate and most interesting program.
-    They served the daily need of a costly tournament; they delighted vast
-    throngs of spectators whose admission fees helped to promote the aërial
-    sport; but they did not of themselves have more than local interest, or
-    constitute an advance in the records of first-class achievement.</p>
-
-  <p>The chief race of the meet, the James Gordon Bennett speed contest,
-    was scheduled for Saturday, October 29th. The prize of $5,000 and the
-    coveted cup were to be awarded to the pilot who should make the best
-    average speed in 20 laps over a 5-kilometer course, aggregating 100
-    kilometers, or 62.14 miles. The winner should have the distinguished
-    honor of taking to his own country the next annual contest for the
-    precious speed prize.</p>
-
-  <p>Grahame-White, England’s foremost aviator and strongest hope in
-    the contest, brought forth his untried 100-horse Blériot in the
-    calmest part of the day, and took wing a quarter before nine. He
-    flew with steady poise and swift, well-sustained speed, completing
-    the 100-kilometer distance in 1 hour 1 minute and 4.7 seconds, at an
-    average speed of 61 miles an hour.</p>
-
-  <p><span class="pagenum" id="Page_326">326</span></p>
-
-  <p>Le Blanc, the most likely winner of all, sailed at nine o’clock. He was
-    mounted on a 100-horse Blériot with nearly flat wings, the swiftest
-    monoplane of French manufacture. He was the boldest, sturdiest and
-    most dexterous pilot in a nation of renowned aviators, the winner of
-    unnumbered trophies, the “Vainquer de l’Est.” He now flew at unwonted
-    speed, establishing new world records at every round of the course. It
-    seemed evident to the timers that only an accident to this impetuous
-    Frenchman could retrieve the glory of England and save that of America.
-    Suddenly the accident came. In the last lap, when victory seemed
-    assured, the gasoline failed; the monoplane shot downward, knocked off
-    a telegraph pole, and, with broken frame and engine, fell crashing
-    to earth, entangling the brave aviator. Le Blanc was cut and bruised
-    about the forehead, and was taken to the hospital to be bandaged,
-    not seriously injured but in a towering rage, suspecting that some
-    trickery had given him a shortage of fuel. He had lost the day, though
-    his average speed for the whole flight was 67 miles an hour as against
-    Grahame-White’s speed of 61 miles.</p>
-
-  <p>No well-tried machine was available to defend the American prestige.
-    Curtiss had constructed a new monoplane designed for speed, but though
-    he had brought the cup to America, he was not chosen as one of its
-    three defenders. The little Wright biplane of 61 horse power had
-    flown a few minutes with great velocity, and was looked to with some
-    confidence. Mounted by Walter Brookins, it set out with tremendous
-    speed, but had only well started when the cylinders began to miss fire.
-    Brookins turned toward the infield to land, struck the ground with
-    terrific shock and tumbled violently on the field beside his broken
-    machine. He, too, was taken to<span class="pagenum" id="Page_327">327</span> the hospital for treatment, but was not
-    seriously injured.</p>
-
-  <p>It was now granted that Grahame-White would be the ultimate winner.
-    Other aviators attempted to defeat him, but lacked either the necessary
-    speed or endurance. The cup was accordingly taken from the nations
-    that had done the most to develop the practical art of aëroplaning. Of
-    these two nations, the one most deserving of victory, by virtue of its
-    more careful preparation, was defeated by an extraordinary mishap, when
-    victory was at hand; the other failed perhaps for want of preparation
-    rather than from lack of manipulative or constructive skill.</p>
-
-  <p>Of the various highly coveted stakes the largest in monetary value was
-    known as the Thomas F. Ryan Statue of Liberty Prize. This was a cash
-    sum of $10,000, to be awarded to the properly qualified contestant who
-    should fly from the aviation ground to and around the Statue of Liberty
-    in New York Harbor, and return in the shortest time, the airline
-    distance being 16 miles each way. The prize was founded by Mr. Thomas
-    F. Ryan, whose son, Allan A. Ryan, was Chairman of the Committee on
-    Arrangements of the tournament, and who though suffering with pain and
-    ill-health, labored so indefatigably to insure the success of the event
-    so germain to the aëronautical prestige of his country.</p>
-
-  <p>The Statue of Liberty race occurred on Sunday afternoon, October 30th,
-    beginning just after three o’clock. Count De Lesseps in a 50-horse
-    Blériot monoplane led the race, followed three minutes later by
-    Grahame-White. They passed toward the southwest in perfect poise and
-    vanished beyond the horizon unchallenged by an American contestant;
-    for Moisant, the American champion, had shortly before injured his
-    racing monoplane, and the other American racing machines had been
-    damaged the<span class="pagenum" id="Page_328">328</span> week before, or had not yet been fully tested. But with
-    admirable enterprise, Moisant telephoned Le Blanc, in New York, who
-    was not racing because of the accident to his 100-horse Blériot the
-    day previously, and offered the Frenchman $10,000 for his 50-horse
-    Blériot monoplane. The sale was effected in time for the race that
-    day. But for all that the enterprise seemed futile; for as Moisant
-    was preparing to start, the others were returning, Grahame-White well
-    in the lead, having overtaken De Lesseps. As these two aviators were
-    receiving the applause of innumerable spectators and the felicitations
-    of their friends, audacious Moisant, the impetuous soldier of fortune,
-    and hero of the famous flight by compass from Paris to London, started
-    toward the declining sun, just after four o’clock. He was determined
-    to win by superior skill and daring. His prudent competitors had
-    followed a circuitous southern route interspersed with landing places;
-    but he flew like a maniac straight over the church spires and crowded
-    buildings of Brooklyn, guided to his goal by a compass, rounded the
-    Statue of Liberty at a great altitude and plunged homeward with all
-    possible speed and directness. The megaphone announced his progress,
-    which indicated some hope of victory so little expected and so much
-    desired by the vast throng that stood gazing toward the western sun.
-    In headlong career the swooping monoplane shot by the judges’ stand,
-    circled and softly landed on the field, triumphant by 43 seconds
-    over the 100-horse Blériot of Grahame-White. As the intrepid aviator
-    approached the vast and delighted throng of spectators to acknowledge
-    its noisy and tumultuous ovation, he was met by the chiefs of the
-    tournament, draped in an American flag, and paraded before the grand
-    stand, “which shook in its effort to do honor to the little air
-    conqueror.” Ultimately, <span class="pagenum" id="Page_329">329</span>however, the prize was awarded to Count
-    De Lesseps, because Moisant had failed to qualify properly, and
-    Grahame-White had fouled the initial pylon.</p>
-
-  <p>The final day of the tournament was made memorable by Johnstone’s
-    altitude flight. The best previous record was that of Wijnmalen to an
-    elevation of 9,104 feet, made at Mourmelon, France. Johnstone ascended
-    on a small Wright machine with powerful propellers adapted to rapid
-    climbing, determined not only to surpass Wijnmalen but to exceed,
-    if possible, the ten-thousand-foot level, and win the special prize
-    offered for such achievement. He actually rose to the great elevation
-    of 9,714 feet, but could not develop power enough to continue upward.
-    On his descent he fully exhausted his fuel at 3,000 feet, and thence
-    glided to earth, landing softly, 1 hour and 43 minutes from the time of
-    starting.</p>
-
-  <p>Thus the greatest tournament of the year terminated with fine new
-    laurels for the science and art of aviation; for the spectacular
-    pilots and for the unseen men behind them—the scientific men in the
-    laboratories, the designing rooms and the workshops. New standards had
-    been established in speed, in altitude, in prowess and daring. In these
-    elements, the spectators could hardly ask for a better exhibition. What
-    is it to the onlooker to have an aëroplane go higher than the cumuli,
-    since at that level a thousand feet makes no perceptible difference?
-    What more could he wish in dexterity of manipulation and audacity in
-    braving the elements? One thing more, doubtless, and that is, security
-    and precision of flight in stormy weather. When these improvements
-    shall have been effected much will have been added to both the sportive
-    interest and practical utility of the aëroplane.</p>
-
-  <p><span class="pagenum" id="Page_330">330</span></p>
-
-  <p>The most businesslike and crucial flying contest of the year was the
-    famous “Circuit de l’Est,” organized by the Paris <cite>Matin</cite>. It was a
-    competitive voyage over an irregular hexagonal course, lying generally
-    northeast of Paris, and having its vertices at various cities to the
-    east and north of the national capital. The main prize offered by
-    the <cite>Matin</cite> was one hundred thousand francs for the first air man to
-    complete the entire course, doing the first side of the hexagon on
-    August 7th, and the succeeding sides in regular order on successive
-    odd days of the month, the place and hour of starting each stage
-    being assigned in advance. Various subsidiary prizes aggregating
-    nearly a hundred thousand francs more, were available for meritorious
-    performances at the various stages and stopping-places along the
-    route.<span class="pagenum" id="Page_331">331</span> But there were also penalizations for those contestants who
-    failed to start on schedule time and observe the rules of the course.</p>
-
-  <div class="figcenter">
-    <a id="Fig_41"><img src="images/i_408.jpg" width="600" height="485" alt="" /></a>
-    <div class="caption smcap">Fig. 41.—Map of the “Circuit de l’Est.”</div>
-  </div>
-
-  <p>The race began at Issy, near Paris, on August 7th, with eight aviators
-    on the wing—Le Blanc, Aubrun, Leganeaux, Mamet, Lindpainter, Weyman. It
-    terminated August 17th, headed by Alfred Le Blanc on his Blériot, and
-    followed by Emile Aubrun on a Blériot, then by Weyman on a Farman, all
-    three driven by Gnome engines actuating Chauvière propellers. Le Blanc
-    completed the tour of six stages, covering an air-line distance of 488
-    miles, in 12 hours’ effective flying, or at the average rate of 40.6
-    miles per hour.</p>
-
-  <p>This long tour on schedule time over a rough and varied country in
-    face of fog, wind and rain, was a most severe trial of the prowess and
-    endurance of the brave pilots who had the hardiness and pertinacity
-    to complete the voyage. Needless to add that it created unbounded
-    enthusiasm among millions of people who witnessed the event, or read of
-    it, and that the clocklike precision of the “grand raid” inspired new
-    confidence in the practicability of the aëroplane.</p>
-
-  <p>A particularly impressive feature of the event was that many of its
-    participants, the aviators, government officers, and members of the
-    controlling committee, assembled at Issy and other posts of duty,
-    not by rail, but by aëroplane, sailing across country from many
-    directions and from great distances. This matter-of-fact procedure led
-    many persons to believe that the period of mere demonstrations had
-    approached its close, and that the epoch of practical utility was at
-    hand; that after marveling so much at the aëroplane, with mingled faith
-    and skepticism, people would next calmly turn it to practical use.</p>
-
-  <p><span class="pagenum" id="Page_332">332</span></p>
-
-  <p>Though the progress in designing and constructing aëroplanes in 1910
-    did not keep pace with the wonderful advance in new records, still the
-    inventors and manufacturers continued industriously to perfect the
-    details of their best standard machines, and in a few instances to
-    make radical innovations. The perfection in details of construction
-    manifested itself in the public performance of aëroplanes, particularly
-    in their greater reliability and their increased capabilities. The
-    radical innovations were mainly experimental, and not generally
-    exhibited, though none the less important for all that. Chief of these
-    perhaps were the hydro-aëroplane developments of Fabre in France, and
-    of Mr. Glenn H. Curtiss in America, which enabled the aviator to launch
-    into the air directly from the water and to alight safely on the water,
-    thus virtually adding a new and very important domain to the empire of
-    dynamic flight.</p>
-
-  <p>Curtiss, in 1909, succeeded in landing his aëroplane safely on the
-    water of Lake Keuka, first with sheet iron cylindrical floats under
-    each wing, and a simple float well to the front of his protruding
-    chassis, then with a hydroplane surface to the front as being more
-    effective than the float. But when he attempted to glide up from the
-    lake with this arrangement, he could not entirely clear the surface,
-    though his aëroplane under the powerful thrust of her aërial screw,
-    very nearly lifted from the water. Then he planned to use hydroplane
-    floats, of hollow wing form, and of such size that they would buoy up
-    the machine when at rest, and during motion would skim over the water
-    like a skipping stone, till the biplane should acquire sufficient speed
-    to rise by the dynamic reaction of the air. In the successful execution
-    of this plan, however, he was anticipated by Fabre, who made the first
-    successful flight from the <span class="pagenum" id="Page_333">333</span>water, on March 28th, 1910, at Martigues,
-    France. But the Frenchman was not left to bear the palm alone. Early in
-    the year 1911, Mr. Curtiss rose and landed successfully on the water at
-    San Diego Bay, Cal., by means of a single float like a flatboat placed
-    centrally under his biplane, seconded by small auxiliary floats at the
-    wing ends. A full account of these valuable contributions to aviation
-    is given in <a href="#appendix_V">Appendix V</a>.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXXI" class="center"><b>PLATE XXXI.</b></div>
-
-  <div class="figcenter w600">
-    <img src="images/i_411a.jpg" width="600" height="297" alt="" />
-    <div class="captionp">FABRE HYDRO-AËROPLANE.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter w600">
-    <img src="images/i_411b.jpg" width="600" height="297" alt="" />
-    <div class="captionp">PAULHAN HYDRO-AËROPLANE.</div>
-    <div class="small right"><i>Photo E. Levick, N. Y.</i></div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_411c.jpg" width="600" height="297" alt="" />
-    <div class="captionp">MOISANT METAL MONOPLANE.</div>
-    <div class="small">(Courtesy A. J. Moisant.)</div>
-  </div>
-
-<p>As shown in Plate XXXI, Fabre’s hydro-aëroplane was substantially a
-    monoplane mounted on three richochet floats. It was propelled by a
-    screw at the rear, and controlled in flight by the usual three-torque
-    system, in this case consisting of horizontal rudders in front,
-    vertical rudders front and rear, and suitable mechanism for twisting
-    the wings. The floats were hollow to give them static buoyancy; they
-    were curved fore and aft like wings, to give them dynamic lift, both in
-    water and in air; they were elastically constructed with thin veneer
-    bottoms and flexibly attached to the framing, so as to endure the
-    severe buffeting, at high speeds, against the uneven water surface;
-    they were capable of landing the machine safely on a sandy beach or
-    meadow, as well as on the water. Indeed, a plan was conceived for
-    rising and alighting on land and water indifferently.</p>
-
-  <div class="figcenter">
-    <a id="Fig_42"><img src="images/i_413.jpg" width="700" height="160" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 42.—Diagram of Curtiss
-      Hydro-aëroplane</span>. (<cite>Scientific American.</cite>)</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_334">334</span>The first machine weighed in flight 950 pounds and spread 280 square
-    feet of surface, giving a loading of 3.4 pounds per square foot. It was
-    driven by a 50-horse Gnome engine actuating a Chauvière propeller 7.5
-    feet in diameter. In the trials of March 28th, the machine cleared the
-    water at a speed of 34 miles per hour, and flew about one-third of a
-    mile, at an elevation of two to three yards; then at the will of the
-    operator it alighted softly on the water.</p>
-
-  <p>The structural design of the Fabre monoplane was novel and unique, not
-    to say radical. The wing framing consisted of a single Fabre trussed
-    beam with ribs attached like the quills of a bird, over which was
-    stretched the light sailcloth cover, then laced to the beam. The girder
-    itself was formed of two ash planks eight inches wide by one-fourth
-    inch thick trussed together by flat steel plates zigzagging trelliswise
-    between them. As all parts of the beam cut the air edgewise it offered
-    very little resistance, while at the same time being very strong. The
-    ribs being attached only at one end allowed the sailcloth to be quickly
-    slipped on and off for washing and proper care.</p>
-
-  <p>The characteristic features of Fabre’s wing construction were adopted
-    by Paulhan in his novel and picturesque biplane shown in <a href="#Plate_XXXI">Plate
-    XXXI</a>. Trussed beams were used for all parts requiring considerable
-    stiffness, the longitudinal ones being covered with fabric to reduce
-    the resistance. The wings whose solid ribs were fastened only at their
-    front ends were quite elastic, a quality conducive to stability, as
-    long taught by writers<a id="FNanchor_55" href="#Footnote_55" class="fnanchor">[55]</a> on aviation. In addition <span class="pagenum" id="Page_335">335</span>to the front
-    rudder, there was at the rear a horizontal rudder with a vertical one
-    just before it. To reduce the air resistance further the pilot and
-    passenger were to sit tandem in a torpedo-shaped car with the 50-horse
-    Gnome engine and fuel tank back of them. Beneath the longitudinal
-    girders were two Farman skids flanked with the usual wheels,
-    elastically connected. The machine, besides flying well, was readily
-    demountable. The wings could be quickly removed, thus allowing the
-    biplane to enter a door fifteen feet wide. The entire machine could be
-    packed in a case 15½ feet long by 3¼ feet square, the whole case cubing
-    less than six solid yards. Hundreds of them, therefore, could be stowed
-    away in an ocean cruiser.</p>
-
-  <p>The flying quality of adequately designed flexible aëroplanes is well
-    illustrated by the swallowlike monoplane shown in Fig. 43. This airy
-    creation of the distinguished Austrian engineer, Igo Etrich, came into
-    public prominence in the spring of 1910, though it had been developing
-    privately for half a decade or more. On May 14th, near Vienna, it
-    carried pilot Illner 84 kilometers in 80 minutes, at an elevation of
-    300 meters, thus surpassing all previous Austrian records for distance,
-    duration and altitude. Its successor, <i>Etrich IV</i>, had wing tips still
-    more turned up, and possessed such stability that during the meet at
-    Johannisthal in October, Illner circled the pylons with his hands off
-    the warping levers. At times he wheeled round curves of only ten meters
-    radius, the whole machine tilted at an alarming angle, yet maintaining
-    its poise with the natural ease and grace of a soaring albatross.</p>
-
-  <p>The prominent feature of Etrich’s monoplane<span class="pagenum" id="Page_336">336</span> was the elastic
-    construction of its wings and tail. Across the rigid main bars of each
-    wing were fastened numerous ribs with bamboo terminals, thus making
-    the rear margin and tip of the wing flexible. Similarly the tail, or
-    horizontal rudder, was framed of bamboo. Hence the pilot, by use of
-    control wires, could flex both the wing margins and the tail up and
-    down at will, to steer the machine, or he could let go the controls and
-    allow the distorted surfaces to spring into their normal positions,
-    and the machine to pursue the even tenor of its way. Moreover, the
-    gusts and whirls in the air, on striking the elastic rear margins of
-    the tail and wings, exert a propulsive effort. Thus could be utilized
-    the wind’s energy of turbulence, as indicated by the present writer
-    in 1893, in a paper on “Windgusts and Their Relation to Flight,”
-    published in the <cite>Proceedings of the International Conference on Aërial
-    Navigation</cite> of that year. In passing it may be remarked that many other
-    aëroplane designers, notably Bréguet, have emulated Mr. Etrich, though
-    unconsciously perhaps, in providing elastic ribs, hinges or pivots to
-    permit the rear parts of the wings and tails of their machines to yield
-    freely to intentional or unusual impulses, and then spring back to
-    their normal positions.</p>
-
-  <div class="figcenter">
-    <a id="Fig_43"><img src="images/i_416.jpg" width="656" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 43.—The Etrich Monoplane of 1910.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_337">337</span>The carefully elaborated monoplane of Robert Esnault-Pélterie, which
-    had been steadily improving for eight years, had now attained great
-    perfection of finish, and merited prominence in actual flight. As shown
-    in <a href="#Plate_XXIX">Plate XXIX</a>, it had a general resemblance to the <i>Antoinette</i>, though
-    differing throughout in its manifold details. The stream-line body was
-    of steel tubing, braced with wire, and tightly covered with smooth
-    fabric to reduce resistance. A five-cylinder R. E. P. motor in front
-    connected directly with the two-blade propeller. The pilot sat between
-    the wings with the passenger before him at the center of gravity, both
-    having control levers when desired for instruction. The wings could be
-    warped and the rudders, at the end of ample empennage planes, occupied
-    the extreme rear as shown. An elastically cushioned skid between the
-    two freely turning wheels served to absorb the shock of hard landing,
-    though usually not touching the ground. The R. E. P. monoplane of 1910
-    was a very graceful, swift and strong machine, of marked efficiency.</p>
-
-  <p>As always happens in the many-minded development <span class="pagenum" id="Page_338">338</span>of a complex
-    invention, the general exhibition and use of the aëroplane led toward
-    uniformity of design. This became particularly noticeable during the
-    world-wide demonstrations of 1909 and 1910. Whatever predilection the
-    inventor might have for his own devices, he would rather cast them
-    aside than lose at the tournament and in the market. Without a monopoly
-    of the flying art, he could ill afford to retain too affectionately
-    his own second-rate device in competition with a rival having a more
-    effective one. Accordingly there was a judicious and general adoption
-    of those devices which had proved best in practice, from whatever lowly
-    intellect they had emanated. Thus there was a marked tendency to the
-    general use of starting wheels, landing skids, large warping surfaces,
-    and, in racing machines, to the stream line concentration of the load,
-    and the severe elimination of resistance.</p>
-
-  <p>A few examples will illustrate this tendency to choose the most
-    practical devices from the world’s general stock. The Wright brothers,
-    who, following Maxim, had been ardent votaries of the forward
-    horizontal rudder, discarded this in 1910 for the elastic rear
-    horizontal rudder introduced by Etrich. At the same time they abandoned
-    the antiquated catapult introduced by Langley, and adopted the
-    combination of wheels and skids introduced by Farman. In their racing
-    machine they no longer placed the aviator beside his engine, presenting
-    a broad front to the wind, but, like Curtiss and foreign designers,
-    they placed the driver and power plant in line, to diminish the
-    atmospheric resistance. These manifold and timely improvements indicate
-    clearly the advantages to mankind of an “open door” in a crescent art.</p>
-
-  <p>But if the Wrights adopted the most successful devices of their
-    neighbors, these in turn were not<span class="pagenum" id="Page_339">339</span> slow to reciprocate that policy.
-    There was ample recognition of the merit of the combination of warping
-    sustainers and double rudder proposed by scientific men before the
-    advent of power aëroplanes, and so admirably employed by the Wrights
-    and Prof. Montgomery in their early coasting flights. The warping wing
-    was quite generally used on monoplanes in 1910; not to mention the
-    <i xml:lang="fr">ailerons</i>, which frequently were an adaptation of the same principle.</p>
-
-  <p>As further illustrations, it may be noted that Voisin brothers adopted
-    the Farman <i xml:lang="fr">ailerons</i> and abandoned the cellular type of sustaining
-    surface introduced by Hargrave, finding the vertical surfaces strongly
-    frictional and unnecessary for lateral equilibrium, in presence of
-    the <i xml:lang="fr">ailerons</i>. They also abandoned the forward horizontal rudder,
-    seeing that it could very well be omitted. On the other hand, it must
-    be observed that the Farmans, Sommer and Curtiss still retained the
-    combined fore and aft rudder. Curtiss and Farman also tried their hands
-    at monoplane construction, though without abandoning the biplane. The
-    most famous monoplanists, however, held firmly to their first love.
-    In this they were emulated by many new designers, Nieuport, Hanriot,
-    Déperdussin, etc. These show a marked tendency to employ smoothly
-    covered hulls shaped after the fish or torpedo.</p>
-
-  <p>To drive the little aëroplanes so far developed, especially the
-    racers, there was a general preference for a single-screw propeller
-    mounted directly on the engine shaft, though doubtless for machines
-    weighing many tons a multiplicity of such propellers would be used.
-    Theoretically the advantage of twin screws was conceded, but in
-    practice they were employed by very few constructors. The Chauvière
-    wooden propeller was the favorite in France, and was approved by
-    the constructors of propellers elsewhere, <span class="pagenum" id="Page_340">340</span>at least in its general
-    features. The Voisin firm, indeed, still adhered to the metal
-    propeller, and occasionally some experimentalist employed the more
-    venerable French screw consisting of radial sticks covered with fabric.
-    But the great records in the sporting world were achieved with solid
-    wooden propellers.</p>
-
-  <p>A special chapter would be required to describe the various motors,
-    even cursorily. Their relative values, however, may be summarized in
-    the following brief words by Réné Gasnier, in the <cite>Aërophile</cite> for
-    November, 1910:</p>
-
-  <blockquote>
-    <p>“Last year we had but few light types; this year there is no dearth
-      of them, and at their head stands that admirable motor <i>Gnome</i>, which
-      has enabled aviators to accomplish all their fine performances. At
-      first many persons had no confidence in the future of the rotatory
-      motor. One must bow to the facts; on considering the nature of this
-      motor it is seen to be of an admirable simplicity. It is evidently the
-      typical aviation motor, and an approach toward the veritable rotatory
-      motor which later will be the turbine. Numerous motors of four to
-      eight cylinders are very well spoken of, but none attain the lightness
-      of the <i>Gnome</i>. Among the air-cooled motors the <i>Esnault-Pélterie</i>
-      is remarkable for the series of trials it has endured, and among
-      water-cooled motors we may cite the splendid performance of the
-      <i>Antoinette</i>—2,100 kilometers in one week at the Bordeaux meeting.
-      This would be quite a good run even in an automobile. It is noticeable
-      that the aëroplane motor tends distinctly to differentiate itself from
-      its senior, the automobile motor, and assume a type absolutely adapted
-      to its special work. In addition to the greatest possible lightness,
-      a demand now arises for a slight consumption of fuel, and a range of
-      speed which is indispensable for landing. It is dangerous<span class="pagenum" id="Page_341">341</span> to descend
-      rapidly with the motor at full speed; on the other hand, in cutting off
-      the ignition to glide down, one risks not being able to restart the
-      motor, if need be, while if the motor relax sufficiently the descent
-      takes place in perfect security. It suffices to speed up at the right
-      moment.”</p>
-  </blockquote>
-
-  <p>The practical utility of aviation began now to be questioned. The
-    aëroplane had passed the primary epoch of experimental development
-    and was becoming a standard article of manufacture representing a
-    considerable industry. But what was it all worth? Aviators had flown
-    faster than the eagle, higher than the clouds, farther than the common
-    distance from metropolis to metropolis. Schools were licensing new
-    pilots from day to day. But what career had these before them, and what
-    essential function in the affairs of humanity could they perform? Some,
-    indeed, might fit themselves for aërial service in warfare, some for
-    the pleasant profession of amusing and entertaining mankind; but in the
-    serious business of life, what important rôle could the air men hope
-    to play? This was the pertinent inquiry, and it was largely a question
-    of the reliability and economy of the aëroplane. Improvement in these
-    two elements might therefore receive attentive consideration in the
-    immediate future.</p>
-
-  <p>The reliability of the aëroplane depends partly on its environment,
-    partly on its plan and structure, partly on the skill of its pilot.
-    The pilot’s skill had been admirably developed in the tournaments and
-    public exhibitions. The aërodynamic design conducive to stability and
-    steadiness, the structural design conducive to maximum strength and
-    resiliency, uniformly proportioned to the stress and work of each
-    part of the complex machine; and above all the design of the motor,
-    to ensure it against a thousand foibles—all these could be improved
-    by the patient<span class="pagenum" id="Page_342">342</span> methods of theoretical and experimental science.
-    The environment could, of course, be chosen. At first only the most
-    favorable regions need be attempted for regular transportation, regions
-    of level plain and farm land, or of lake and river surrounded by
-    country not too rough and precipitous.</p>
-
-  <p>The general cost of the aëroplane to mankind depends on its plan and
-    structure, on the methods of manufacture, on the material running
-    expense; but its particular cost to the passenger is determined largely
-    by the cupidity or business acumen of those who furnish the machine
-    and those who operate it. Naturally when the world first awoke in
-    the morning of practical sporting aviation, with a sudden and strong
-    relish for flying, the prices would be fabulous, not to say ridiculous.
-    During that hour no commercial transportation could be contemplated.
-    But without monopoly the prices must quickly abate; for neither the
-    manufacture nor manipulation of the aëroplane demand rare ability or
-    training. The cost of manufacture would promptly be diminished by means
-    of specialized tools and operatives, immediately upon the assurance
-    of large and continuous orders. The cost of pilotage would become
-    insignificant when a single chauffeur could take a dozen passengers on
-    one aëroplane.</p>
-
-  <p>So much for the human and external elements in the cost of aviation.
-    The inherent and material cost of the aëroplane could also be reduced,
-    though perhaps less readily. It was unlikely that the machine would
-    be built of much cheaper materials, or made much lighter per pound of
-    cargo. Nor were such improvements of so much importance since they
-    would affect only the first cost of the flyer. But an increase of
-    aërodynamic efficiency in the propeller and aëroplane proper, together
-    with increased thermodynamic efficiency in the motor, would materially<span class="pagenum" id="Page_343">343</span>
-    lower the current cost of transportation at any given speed. These
-    improvements would require careful research in the laboratory and
-    patient trial in the workshop and field. The refinement and perfection
-    of the aëroplane might therefore be looked for in those communities
-    where men have sufficient foresight, enterprise and liberality to endow
-    research, and to encourage the science and the art of aviation to
-    supplement each other.</p>
-
-  <hr class="page" />
-  <div class="chapter" >
-    <span class="pagenum" id="Page_345">345</span>
-    <h2>PART III<br />
-      <span class="xlarge">AËRONAUTIC METEOROLOGY</span></h2>
-  </div>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XIII">
-    <span class="pagenum" id="Page_347">347</span>
-    <h3>CHAPTER XIII</h3>
-    <span class="small">GENERAL PROPERTIES OF FREE AIR</span>
-  </div>
-
-  <p><span class="smcap">For</span> aëronautic uses the atmosphere may be regarded as a mixture of two
-    substances, dry air and water. The first remains always in the gaseous
-    state; the second shifts erratically through all possible states. Rain
-    drops freeze or evaporate; sleet, snow, and hail evaporate or melt;
-    the aqueous vapor condenses or congeals. Thus the world is wrapped in
-    a dual sea, one part naturally serene, the other capricious, protean,
-    and turbulent. Dry air, indeed, is a composite of many gases of vast
-    concern in chemistry and biology; but in relation to aëronautics it
-    is practically a single permanent gas. This placid element and its
-    inconstant mate, so curiously mingled, constitute the medium whose flux
-    and vicissitudes the aërial sailor has duly to learn before he can
-    navigate with skill or safety.<a id="FNanchor_56" href="#Footnote_56" class="fnanchor">[56]</a></p>
-
-  <p>But these aërial oceans, the moist and dry, are of very different
-    depth. They commingle only in the lower levels of the atmosphere, whose
-    qualities vary accordingly, both physical and transportational. While
-    the dry air may reach up to more than a hundred miles, substantial
-    enough to singe a meteorite, the sea of aqueous vapor is bounded
-    practically by the shallow region of the visible clouds. Beyond the
-    feather-like cirri, which just overtop the loftiest <span class="pagenum" id="Page_348">348</span>mountain peaks,
-    there is scant, if any, moisture. Never rain, nor cloud is there, nor
-    tempest nor any great perturbation. Beyond the highest excursions of
-    the cirri, at an elevation of some ten miles, stretches the deep ocean
-    of eternal sunshine, of equable and nearly constant temperature. Into
-    that zone of perpetual serenity no tumult of the nether atmosphere
-    can penetrate; against the floor of the isothermal layer the cyclonic
-    currents spread and dissipate. The upper air has, of course, a
-    considerable drift, like a majestic river or stream of the sea, but
-    never turmoil or tempest disturbs its stately march.</p>
-
-  <p>In some respects, therefore, that lofty ocean is an ideal one for swift
-    transportation. But at present it is beyond the range of any navigable
-    craft of human invention. Occasionally, indeed, a gauzy balloon from
-    the hand of some inquisitive weather sage penetrates a little way into
-    the exalted deep next the cosmic void, bearing its delicate recorders
-    of heat and pressure; but it wanders alone in a silent and vast
-    solitude outcubing all the habitable space allotted to bird, beast
-    and fish; then at last sinks down to deliver the story of its strange
-    voyage in that lifeless outer sphere. Volcanic and celestial dust may
-    flourish there, tingeing the twilight with rosy flush, but no biologic
-    forms from the teeming underworld may find refuge or sustenance. It is
-    the unconquered domain of who knows what meteoric craft of the future,
-    sweeping the globe from continent to continent, with now unimaginable
-    celerity, grace and precision.</p>
-
-  <p>Incidentally and aside from its aëronautic interest, the composition
-    of the atmosphere may be presented in fuller detail, showing the
-    wide variations from level to level, and the manifold complexity of
-    the fluid we daily breathe, not to mention the<span class="pagenum" id="Page_349">349</span> myriads of motes and
-    germs inhabiting every inch of it. The gaseous components and their
-    distribution are well exhibited in the following table,<a id="FNanchor_57" href="#Footnote_57" class="fnanchor">[57]</a> which
-    represents an average condition:</p>
-
-  <div class="center mt5">TABLE I</div>
-
-  <p class="center"><i>Percentage Distribution of Gases in the Atmosphere</i></p>
-
-  <table class="collapse" summary="Gas distribution">
-    <tbody>
-      <tr class="small">
-        <th rowspan="2" class="bt bb br"><span class="smcap">Height in Kilo-<br />meters.</span></th>
-        <th colspan="7" class="bt bb br"><span class="smcap">Gases.</span></th>
-        <th rowspan="2" class="bt bb">Total Pressure in Millimeters.</th>
-      </tr>
-      <tr class="small">
-        <th class="bt bb br">Argon.</th>
-        <th class="bt bb br">Nitro-<br />gen.</th>
-        <th class="bt bb br">Water<br />Vapor.</th>
-        <th class="bt bb br">Oxygen.</th>
-        <th class="bt bb br">Carbon<br />Dioxide.</th>
-        <th class="bt bb br">Hydro-<br />gen.</th>
-        <th  class="bt bb br">He-<br />lium.</th>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>150</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>99.73</div></td>
-        <td class="br tdr"><div>0.27</div></td>
-        <td class="tdr"><div>0.0043</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>140</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>99.70</div></td>
-        <td class="br tdr"><div>0.30</div></td>
-        <td class="tdr"><div>0.0048</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>130</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.02</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>99.64</div></td>
-        <td class="br tdr"><div>0.34</div></td>
-        <td class="tdr"><div>0.0054</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>120</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.10</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>99.52</div></td>
-        <td class="br tdr"><div>0.38</div></td>
-        <td class="tdr"><div>0.0060</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>110</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.40</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.02</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>99.16</div></td>
-        <td class="br tdr"><div>0.42</div></td>
-        <td class="tdr"><div>0.0067</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>100</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>1.63</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.07</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>97.84</div></td>
-        <td class="br tdr"><div>0.46</div></td>
-        <td class="tdr"><div>0.0076</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>90</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>6.57</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.32</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>92.62</div></td>
-        <td class="br tdr"><div>0.49</div></td>
-        <td class="tdr"><div>0.0090</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>80</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>22.70</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>1.38</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>75.47</div></td>
-        <td class="br tdr"><div>0.45</div></td>
-        <td class="tdr"><div>0.0123</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>70</div></td>
-        <td class="br tdr"><div>0.02</div></td>
-        <td class="br tdr"><div>53.73</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>4.0</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>41.95</div></td>
-        <td class="br tdr"><div>0.27</div></td>
-        <td class="tdr"><div>0.0248</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>60</div></td>
-        <td class="br tdr"><div>0.04</div></td>
-        <td class="br tdr"><div>78.16</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>7.32</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>14.33</div></td>
-        <td class="br tdr"><div>0.15</div></td>
-        <td class="tdr"><div>0.0810</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>50</div></td>
-        <td class="br tdr"><div>0.08</div></td>
-        <td class="br tdr"><div>86.16</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>10.01</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>3.72</div></td>
-        <td class="br tdr"><div>0.03</div></td>
-        <td class="tdr"><div>0.466&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>40</div></td>
-        <td class="br tdr"><div>0.16</div></td>
-        <td class="br tdr"><div>86.51</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>12.45</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.88</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>1.65&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>30</div></td>
-        <td class="br tdr"><div>0.22</div></td>
-        <td class="br tdr"><div>84.48</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>15.10</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>0.20</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>8.04&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>20</div></td>
-        <td class="br tdr"><div>0.55</div></td>
-        <td class="br tdr"><div>81.34</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>18.05</div></td>
-        <td class="br tdr"><div>0.01</div></td>
-        <td class="br tdr"><div>0.05</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>39.6&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>15</div></td>
-        <td class="br tdr"><div>0.74</div></td>
-        <td class="br tdr"><div>79.56</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="br tdr"><div>19.66</div></td>
-        <td class="br tdr"><div>0.02</div></td>
-        <td class="br tdr"><div>0.02</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>88.2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>11</div></td>
-        <td class="br tdr"><div>0.94</div></td>
-        <td class="br tdr"><div>78.02</div></td>
-        <td class="br tdr"><div>0.01</div></td>
-        <td class="br tdr"><div>20.99</div></td>
-        <td class="br tdr"><div>0.03</div></td>
-        <td class="br tdr"><div>0.01</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>168&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>5</div></td>
-        <td class="br tdr"><div>0.94</div></td>
-        <td class="br tdr"><div>77.89</div></td>
-        <td class="br tdr"><div>0.18</div></td>
-        <td class="br tdr"><div>20.95</div></td>
-        <td class="br tdr"><div>0.03</div></td>
-        <td class="br tdr"><div>0.01</div></td>
-        <td class="br tdr"><div>&nbsp;</div></td>
-        <td class="tdr"><div>405&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="bb br tdr"><div>0</div></td>
-        <td class="bb br tdr"><div>0.93</div></td>
-        <td class="bb br tdr"><div>77.08</div></td>
-        <td class="bb br tdr"><div>1.20</div></td>
-        <td class="bb br tdr"><div>20.75</div></td>
-        <td class="bb br tdr"><div>0.03</div></td>
-        <td class="bb br tdr"><div>0.01</div></td>
-        <td class="bb br tdr"><div>&nbsp;</div></td>
-        <td class="bb tdr"><div>760&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>Fixing attention first upon the gases other than water, it will be
-    at once observed from the table that these gases show a very uniform
-    mixture in the moist and turbulent region, while farther aloft the
-    lighter of them tend to predominate in relative proportion. This
-    uniformity of composition at the lower levels, which accords with
-    experience, is due to the constant circulation and turmoil in that
-    region. But for this constant agitation, the uniformity<span class="pagenum" id="Page_350">350</span> of mixture
-    could not last. If the atmosphere were perpetually at rest throughout,
-    or moving only in horizontal flow, each constituent gas would assume
-    the same status and distribution as if the others were absent. Each,
-    therefore, obeying Dalton’s law of diffusion, would form an atmosphere
-    of itself, independent of the others, and unaffected in density by
-    them. Such a condition is assumed for the higher levels. The percentage
-    distribution in the higher levels is calculated from the known
-    elasticity and density of the gases, assumed as resting in perpetual
-    calm at a constant temperature of .55° C. beyond eleven kilometers, or
-    above the highest ascent of man, and, furthermore, as having at the
-    earth’s surface 1.2 per cent moisture and a temperature of 11° C.</p>
-
-  <p>But only in the quiescent outersphere can that dynamic gradation be
-    established or perpetuated. Below this lofty region is the sea of
-    water vapor, mingled intimately with the dry air, and churned with
-    it, yet not sharing its uniformity of distribution. Why this rapid
-    diminution of moisture with elevation, as shown in the table? Because
-    throughout the moist region the temperature falls rapidly—about 6° C.
-    per kilometer ascent above the earth—thus chilling and precipitating
-    the vapor, whose pressural resistance to liquefaction diminishes with
-    waning temperature. The explanation is obvious; but why does it not
-    apply as well to the other elements of the atmosphere: why do not the
-    other gases present liquefy with falling temperature as well as the
-    water vapor, which is merely water in the gaseous state? The question
-    cannot be answered very profoundly, but an essential condition of
-    liquefaction of any gas can be stated in learned phraseology, after the
-    preliminary exposition of certain general properties of matter.</p>
-
-  <p><span class="pagenum" id="Page_351">351</span></p>
-
-  <p>We may first set forth those general physical properties, then apply
-    them to answering the above question. Every known substance may exist
-    in either of three states, the solid, liquid or gaseous. For every
-    substance there is a critical temperature above which it can exist
-    only as a gas, and cannot be liquefied by any pressure, but below
-    which a suitable pressure will cause liquefaction. Below its critical
-    temperature a gas is called a vapor, above it a permanent gas. Now in
-    the free atmosphere some of the gases are never below their critical
-    temperatures and, therefore, cannot be liquefied by any pressure,
-    without special cooling; others are sometimes below their critical
-    temperatures and are then capable of liquefaction by sufficient
-    pressure, which however is not always found in free space, but can be
-    supplied by a compression pump; one other gas, that is water vapor,
-    is always below its critical temperature in the free atmosphere, and
-    therefore may always be turned into water by sufficient pressure at its
-    actual atmospheric temperature. Such sufficient pressure in the water
-    vapor actually occurs from time to time in all parts of the atmosphere
-    from the earth’s sur<span class="pagenum" id="Page_352">352</span>face to the highest cirrus region, but more
-    frequently in the nimbus levels, a mile or two above the earth. Thus
-    at all parts of the lower atmosphere liquefaction of aqueous vapor is
-    sometimes observed, either as mist or rain, snow or ice particles, and
-    on the earth as dew or frost. In order to illustrate the above ideas
-    by numerical citation, the accompanying table is given, showing the
-    critical temperature and pressure of the chief gaseous constituents of
-    the atmosphere.</p>
-
-
-  <div class="center mt5">TABLE II</div>
-
-  <p class="center"><i>Critical Temperature and Corresponding Pressure of Liquefaction for
-    the Chief Constituent Gases of the Atmosphere.</i></p>
-
-  <table id="gastemp" class="collapse" summary="Gas temperatures and pressures">
-    <tbody>
-      <tr class="small">
-        <th class="bt bb br">Substance</th>
-        <th class="bt bb br">Critical<br />Temperature<br />C.</th>
-        <th class="bt bb">Critical<br />Pressure<br />Atmospheres.</th>
-      </tr>
-      <tr>
-        <td class="br">Dry Air</td>
-        <td class="br tdr"><div>−140</div></td>
-        <td class="tdr"><div>39</div></td>
-      </tr>
-      <tr>
-        <td class="br">Nitrogen</td>
-        <td class="br tdr"><div>−146</div></td>
-        <td class="tdr"><div>34</div></td>
-      </tr>
-      <tr>
-        <td class="br">Oxygen</td>
-        <td class="br tdr"><div>−118</div></td>
-        <td class="tdr"><div>50</div></td>
-      </tr>
-      <tr>
-        <td class="br">Carbonic Acid</td>
-        <td class="br tdr"><div>−&nbsp;&nbsp;31</div></td>
-        <td class="tdr"><div>75</div></td>
-      </tr>
-      <tr>
-        <td class="br">Argon</td>
-        <td class="br tdr"><div>−120</div></td>
-        <td class="tdr"><div>51</div></td>
-      </tr>
-      <tr>
-        <td class="br">Hydrogen</td>
-        <td class="br tdr"><div>−242</div></td>
-        <td class="tdr"><div>20</div></td>
-      </tr>
-      <tr>
-        <td class="br">Ammonia</td>
-        <td class="br tdr"><div>130</div></td>
-        <td class="tdr"><div>115</div></td>
-      </tr>
-      <tr>
-        <td class="br">Water</td>
-        <td class="br tdr"><div>+365</div></td>
-        <td class="tdr"><div>200</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>A glance at this table shows that for the pressures and temperatures
-    prevailing in our atmosphere most of the constituents are permanent
-    gases. The conspicuous exception is water which, when in the gaseous
-    state, always exists as a vapor, and never as a permanent gas, since
-    it never even approaches the critical temperature. Fortunately for all
-    life on earth the aqueous vapor condenses at very ordinary temperatures
-    and pressures, else there would be no rainfall for irrigation and
-    drinking. Fortunately also the other gases do not so precipitate, else
-    the world might be flooded with liquid nitrogen and oxygen, entailing
-    who knows what disastrous consequences.</p>
-
-  <p>After this digression on the composition of the atmosphere, we may
-    henceforth regard the aërial ocean as a mixture of two substances,
-    dry air and water; the first, a permanent gas; the second, a
-    variable element, existing at times in either the solid, liquid, or
-    vaporous state. For the sake of convenience we may first study the
-    dry atmosphere, then the moist. The dynamic properties of the dry
-    atmosphere may in large measure be deduced by an application of two
-    well-established laws of physics. These will be taken in order.</p>
-
-  <p>By careful investigation it has been proved that throughout a
-    considerable range of pressure and<span class="pagenum" id="Page_353">353</span> temperature the permanent gases
-    very approximately obey the following law; the volume of a permanent
-    gas varies directly as its absolute temperature and inversely as its
-    pressure. In other words the product of its pressure and volume equals
-    the absolute temperature multiplied by a numerical constant. This may
-    be expressed algebraically by the following formula:</p>
-
-  <p class="center"><i>PV</i> = <i>RT</i>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (1)  </p>
-
-  <p class="noindent">in which <i>P</i> is the pressure and <i>V</i> the volume of a given portion of
-    gas at the absolute temperature <i>T</i>, and <i>R</i> is a numerical constant
-    for the gas in question.</p>
-
-  <p>The value of <i>R</i> in the foregoing equation has been determined
-    experimentally for the component gases of the atmosphere, and for dry
-    air as a whole. For dry air, which, under such conditions as surround
-    the aëronaut, may be treated as a single uniform gas, the equation
-    applied to one kilogram gives R = <i>PoVo/To</i> = 29.27, where <i>Po</i>, <i>Vo</i>,
-    <i>To</i>, are respectively the pressure, volume and temperature, in the
-    metric system, of the one kilogram of air under standard conditions;
-    i. e., <i>Po</i> = 10,330 kilograms per square meter, being the normal
-    atmospheric pressure; <i>Vo</i> = 1/1.293 cubic meter, being the volume of
-    one kilogram of dry air at normal pressure and freezing temperature;
-    <i>To</i> = 273° C., being the absolute temperature of freezing. In passing,
-    be it said that the absolute temperature is that measured from the
-    absolute zero, which on the Centigrade scale is 273° below freezing, on
-    the Fahrenheit, 460.6° below freezing.</p>
-
-  <p>The second law referred to follows directly from the principle of the
-    permanence of mass. It is a general observation in physics that a given
-    portion of matter is of constant mass, however its<span class="pagenum" id="Page_354">354</span> pressure, volume,
-    temperature and other conditions may vary. In particular, the mass of a
-    given portion of matter always equals the product of its mean density
-    and volume, since density is defined as the amount of mass in the unit
-    volume. Expressing this physical law, or relation algebraically, gives
-    ρ<i>V</i> = mass = ρ<i>o</i>, <i>Vo</i>, in which ρ, <i>V</i>, are the general symbols
-    for the density and volume of the given portion of matter under any
-    condition, while ρ<i>o</i>, <i>Vo</i>, are the specific values of ρ and <i>V</i>
-    observed for some one state and circumstance of the substance in
-    question. In particular, if the mass of air be unity, we may write:</p>
-
-  <p class="center">ρ<i>V</i> = 1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (2)</p>
-
-  <p class="noindent">This relation, together with that expressed in equation (1), will
-    enable us to deduce many of the properties of dry air and of a dry
-    atmosphere.</p>
-
-  <p>First let us observe from equation (1) the effect, in turn, of keeping
-    constant one of the quantities <i>P</i>, <i>V</i>, <i>T</i>, while the other two vary.
-    The equation shows that if the temperature of a gas is kept constant
-    the volume is inversely proportional to the temperature. This is called
-    the law of Boyle and Mariotte from its two independent discoverers,
-    of whom Boyle seems to have been the first. As an example of Boyle’s
-    law, if any empty glass, or diving bell, be inverted over water,
-    then submerged deeper and deeper, the air within it will shrink with
-    increase of pressure, its volume becoming one half when the pressure is
-    doubled, one third when the pressure is trebled, etc. In particular, if
-    the pressure changes by one unit, the corresponding change of volume
-    is 1/<i>P</i> part of that volume. For example, if a captive balloon is
-    anchored in air at constant temperature, while the barometric pressure
-    changes from 30.0 inches to 30.1 inches, the<span class="pagenum" id="Page_355">355</span> volume of the balloon
-    will contract 1/300 part of itself.</p>
-
-  <p>Again equation (1) shows that if the pressure of a gas is kept
-    constant, the volume is proportional to the absolute temperature. This
-    is the law of Charles and Gay Lussac, so called from its discoverers,
-    of whom Charles is thought to have been the first. As an example of
-    this law, if a captive thin rubber balloon is heated, or cooled, its
-    volume will vary directly as its absolute temperature. In particular,
-    if the temperature is changed one degree, the volume changes 1/<i>T</i>
-    part of itself. For example, if the temperature of a balloon in air of
-    constant barometric pressure is heated from 300° C. to 301° C., its
-    volume will expand 1/300 part of itself. Historically, be it said, this
-    law of Charles and the law of Boyle were discovered separately, then
-    combined, giving equation (1).</p>
-
-  <p>Still a third, though not independent relation may be read from
-    equation (1), thus: when the volume of a gas is kept constant, the
-    pressure is proportional to the absolute temperature. In particular, if
-    the temperature is changed one degree, the pressure varies accordingly
-    by 1/<i>T</i> part of itself. For example, if an air tank or gas tank, in a
-    room at 500° F., changes one degree in temperature, its pressure will
-    change 1/500 part.</p>
-
-  <p>With minute detail these three conclusions from the general equation
-    (1) have been set forth and illustrated, because of their practical
-    importance. Other valuable results may be obtained by similar
-    reasoning. Thus equation (2) may be read; the volume of a unit mass of
-    any substance is the reciprocal of its density. Hence, if in the three
-    foregoing conclusions, the reciprocal of the density is everywhere
-    written for the volume, three new relations will be obtained which
-    are of frequent practical use. Two<span class="pagenum" id="Page_356">356</span> of them may be expressed in the
-    following important law; the density of a gas varies directly as its
-    pressure and inversely as its temperature. Useful applications of this
-    law in aëronautics suggest themselves at once.</p>
-
-  <p>By means of the various foregoing equations, the value of either one
-    of the four quantities <i>P</i>, <i>V</i>, <i>T</i>, ρ, representing respectively
-    the pressure, volume, absolute temperature, and the density, may be
-    obtained in terms of any two of the others. If then any two of the
-    quantities is observed, the others can be at once computed. If, for
-    example, the pressure and temperature of dry air be observed at any
-    point, its density can be computed from the formulæ, also its volume
-    per kilogram weight, and thence its volume for any other weight. It is
-    important therefore to be able to measure satisfactorily at least two
-    of the four quantities. In usual studies of the atmosphere the pressure
-    and temperature are observed directly. The method and instruments
-    employed for that purpose are too well known to require description
-    here.</p>
-
-  <p>In some speculations the pressure and temperature of the atmosphere
-    are assumed, and certain interesting conclusions drawn. For instance,
-    if the temperature is assumed constant throughout a dry atmosphere,
-    the fluid will obey Boyle’s law, and it can be easily shown that the
-    height of such a medium is the same whether it comprise much gas or
-    little.<a id="FNanchor_58" href="#Footnote_58" class="fnanchor">[58]</a> Again assuming the temperature and pressure constant, the
-    height of the normal homogeneous atmosphere can be computed by dividing
-    the pressure per square unit by its weight per cubic unit. In this way
-    the height of the normal homogeneous atmosphere has been found to be
-    about five miles. But these are hypothetical cases, of purely theoretic
-    <span class="pagenum" id="Page_357">357</span>interest. In practice the temperature may, on the average, be assumed
-    to decrease 6° C. for each kilometer of ascent, and the pressures may
-    then be computed for various elevations by use of Boyle’s law, as done
-    for Table I.</p>
-
-  <p>This leads us to a study of the gaseous properties of moist air. By
-    moist air is meant a mixture of dry air and aqueous vapor in the form
-    of an invisible elastic gas. The definition does not comprise air
-    containing visible steam, or mist, or cloud, but clear moist air such
-    as one ordinarily breathes. The study of this mixture may be preceded
-    by a brief account of the gaseous properties of the vapor alone.</p>
-
-  <p>If water in sufficiently small quantity be introduced in a vacuum
-    bottle at any ordinary temperature, it will promptly evaporate,
-    forming an invisible gas known as aqueous vapor, filling the bottle
-    and exerting a uniform pressure on its walls, except for the minute
-    difference at top and bottom due to gravity. The vapor weighs 0.622 as
-    much as dry air having the same volume, temperature and pressure, or
-    quite accurately ⅝ as much. It obeys all the laws given above for
-    ordinary gases and dry air. But it has one singularity; at ordinary
-    atmospheric temperatures, it cannot be indefinitely compressed
-    without condensing to a liquid. In this respect it differs from the
-    chief components of the atmosphere, which at ordinary temperatures
-    can endure indefinite pressure without liquefaction. The ammonia and
-    carbon dioxide in the air can, it is true, be condensed by pressure at
-    their usual temperatures, but not by such pressures as occur in the
-    free atmosphere, thus still leaving aqueous vapor the one singular
-    constituent.</p>
-
-  <p>Reverting to the behavior of the water in the assumed vacuum
-    bottle at fixed temperature, it may be observed that the pressure
-    of the invisible vapor is<span class="pagenum" id="Page_358">358</span> directly proportional to the amount of
-    liquid evaporated. In other words, for any fixed temperature the
-    vapor pressure is directly proportional to its density. When this
-    density reaches a certain definite amount, dependent solely upon the
-    temperature, no further evaporation will occur, unless some of the
-    vapor condenses. The pressure of saturation for that temperature has
-    been reached, and any attempt to increase the pressure, by diminishing
-    the volume of the vapor, will cause liquefaction at constant
-    temperature.</p>
-
-  <p>If, however, the space is not saturated, the mass of vapor present may
-    be expressed as a percentage of the amount required for saturation at
-    that temperature. This percentage is called the relative humidity. Thus
-    if the relative humidity is seventy per cent, the actual mass of water
-    vapor present at the observed temperature is seventy per cent of the
-    maximum that can exist in the given space, at the given temperature. In
-    other words, the relative humidity is the ratio of the actual to the
-    possible humidity at a given temperature.</p>
-
-  <p>In like manner, for any given vapor pressure there is a definite
-    saturation temperature, known as the dew-point. If with constant
-    pressure the vapor is given various temperatures higher than the
-    dew-point, it will remain gaseous and invisible; but if it falls in
-    temperature to the dew-point, liquefaction occurs, and drops of water
-    appear on the inner wall of the vessel. Further cooling will entail
-    still further liquefaction and reduction of pressure; for the lower
-    the temperature the less the possible mass and pressure of saturation.
-    But for all temperatures, down to freezing and considerably below,
-    some vapor exists, and obeys the same laws as at higher temperatures.
-    When, however, saturation occurs below freezing, the vapor may be
-    precipitated<span class="pagenum" id="Page_359">359</span> as snow instead of water. This is a familiar phenomenon
-    in the free atmosphere.</p>
-
-  <p>The actual mass of water vapor present in a cubic unit of space
-    is sometimes called the absolute humidity. A formula giving the
-    absolute humidity <i>f</i>, in kilograms per cubic meter, for any observed
-    temperature <i>t</i>, and vapor pressure <i>e</i>, may be written as follows:</p>
-
-  <p class="center"><i>f</i> = 0.00106 <i>e</i> / (1 + 0.00367 <i>t</i>)</p>
-
-  <p class="noindent">in which <i>e</i> is the vapor pressure in millimeters of mercury, and <i>t</i>
-    is the common Centigrade reading. As an illustration of the actual
-    values of the pressure, temperature and density of saturated water
-    vapor, for various conditions, the following table is presented:</p>
-
-
-  <div class="center mt5">TABLE III</div>
-
-  <p class="center"><i>Temperature, Pressure and Density of Aqueous Vapor, in Metric
-    Measures.</i></p>
-
-  <table id="aqueous" class="collapse" summary="Aqueous vapor">
-    <tbody>
-      <tr class="small">
-        <th class="bt bb br">Temperature,<br />Centigrade.</th>
-        <th class="bt bb br">Pressure,<br />Millimeters.</th>
-        <th class="bt bb">Density Kilos.<br />per cubic meter.</th>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>−25</div></td>
-        <td class="br tdr"><div>0.61</div></td>
-        <td class="tdr"><div>.557</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>−20</div></td>
-        <td class="br tdr"><div>0.94</div></td>
-        <td class="tdr"><div>.892</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>−15</div></td>
-        <td class="br tdr"><div>1.44</div></td>
-        <td class="tdr"><div>1.395</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>−10</div></td>
-        <td class="br tdr"><div>2.15</div></td>
-        <td class="tdr"><div>2.154</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>−&nbsp;&nbsp;5</div></td>
-        <td class="br tdr"><div>3.16</div></td>
-        <td class="tdr"><div>3.244</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>4.57</div></td>
-        <td class="tdr"><div>4.835</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>+&nbsp;&nbsp;5</div></td>
-        <td class="br tdr"><div>6.51</div></td>
-        <td class="tdr"><div>6.761</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>10</div></td>
-        <td class="br tdr"><div>9.14</div></td>
-        <td class="tdr"><div>9.329</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>15</div></td>
-        <td class="br tdr"><div>12.67</div></td>
-        <td class="tdr"><div>12.712</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>20</div></td>
-        <td class="br tdr"><div>17.36</div></td>
-        <td class="tdr"><div>17.117</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>25</div></td>
-        <td class="br tdr"><div>23.52</div></td>
-        <td class="tdr"><div>22.795</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>30</div></td>
-        <td class="br tdr"><div>31.51</div></td>
-        <td class="tdr"><div>30.036</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>35</div></td>
-        <td class="br tdr"><div>41.78</div></td>
-        <td class="tdr"><div>39.183</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>40</div></td>
-        <td class="br tdr"><div>54.87</div></td>
-        <td class="tdr"><div>&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br bb tdr"><div>45</div></td>
-        <td class="br bb tdr"><div>71.36</div></td>
-        <td class="bb tdr"><div>&nbsp;</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>Now by Dalton’s law, each gas or vapor in a mixture of several behaves
-    as if it were alone. Thus if the foregoing experiment be conducted in
-    a bottle<span class="pagenum" id="Page_360">360</span> containing various gases chemically inert to water, the same
-    mass of water will be evaporated, and exert the same uniform pressure,
-    in addition to those exerted by the gases. Now the density of each
-    gas or vapor present, will equal its mass divided by its volume, and
-    the density of the mixture will equal the total mass divided by the
-    volume. Furthermore, it is well known that aqueous vapor is less dense
-    than dry air at the same temperature and pressure. From this it is at
-    once evident that moist air, which is merely a mixture of dry air and
-    aqueous vapor, must be lighter than dry air at the same temperature and
-    pressure. This is true whether the two fluids compared be in closed
-    vessels or in the free atmosphere.</p>
-
-  <p>Accordingly in all precise dealing with the free air, whether involving
-    its buoyancy, its resistance, its energy or any other mass function,
-    its density as affected by the humidity must be taken into account.
-    This can be computed from the observed pressure, temperature and
-    relative humidity as revealed by well known instruments, the barometer,
-    thermometer and hygrometer. Thus from the observed temperature and
-    relative humidity, the mass of vapor present per cubic meter is read
-    from Table III, the reader, of course, multiplying the given tabulated
-    mass by the observed percentage of humidity. To this aqueous mass must
-    be added the mass of dry air present. Then the total mass per cubic
-    meter is the density.</p>
-
-  <p>Various formulæ are available for computing the density of moist
-    air from the readings of the three instruments mentioned above.
-    Also, tables have been worked out giving the density without further
-    calculation. Moreover, the density of free air may be directly
-    measured, accurately enough for most purposes, by means of a
-    densimeter. A simple formula <span class="pagenum" id="Page_361">361</span>for finding the density of moist air is
-    as follows:</p>
-
-  <p class="center">ρ = 0.465 (<i>b−e</i>)/<i>T</i></p>
-
-  <p class="noindent">in which <i>b</i>, <i>e</i>, are the pressures in millimeters mercury
-    respectively of the moist air and its vapor, as revealed by the
-    barometer and hygrometer.</p>
-
-  <p>In practice no great error will be made in assuming the relative
-    humidity to be fifty per cent. For the moisture content never exceeds
-    five per cent of the mass of the moist air, and hence in assuming a
-    fifty per cent relative humidity, when there is actually a maximum
-    or minimum humidity, the greatest possible error in estimating the
-    moisture content is 2.5 per cent of the mass of moist air. Now if 2.5
-    per cent of a mass of air be assumed to be aqueous vapor when all is
-    really dry air, or conversely if 2.5 per cent of the whole mass be
-    assumed as dry air when it is really aqueous vapor, an error of much
-    less than 2.5 per cent is made in estimating the true density. No error
-    at all would ensue if both air and vapor were of the same density; but
-    since one is ⅝ as heavy as the other, the possible error is ⅜ of
-    2.5 per cent, or 0.6 per cent. This is a negligible quantity in all
-    mechanical considerations, except where great accuracy is required.</p>
-
-  <p>When any gas changes density or volume it also changes temperature,
-    unless there be transfer of heat between it and its environment. When
-    change of volume occurs without such transfer of heat the expansion,
-    or contraction, is called “adiabatic;” when it occurs at constant
-    temperature, the expansion is called “isothermal,” the temperature
-    being kept uniform by suitable transfer of heat; when it occurs at
-    constant pressure it is called “isopiestic.” In either case work may
-    be done by the enlarging gas, if it press against a moving piston,
-    or yielding<span class="pagenum" id="Page_362">362</span> envelope of some kind; and conversely work may be spent
-    on the gas in compressing it either isothermally, adiabatically or
-    isopiestically.</p>
-
-  <p>If, for example, a balloon rises rapidly its contents will expand
-    adiabatically, pushing the envelope out in all directions against the
-    static pressure of the embracing atmosphere. Thus it will do work and
-    rapidly cool. But if it rapidly sinks, it will contract adiabatically
-    and grow warm, owing to the work done by the surrounding air in
-    compressing it. A like thing occurs when a great volume of air rises
-    or sinks quickly in the free atmosphere. In this case the change of
-    temperature is about 6° C. for each kilometer change of level, so long
-    as the air remains unsaturated. A familiar example of this effect in
-    Nature is manifested when an uprushing column of moist air chills, and
-    precipitates moisture, forming a cloud toward its top. Thus a lone
-    thundercloud in a clear sky may mark the upper part of such a column,
-    or upward vortex in the air. And contrarywise, a descending column may
-    absorb its visible moisture, causing it to become clear aqueous vapor,
-    and thus vanish from view.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XIV">
-    <span class="pagenum" id="Page_363">363</span>
-    <h3>CHAPTER XIV</h3>
-    <span class="small">GENERAL DISTRIBUTION OF HEAT AND PRESSURE</span>
-  </div>
-
-  <p><span class="smcap">Having</span> thus briefly examined the composition and certain gaseous
-    properties of free air, both dry and moist, we may now study the
-    atmosphere as a whole. We wish particularly to know of its distribution
-    of temperature and pressure; of its general and permanent circulation;
-    of its great periodic currents; of its vertical movements, and its
-    minor local winds with their pulsations of velocity and direction.
-    Fortunately much information is available, due both to governmental
-    and private research, though this was collected more for purposes of
-    meteorology than of aërial locomotion. Of late, however, attention has
-    been given to the aëronautic study of the atmosphere, which will, it is
-    hoped, prove valuable to the aërial navigator.</p>
-
-  <p>The movements of the atmosphere are due mainly to the sun’s heat and
-    to the rotation of the earth. The earth’s internal heat and the moon’s
-    attraction are other minor agencies, but these may be neglected by
-    comparison. The earth’s rotation also would be ineffectual in modifying
-    the aërial movements, except for the coöperation of the sun. Without
-    his influence the atmosphere, always stagnant, would simply rotate with
-    the globe, at constant angular velocity and uniformly graded density at
-    various levels. This evenness of density for any level is broken by the
-    solar radiation increasing the temperature <span class="pagenum" id="Page_364">364</span>and moisture, otherwise the
-    air would remain practically at a standstill.</p>
-
-  <p>Though the moisture by its lesser density causes some lightening of
-    the air at fixed temperature, this at most is hardly one per cent, as
-    already shown, and on the average is much less. Its effect, therefore,
-    is equivalent to less than that caused by a rise of temperature of
-    three degrees. But if precipitation occurs, an enormous amount of
-    stored sunshine, or latent heat, is liberated and applied to warming
-    the associated air. Thus each pound of vapor condensed may, by the
-    release of its thermal store, heat more than a ton of air one degree
-    in temperature, or more than half a ton of air two degrees, etc.
-    The actual number of pounds of air at constant pressure, raised one
-    degree Centigrade by the condensation of one pound of vapor at various
-    temperatures, is given in the following table:</p>
-
-  <div class="center mt5">TABLE IV</div>
-
-  <table class="collapse" summary="Condensation">
-    <tbody>
-      <tr>
-        <td class="br bt">Temperature of condensation</td>
-        <td class="br bt tdr"><div>0°</div></td>
-        <td class="br bt tdr"><div>25°</div></td>
-        <td class="bt tdr"><div>50°</div></td>
-      </tr>
-      <tr>
-        <td class="br bb">Pounds of air heated one degree</td>
-        <td class="br bb tdr"><div>2550&nbsp;&nbsp;</div></td>
-        <td class="br bb tdr"><div>2480&nbsp;&nbsp;</div></td>
-        <td class="bb tdr"><div>2407&nbsp;&nbsp;</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>The sun then is father of the wind. By uneven heating of the atmosphere
-    it disturbs the uniform density gradation that would otherwise exist.
-    Thus abnormal pressures are generated which disturb the repose of the
-    aërial sea, causing the fluid to flow from regions of excessive to
-    regions of defective pressure. Hence the study of insolation<a id="FNanchor_59" href="#Footnote_59" class="fnanchor">[59]</a> and
-    temperature distribution is fundamental to the science of the winds.</p>
-
-  <p>Without detailed study, we may note the aggregate insolation received
-    by the earth, at various lati<span class="pagenum" id="Page_365">365</span>tudes, and its general effect on
-    terrestrial temperature. The sun emits a nearly constant stream of
-    radiation, from year to year, which plays continuously upon the earth
-    as a whole, with an intensity which varies but slightly from month to
-    month, due to the slightly varying distances of the earth from the
-    sun. Owing to the sun’s seasonal wandering across the equator, the
-    insolation at any latitude varies considerably month by month, and
-    the polar regions receive much more light than if no such wandering
-    occurred. The total yearly insolation for every 5° of latitude is shown
-    in the following table from Hann, in which the unit is the amount that
-    the earth would receive in one day at the time of the equinox, if the
-    sun were at its mean distance from the earth:</p>
-
-  <div class="center mt5">TABLE V</div>
-
-  <p class="center"><i>Annual Amounts of Insolation</i></p>
-
-  <table id="insolation" class="collapse" summary="Insolation">
-    <tbody>
-      <tr class="small">
-        <th class="br bt bb">Latitude.</th>
-        <th class="br bt bb">Thermal<br />Days.</th>
-        <th class="bt bb">Difference.</th>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>0°</div></td>
-        <td class="br tdr">350.3</td>
-        <td class="tdr"><div>&nbsp;</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>5°</div></td>
-        <td class="br tdr">349.1</td>
-        <td class="tdr"><div>1.2</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>10°</div></td>
-        <td class="br tdr">345.5</td>
-        <td class="tdr"><div>3.6</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>15°</div></td>
-        <td class="br tdr">339.4</td>
-        <td class="tdr"><div>6.1</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>20°</div></td>
-        <td class="br tdr">331.2</td>
-        <td class="tdr"><div>8.2</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>25°</div></td>
-        <td class="br tdr">320.5</td>
-        <td class="tdr"><div>10.7</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>30°</div></td>
-        <td class="br tdr">307.9</td>
-        <td class="tdr"><div>12.6</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>35°</div></td>
-        <td class="br tdr">293.2</td>
-        <td class="tdr"><div>14.7</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>40°</div></td>
-        <td class="br tdr">276.8</td>
-        <td class="tdr"><div>16.4</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>45°</div></td>
-        <td class="br tdr">258.7</td>
-        <td class="tdr"><div>18.1</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>50°</div></td>
-        <td class="br tdr">239.6</td>
-        <td class="tdr"><div>19.1</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>55°</div></td>
-        <td class="br tdr">219.4</td>
-        <td class="tdr"><div>20.2</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>60°</div></td>
-        <td class="br tdr">199.2</td>
-        <td class="tdr"><div>20.2</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>65°</div></td>
-        <td class="br tdr">180.2</td>
-        <td class="tdr"><div>19.0</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>70°</div></td>
-        <td class="br tdr">166.2</td>
-        <td class="tdr"><div>14.0</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>75°</div></td>
-        <td class="br tdr">156.5</td>
-        <td class="tdr"><div>9.7</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>80°</div></td>
-        <td class="br tdr">150.2</td>
-        <td class="tdr"><div>6.3</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>85°</div></td>
-        <td class="br tdr">146.5</td>
-        <td class="tdr"><div>3.7</div></td>
-      </tr>
-      <tr>
-        <td class="br tdr"><div>90°</div></td>
-        <td class="br tdr">145.4</td>
-        <td class="tdr"><div>1.1</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>From this it appears that the equator receives nearly 2.5 times as much
-    heat yearly as the poles. Since, moreover, the equator enjoys nearly
-    constant insolation, while the polar regions suffer great variations of
-    heat, with the varying altitude of the sun, the equatorial atmosphere
-    is both much hotter and more equable than the poles, and high latitudes
-    generally. <span class="pagenum" id="Page_366">366</span>Thus at the equator the frost level stands constantly
-    at 18,000 feet, while in the middle latitudes it varies greatly in
-    height from season to season. If, for example, a circle be drawn to
-    represent the earth, and above it a line to indicate the mean altitude
-    of the frost level in July, the frost line starting at the equator
-    at an elevation of 18,000 feet will decline north and south, finally
-    touching the earth well toward the frigid zones. The levels for other
-    temperatures, above and below freezing, are similarly inclined downward
-    from the equator to north and south. Obviously these isothermal
-    levels vary with the varying season, and at any fixed time differ on
-    different longitudes. On the plane of any given latitude the frost
-    line varies much less in altitude, and so for the other isothermals.
-    This is particularly true at the poles and equator, and everywhere at
-    considerable altitude. If one voyaged around the earth at the equator
-    at an elevation of 5,000 feet, he should find the average temperature
-    about 65° F. In the temperate zone, following a line of latitude
-    at the same height, he should have a lower temperature, but still
-    comparatively equable. The average annual temperature of the earth’s
-    entire surface is about 60° F.</p>
-
-  <p>In practical meteorology the temperature is observed at many points
-    simultaneously over a wide stretch of the earth’s surface. These
-    are then plotted on a weather chart, and through all points of like
-    temperature are drawn lines known as isothermals. These lines not only
-    map the earth’s surface into regions of equal temperature, but they
-    also show the direction of fall or rise of temperature, and its space
-    rate of change. This rate is called the “temperature gradient,” and
-    when estimated straight across from isothermal to isothermal, that is
-    in the direction of liveliest change of temperature,<span class="pagenum" id="Page_367">367</span> it is the maximum
-    gradient. Such a map is very useful in forecasting the weather. It is
-    but a particular instance of the more general map conceived by the
-    physicist, exhibiting the thermal condition of the entire atmosphere by
-    means of a series of equal temperature surfaces one above the other.
-    Here, of course, the temperature gradient at any point is the space
-    rate of change of temperature in any direction, being zero along the
-    isothermal surface and greatest normal to it.</p>
-
-  <p>The vertical temperature gradient is of particular interest, since
-    it determines the condition of fluid equilibrium at any point in the
-    atmosphere when the level surfaces are isothermal. If, for example, a
-    balanced balloon or portion of air, on starting upward from any level,
-    cools faster than the environing stagnant air, it will become more
-    dense, and cease to ascend, in which case the atmospheric equilibrium
-    is stable. Again, if the ascending gas or air cools more slowly than
-    the surrounding medium, it will become less dense, and so continue
-    to ascend, in which case the atmospheric equilibrium at the point
-    is unstable. Thirdly, if the rate of cooling be identical for the
-    ascending gas and its surrounding medium, the equilibrium is neutral,
-    and the motion will be stopped by friction but unaffected by change
-    of buoyancy, since no such change can occur. Of these three states of
-    equilibrium, the stable is dominant above the cirrus level, while below
-    that level each state may be found, at various times, prevailing at
-    random in all parts of the world, but more generally the stable and
-    neutral states. When the unstable condition occurs at any locality and
-    any level, it is usually followed ere long by a commotion or upheaval
-    in the atmosphere, until the temperature gradient alters to the neutral
-    or stable.</p>
-
-  <p>Many observations have been made to determine<span class="pagenum" id="Page_368">368</span> the variation of
-    temperature along the verticle in various places and in different
-    seasons. From the temperature records obtained in 722 balloon
-    ascensions near Paris, France, the mean fall of temperature per 1000
-    feet up to 20,000 feet was found to be 2°.4 in winter, 2°.8 in spring,
-    2°.6 in summer, 2°.5 in autumn and 2°.6 for the year. Near Berlin 3°.1
-    for the year was found from 75 balloon ascensions, the rate being
-    nearly the same for the halves of the year. Fig. 44 gives the average
-    of 52 winter and 65 summer temperature gradients, taken at about 8 <span class="smcap">a.m.</span>
-    by means of sounding balloons sent up at Munich, Strassburg, Trappe and
-    Uccle. It will be noted that in both summer and winter the temperature
-    falls rapidly with increase of elevation, up to ten or eleven
-    kilometers, but above twelve remains nearly constant for all altitudes.
-    The difference in temperature summer and winter is interesting, also in
-    its gradual diminution with altitude. Another striking feature is the
-    inversion of gradient shown at twelve kilometers elevation, where the
-    temperature ceases to diminish, and may even increase with altitude.
-    This region is known as the upper inversion level of the atmosphere, as
-    distinguished from other levels at or below three kilometers height,
-    known as lower inversions, where the temperature gradient is sometimes
-    reversed, though not so illustrated in the diagram.</p>
-
-  <p>Thus the atmosphere divides into three marked layers. The lower
-    layer, three kilometers deep, is the region of turbulence and storm,
-    the home of heavy rain clouds, lightning, wind gusts and irregular
-    temperatures. The middle layer, some seven kilometers thick, bounded
-    top and bottom by the upper and lower inversion levels, is a clear
-    region of steady-falling temperature, for the most part frigid—a region
-    of far reaching and rapid winds, sweeping<span class="pagenum" id="Page_369">369</span> eastwardly, except near the
-    equator, and bearing on their backs the frosty cirrus clouds. The upper
-    layer reaching from the cirri to the cosmic void, is always cloudless
-    and very frigid, with temperature nearly constant, or maybe slightly
-    increasing with elevation.</p>
-
-  <div class="figcenter">
-    <a id="Fig_44"><img src="images/i_449.jpg" width="600" height="697" alt="" /></a>
-    <div class="caption smcap">Fig. 44.—Summer and Winter Average Vertical
-      Temperature Gradients.</div>
-  </div>
-
-  <p>A striking peculiarity of these three regions is that the lower and
-    middle layers may freely intermingle with each other, but never with
-    the upper, or<span class="pagenum" id="Page_370">370</span> isothermal layer. Owing to its constant temperature, the
-    upper layer floats on its neighbor like oil on water.<a id="FNanchor_60" href="#Footnote_60" class="fnanchor">[60]</a> If a mass of
-    dry air were forced up into it from below, with the natural cooling due
-    to adiabatic expansion, such mass would be denser than the surrounding
-    medium, and hence would promptly sink back to its initial position.
-    Thus whatever turmoil may vex the middle or lower region, it can at
-    most upheave the floor of the isothermal layer, leaving inviolate the
-    crystal depths of the empyrean.</p>
-
-  <p>We may now turn to the distribution of barometric pressure in
-    the atmosphere and the effect of its variation. In general, the
-    distribution is not very uniform, but it can be graphically pictured by
-    drawing a series of surfaces connecting all points of equal pressure.
-    These are called isobaric surfaces. In a stagnant uniformly heated
-    atmosphere, for example, these surfaces would lie one above the other
-    parallel to the ocean face; but where turmoil exists, and irregular
-    temperature distribution, the isobaric surfaces are bent into hills
-    and hollows of varied form. These surfaces not only map the aërial sea
-    into regions of equal pressure, but they also show the direction of
-    fall or rise of pressure, and its space rate of change. This rate is
-    called the “pressure gradient.” When estimated straight across from
-    surface to surface, that is, in the direction of the liveliest change
-    of pressure, it is the maximum pressure gradient. Along this normal
-    direction the air tends to flow with an acceleration proportional to
-    the gradient. The velocity thus acquired by any portion of air in
-    being pushed along the line of falling pressure, combined with its
-    velocity due to other causes, gives its true velocity. A most important
-    consideration, <span class="pagenum" id="Page_371">371</span>therefore, in a scientific study of the wind is the
-    pressure distribution.</p>
-
-  <p>In practical meteorology, observations of the barometric pressure are
-    made simultaneously at many points on the earth’s surface, and the
-    readings then plotted on a map, after “reduction to sea level.” This
-    reduction is made by adding to each barometric reading the weight of a
-    column of air between the barometer level and the sea level, according
-    to tables prepared for this purpose. Lines called “isobars”<a id="FNanchor_61" href="#Footnote_61" class="fnanchor">[61]</a> are
-    then drawn, at regular intervals, through all points of like sea-level
-    pressure, the indicated change of pressure between consecutive isobars
-    on the U. S. weather map being usually one-tenth of an inch of mercury.
-    These exhibit at once, over the entire field of observation, the
-    horizontal pressure gradient reduced to sea level, and commonly called
-    the “barometric gradient.” In meteorology, the pressure normal to the
-    isobar is called the gradient, and is expressed in millimeters of
-    mercury per degree of a great circle. On the same weather chart are
-    mapped the isothermal lines and wind directions for all the stations
-    of the weather service. From these data and the reported moisture
-    conditions, the meteorologist forecasts the probable weather some hours
-    or days in advance.</p>
-
-  <p>No perfectly comprehensive formula can be given for the barometric
-    pressure at any place and altitude, but certain general laws may be
-    observed. Where, for example, the speed of the air is increased along
-    any level of an air stream, the pressure is lessened, and conversely.
-    Thus, if the wind blows squarely against the front of an isolated
-    house, the speed will be greatly checked at the center front, <span class="pagenum" id="Page_372">372</span>and
-    accelerated at both sides and over the roof, thereby increasing the
-    apparent barometric pressure on the front, and lessening it on the
-    sides and over the top. A similar effect may be observed when the air
-    flows round the hull and framing of air craft.</p>
-
-  <p>Again, if the atmosphere over any locality is heated appreciably more
-    than its environment, the heated column tends to expand upward and
-    overflow aloft in all directions toward the cooler neighborhood, thus
-    lessening the pressure throughout the heated column, and increasing
-    the pressure throughout the environing atmosphere laterally. When this
-    effect is marked the plotted isobars often form a series of closed
-    curves about the heated region, manifesting a pressure gradient at the
-    lower levels in all directions toward the heated area. This grouping of
-    the isobars exhibits the familiar low pressure area of the weather map.
-    On the other hand, if any locality be cooled appreciably more than its
-    environment, the cooled column sinks, so that the surrounding warmer
-    air aloft flows in over it, thereby increasing the pressure over the
-    cooled area, and diminishing it throughout the environment. The isobars
-    may then form a series of closed curves about the cooled region, with a
-    pressure gradient along the higher levels in all directions away from
-    the cooled area. Of course, if heat were the only agency disturbing
-    the earth’s barometric pressure, there should be a parallelism between
-    the heat and pressure gradients; but, as already noted, the speed
-    or momentum of the aërial currents is also a substantial agency in
-    modifying the pressure lines.</p>
-
-  <p>It is well to remember that, while the base of a warm column of air
-    may, due to the overflow aloft, have less pressure than the base of
-    the cool environing <span class="pagenum" id="Page_373">373</span>column which receives the overflow, the high part
-    of the column may have greater pressure than the equally high part of
-    the cool. For if the columns be initially of the same temperature and
-    pressure, heating one of them uplifts its levels of given pressure
-    above those of its neighbor. When the overflow begins, a partial
-    equalization of pressure levels occurs, but not a complete one so long
-    as the flow has any head.</p>
-
-  <p>An interesting hygrometric feature of these highs and lows may here
-    be observed in passing. As already explained, when a column of air
-    ascends it cools by expansion, and tends to precipitate its water
-    content as cloud or rain; and conversely, when the air sinks it heats
-    by compression, thus acquiring greater moisture capacity and tending
-    to clarify. As a consequence, the areas of low pressure and a rising
-    atmosphere are usually marked by clouds and rainfall, while the areas
-    of high pressure and falling atmosphere are marked by clear, or
-    clearing weather. In the low, damp areas, then, the air feels heavy
-    while it is really light; in the high and dry area the air feels light,
-    while it is really dense, and most favorable to air men for carrying
-    heavy loads in their balloons or flyers. Similarly when air flows over
-    a mountain range the ascending stream precipitates moisture, due to
-    cooling by expansion, while the descending stream, on the other side,
-    comes down hot and dry, due to compression.</p>
-
-  <p>A characteristic mechanical feature of the high and low pressure areas
-    is the closed circulation between them, involving practically the whole
-    atmosphere below the isothermal layer. If we conceive the entire globe
-    spotted with high and low areas, we may picture the air surging upward
-    in the lows, flowing outward under the isothermal layer, descending <span class="pagenum" id="Page_374">374</span>in
-    the highs, then flowing outward along the earth’s surface toward the
-    lows in a continuous cycle. Thus, chiefly is maintained the vast and
-    multifold circulation of the atmosphere over the entire world.</p>
-
-  <p>In general the motion is of a vortical nature, by which is meant that
-    the masses of air as they flow along stream suffer more or less change
-    of orientation in space, the rotation at times being so slight as to
-    be undetectable, and again so marked as to excite wonder, as in the
-    whirlwind. Many of these atmospheric vortices, even though varying
-    in diameter from a few yards to hundreds of miles, resemble in their
-    behavior the gyrating column of water in a common circular basin
-    emptying through an orifice at its bottom. If the water is very still
-    when the drain opens, the column descends with imperceptible, if any,
-    rotation; but if the column has an initial whirl, or angular velocity,
-    this is magnified as the water approaches the axis of the vortex,
-    the tendency of the mass being to preserve its angular momentum, or
-    fly wheel property. A like action obtains in the great atmospheric
-    vortices, though here the motion far from the axis may seem like a
-    straight-blowing wind, rather than part of a vast whirl covering
-    thousands of square miles.</p>
-
-  <p>But even if all the air started directly for the axis of the ascending
-    column, like still water in a basin, it would promptly acquire vortex
-    motion, because it flows on the surface of a rotating sphere. The
-    deflection so produced is evidently greatest at the poles, and for
-    other places equals the polar value multiplied by the sine of the
-    latitude. The effect is similar to what occurs when a basin, rotating
-    about a vertical axis and carrying water with the same angular
-    velocity, is opened at the bottom. In this case<span class="pagenum" id="Page_375">375</span> the water at once
-    begins to gyrate within the basin, as the particles move toward its
-    axis.</p>
-
-  <p>With these preliminary generalities we may proceed to study the more
-    prominent movements in the atmosphere.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XV">
-    <span class="pagenum" id="Page_376">376</span>
-    <h3>CHAPTER XV</h3>
-    <span class="small">PERMANENT AND PERIODIC WINDS</span>
-  </div>
-
-  <p><span class="smcap">The</span> winds of the world are commonly classified as the permanent, the
-    periodic and the nonperiodic, according to their genesis and character.
-    Their chief features may be briefly outlined.</p>
-
-  <p>The most conspicuous and important aërial current on the globe is
-    the permanent double vortex playing between the equator and the
-    poles. The heated air of the equatorial belt, uplifted by expansion,
-    overflows beneath the isothermal layer toward the north and south,
-    thereby increasing the pressure in the higher latitudes sufficiently
-    to generate a surface inflow along the earth, and thus maintaining a
-    perpetual closed circulation which is felt all over the globe. The
-    main features of this motion have been determined mathematically by
-    Ferrel,<a id="FNanchor_62" href="#Footnote_62" class="fnanchor">[62]</a> and summarized as follows:</p>
-
-  <blockquote>
-    <p>“In the preceding part of this chapter it has been shown that, if
-      all parts of the atmosphere had the same temperature, there would be
-      a complete calm over all parts of the earth’s surface. But that, in
-      consequence of the difference of temperature between the equatorial and
-      polar regions of the globe, and the consequent temperature gradient,
-      there arise pressure gradients and forces which give rise to and
-      maintain a vertical circulation of the atmosphere, with a motion of the
-      air of the upper strata of the <span class="pagenum" id="Page_377">377</span>atmosphere from the equator toward the
-      poles, and a counter current in the lower part from the poles toward
-      the equator, as represented by the arrows in the following figure, and
-      that this of course requires a gradual settling down of the air from
-      the higher to the lower strata in the middle and higher latitudes and
-      the reverse in the lower latitudes. It has also been shown that in
-      case the earth had no rotation on its axis, this would be exclusively
-      a vertical circulation in the planes of the meridians without any east
-      or west components of motion in any part; but that, in consequence of
-      the deflecting forces arising from the earth’s rotation, the atmosphere
-      at the earth’s surface has also an east component of motion in the
-      middle and higher latitudes, and the reverse in the lower latitudes,
-      and that the velocities of the east components increase with increase
-      of elevation, so that at great altitudes they become very much greater
-      than those at the earth’s surface; while those of the west components
-      decrease with increase of altitude up to a certain altitude, where they
-      vanish and change signs and become east velocities, now increasing with
-      increase of altitude to the top of the atmosphere.</p>
-
-    <p>“It has been further shown that the deflecting forces arising from the
-      east components of motion of each hemisphere from the earth’s surface
-      to the top of the atmosphere, in the middle and higher latitudes and
-      of the upper part of the atmosphere in the lower latitudes, drives
-      the atmosphere from the polar regions toward the equator, while
-      those arising from the west components of motion in the lower part
-      of the atmosphere in the lower latitudes, having a contrary effect,
-      but small in comparison with the other on account of the weakness of
-      these forces near the equator, tend to drive the air a little from the
-      equator toward the poles. There is, therefore,<span class="pagenum" id="Page_378">378</span> a depression of the
-      isobaric surfaces at all altitudes in the polar regions, especially in
-      the southern hemisphere, a much smaller depression in the equatorial
-      regions, and a bulging up of the isobaric surfaces in the vicinity of
-      the parallel of 30° in the lower part of the atmosphere, the maximum
-      being nearer the equator as the altitude increases, as represented
-      in Fig. 45, but at high altitudes there is a minimum of barometric
-      pressure at the poles and a maximum at the equator.</p>
-  </blockquote>
-
-  <div class="figcenter">
-    <a id="Fig_45"><img src="images/i_458.jpg" width="460" height="498" alt="" /></a>
-    <div class="caption smcap">Fig. 45.—General Circulation of the Atmosphere.</div>
-  </div>
-
-  <blockquote>
-    <p>“In the accompanying figure the solid arrows in the interior part
-      represent the resultant motions of the winds (longer arrows indicating
-      greater velocities), in case of an earth with a homogeneous surface
-      over both hemispheres, in which the motions would be symmetrical in
-      both and the same at all<span class="pagenum" id="Page_379">379</span> longitudes, and the equatorial and tropical
-      calm belts would be situated at equal distances from each pole. The
-      dotted arrows indicate the strong, almost eastern motion of the air at
-      all latitudes at some high altitude, as that of the cirrus clouds.</p>
-
-    <p>“The outline of the outer part of the figure represents an isobaric
-      surface high up where the bulging up near the parallel of 30°
-      disappears and the maximum pressure at the same altitude is transferred
-      to the equator. For lower altitudes the isobaric surfaces have a
-      bulging up at the parallel of 30°, and a slight depression at and near
-      the equator. The arrows in this part represent the polar and equatorial
-      components of motion, the former above and the latter below, except
-      near the earth’s surface on the polar sides of the tropical calm-belts,
-      where there is a polar component of motion arising from the air’s being
-      pressed out from under the belt of high pressure. This, perhaps, does
-      not extend beyond the polar circles, beyond which there can be little
-      motion in any direction, except from abnormal disturbances.</p>
-
-    <p>“For reasons given in § 103, the actual mean position of the equatorial
-      and tropical calm-belts are not precisely as here represented, but are
-      all a little displaced toward the north pole, and the polar depression
-      of the isobaric surfaces is greater in the southern than in the
-      northern hemisphere.”</p>
-  </blockquote>
-
-  <p>The conclusions from this approximate analysis are in the main
-    supported by observation, except as modified by the heterogeneity
-    of the earth’s surface. The sea-level distribution of barometric
-    pressure between the equator and poles, as found by Ross’ long series
-    of measurements, manifests a variation of about one inch of mercury,
-    with maxima at about 30° of latitude, north and south, as required
-    by Ferrel’s theory. As a further cause of the depression toward<span class="pagenum" id="Page_380">380</span> the
-    poles, may be mentioned the greater speed of the permanent east wind
-    with the consequent centrifugal lift in the atmosphere.</p>
-
-  <p>As to the general easterly direction of the winds at middle and
-    higher latitudes, that is well known from observation of the motion
-    of clouds and of the air near the earth. At the cirrus level the
-    velocity in those latitudes is almost exactly eastward. But the flow
-    in longitude, illustrated by the outer arrows in Fig. 45, has not
-    been fully determined by observation. Moreover, as Ferrel himself
-    showed, the unequal heating of continents and oceans sets up gradients
-    in longitude, especially in the northern hemisphere, thus adding
-    considerable disturbance to the general circulation. To this agency
-    must be added also the latitudinal shifting of insolation, due to the
-    annual march of the sun across the equator, entailing an oscillatory
-    seasonal shift of the hot belt, and therefore of the twin-hemispheric
-    cycle of the atmosphere.</p>
-
-  <p>Some currents of the general and permanent circulation are sufficiently
-    prominent to have special names, such as the <em>trade-winds</em>, the
-    <em>antitrade-winds</em>, the <em>prevailing westerlies</em>, and, in the lower
-    latitudes, the <em>calm belts</em>, where the flow is exceptionally feeble.
-    All these currents have been known to sailors since early times, and
-    have been of considerable importance in marine navigation. Eventually,
-    perhaps, they may be of like importance in aërial navigation.</p>
-
-  <p>The trade-winds are mild tropical surface currents of remarkably steady
-    speed and direction. Springing from the high-pressure belts in either
-    hemisphere, at about latitude 30°, they blow toward the equator with
-    increasing westerly trend. As shown in charts 46 and 47 for midwinter
-    and midsummer, the trade winds cover a large portion of the tropical
-    zones in both oceans, and shift slightly in latitude with the sun.
-    They are separated at the heat equator by the equatorial calm belts, or
-    doldrums, and are bounded north and south respectively by the calms of
-    Cancer and of Capricorn. Particularly interesting are the trade-winds
-    blowing from Spain to the West Indies, which favored Columbus on his
-    westward voyage, and which certain adventurous Germans have proposed
-    using to duplicate that memorable voyage, in air ships.</p>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_381">381</span>
-    <a id="Fig_46"><img src="images/i_461.jpg" width="700" height="292" alt="" /></a>
-    <div class="caption smcap">Fig. 46.—Normal Wind Direction and Velocity for
-      January and February. (Köppen.)</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_382">382</span>The antitrade-winds, or counter trades, are lofty winds blowing over
-    and contrary to the trade winds. As some doubt regarding the direction
-    of these counter trades had existed, an expedition was sent in 1905, by
-    two distinguished meteorologists, Teisserenc de Bort of France, and A.
-    Lawrence Rotch of America, to explore the atmosphere above the tropical
-    Atlantic. Mr. Rotch has summarized their measurements and conclusions
-    as follows:<a id="FNanchor_63" href="#Footnote_63" class="fnanchor">[63]</a></p>
-
-  <blockquote>
-    <p>“Pilot balloons, dispatched from the island of Teneriffe and St.
-      Vincent, were observed with theodolites at the ends of a base-line,
-      and in this way the heights at which the balloons changed direction
-      could be ascertained. Later the balloons were sent up from the yacht
-      itself, which steamed after them, measurements being made of their
-      angular elevation. The observations which are plotted in Fig. 46 prove
-      conclusively the existence of the upper counter-trade. The courses of
-      the balloons are represented as if projected upon the surface of the
-      sea and show that the northeast trade-wind extended only to the height
-      of 3,200 or 4,000 meters, and then gradually turned into a southerly
-      current which, higher up, came from the southwest. The width of the
-      dotted band represents approximately the varying velocity of the trade
-      and counter-trade. Similar proofs of the northwest trade-wind,
-      south of the equator were obtained by the same expedition during
-      the following year, but the above suffices to show that it would be
-      possible for an aëronaut in the ordinary balloon to start from the
-      African coast, or from some of the islands in the trade-wind region,
-      and, after drifting towards the southwest, to rise a few miles into the
-      current, which would carry the balloon north and eventually northeast
-      back to land. Nevertheless, it does happen in certain atmospheric
-      situations over the tropical north Atlantic that the winds from the
-      general northwesterly direction prevail up to great heights without any
-      evidence of the return-trade. Near the equator the winds are easterly
-      up to the greatest heights which have been attained.”</p>
-  </blockquote>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_383">383</span>
-    <a id="Fig_47"><img src="images/i_463.jpg" width="700" height="292" alt="" /></a>
-    <div class="caption smcap">Fig. 47.—Normal Wind Direction and Velocity for July
-      and August. (Köppen.)</div>
-  </div>
-
-  <div class="figcenter">
-    <span class="pagenum" id="Page_384">384</span>
-    <a id="Fig_48"><img src="images/i_464.jpg" width="520" height="515" alt="" /></a>
-    <div class="caption smcap">Fig. 48.—Trade and Counter Trade-winds.</div>
-  </div>
-
-  <p>The prevailing westerlies are high-latitude surface <span class="pagenum" id="Page_385">385</span>winds of the
-    permanent circulation. In the southern hemisphere they are particularly
-    strong and steady owing to the comparatively unbroken stretch of
-    ocean. In the north also they are strong and persistent, but variable
-    in direction because of disturbances by local winds due to unequal
-    heating of tracts of land and sea. These features are well illustrated
-    in charts 47 and 48. Of particular interest in aëronautics is the
-    prevailing wind blowing from the United States to Europe, which has
-    been considered a suitable current for transoceanic balloon voyages.<a id="FNanchor_64" href="#Footnote_64" class="fnanchor">[64]</a></p>
-
-  <p>The periodic winds are those whose gradient alternates annually or
-    daily, due to annual or daily fluctuations of temperature on sloping
-    or on heterogeneous parts of the globe. The annually fluctuating winds
-    due to alternate heating and cooling of continents, or large land
-    areas, bear the general name of monsoon. Among diurnal winds the most
-    prominent are the land-and-sea breezes, and the mountain-and-valley
-    breezes. Both kinds are practically available in aëronautics; the
-    monsoons for long-distance travel, the diurnal winds for local use.</p>
-
-  <p>The general motive cause is the same for all periodic winds. When any
-    portion of the earth’s surface is periodically more heated above its
-    normal temperature, or average for the year, than the neighboring
-    region, the resulting abnormal temperature gradient causes a periodic
-    surface wind tending toward the excessively heated place, and a counter
-    wind above. That is, the cooler and heavier column of air sinking and
-    uplifting the lighter, results in a lowering of the common center of
-    gravity of the two <span class="pagenum" id="Page_386">386</span>columns of air, and thus furnishes the driving
-    power of the wind. For example, an island or a peninsula may be
-    considerably hotter by day and cooler by night than the surrounding
-    water; a continent may be much hotter in summer and much colder in
-    winter than the bordering ocean. Thus during the hot period a moist
-    wind blows landward; during the cold period a dry wind blows seaward.
-    If the land has vast and lofty slopes the uprush of air during the hot
-    period and the downrush during the cool period may be very powerful.
-    The currents so produced by the aggregate of local agencies, including
-    the deviation caused by the earth’s rotation, combine with the general
-    circulation of the atmosphere to form the actual wind of the place.
-    Thus the periodic current may conspire with the general circulation,
-    or oppose it; may intensify, weaken or obliterate it; may overmaster,
-    reverse or mask it completely.</p>
-
-  <p>Of the various continental monsoons of the globe the most powerful
-    spring from the annual flux and reflux of the atmosphere over the vast
-    declivities and table-lands of Asia. Here the conditions are especially
-    favorable. As the sun approaches Cancer, the burning deserts and high
-    plateaus, combining their force with the draft on the mountain sides,
-    generate a continental uprush that sucks in all the aërial currents of
-    the surrounding seas, hurling them aloft to the isothermal layer whence
-    they radiate as the four winds of heaven; for here at this season the
-    planetary circulation is disrupted, obliterated or reversed, appearing
-    merely as a perturbation of the monsoon at its height. In India the
-    force is particularly effective. Along the north the Himalayas stretch
-    1,300 miles in latitude, with an average height of 18,000 feet and
-    with sunburned areas on either side. North of this range are the lofty
-    plateaus of Thibet<span class="pagenum" id="Page_387">387</span> and Cashmere, south of it the desert of Gobi and
-    the borders of the Indian Ocean. Over this watery tract from beyond the
-    equatorial line, from the isles of Oceanica and from the wintry plains
-    of Australia, the air flows in with accumulated strength, sweeping the
-    Bay of Bengal and the Arabian Sea in a continuous gale bearing up the
-    mountain slopes incredible floods of water. Over the Arabian Sea in
-    summer the gale is so steady and swift that no ordinary ship can force
-    a passage from Bombay to the Gulf of Aden. Above the Bay of Bengal the
-    moist south winds, converging between the coast and headlands, pour
-    cloud laden up the Himalayan slopes, precipitating their whole vapor
-    in prodigious torrents seldom seen elsewhere. Khasia at this season
-    sustains a Noachian deluge, the rain at times falling nearly a yard
-    deep in one day and night.<a id="FNanchor_65" href="#Footnote_65" class="fnanchor">[65]</a> Quite appropriately, therefore, the
-    summer monsoon over India, especially its component southwest wind from
-    the Arabian Sea, and southerly wind from the Bengal Bay and farther
-    east, is called the wet monsoon.</p>
-
-  <p>The winter monsoon of Asia, is the reverse of the summer one, both
-    in direction of gradient and in physical character. It is a cold
-    flood of air pouring from the frigid table-lands and wintry depths
-    of the desert, down the mountains and valleys in continual overflow
-    on all sides of the continent, and then far out over the sea, where
-    it reascends to complete its long cycle. In its descent all moisture
-    vanishes by heating, and no intensive temperature gradient occurs, as
-    in summer, to accelerate its gently modulated tide. In India the winds
-    from Cashmere and Thibet pour down the Himalayas toward the Arabian Sea
-    a clear current of air which unites with the <span class="pagenum" id="Page_388">388</span>trade-wind, increasing
-    its force, and forming the moderate winter monsoon of that region, or
-    as it is commonly called, from its lack of moisture, the dry monsoon.</p>
-
-  <p>The kinematic character, and the extent of both summer and winter
-    currents, are well portrayed in charts 47 and 48 for all the south and
-    southeast of Asia. Across the islands of Japan, it will be observed,
-    the winds blow in opposite directions summer and winter. In Siberia
-    the monsoon winds trend along her great rivers and valleys, generally
-    northward in the winter and the reverse in the summer, combining in
-    both seasons with the prevailing westerlies, due to the rotation of the
-    earth.</p>
-
-  <p>All the other continents have their monsoons, though less powerful
-    than those of Asia. In the great desert of Sahara, for example, there
-    is an ascending hot current in the summer, causing a strong indraught
-    from the Atlantic and the Mediterranean; but this is far less intense
-    than if its action were fortified by lofty slopes and table-lands. In
-    winter when the Sahara cools to nearly the oceanic temperature, little
-    monsoon effect is perceptible, and the general circulation continues
-    unperturbed. In Australia the monsoon influence is still feebler,
-    owing to the limited extent of the country and to the general lowness
-    and flatness of the land. Over parts of South America, the annual
-    ebb and flow of the atmosphere is considerable, particularly along
-    the northeastern coast, and in the whole Amazon Valley, whose aërial
-    currents in general conspire with the trade-winds, strengthening them
-    materially in the southern summer, though it is less in winter when the
-    continental temperature more nearly approximates that of the ocean. The
-    monsoons of North America have been described in some detail by Ferrel
-    as follows:</p>
-
-  <p><span class="pagenum" id="Page_389">389</span></p>
-
-  <blockquote>
-    <p>“On the continent of North America we have monsoon influences similar
-      to those of Asia, but not nearly so strong, because the extent of the
-      continent, and consequently the annual range of temperature, are not
-      so great. They are, for the most part, not sufficiently strong to
-      completely overcome and reverse the current of the general circulation
-      of the atmosphere, and so to produce a real monsoon, but they cause
-      great differences between the prevailing directions of the winter and
-      summer winds.</p>
-
-    <p>“In the summer the whole interior of the continent becomes heated up
-      to a temperature much above that of the oceans on the same latitudes
-      on each side—indeed, above that of the Gulf of Mexico and the Pacific
-      Ocean on its southern and southwestern borders. The consequence is that
-      the air over the interior of the continent becomes more rare than over
-      the oceans, rises up and flows out in all directions above while the
-      barometric pressure is diminished, and the air from all sides, from the
-      Atlantic on the east to Pacific Ocean on the west, the Gulf of Mexico
-      on the south, and the polar sea on the north, flows in below to supply
-      its place. On the east the tendency to flow in is not strong enough
-      to counteract the general easterly motion of the air at the earth’s
-      surface in the middle latitudes, and to cause a westerly current,
-      but it simply retards the general easterly current and gives rise to
-      a greater prevalence of easterly winds along the Atlantic sea-coast
-      during the summer season....</p>
-
-    <p>“In winter the thermal conditions over the continent are reversed.
-      The interior of the continent is now the coldest part, and it is
-      especially colder than the surrounding oceans at that season. It has
-      also very high plateaus and mountain ranges. The air, therefore, of
-      the lower strata, and especially those next the earth’s surface, now
-      tends to flow<span class="pagenum" id="Page_390">390</span> out in all directions to the warmer oceans and the Gulf
-      of Mexico, and especially to run down the long slope of plateau from
-      the Rocky Mountains into the Mississippi Valley. The effect over the
-      whole of the United States east of the Rocky Mountains is to cause the
-      winds, which otherwise would be westerly and southwesterly, to become
-      generally northwesterly winds, instead of southerly and southwesterly
-      ones, as in summer. There is not a complete monsoon effect, but simply
-      a great change between summer and winter in the prevailing directions
-      of the winds. In Texas, however, and farther east along the northern
-      border of the Gulf, the effect is somewhat that of a complete monsoon.
-      In New England and farther south in the Eastern States the monsoon
-      effect is to cause the prevailing winds to be from some point north of
-      west, instead of south of west as in summer.</p>
-
-    <p>“In summer, Central America and Mexico have a much higher temperature
-      than that of the adjacent tropical sea on the southwest, and having
-      high mountain ranges and elevated plateaus, there is consequently a
-      strong tendency to draw in air from the southwest at this season,
-      which not only entirely counteracts the regular trade-winds of these
-      latitudes, but even reverses them and causes southwest winds. The
-      effect is to cause in midsummer a large area here, extending far
-      westward, of calms and irregular and light winds, mostly southwesterly
-      ones, and an apparent widening of the equatorial calm-belt at this
-      season so as to make its northern limit reach up, along the coast,
-      nearly to the parallel of 20°. The effect is similar to that in the
-      Atlantic west of the Gulf of Guinea and Liberia, except that it here
-      appears to be some greater, and causes a true monsoon effect, since
-      during the winter the regular northeasterly trade-winds prevail, but
-      strengthened<span class="pagenum" id="Page_391">391</span> by the reverse thermal conditions of the winter season.
-      On the eastern side, and over the western end of the Gulf of Mexico,
-      there is a somewhat regular monsoon effect, the prevailing winds being
-      easterly, or blowing toward the land, during the summer, and the
-      reverse in winter.</p>
-
-    <p>“Along the west coast of North America in the middle latitudes there
-      is a strong monsoon influence; for the interior of the continent
-      becomes heated in summer to a much higher temperature than that of the
-      southwesterly ocean, and hence a strong current is drawn in from this
-      direction, at right angles to the general trend of the coast which,
-      combining with the general southwesterly winds of these latitudes in
-      the general circulation of the atmosphere, causes the strong and steady
-      westerly and southwesterly winds of this region during the summer.
-      Farther north, up toward Alaska, the summer monsoon effect is combined
-      with the current caused by the deflection of the continent as well
-      as the general easterly current of high latitudes, so that the winds
-      here are generally southerly, but still have somewhat of a monsoon
-      character, being southerly and southwesterly in summer and easterly and
-      southeasterly during the winter.</p>
-
-    <p>“Along the northern coast of America, as along that of Siberia, the
-      monsoon tendency is to draw the air from the colder land to the
-      warmer ocean in winter, and the reverse in summer; and these effects,
-      combined with the general easterly motion of the atmosphere in these
-      latitudes, gives rise to prevailing southwesterly winds in winter and
-      northwesterly ones in summer. The winter monsoon influence, however,
-      is small here—much more so than in Siberia, for the ocean contains so
-      many large islands that it has rather a continental than an oceanic
-      winter temperature; and besides, it has not the influence <span class="pagenum" id="Page_392">392</span>of a warm
-      current—such as the continuation of a part of the Gulf Stream along the
-      northern coast of Europe and Asia.”</p>
-  </blockquote>
-
-  <p>Similar to the monsoons in essential nature are the diurnal winds of
-    seacoast and mountain side. They begin with the heating of the land
-    in the morning, attain their maximum intensity about mid afternoon,
-    or during the hottest of the day, and finally are reversed at night.
-    Besides being so much briefer than monsoons, they are also in general
-    feebler and less extensive. They may be quite noticeable on calm
-    days, especially in clear weather and in hot climates; but usually
-    they are masked or entirely overwhelmed where other marked currents
-    occur—currents due either to the general circulation or monsoons, or
-    other powerful disturbing agencies.</p>
-
-  <p>In land-and-sea breezes, which usually extend not far inland, there is
-    a surface inflow of sea air during the forenoon and early afternoon,
-    balanced by an outflow of warm air above, rising from the heated soil.
-    After sundown this is reversed, the chilled air from inland pouring
-    out to sea, while overhead the warmer sea air is forced landward at a
-    higher level. These currents are strongest where the diurnal range of
-    temperature is greatest and where the local topography is of suitable
-    configuration. Particularly favorable are steeply declining shores,
-    narrow bays and inlets, girded by mountains or lofty hills. During
-    the day heated air ascends such declivities with alacrity, like smoke
-    through an inclined flue, while at night, when cooled by radiation
-    and contact with the soil, it rushes torrentlike down the valleys and
-    hillsides, passing out to sea, often in sudden squalls that embarrass,
-    or endanger, small sailing craft. Circulatory currents like the above
-    have sometimes been used by aëronauts to carry them out to sea and back
-    again to land at a different level.</p>
-
-  <p><span class="pagenum" id="Page_393">393</span></p>
-
-  <p>In like manner the mountain-and-valley winds may be used by the
-    skillful aëronaut. It is well known that these flow up the courses of
-    rivers, cañons and land slopes generally by day, but at night reverse
-    their course and pour down again with considerable force. For this
-    reason experienced hunters place their camp fires below tent in a
-    sloping valley. The strength of the breeze depends, of course, upon
-    the daily range of temperature, and the steepness and expanse of the
-    slope. Such winds are deftly used by the masters of soaring flight, the
-    great robber and scavenger birds, and no doubt may be used by men in
-    motorless aëroplanes, to gain elevation, and journey great distances
-    without expenditure of energy.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XVI">
-    <span class="pagenum" id="Page_394">394</span>
-    <h3>CHAPTER XVI</h3>
-    <span class="small">CYCLONES, TORNADOES, WATERSPOUTS</span>
-  </div>
-
-  <p><span class="smcap">Besides</span> the periodic winds so far treated, there are prominent aërial
-    movements having no regular course or season. These are the nonperiodic
-    winds which so exercise or perplex the weather forecaster and those who
-    confide in him. In general such winds are of a temporary character,
-    arising from an unstable condition of the air in some locality, or
-    from unequal heating, either of which causes may generate, or briefly
-    sustain, an updraught, with its attendant gyration. Owing to the
-    whirling character of such ascending currents, they have received
-    various significant names, such as cyclone, tornado, whirlwind; the
-    three terms applying to vortices in decreasing order of magnitude. Each
-    in turn may be treated briefly.</p>
-
-  <p>The cyclone is a temporary large gyratory wind. It may last a few hours
-    or a few days. It may measure fifty to a hundred miles across, or it
-    may measure more than a thousand miles. On the weather map it is in
-    general marked by a group of closed isobars, showing a considerable
-    pressure gradient toward a small internal area where the pressure is
-    a minimum. To an observer looking about the earth’s surface and lower
-    levels of the atmosphere, the cyclone appears merely as an ordinary
-    wind, accompanied perhaps by rain or snow. It is not a swiftly rotating
-    narrow column, or cone of air,<span class="pagenum" id="Page_395">395</span> like a tornado or whirlwind, full of
-    gyrating dust and débris.</p>
-
-  <p>The motive power of a cyclone, though in general due to the buoyancy
-    of heated air, may spring from more than one set of conditions. Notice
-    has already been taken of vortices due to a hot column of air at lower
-    barometric pressure than its lateral environment. Take another case.
-    If a dry atmosphere is of uniform temperature and pressure at various
-    levels, but has a vertical temperature gradient a little greater than
-    the normal cooling of an ascending gas, a portion of air started upward
-    in any casual way becomes warmer than its lateral environment, and
-    hence continues to rise until the unstable condition due to abnormal
-    temperature gradient ceases. Again, while the surface stratum is in
-    stable equilibrium, it may happen that the second mile of air is
-    abnormally hot, and the third mile abnormally cold, and thus a vortex
-    may occur in mid air, without disturbing the face of the earth.</p>
-
-  <p>Whatever be the initial atmospheric condition causing the vertical
-    uprush, the nature of the resulting circulation is in general that of
-    the cyclone, illustrated, in part, by the whirling vortex of water in
-    a basin. As the current ascends, an indraught occurs in all the lower
-    regions of air, and an outflow in all directions above, sometimes
-    at the height of a mile or two, again in all the region next to the
-    isothermal layer. As the earth has at all places above the equator
-    a component of rotation about the vertical line, it follows that in
-    northern latitudes all the air flowing toward the vortex is in a whirl
-    opposite in motion to the hands of a watch lying face upward, and all
-    the outflowing air above has a like angular motion, but gradually
-    diminishing until it is reversed. At the lower portion of the vortex
-    the air whirls inward and upward with increasing velocity,<span class="pagenum" id="Page_396">396</span> while
-    above, it whirls outward and upward, with waning velocity, thus moving
-    in a double-spiral path shaped like a cord wound on an hourglass. In
-    the constricted part, or neutral plane of the vortex, the air moves
-    neither outward nor inward, but spirals straight upward. To match the
-    upflow, and complete the closed circulation, there must be a downflow
-    on the exterior of the cyclone, and since the whirl is reversed
-    in direction, this outer mass of downflowing reverse-whirling air
-    embracing the cyclone is called the anticyclone.</p>
-
-  <p>Between the inner and outer vortex the air is comparatively calm and
-    the pressure is a maximum, with steepest gradient toward the center
-    of the cyclone. Also the air is calm just at the axis of the vortex,
-    while for some distance away its speed increases as the radius of its
-    whirl, so that the central mass rotates practically as a solid column,
-    thus still further lowering the pressure near the axis. This solidly
-    rotating central column of air is sometimes called the core of the
-    vortex.</p>
-
-  <p>High above the center of the cyclone, where perhaps the air is sucked
-    downward, clarified by compression, then whirled outward, the sky is
-    usually clear, or thinly fogged, while without this central patch are
-    heavy clouds. The obscure or clear central part is called the “eye<a id="FNanchor_66" href="#Footnote_66" class="fnanchor">[66]</a>
-    of the storm.” Through this the cirrus clouds may sometimes be seen
-    high above, either stationary or radiating away, if the vortex extends
-    so high. Sailors on the deck of a vessel passing through a cyclone have
-    often noticed the eye of the storm overhead, perhaps ten or twelve
-    degrees in diameter, and with special clearness in <span class="pagenum" id="Page_397">397</span>the tropics. To the
-    white, feathery cirrus clouds, scurrying away radially from the top of
-    the vortex, they have given the name “plumes of the storm,” or “mares’
-    tails.” In sailing their vessel through the center of a cyclone, they
-    have observed the circulatory motion of the winds and clouds, and
-    frequently have found the deck covered or surrounded with cyclone
-    sweepings, such as land and water birds, insects, butterflies, etc.,
-    brought into the quiet core of the vortex from the incurving winds
-    beyond. Further details of the motion in a cyclone vortex are given as
-    follows by Ferrel, §178:</p>
-
-  <blockquote>
-    <p>“In Fig. 49 is given a graphic representation of the resultant motions
-      and of the barometric pressures for both the surface of the earth and
-      for some level high up in the atmosphere and above the neutral plane,
-      where the motions in the vertical circulation are outward from the
-      center. The solid circles represent isobars at the earth’s surface
-      and the solid arrows the directions, and in some measure, by their
-      different lengths, the relative velocities of the wind. The heavy
-      circle represents the circle of greatest barometric pressure at the
-      earth’s surface, say 765 mm., while the pressure of the outer border is
-      760 mm., and the dividing line between the cyclone and the anticyclonic
-      gyrations. Within this limit the pressure diminishes to the center,
-      and the gyrations are cyclonic, and the direction of the resultant
-      of motion inclines in toward the center, but beyond that limit the
-      gyrations are anticyclonic, and the direction of resultant motion
-      inclines toward the outer border of these gyrations. The heavy dotted
-      circle represents the circle of maximum pressure at some high level,
-      and is much nearer the center than that at the earth’s surface. It is
-      also the dividing line between the cyclonic and anticyclonic gyrations
-      at that level. The dotted arrows indicate the directions<span class="pagenum" id="Page_398">398</span> and in some
-      measure the relative velocities, of the wind at this level. The arrows
-      in the cyclonic part represent the direction of the wind as declining
-      outward, because the plane here considered is supposed to be above
-      the neutral plane, where the radial component of motion is outward,
-      but for any level below the neutral plane the inclination is still
-      inward. The arrows are shorter above in the cyclonic part and longer
-      in the anticyclonic part than they are at the earth’s surface, since
-      the cyclonic gyratory velocities decrease and the anticyclonic increase
-      with increase of altitude.</p>
-  </blockquote>
-
-  <div class="figcenter">
-    <a id="Fig_49"><img src="images/i_478.jpg" width="534" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 49.—Velocity Diagram in Horizontal Section of a Cyclone.</div>
-  </div>
-
-  <p><span class="pagenum" id="Page_399">399</span></p>
-
-  <blockquote>
-    <p>“The upper part of the figure is a representation of a vertical
-      section of the air, very much exaggerated in altitude, in which the
-      solid curved line represents a section of an isobaric surface near the
-      earth’s surface, say of 740 mm. barometric pressure. The lowest part
-      corresponds with the center of the cyclone and the highest part with
-      the heavy circle in the lower part of the figure, and the steepest
-      gradients with the longest solid arrows, since the greater the gyratory
-      velocities at the earth’s surface the greater the gradients, though
-      they are not strictly proportional. The second dotted curved line from
-      the top represents a section of the isobaric surface of high altitudes,
-      in which the highest parts correspond with the heavy dotted circle
-      below, since the highest pressure at all altitudes is very nearly where
-      the cyclonic gyrations vanish and change to the anti-cyclonic. The
-      depression here is smaller because the cyclonic area is smaller, and
-      the gyratory velocities less, than at the earth’s surface. The upper
-      dotted line belongs to an isobaric surface still higher, where the
-      gyrations are supposed to be all anti-cyclonic, and here, consequently,
-      the greatest pressure is in the center, as indicated by the curved line.</p>
-
-    <p>“As the interior of the whole cyclonic system is warmer than the
-      exterior, and consequently the air less dense, the distances between
-      the isobaric surfaces are necessarily greater in the interior than the
-      exterior part, and so, however much the isobaric surface at or near the
-      earth’s surface may be depressed by the cyclone gyration there, at a
-      considerable altitude, if the temperature difference is great enough,
-      it must become convex instead of concave.</p>
-
-    <p>“The track of any given particle of air in a cyclone, resulting from
-      the vertical and gyratory circulation, is that of a large converging
-      and ascending spiral in the lower part, but of a diverging and
-      ascending <span class="pagenum" id="Page_400">400</span>spiral in the upper strata of the atmosphere, and the nearer
-      the earth’s surface the more nearly horizontal is the motion, since the
-      vertical component gradually decreases and vanishes at the surface.</p>
-
-    <p>“The whole energy of the system by which the inertia of the air and
-      the frictional resistance are overcome and the motions maintained, is
-      in the greater interior temperature and the temperature gradients,
-      by which the circulation is maintained. This being kept up, the
-      deflections and gyrations are merely the result of the modifying
-      influence of the earth’s rotation, which is not a real force, since
-      it does not give rise to kinetic energy, but merely to changes of
-      direction.</p>
-
-    <p>“It must be borne in mind that the preceding is a representation of the
-      motions and pressures of a cyclone resulting from perfectly regular
-      conditions, in an atmosphere otherwise undisturbed, and having a
-      uniform temperature, except so far as it is affected by the temperature
-      disturbance arising from the cyclonic conditions. Accordingly results
-      so regular are not to be found in Nature, but generally only rough
-      approximations to them.</p>
-
-    <p>“Since the wind inclines less and less toward the center of the
-      cyclone below the neutral plane and declines from the center above it,
-      the upper currents above this plane in a cyclone are always from a
-      direction, in the northern hemisphere, a little to the right of that of
-      the lower currents, when not affected by abnormal circumstances.”</p>
-  </blockquote>
-
-  <p>Observation of cyclones in Nature very well confirms the leading
-    features set forth on theoretical grounds. If the vortex pass centrally
-    over an observatory there is noted first a high barometer and calm air,
-    attended perhaps by scurrying cirrus clouds; next a rapidly falling
-    pressure and increasing wind, with dark clouds and precipitation,
-    commonly <span class="pagenum" id="Page_401">401</span>accompanied by thunder and lightning; then the hushing of
-    the storm to a dead calm, and low barometer and thinning or clearing
-    of the clouds overhead; then a rising barometer with renewed winds in
-    the reverse direction, and finally subsiding winds, rising barometer
-    and clearing weather. These phenomena are the more definitely presented
-    if the whirl is strong while its travel along the earth is slow. But
-    owing to their progressive easterly motions, cyclones in the north have
-    their moist hot southern masses elevated, chilled and precipitated
-    on their eastern fronts and beyond, while their rear experiences the
-    opposite action and is called the clearing side. Conversely in the
-    tropics the westerly moving cyclones have cloudy and wet rears, because
-    the easterly drift on high carries the precipitating masses toward the
-    rear. The general hygrometric appearance of a centrally passing cyclone
-    in middle latitude is thus described by Ferrel, §207:</p>
-
-  <blockquote>
-    <p>“In the regular progression of a cyclone in the middle latitudes
-      somewhat centrally over a place, the cloud and rain area of the front
-      part, extending far toward the east, first passes over, occupying a
-      half-day, or a day and more, and then the front part of the ring of
-      dense cloud with a heavy shower of rainfall. After this there are
-      indications of a clearing up, and even the sun may break through the
-      cloud for an hour or two; but presently there is an apparent gathering
-      and thickening of the cloud and a second shower. This is at the time of
-      the passage of the rear side of the ring of denser cloud. After this
-      there is the final clearing up.”</p>
-  </blockquote>
-
-  <p>Except for special conditions, cyclones are never stationary, but drift
-    along with the general march of the atmosphere, like dimpling eddies in
-    a stately flowing river. In general, therefore, their trend is westward
-    in lower latitudes, eastward in middle and<span class="pagenum" id="Page_402">402</span> higher latitudes, with a
-    pace slow or swift according to the prevailing current. Notably also
-    they have a poleward trend. Thus, if the path extends from tropic to
-    temperate clime, it is frequently concave toward the east and sensibly
-    parabolic in form. This is markedly true of those swift-whirling, small
-    cyclones called hurricanes,<a id="FNanchor_67" href="#Footnote_67" class="fnanchor">[67]</a> and particularly those vigorous ones
-    blowing past the West Indies and the Philippines, and those that vex
-    the Indian Ocean.</p>
-
-  <p>As to the speed of travel of cyclones, that may be judged, at least for
-    northern latitudes, from the accompanying table, taken from Loomis,<a id="FNanchor_68" href="#Footnote_68" class="fnanchor">[68]</a>
-    and showing the average monthly rate of progression in miles per hour,
-    of cyclone centers over the United States, the Atlantic Ocean and
-    Europe. In general, beyond the tropics tall cyclones travel faster than
-    short ones, owing to the faster drift of the higher strata.</p>
-
-  <table class="collapse" summary="Cyclone speed">
-    <tbody>
-      <tr class="small">
-        <th class="br bt bb">Month.</th>
-        <th class="br bt bb">United States.</th>
-        <th class="br bt bb">Atlantic Ocean<br />Middle Latitudes.</th>
-        <th class="bt bb">Europe.</th>
-      </tr>
-      <tr>
-        <td class="br">January</td>
-        <td class="br tdc">33.8</td>
-        <td class="br tdc">17.4</td>
-        <td class="tdc">17.4</td>
-      </tr>
-      <tr>
-        <td class="br">February</td>
-        <td class="br tdc">34.2</td>
-        <td class="br tdc">19.5</td>
-        <td class="tdc">18.0</td>
-      </tr>
-      <tr>
-        <td class="br">March</td>
-        <td class="br tdc">31.5</td>
-        <td class="br tdc">19.7</td>
-        <td class="tdc">17.5</td>
-      </tr>
-      <tr>
-        <td class="br">April</td>
-        <td class="br tdc">27.5</td>
-        <td class="br tdc">19.4</td>
-        <td class="tdc">16.2</td>
-      </tr>
-      <tr>
-        <td class="br">May</td>
-        <td class="br tdc">25.5</td>
-        <td class="br tdc">16.6</td>
-        <td class="tdc">14.7</td>
-      </tr>
-      <tr>
-        <td class="br">June</td>
-        <td class="br tdc">24.4</td>
-        <td class="br tdc">17.5</td>
-        <td class="tdc">15.8</td>
-      </tr>
-      <tr>
-        <td class="br">July</td>
-        <td class="br tdc">24.6</td>
-        <td class="br tdc">15.8</td>
-        <td class="tdc">14.2</td>
-      </tr>
-      <tr>
-        <td class="br">August</td>
-        <td class="br tdc">22.6</td>
-        <td class="br tdc">16.3</td>
-        <td class="tdc">14.0</td>
-      </tr>
-      <tr>
-        <td class="br">September</td>
-        <td class="br tdc">24.7</td>
-        <td class="br tdc">17.2</td>
-        <td class="tdc">17.3</td>
-      </tr>
-      <tr>
-        <td class="br">October</td>
-        <td class="br tdc">27.6</td>
-        <td class="br tdc">18.7</td>
-        <td class="tdc">19.0</td>
-      </tr>
-      <tr>
-        <td class="br">November</td>
-        <td class="br tdc">29.9</td>
-        <td class="br tdc">20.0</td>
-        <td class="tdc">18.6</td>
-      </tr>
-      <tr>
-        <td class="br">December</td>
-        <td class="br tdc">33.4</td>
-        <td class="br tdc">18.3</td>
-        <td class="tdc">17.9</td>
-      </tr>
-      <tr>
-        <td class="br bt">&nbsp;&nbsp;&nbsp;Year</td>
-        <td class="br bt tdc">28.4</td>
-        <td class="br bt tdc">18.0</td>
-        <td class="bt tdc">16.7</td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>To find the actual speed of the wind at a place, of course, the linear
-    velocities of whirl and of translation must be combined; or, vice
-    versa, if one of these <span class="pagenum" id="Page_403">403</span>be known it can be graphically subtracted from
-    the observed wind velocity to find the other. This combination of two
-    wind components to find their resultant, or, vice versa, can easily be
-    done by laying off on paper, arrows of suitable length and direction
-    to represent the two known velocities, placing the head of one arrow
-    to the tail of the other, then completing the triangle, and taking its
-    third side to represent the required wind velocity, in magnitude and
-    direction. Obviously if the cyclone moves eastward, whirling oppositely
-    to the hands of a watch, the swiftest wind is on its right side,
-    which consequently is known as the dangerous side. In the northern
-    hemisphere, therefore, the rule for dodging a great whirlwind is to run
-    north, if that be practicable.</p>
-
-  <p>Stationary cyclones occur under favorable conditions. At least that
-    name has been applied to columns of hot air streaming up from a fixed
-    base, more or less circular. Every island in the ocean generates such
-    a vortex on a clear, hot summer day, since its temperature far exceeds
-    that of the surrounding water. All day long this uprush continues
-    whatever be the humidity. And if the soil slopes upward steeply, the
-    vortex is so much the stronger, particularly if the island be in a calm
-    region. Above such a tract the gulls and vultures, and possibly even
-    man, might soar all day without motive power. This condition and its
-    interesting possibility deserve investigation.</p>
-
-  <p>Cyclones may occur at any season, but in general they are most abundant
-    when the greatest temperature disturbances occur. The relative
-    frequency of tropical cyclones for various localities and for the
-    twelve months of the year is seen in the following table<a id="FNanchor_69" href="#Footnote_69" class="fnanchor">[69]</a>:</p>
-
-  <p><span class="pagenum" id="Page_404">404</span></p>
-
-  <p class="center mt5"><i>The Yearly Periods of Cyclone Frequency in Several Seas</i></p>
-
-  <table id="cyclones" class="collapse" summary="Cyclone frequency">
-    <tbody>
-      <tr class="small">
-        <th class="br bt bb">&nbsp;</th>
-        <th class="br bt bb">Arabian Sea.</th>
-        <th class="br bt bb">Bay of Bengal.</th>
-        <th class="br bt bb">S. Indian Ocean.</th>
-        <th class="br bt bb">Java Sea.</th>
-        <th class="br bt bb">China Sea.</th>
-        <th class="bt bb">Havana.</th>
-      </tr>
-      <tr>
-        <td class="br">No. of years</td>
-        <td class="br tdr"><div>234</div></td>
-        <td class="br tdr"><div>139</div></td>
-        <td class="br tdr"><div>40</div></td>
-        <td class="br tdr"><div>...</div></td>
-        <td class="br tdr"><div>85</div></td>
-        <td class="tdr"><div>363</div></td>
-      </tr>
-      <tr>
-        <td class="br">No. of cyclones</td>
-        <td class="br tdr"><div>70</div></td>
-        <td class="br tdr"><div>115</div></td>
-        <td class="br tdr"><div>53</div></td>
-        <td class="br tdr"><div>12</div></td>
-        <td class="br tdr"><div>214</div></td>
-        <td class="tdr"><div>355</div></td>
-      </tr>
-      <tr class="small">
-        <th class="br bb">Authority.</th>
-        <th class="br bb">Chambers.</th>
-        <th class="br bb">Blanford.</th>
-        <th class="br bb">Piddington<br />Thom and Reid.</th>
-        <th class="br bb">Piddington<br />and Thom.</th>
-        <th class="br bb">Schuck.</th>
-        <th class="bb">Poey.</th>
-      </tr>
-      <tr>
-        <td class="br">Jan.</td>
-        <td class="br tdr"><div>6</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="br tdr"><div>17</div></td>
-        <td class="br tdr"><div>25</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="tdr"><div>1</div></td>
-      </tr>
-      <tr>
-        <td class="br">Feb.</td>
-        <td class="br tdr"><div>4</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>25</div></td>
-        <td class="br tdr"><div>42</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="tdr"><div>2</div></td>
-      </tr>
-      <tr>
-        <td class="br">Mar.</td>
-        <td class="br tdr"><div>3</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="br tdr"><div>19</div></td>
-        <td class="br tdr"><div>8</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="tdr"><div>3</div></td>
-      </tr>
-      <tr>
-        <td class="br">April</td>
-        <td class="br tdr"><div>13</div></td>
-        <td class="br tdr"><div>8</div></td>
-        <td class="br tdr"><div>15</div></td>
-        <td class="br tdr"><div>8</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="tdr"><div>3</div></td>
-      </tr>
-      <tr>
-        <td class="br">May</td>
-        <td class="br tdr"><div>18</div></td>
-        <td class="br tdr"><div>16</div></td>
-        <td class="br tdr"><div>7</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>5</div></td>
-        <td class="tdr"><div>1</div></td>
-      </tr>
-      <tr>
-        <td class="br">June</td>
-        <td class="br tdr"><div>29</div></td>
-        <td class="br tdr"><div>9</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>5</div></td>
-        <td class="tdr"><div>3</div></td>
-      </tr>
-      <tr>
-        <td class="br">July</td>
-        <td class="br tdr"><div>3</div></td>
-        <td class="br tdr"><div>3</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>10</div></td>
-        <td class="tdr"><div>12</div></td>
-      </tr>
-      <tr>
-        <td class="br">Aug.</td>
-        <td class="br tdr"><div>3</div></td>
-        <td class="br tdr"><div>4</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>19</div></td>
-        <td class="tdr"><div>27</div></td>
-      </tr>
-      <tr>
-        <td class="br">Sept.</td>
-        <td class="br tdr"><div>4</div></td>
-        <td class="br tdr"><div>5</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>27</div></td>
-        <td class="tdr"><div>23</div></td>
-      </tr>
-      <tr>
-        <td class="br">Oct.</td>
-        <td class="br tdr"><div>6</div></td>
-        <td class="br tdr"><div>27</div></td>
-        <td class="br tdr"><div>2</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>16</div></td>
-        <td class="tdr"><div>17</div></td>
-      </tr>
-      <tr>
-        <td class="br">Nov.</td>
-        <td class="br tdr"><div>14</div></td>
-        <td class="br tdr"><div>16</div></td>
-        <td class="br tdr"><div>7</div></td>
-        <td class="br tdr"><div>0</div></td>
-        <td class="br tdr"><div>8</div></td>
-        <td class="tdr"><div>5</div></td>
-      </tr>
-      <tr>
-        <td class="br bb">Dec.</td>
-        <td class="br bb tdr"><div>3</div></td>
-        <td class="br bb tdr"><div>8</div></td>
-        <td class="br bb tdr"><div>6</div></td>
-        <td class="br bb tdr"><div>17</div></td>
-        <td class="br bb tdr"><div>3</div></td>
-        <td class="bb tdr"><div>2</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>The tornado is a slender cyclone or hurricane. It is usually but a
-    few yards or rods in diameter, and seldom exceeds one mile across its
-    active column, whereas a cyclone may cover an area of any size from
-    fifty to one or two thousand miles in diameter. Moreover, the cyclone
-    requires for its inception an extensive pressure gradient marked by
-    closed isobars, and once generated may last several days. A tornado per
-    contra may spring into action where the lateral pressure is uniform,
-    spend its force in a few moments, and leave a uniform barometric field
-    in its wake. In shape the tornado is usually of greater height than
-    width. The cyclone is far-flung laterally, but in height may not exceed
-    the narrow tornado, since both must terminate beneath the isothermal
-    layer, and commonly do not extend so high. Both vortices are caused
-    by the ascensional force of hot air. In both the air spirals in and
-    upward at the bottom, out and upward at the top, constantly<span class="pagenum" id="Page_405">405</span> cooling
-    by expansion, and finally descends on the outside to complete the
-    closed circulation. In general the tornado is the more violent and
-    destructive, though limited to a brief and narrow path. More aptly,
-    perhaps, the tornado may be called a slender hurricane of brief
-    duration; both of them being small cyclones, or aërial vortices, of
-    minor size and concentrated intensity. The relation of the tornado and
-    cyclone has been defined as follows, by Professor Moore:</p>
-
-  <blockquote>
-    <p>“The cyclone is a horizontally revolving disk of air of probably 1,000
-      miles in diameter, while the tornado is a revolving mass of air of
-      only about 1,000 yards in diameter, and is simply an incident of the
-      cyclone, nearly always occurring in its southeast quadrant. The cyclone
-      may cause moderate or high winds through a vast expanse of territory,
-      while the tornado, with a vortical motion almost unmeasurable, always
-      leaves a trail of destruction in an area infinitesimal in comparison
-      with the area covered by the cyclone.”</p>
-  </blockquote>
-
-  <p>Two initial conditions seem essential to the genesis of a substantial
-    tornado. In the first place, the atmosphere of its immediate locality
-    must have appreciable gyration. Of course, in all extra equatorial
-    regions the air has some incipient whirl due to the earth’s rotation,
-    and this whirl is magnified as the fluid is sucked into the vortex. But
-    the magnification may be slight owing to the brief lateral displacement
-    of the air feeding the tornado. If, however, the fluid be drawn from a
-    considerable distance, and have from local conditions some additional
-    whirl superadded to that due to the earth’s rotation, the gyratory
-    flow in the medium near the vortical axis may be very swift. On the
-    other hand, the additional whirl, due to local conditions, may tend
-    to neutralize that due to the earth’s component, thereby leaving<span class="pagenum" id="Page_406">406</span> a
-    very feeble gyration, if any. But in general the rotation of tornadoes
-    is observed to be in the direction of the earth’s component; to the
-    left north of the equator, to the right south of it. This observation
-    is doubtless the more striking because when the accidental local spin
-    conspires with the permanent terrestrial one, the resultant whirl
-    is intensified, while in the opposite case it is so enfeebled as to
-    attract scant, if any attention.</p>
-
-  <p>In the second place, the genesis of a tornado requires unstable
-    equilibrium in the local atmosphere. This instability, as in cyclones,
-    may arise from abnormal temperature gradation. Thus, if along any
-    vertical the temperature falls more than six degrees Centigrade for one
-    thousand meters ascent, a mass of air started upward will continue to
-    rise, since it cools less rapidly than the environing medium. In this
-    way there will ensue a continuous uprush of air so long as the unstable
-    state endures; and the action may be very vigorous if a large stratum
-    of air is greatly heated before it disrupts into the cold upper layers.
-    In general, the loftier the tornado the more violent it is, just as
-    the taller flue generates the stronger draft with the same temperature
-    gradient.</p>
-
-  <p>Dynamically, the tornado may be treated as a rotating pillar of air
-    in which each mass of fluid fairly retains its angular momentum. This
-    means that for any mass of the whirling air the radius of its path,
-    multiplied by its circular speed, remains a constant product; in
-    other words, the velocity of whirl varies inversely as the radius.
-    Accordingly, the circular velocity is exceedingly rapid where the
-    radius is very small. Now, when any mass runs round a circle its
-    centrifugal force is known to be directly as the square of the speed of
-    its centroid and inversely as the radius. But by the above assumption
-    the speed itself is inversely as the radius. Hence, the centrifugal
-    <span class="pagenum" id="Page_407">407</span>force varies inversely as the cube of the radius of the inflowing
-    mass of air. This centrifugal force, acting on the inner layers of
-    air of the rotating column, must be supported by the pressure against
-    them exerted by the outer layers as they pass inward. Thus there is a
-    strong barometric gradient from the remote still air toward the swiftly
-    whirling parts of the vortex.</p>
-
-  <p>It follows from the above argument that inside a tornado the barometric
-    pressure may be much below the normal; and it is easy to see that if
-    a barometer, starting from some point on the tornado base, be moved
-    vertically upward it must show a declining pressure, but if moved
-    upward and outward it may be made to show a constant pressure all the
-    way to the upper portion of the vortex. The instrument would thus
-    travel along an isobaric, bell-shaped surface opening upward. On a
-    series, therefore, of concentric circles on the base of a tornado,
-    we may erect a family of coaxial bell-shaped surfaces to mark the
-    points of equal pressure, and thus map out the isobars of the vortex.
-    Inside these coaxial surfaces reaching to earth, others of still
-    lower pressure may be drawn tapering downward to a rounded point and
-    terminating at various places on the axis. In an actual tornado one of
-    these infinitely numerous funnel-shaped isobaric surfaces may become
-    distinctly outlined and visible, if the air has sufficient moisture to
-    start precipitation when it reaches a surface of suitably low pressure.
-    This quite usually occurs in Nature, the funnel sometimes reaching to
-    earth, sometimes only part way, according to the pressure at which
-    precipitation begins, this pressure depending, of course, on the
-    percentage of humidity of the uprushing air.</p>
-
-  <p>The form of the funnel-like cloud ere it reaches the earth is
-    interesting. Being an isobaric surface,<span class="pagenum" id="Page_408">408</span> it would support in static
-    equilibrium a free particle resting on it and sharing its rotatory
-    motion. The lower rounded part of the funnel is parabolic, the upper
-    outer part hyperbolic; the two together delineating the well-known
-    Rankine double vortex of hydrodynamics. Students of hydrostatics know
-    that when a glass of water is spun round its axis at a fixed velocity,
-    the dimple observed is of parabolic form, and if frozen will sustain
-    in repose a small shot resting on its surface and whirling with it.
-    Similarly the lower part of the funnel is parabolic because in it the
-    air rotates, as one solid body, while the broader part of the funnel is
-    hyperbolic because in it the air has a speed inversely proportional to
-    its radius of motion.</p>
-
-  <p>If everywhere in a tornado the circular velocity of the inflowing air
-    were inversely proportional to the radius, as above assumed, the speed
-    near the axis would be indefinitely great. This cannot be admitted.
-    Practically, the inflow ceases when the centrifugal force of the
-    gyrating stratum equals the pressure urging it toward the axis. Within
-    this stratum is a column of air rotating everywhere with constant
-    angular velocity about the vortical axis, and thus having quite calm
-    air at its center. Outside this solidly rotating core the air spirals
-    radially inward and upward. Some idea of the stream lines in such
-    spiral flow may be obtained from Fig. 50 if a rapid circular motion be
-    added to the inward and upward velocity represented by the arrows.</p>
-
-  <p>In the foregoing discussion no account of friction was taken. Near the
-    earth’s surface this dampens the whirl and centrifugal force, so that
-    the air flows more directly into the vortex, while farther aloft the
-    centrifugal force near the axis so effectually checks the inflow as
-    to allow the central core of air to rush up nearly unimpeded, as in
-    a walled flue, taking its<span class="pagenum" id="Page_409">409</span> draught mostly from the lower part. As a
-    consequence, the upward speed of the heated air in the tornado tube may
-    be enormous, supporting in its stream objects of considerable mass.</p>
-
-  <div class="figright">
-    <a id="Fig_50"><img src="images/i_489.jpg" width="350" height="210" alt="" /></a>
-    <div class="small right"><i>Morey</i></div>
-    <div class="caption smcap">Fig. 50.—Funnel-like Cloud<br />Sometimes Observed in a Tornado.</div>
-  </div>
-
-  <p>The true horizontal speed anywhere in a tornado is compounded of the
-    velocities of gyration and of translation, as in the cyclone. Hence the
-    advancing side may be considerably the swifter and more destructive,
-    particularly more destructive since the impact of air increases as
-    the square of the velocity. If the vortex were stationary it would
-    be equally dangerous on all sides, standing erect and symmetrical;
-    but it drifts with the whole mass of air, sometimes quite swiftly and
-    often with varying speed of travel at different levels; thus, in its
-    slenderest forms, appearing bent and not infrequently twisted, as
-    it advances writhing serpentlike through the sky. Furthermore, the
-    intensity of whirl may fluctuate momentarily, with consequent shifting
-    of the isobaric surface, including that one whose form is visible
-    by reason of incipient condensation; and thus the funnel-like misty
-    tongue appears to dart earthward as a foggy downshoot from the cloud
-    above, whereas its parts are really rushing upward at all times very
-    swiftly, whether visible or not. This agile protrusion of the nimbus,
-    now a tongue, now a dark and mighty tower, is the strenuous part of
-    the storm, the abominated “twister” which the Kansan farmer sedulously
-    shuns, or peeps at from a hole in the ground. Unwelcome, indeed, are
-    its visitations,<span class="pagenum" id="Page_410">410</span> when, with mickle and multitudinous roar, it claps
-    his house in sudden darkness, hurls it aloft and sows its sacred relics
-    over all the adjoining township, “that with the hurly-burly hell itself
-    awakes.”</p>
-
-  <p>Theory, as well as experience, accredits the tornado with vast energy
-    and power. For, suppose a surface stratum of air one mile in area
-    and one thousand feet thick to increase in absolute temperature one
-    per cent, thus uplifting the superincumbent atmosphere ten feet. The
-    total energy stored in this way equals the weight lifted multiplied by
-    its upward displacement. The weight is a ton per square foot and the
-    displacement is ten feet; hence the stored energy is ten-foot tons per
-    square foot of the heated tract, or about 280,000,000 foot tons for
-    the square mile of heated air. This is equivalent to the work of one
-    million horses for over a quarter of an hour. A goodly percentage of
-    this stored work may be converted into kinetic energy in the active
-    part of the dry tornado. It is the energy of a vast reservoir suddenly
-    gushing through a tall penstock. It is a colossal upward cataract, an
-    aërial Niagara, a Johnstown flood suddenly liberated and quickly spent.</p>
-
-  <p>A vortex of that description possesses enormous devastating power, for
-    it is endowed with four destructive elements: rapid onset for razing,
-    violent spin for distorting, swift uprush for lifting, low pressure for
-    disrupting. These four grim powers may operate at once and in accord.
-    When, for example, they assault a house, the horizontal blasts push and
-    wrench it on the foundation, the cellar air suddenly expanding puffs it
-    aloft, the internal air bursts its walls or windows, the uprush carries
-    its members on high and scatters them wantonly to the four winds.
-    These powers are abundantly attested by authentic reports from many
-    localities.</p>
-
-  <p><span class="pagenum" id="Page_411">411</span></p>
-
-  <p>When the tornado appears as a misty column it is familiarly called
-    a “waterspout,” particularly if it appears over a sea or lake. As
-    already explained, the visible and cloudy portion of the column is
-    due to condensation of the aqueous vapor in the air, as it rushes
-    expanding and cooling into the low pressure part of the vortex. From
-    the lashed and rippling sea surface, where it upcones into the base of
-    the spout, some water is carried aloft as spray mingling with the mist
-    of the chilled vapor, but not necessarily in very large proportion,
-    and never rising in solid body to the cloud, as popularly supposed. On
-    the contrary, waterspouts, however massive and formidable looking, are
-    very tenuous, and may occur on land or water indifferently. Doubtless
-    they are better defined, more regular and more familiar over water,
-    and hence their name; but essentially they are vapor spouts, though
-    mingled at times with dust or spray. Owing to rapid precipitation of
-    the uprushing aqueous vapor, there may be heavy rainfall on all sides
-    of the waterspout, so that at sea it may be difficult for the observer
-    to ascertain how much of the downpour is salt water and how much is
-    fresh.<span class="pagenum" id="Page_412">412</span> On land the downpour is sometimes mingled with débris, and even
-    with live fish and frogs caught up from neighboring bodies Of water.
-    Copious hail also may fall with the rain, if the vortex be a lofty one.</p>
-
-  <div class="figcenter">
-    <a id="Fig_51"><img src="images/i_491.jpg" width="600" height="259" alt="" /></a>
-    <div class="caption smcap">Fig. 51.—Vertical Section of the St. Louis, Mo., Tornado of May 27, 1896,
-      Showing the Vortex Tubes in a Theoretical, Truncated, Dumbbell-shaped Vortex.</div>
-  </div>
-
-  <div class="figcenter">
-    <a id="Fig_52"><img src="images/i_492.jpg" width="600" height="598" alt="" /></a>
-    <div class="caption smcap">Fig. 52.—Horizontal Section of St. Louis Tornado of May 27, 1896.</div>
-  </div>
-
-  <p>The following description and analysis of a representative spout is due
-    to Professor Bigelow of the U. S. Weather Bureau:<a id="FNanchor_70" href="#Footnote_70" class="fnanchor">[70]</a></p>
-
-  <blockquote>
-    <p>“The tornado may be illustrated by the St. Louis storm of May 27,
-      1896. It is a truncated dumbbell vortex out off at the ground on the
-      plane where the inflowing angle is about 30°. This vortex is much
-      <span class="pagenum" id="Page_413">413</span>smaller than the hurricane, although of the same type. It is about
-      1,200 meters high and about 2,000 meters in diameter on the surface.
-      The vortex tubes are shown in Figs. 51 and 52. In these figures can
-      be seen the vortex tubes, geometrically spaced, through each of which
-      the same amount of air rises. The rotating velocity is greatest about
-      300 meters above the ground, but the dimensions are such as to produce
-      enormous velocities in the lower levels. The radius in the outer tube
-      is taken to be 960 meters, and the inner tube 55 meters. The radial
-      inward velocity on the outer tube is—8 meters per second; on the outer
-      tube the tangential velocity is 13 meters per second, and on the inner
-      224 meters per second; on the outer tube the vertical velocity is
-      0.27, and on the inner tube it is 80 meters per second. On the outer
-      tube the total velocity is 15 meters per second, and on the inner tube
-      270 meters per second. The volume of air ascending in each tube is
-      774,500 cubic meters per second. On account of the distortion of the
-      theoretical vortex, due to the cutting of the lower portion by the
-      truncated plane, and to the progressive motion of the whole system that
-      constitutes the tornado, there is difficulty in computing the pressure
-      to fit these observed velocities and radii.</p>
-
-    <p>“Tornadoes occur in the southern and southeastern quadrants of areas
-      of low pressure, along the borders of the cold and the warm masses
-      which entered into the structure of the cyclone. When a cold mass is
-      superposed upon a warm mass, as was the case at St. Louis, a tornado
-      will occur if the difference in specific gravity be sufficient to
-      inaugurate a violent mixing, and the rotation be about a vertical axis,
-      instead of about a horizontal axis, as in the case of thunderstorms.”</p>
-  </blockquote>
-
-  <div class="figleft">
-    <a id="Fig_53"><img src="images/i_494.jpg" width="350" height="190" alt="" /></a>
-    <div class="small right"><i>Morey</i></div>
-    <div class="caption smcap">Fig. 53.—Vertical Section of Short Tornado.</div>
-  </div>
-
-  <p>The size and form of waterspouts alter greatly with the state of the
-    atmosphere. As Ferrel observes, <span class="pagenum" id="Page_414">414</span>they may vary “from that of a cloud
-    brought down over a large area of the earth’s surface in a tornado
-    where the air is nearly saturated with vapor and the general base of
-    the clouds very low, somewhat as represented in Fig. 53, to that which
-    occurs when the air is very dry, and when the tornadic action is barely
-    able to bring the cloud down from a great height into a slender spout
-    of small diameter, somewhat as represented in Fig. 54. Horner says that
-    their diameters range from 2 to 200 feet, and their heights from 30
-    to 1,500 feet. Dr. Reye states that their diameters on land, at base,
-    are sometimes more than 1,000 feet. Oersted puts the usual height of
-    waterspouts from 1,500 feet to 2,000 feet, but states that in some rare
-    cases they cannot be much less than 5,000 or 6,000 feet. On the 14th of
-    August, 1847, Professor Loomis observed a waterspout on Lake Erie, the
-    height of which, by a rough estimate, was a half mile, and the diameter
-    about 10 rods at the base and 20 rods above.</p>
-
-  <p>“Judge Williams, in speaking of the tornado of Lee’s Summit, where he
-    saw it, says: ‘It seemed to be about the size of a man’s body where it
-    touched the clouds above, and then tapered down to the size of a mere
-    rod.’”</p>
-
-  <div class="figright">
-    <a id="Fig_54"><img src="images/i_495.jpg" width="350" height="378" alt="" /></a>
-    <div class="small right"><i>Morey</i></div>
-    <div class="caption smcap">Fig. 54.—Vertical Section of a Tall Tornado.</div>
-  </div>
-
-  <p>When the tornado vortex is so tall and strong as to carry raindrops up
-    to freezing strata it is commonly known as a hailstorm. The congealing
-    occurs usually in those isobaric surfaces which dip down in the center
-    of the vortex, but reach only part<span class="pagenum" id="Page_415">415</span> way to the earth. As indicated
-    in Fig. 55, the clear aqueous vapor near the earth is condensed to
-    cloud on crossing an isobaric surface of sufficiently low pressure
-    and temperature; then it proceeds as mingled cloud and rain till it
-    crosses the freezing isobar into the region of snow and hail formation;
-    thence finally curves outwardly to stiller air and descends as a cloud
-    of mingled vapor, rain and frozen parts. Of this frozen shower one
-    part may come to earth as hail or rain, the snow and sleet melting on
-    the way; while another part may be redrawn into the swift uprush, and
-    carried aloft till its frozen drops, or pellets, have grown so large by
-    accretion as to plunge to earth by sheer bulk, even though they must
-    traverse a furious ascending wind. A good illustration from Nature of
-    this cycle in the center of a hailstorm is presented in the following
-    by Mr. John Wise, America’s adventurous pioneer balloonist:</p>
-
-  <blockquote>
-    <p>“This storm originated over the town of Carlisle, Pa., on the 17th of
-      June, 1843. I entered it just as it was forming. The nucleus cloud
-      was just spreading out as I entered the vortex unsuspectingly. I was
-      hurled into it so quickly that I had no opportunity of viewing the
-      surroundings outside, and must therefore confine this relation to its
-      internal action. On entering it the motions of the air<span class="pagenum" id="Page_416">416</span> swung the
-      balloon to and fro and around in a circle, and a dismal, howling noise
-      accompanied the unpleasant and sickening motion, and in a few minutes
-      thereafter was heard the falling of heavy rain below, resembling in
-      sound a cataract. The color of the cloud internally was of a milky hue,
-      somewhat like a dense body of steam in the open air, and the cold was
-      so sharp that my beard became bushy with hoar frost. As there were no
-      electric explosions in this storm during my incarceration, it might
-      have been borne comfortably enough but for the seasickness occasioned
-      by the agitated air-storm. Still, I could hear and see, and even smell,
-      everything close by and around. Little pellets of snow (with an icy
-      nucleus when broken) were pattering profusely around me in promiscuous
-      and confused disorder, and slight blasts of wind seemed occasionally to
-      penetrate this cloud laterally, notwithstanding there was an upmoving
-      column of wind all the while. This upmoving stream would carry the
-      balloon up to a point in the upper clouds, where its force was expended
-      by the outspreading of its vapor, whence the balloon would be thrown
-      outward, fall down some distance, then be drawn into the vortex, again
-      be carried upward to perform the same revolution, until I had gone
-      through the cold furnace seven or eight times; and all this time the
-      smell of sulphur, or what is now termed ozone, was perceptible, and I
-      was sweating profusely from some cause unknown to me, unless it was
-      from undue excitement. The last time of descent in this cloud brought
-      the balloon through its base, where, instead of pellets of snow, there
-      was encountered a drenching rain, with which I came into a clear field,
-      and the storm passed on.”</p>
-  </blockquote>
-
-  <p>As might be expected the hailstones vary much in form, size and
-    quantity. If by chance any stones become slightly flattened they ride
-    level in the<span class="pagenum" id="Page_417">417</span> ascending current, and hence by aggelation grow most
-    rapidly on the periphery which is a line of diminished pressure. At
-    times they are more or less oval, and again they appear as fragments of
-    considerable masses of ice, broken perhaps by collision in the violent
-    parts of the tornado tube. Their great variety in shape and bulk may be
-    appreciated from the following extracts taken from the records of the
-    Signal Service:</p>
-
-  <div class="figcenter">
-    <a id="Fig_55"><img src="images/i_497.jpg" width="523" height="600" alt="" /></a>
-    <div class="caption smcap">Fig. 55.—Vertical Section of a Hail Tornado.</div>
-  </div>
-
-  <p>In <cite>Professional Paper of the Signal Service No. 4</cite>, describing the
-    tornadoes of May 29th and 30th, 1879, in Kansas, Nebraska, Missouri,
-    and Iowa, this passage occurs relative to a tornado at Delphos, Mo.:</p>
-
-  <p><span class="pagenum" id="Page_418">418</span></p>
-
-  <blockquote>
-    <p>“On the farm of Mr. Peter Bock, in the adjoining township of Fountain,
-      about 4 miles W. of the storm’s centre, and during the hailstorm that
-      preceded the tornado, masses of ice fell as large as a man’s head,
-      breaking in pieces as they struck the earth. One measured 13 inches
-      in circumference, another 15, and a hole made by one that fell near
-      the place of Mr. J. H. Kams measured 7 inches across one way and 8 the
-      other. This immense fragment of aërial ice broke into small pieces, so
-      that its exact size could not be determined.”</p>
-  </blockquote>
-
-  <p>The following description is given of the tornado that visited Lincoln
-    County, Neb., at that time:</p>
-
-  <p>“At first the hailstones were about the size of marbles, but they
-    rapidly increased in diameter until they were as large as hens’ eggs
-    and very uniform in shape. After the precipitation had continued about
-    fifteen minutes, the wind ceased and the small hail nearly stopped,
-    when there commenced to fall perpendicularly large bodies of frozen
-    snow and ice, some round and smooth and as large as a pint bowl, others
-    inclined to be flat, with scalloped edges, and others resembled rough
-    sea-shells. One of the latter, after being exposed an hour to the sun,
-    measured fourteen inches in circumference.”</p>
-
-  <p>The following was reported by the Signal Service observer at Fort
-    Elliott, Tex., 1888:</p>
-
-  <blockquote>
-    <p>“A thunder-storm began at 4.10 <span class="smcap">p.m.</span> and ended at 7.40
-      <span class="smcap">p.m.</span>, moving from southwest to northwest. Hail began at 5.18
-      <span class="smcap">p.m.</span> and ended at 5.26 <span class="smcap">p.m.</span>, the hailstones being
-      spheroidal in shape and about two inches in diameter; formation, solid
-      snow. The ‘break’ (hills) at the foot of the plains several miles
-      northwest of station were absolutely white with hailstones for three
-      hours after the storm. This was observed by everybody at the station;
-      on the<span class="pagenum" id="Page_419">419</span> morning of the 26th I walked down to the Sweetwater Creek,
-      three fourths of a mile distant, and saw great banks of hailstones
-      which had been washed down during the night. The bottoms along the
-      Sweetwater were literally covered with banks of hailstones from six
-      to eight feet in depth. It was estimated that there was enough hail
-      to cover ten acres to a depth of six feet. The hailstones killed five
-      horses which were out on the prairie on a ranch six miles north of
-      station. The Sweetwater Creek was higher than ever known before, the
-      freshet destroying nearly the entire post garden. The high water is
-      supposed to have been caused by a ‘cloud-burst’ at or near the foot of
-      the plains, where the Sweetwater has its source; there was only 0.36
-      inch of rainfall at the station. On Sunday, May 27th, hailstones were
-      collected on the banks of the Sweetwater, which had been washed down
-      and lay in drifts 6 feet deep, actual measurement by the observer.”</p>
-  </blockquote>
-
-  <p>When, after imprisonment and long sustention in a powerful tornadic
-    vortex, the accumulated rain or hail finally breaks through and pours
-    down to earth, in solid cataract, the phenomenon is commonly called
-    a cloud-burst. The foregoing example is a partial illustration.
-    The following is quoted from Espy, describing a cloud-burst near
-    Hollidaysburg, Penn., in which the water seems to have poured down
-    nearly in a solid stream:</p>
-
-  <blockquote>
-    <p>“On examining the northern side of this ridge, large masses of gravel
-      and rocks and trees and earth, to the number of 22, were found lying
-      at the base on the plain below, having been washed down from the side
-      of the ridge by running water. The places from which these masses
-      started could easily be seen from the base, being only about 30 yards
-      up the side. On going to the head of these washes<span class="pagenum" id="Page_420">420</span> they were found
-      to be nearly round basins from 1 to 6 feet deep, without any drains
-      leading into them from above. The old leaves of last year’s growth,
-      and other light materials, were lying undisturbed above, within an
-      inch of the rim of these basins, which were generally cut down nearly
-      perpendicularly on the upper side, and washed out clean on the lower.
-      The greater part of these basins were nearly of the same diameter,
-      about 20 feet, and the trees that stood in their places were all washed
-      out. Those below the basin were generally standing, and showed by the
-      leaves and grass drifted on their upper side how high the water was in
-      running down the side of the ridge; on some it was as high as three
-      feet. It probably, however, dashed up on the trees above its general
-      level.”</p>
-  </blockquote>
-
-  <p>Dry whirlwinds of moderate size, but sometimes of considerable
-    violence, frequently occur in clear weather when the percentage of
-    humidity is small and when the vertical temperature gradient is
-    unusually pronounced. In this case there may be strong agitation of
-    the air, rendered visible at the earth’s surface by light débris on
-    land, or boiling of the water at sea; but the main body of the tube is
-    invisible and free from mist except high up where precipitation begins,
-    capped by a growing patch of white cloud in a clear sky, and which
-    may gradually broaden and condense sufficiently to cause a shower of
-    rain. On land the dry whirlwind may be delineated as a tall column, by
-    whirling dust or sand. In this case, if the gyration is violent, the
-    central core may appear clean and clear owing to the centrifugal force
-    which keeps the grains out where they are balanced by the pressure of
-    the inrushing air. In such vortices the sand spout may appear to be
-    hollow as in the case of waterspouts whose interior cores are free
-    from cloud or condensed vapor. On<span class="pagenum" id="Page_421">421</span> the other hand, myriads of mild
-    transparent whirlwinds unmarked, except by down or humanly invisible
-    dust, or dim aërial refractions, may frisk and play in the boundless
-    sky unnoticed by the blunt eyes of men, yet constantly engaged in
-    generating or marshaling the clouds and in buoying upward the ponderous
-    eagles, the vultures and the whole brood of passive flyers whom we
-    have not yet learned to emulate. Thus when we remember that an upward
-    trend of air of scarcely one yard per second, and too feeble to support
-    a falling hair, is yet sufficient to carry the condor and albatross
-    without wing beat, it seems important to explore these minor vortices
-    and to ascertain their availability and practical usefulness for human
-    soaring.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="chapter_XVII">
-    <span class="pagenum" id="Page_422">422</span>
-    <h3>CHAPTER XVII</h3>
-    <span class="small">THUNDERSTORMS, WIND GUSTS</span>
-  </div>
-
-  <p><span class="smcap">Still</span> another interesting kind of aërial disturbance is the familiar
-    heat thunderstorm. This is not synonymous with those electrified
-    tornadoes and cyclones which are accompanied by thunder and lightning,
-    sometimes of great violence. Most tornadoes are thunderstorms, but
-    not vice versa. The thunderstorm is not essentially a vortex, but
-    rather a wind squall marked by sudden changes of temperature and
-    pressure, bearing with it massive clouds fraught with rain, or hail,
-    and disruptive electric charges flashing frequently to earth, or
-    from point to point in the sky. Its approach is usually announced by
-    rumbling thunder and heavy black clouds along the horizon. Its duration
-    is brief, varying from a few minutes to an hour or two. Further
-    characteristics are thus expressed by Moore:</p>
-
-  <blockquote>
-    <p>“On land, thunderstorms occur most frequently at specific hours of
-      the day or night, such as 3 to 5 in the afternoon or 9 to 10 in the
-      evening and sometimes even at 2 or 3 <span class="smcap">a.m.</span>, but no such diurnal
-      period is observed in midocean. The phenomena usually occur in a pretty
-      regular order of succession. After several hours of fair weather, with
-      gentle winds, there comes a calm; the cumulus clouds grow larger, the
-      lower stratum of clouds is seen to be moving rapidly; gusts of wind
-      start up with clouds of dust, rain is seen to be falling at a distance;
-      the movement of rain and dust shows that the wind is blowing out<span class="pagenum" id="Page_423">423</span> from
-      this rain cloud near the ground no matter which way the rainy region is
-      advancing; a few large drops fall from slight clouds and then suddenly
-      the heavy rain begins. Lightning that may have occurred during the
-      preceding few minutes becomes more frequent and more severe as the rain
-      increases. After the maximum severity of rain and wind, the lightning
-      also diminishes or entirely ceases, and we are soon able to say that
-      the storm has passed by. If we watch its retreat from us in the
-      afternoon we shall see the rear of a great cumulus on which the sun is
-      shining, but through whose dark-blue curtain of cloud and rain nothing
-      save occasional lightning is visible. After the storm has passed, the
-      lower atmosphere soon becomes appreciably cooler and drier, the sky is
-      nearly clear of clouds, and the wind has shifted to some other point of
-      the compass than that which prevailed before the storm.”</p>
-  </blockquote>
-
-  <p>The genesis of thunderstorms is varied and manifold. In one simple
-    type, a large tract of heated air in the unstable state and with a high
-    percentage of humidity swells upward at the center, the ascending moist
-    air forming, at the precipitation altitude, a growing cloud which may
-    become very broad, dark and bulky, drifting along over the earth with
-    the prevailing current. Eventually rain begins to form, or may be hail
-    or snow, if the heated column reaches to a great height. The falling
-    shower cools the air from the cloud down to the earth, increasing its
-    density and materially weighting it with the descending liquid or
-    solid particles. The showery column then sinks, especially along its
-    inner part where it is maturest, thus causing an outrush of cool air
-    along the earth, the immediate forerunner and herald of the rain. This
-    outrushing current pushes upward the environing clear moist air, thus
-    forming new margins of massive cumuli around the older<span class="pagenum" id="Page_424">424</span> nimbus widening
-    within, showering, cooling and sinking. Thus the rain area is broadened
-    and propagated, sometimes with nearly equal speed in all directions,
-    but generally fastest in the direction of the most unstable condition,
-    or of the then prevailing drift of the atmosphere. Indeed, the forward
-    cloud ranks may far outspeed the wind, seeming by their imperious
-    bluster and gigantic gloom to commandeer new recruits, as if by magic,
-    out of the clear sky. Before this solemn mustering and turbulent front
-    of the storm the black vapors suddenly startled into visible shape,
-    rush buoyantly upward in ragged shreds, like smoke from unseen fires,
-    and quickly blend with the general array of compact cloud expanding
-    across the sky. Again, several thunderstorms, merged like a mountain
-    range in solid phalanx, may sweep abreast over a continent, with long
-    horizontal<a id="FNanchor_71" href="#Footnote_71" class="fnanchor">[71]</a> roll, ever rising in front and upheaving the sultry
-    air, thus replenishing perpetually the ponderous cumuli which form
-    the vanguard of this far-flung and titanic march of the clouds. Such
-    a storm is usually powerful and persistent, commonly enduring until
-    the sun’s decline and the shades of night have cooled the lower air,
-    and thus allayed the commotion by enfeebling the forces that favor its
-    progress.</p>
-
-  <p>The speed of rise of the air beneath the base of the thunderhead is
-    a question of some interest in aëronautics. If the ascent be so much
-    as a foot or two per second, one may expect the vultures to prefer
-    soaring beneath the thundercloud during its formative period. Here
-    also the aëroplanist might attempt a record flight, if the cloud were
-    high enough to be out of his way. But if he ventured to penetrate the
-    base of the thunderhead, he might find <span class="pagenum" id="Page_425">425</span>the turmoil too irregular and
-    strenuous for his comfort.</p>
-
-  <p>Of like interest is the long aërial swell that leads the advancing
-    storm. When will aviators make this the theater of their adventurous
-    frolic, careering playfully before the brow of the tempest and the
-    harmless rage of the lightning, gay-winged heralds of the coming
-    tumult, sailing perhaps with slackened motive power, yet swift and
-    secure as the storm-riding petrels at sea?</p>
-
-  <p>Besides the winds and aërial currents commonly studied by
-    meteorologists, are the minor disturbances which affect more
-    particularly the wayfarers of the sky, whether birds or men. The
-    atmosphere quite usually is vexed with invisible turmoils; most
-    sensible, indeed, over rough territory, but conspicuous also above
-    the smooth terrene, and at all elevations from earth to the highest
-    cloudland. Before sunrise, and generally in weather uniformly overcast,
-    these miscellaneous and nondescript movements of the air are least
-    active, for any given speed of the general drift of the atmosphere;
-    but when the sun shines and the soil is nonuniformly heated, the
-    disturbances become most pronounced. A whole troop of playful zephyrs
-    rise and set with the sun, in addition to the diurnal winds already
-    studied. Over the dusty plain they reveal their presence and shape
-    in those coiling columns that constitute the safety vents of the
-    atmosphere, and obviate the disruptive violence of the uprush that
-    would occur should a considerable region of surface air become
-    excessively heated. Over the city, particularly in winter, the local
-    turmoils of the atmospheric surf are revealed in the play of a thousand
-    smoky columns, and better still, when it snows, by the incessant
-    swell and veering of the flaky flood whose surges and eddies bewilder
-    the vision by their complexity. Over the<span class="pagenum" id="Page_426">426</span> water the clouds of fog
-    and steaming vapor are the best index of the local zephyrs, where,
-    it must be remembered, the rising and veering of the vapor wreaths
-    accompany like motions in the atmosphere. Over the forest, field and
-    meadow the interminable wandering of thistle down and gauzy shreds of
-    vegetation, now fast, now slow, now high aloft, then sheer earthward,
-    indicate what erratic and perpetual motions prevail throughout the open
-    country even on the stillest days. In the deep bosom of the atmosphere,
-    the parallel ranks of the cirri all across the sky mark the crests
-    of undulations quite as regular and tumultuous as the billows of a
-    wind-swept sea; while the fierce seething and upsurging of the separate
-    cumuli manifest the operation of vortices of prodigious energy. These
-    visible billows and whirlwinds suggest an infinitude of transparent
-    ones hardly less powerful, at the various levels unmarked by clouds.
-    For wherever two streams of abnormally graded densities neighbor each
-    other, a readjustment may occur agitating the entire region with a host
-    of pulsations, squalls, cataracts and fountains which the bird and
-    navigator must parry with proportionate care and skill.</p>
-
-  <p>And it is because of the amazing resistance of these wandering zephyrs,
-    waves and eddies that they demand the attention of aëronauts; nay,
-    more, it is because of the substantial labor they can perform when
-    adroitly encountered and duly employed. For the simplest elements of
-    aërodynamic science make clear that a rising zephyr hardly strong
-    enough to support a falling leaf is adequate to sustain the heaviest
-    soaring birds and aëroplanes gliding swiftly through it. In fact, the
-    sailors of fast air ships feel a heavy impulse and distinct shock in
-    plowing those mild cross winds which, to the fixed observer, seem not
-    like blasts, but rather as gentle<span class="pagenum" id="Page_427">427</span> swells or harmless currents. These,
-    therefore, have been made the subject of investigation by various
-    students of aëronautics.</p>
-
-  <p>The first incentive to the instrumental study of the fluctuations
-    of the wind in speed and direction seems to have been the hope to
-    furnish a quantitative basis for various theories of soaring flight.
-    Pénaud,<a id="FNanchor_72" href="#Footnote_72" class="fnanchor">[72]</a> in 1875, had explained this phenomenon by postulating
-    an upward current. Lord Rayleigh,<a id="FNanchor_73" href="#Footnote_73" class="fnanchor">[73]</a> in 1883, had made the more
-    general assumption of a wind having either a variable speed or a
-    variable direction as a necessary and sufficient condition for such
-    flight. Marey,<a id="FNanchor_74" href="#Footnote_74" class="fnanchor">[74]</a> in 1889, and Langley,<a id="FNanchor_75" href="#Footnote_75" class="fnanchor">[75]</a> in 1893, gave elementary
-    qualitative explanations of soaring in a horizontal wind of variable
-    velocity, though neither adduced concrete data to prove that the feat
-    could be performed in an actual wind. Each and all of those theories
-    may be sound enough in the abstract, but to show that they represent
-    realities of art or Nature they should be applied to a concrete
-    instance of soaring of a machine or a bird of known resistance, in a
-    wind of known variability.</p>
-
-  <p>To such end the writer in 1892 devised an anemograph for recording
-    simultaneously the speed of the wind and its horizontal and vertical
-    components of direction, while Dr. Langley devised a very light and
-    delicate cup anemometer for recording the variations of wind speed in
-    a horizontal plane, but not the changes of direction. Both instruments
-    were set up in January, 1893, and both investigations were published
-    with the <cite>Proceedings of the International Conference on Aërial
-      Navigation</cite> of that <span class="pagenum" id="Page_428">428</span>year; but neither investigation was pushed far
-    enough to prove conclusively the possibility of a particular bird
-    or model soaring in the particular wind recorded. The two together
-    did, however, reveal quite astonishing fluctuations of the wind in
-    both speed and direction, results that have since received ample
-    exemplification in the more extended records of other observers.</p>
-
-  <div class="figcenter">
-    <a id="Fig_56"><img src="images/i_508.jpg" width="362" height="600" alt="" /></a>
-    <div class="caption"><span class="smcap">Fig. 56.—Universal Anemograph.</span> (The vanes are
-    high above the point indicated by the break in the vertical pipe.)</div>
-  </div>
-
-  <p>Fig. 56 shows the recording anemometer for<span class="pagenum" id="Page_429">429</span> speed and double direction
-    constructed by the writer in 1892. A large weather vane was firmly
-    strapped to a vertical pipe which turned freely on ball bearings and,
-    by means of a small crank actuating a chronograph pencil, recorded its
-    fluctuations on a long sheet of paper winding on the drum from a roll
-    behind. On top of the pipe and about fifteen feet from the ground,
-    was mounted a carefully balanced horizontal vane, from which a fine
-    steel wire ran down the axis of the pipe to a fixed pulley, thence
-    to a second recording pencil. A third pencil recorded the beats of a
-    pendulum, thus standardizing the speed of the paper. A fourth pencil,
-    not shown, was designed to record the turns of an anemometer mounted
-    near the top of the pipe. The records of the wind speed thus secured
-    are omitted for lack of standardization, as the experiments were
-    prematurely terminated.</p>
-
-  <div class="figcenter">
-    <a id="Fig_57"><img src="images/i_509.jpg" width="700" height="205" alt="" /></a>
-    <div class="caption smcap">Fig. 57.—Records of Wind Variation in Horizontal and
-      Vertical Direction.</div>
-  </div>
-
-  <p>Typical records of the wind direction are shown in Fig. 57 in which
-    the circles represent <span class="pagenum" id="Page_430">430</span>the paths swept by the wind-vane cranks that
-    operated the corresponding pencils. Both vanes, as shown by their
-    diagrams, veered quite frequently ten degrees in a short interval of
-    time, and not seldom twenty to thirty degrees. Frequently, also, it was
-    observed, in scanning the various records, that a rise or lull in the
-    wind speed was accompanied by a corresponding variation in direction;
-    but the observations were not sufficiently numerous and extended to
-    establish this phenomenon as a general occurrence. But as it can be
-    shown theoretically that a horizontal stream of air of constant cross
-    section and uniform velocity at each section, can not greatly fluctuate
-    in velocity from point to point, without more pronounced changes of
-    density than the barometer records, it naturally follows that the
-    stream must broaden where the air speed lags, and narrow where it
-    accelerates; in other words, it follows that there must be some change
-    in direction. The records were taken in the middle of a clear open
-    space of two hundred acres at Notre Dame University on a sunless day in
-    January, 1893, when the temperature was 24° F., and the wind eight to
-    twelve miles per hour. Their application to the theory of soaring need
-    not be considered here.</p>
-
-  <p>Further studies of the wind pulsations were made by use of a toy
-    balloon attached to a long thread. The first trials are thus recounted
-    in the paper above cited:</p>
-
-  <blockquote>
-    <p>“After some preliminary tests from the top of the Physical Laboratory
-      of the Johns Hopkins University, during the Easter vacation of 1893,
-      I ascended the Washington Monument at Baltimore, where I paid out the
-      exploring line at a height of 200 feet. The wind was blowing toward
-      the southeast at the speed of 25 to 35 miles per hour, and the sky,
-      which had remained clear till 3 o’clock, was rapidly <span class="pagenum" id="Page_431">431</span>darkening,
-      with indications of approaching rain. The balloon, when let forth,
-      immediately fell to a depth of 30 or 40 feet, being caught in the eddy
-      of the monument, then presently encountering the unbiased current,
-      sailed in it toward the southeast, approximately level with the spool
-      end of the thread. After the balloon had drawn out 100 feet of thread I
-      checked it to observe the behavior of this much of the exploring line.
-      The balloon rose and fell with the tossing of the wind, but did not
-      flutter like a flag, as it would do if formed of irregular outline.
-      Neither did the thread flutter, nor do I believe there is ever a
-      tendency in a line greatly to flutter in a current as does a flag or
-      sail. Presently I paid out 300 feet of the exploring line, whereupon
-      the waves in the thread became quite remarkable. The thread then, as
-      a rule, was never approximately straight. Sometimes it was blown into
-      the form of a helix of enormous pitch; at other times into the form
-      of a wavy figure lying nearly in a single vertical plane; and again,
-      the entire exploring line should veer through an angle of 40° to 60°,
-      either vertically or horizontally. The balloon, of course, seldom
-      remained quiet for more than a few seconds at a time, but tossed about
-      on the great billows like a ship in a storm. Quite usually the billows
-      could be seen running along the line from the spool to the balloon,
-      and, as a rule, several different billows occupied the string at one
-      time.</p>
-
-    <p>“The observations just delineated, however curious they may be, afford
-      no adequate conception of the behavior of the air currents over an open
-      plane, nor at a great height above the earth, because the Washington
-      Monument at Baltimore stands but 100 feet above the surrounding
-      buildings, which undoubtedly send disturbances to a greater height than
-      200 feet. To supplement these explorations, therefore, I<span class="pagenum" id="Page_432">432</span> determined
-      to have them repeated from the top of the Washington Monument at
-      Washington and the Eiffel Tower at Paris.”</p>
-  </blockquote>
-
-  <p>Some months later in the year, the experiment was repeated at the top
-    of the Washington Monument in Washington, at a height of five hundred
-    feet. The balloon, with a stone attached, was paid out from the north
-    window of the monument till it reached the ground. Then the stone was
-    removed by an assistant who drew the balloon well away from the huge
-    eddy of the great shaft, and let it fly toward the east, drawing the
-    thread after it like a mariner’s log in the wake of a ship. When six
-    hundred feet of the thread had been let out, it was observed to veer in
-    all directions under the varying surges of the wind. These variations
-    seemed larger than could be expected from the wake of the shaft alone
-    near its summit, where it measures about thirty feet in thickness.</p>
-
-  <p>Such qualitative observations, though interesting and suggestive,
-    are not wholly satisfactory. The same may be said of the study of
-    air currents by aid of smoke from tall chimneys. The eddy about such
-    columns may extend to a considerable height above them, and the wake
-    is farreaching. The experiments would therefore best be made from high
-    open-work towers above plane country or a broad sheet of water.</p>
-
-  <p>A better method perhaps would be to liberate a pilot balloon, or
-    discharge a bomb giving a bright compact cloud, and to trace its path
-    by means of two cameras, as it floats from point to point in the
-    aërial current. The instruments, if suitably stationed, would give the
-    continuous space history of the floating object; that is, its actual
-    path and the speed at each part thereof, or, in other words, the
-    magnitude and direction of the velocity at each point. But, of course,
-    this method would not reveal<span class="pagenum" id="Page_433">433</span> the wind’s history at any given fixed
-    point, as recorded by the anemograph above described.</p>
-
-  <div class="figcenter">
-    <a id="Fig_58"><img src="images/i_513.jpg" width="486" height="700" alt="" /></a>
-    <div class="caption smcap">Fig. 58.—Records of Wind Speed Obtained by Langley.</div>
-  </div>
-
-  <p>Fig. 58 is a typical wind-speed record obtained by Langley in January,
-    1893, by means of a very light cup anemometer mounted eleven feet
-    above<span class="pagenum" id="Page_434">434</span> the north tower of the Smithsonian Institution, and 153 feet
-    from the ground. The abscissæ represent time in minutes, the ordinates
-    wind speed in miles per hour. The records were taken in cloudy weather
-    and in a south-southeast wind. Other records were taken during the
-    month of February, showing like deviations from the mean, though at
-    times more pronounced; for Dr. Langley noted that “the higher the
-    absolute velocity of the wind, the greater the relative fluctuations
-    which occur in it.”</p>
-
-  <p>It will be observed from this record that, when the average speed was
-    about twelve miles an hour, the extreme fluctuation was rarely one
-    third greater or less than that, and on the average varied hardly
-    one sixth. It must be further added that the air on approaching the
-    anemometer had traversed a mile of the lower residential section of
-    the city, then crossed the body of the Smithsonian building, which
-    itself is half as high as the tower. It should be expected, therefore,
-    that this wind was, other things equal, naturally more turbulent than
-    if flowing in from a level plain. This surmise is justified by the
-    more extensive records of wind speeds shown in meteorological records
-    taken respectively in clear and in obstructed places. On the other
-    hand, even in level places where no obstruction is visible for several
-    miles, the wind, though it may be steady at one time, can at another
-    time be gustier than that shown in Langley’s record, according to the
-    state of the weather; for the gusts are not all due to neighboring
-    obstacles, but may be transmitted from afar, even from the depths of
-    the atmosphere.</p>
-
-  <p>Assuming the wind speed at any instant to vary by one sixth of the
-    mean, its impactual pressure will then vary by thirty-six per cent of
-    the pressure of the mean wind, remembering that the pressure varies as
-    the square of the speed. This fluctuation<span class="pagenum" id="Page_435">435</span> of the impactual pressure
-    tallies fairly well with that found by Professor Marvin at the top of
-    Mount Washington, in 1890, by means of a pressure plate.<a id="FNanchor_76" href="#Footnote_76" class="fnanchor">[76]</a> He found
-    the variation to be approximately thirty-five per cent of the mean
-    pressure. Professor Hazen, however, reports but little variation in
-    the wind speed in the free atmosphere well above the earth. In several
-    balloon ascensions he suspended from the basket a lead weight by means
-    of a cord to which was looped the thread of a toy balloon. He found
-    that the little balloon sometimes moved ahead if the weight sometimes
-    followed it, but that in general the relative motion was very feeble,
-    thus indicating that the fluctuations of the velocity in the depth of
-    the atmosphere at those times were very slight.<a id="FNanchor_77" href="#Footnote_77" class="fnanchor">[77]</a> However this be for
-    such distances from the earth and its protuberances, the fluctuations
-    of wind speed found at meteorological stations sufficiently resemble
-    those reported by Dr. Langley. As corroborative evidence, the reader
-    may be referred to the wind records published in the <cite>Interim Report</cite>
-    for 1909, of the British Advisory Committee for Aëronautics.</p>
-
-  <p>Without the material evidence of commotion in the atmosphere, a
-    moment’s reflection will make clear that such turmoil must exist, even
-    over a vast, smooth plain, especially in bright weather, and more
-    particularly over bare ground in dry weather. For it is well known
-    that clear, dry air transmits radiation with very slight absorption,
-    when the sun is well toward the zenith, and hence that the temperature
-    in the depth of the atmosphere is but little changed from moment
-    to moment, due to the passage of sunlight. At the earth’s surface,
-    however, the air by <span class="pagenum" id="Page_436">436</span>contact with heating or cooling soil may change
-    temperature rapidly. The direct sunlight falling perpendicularly upon
-    a perfectly absorbent material transmits nearly two calories of heat
-    per minute to each square centimeter of the receiving surface. It
-    would, therefore, under favorable circumstances, elevate by nearly
-    two degrees C. per minute a layer of water one centimeter deep, or
-    a layer of air something over a hundred feet thick, if all the heat
-    falling on the assumed surface were communicated to the neighboring air
-    stratum. In practice, a large percentage of the incident sunlight is
-    reflected and radiated by the soil, into sidereal space without heating
-    the air. But every one per cent of it caught up by the air in contact
-    with the earth is sufficient to heat a layer roughly one foot thick
-    one degree per minute. Hence, unless the heated air streamed upward
-    continually, the layer next the earth would quickly be raised to a
-    very abnormal temperature, which would result in a violent uprush. The
-    gradual ascension of the surface air may take place in large or small
-    columns, or in both kinds at once. In either case, the composition of
-    the ascensional motion with the general movement of the wind due to
-    barometric gradient must cause gustiness and marked irregularity of
-    speed and direction.</p>
-
-  <p>Various causes have been assigned for the gustiness of the winds.
-    Ferrel and many other writers assume that the air, especially near
-    the earth, is full of small vortices rotating about axes of various
-    inclination. These whirls, on passing squarely across a weather vane,
-    cause it to point one way for a moment, then presently the opposite
-    way, while if they cross obliquely they cause a like sudden veering of
-    the vane, but less extensive.</p>
-
-  <p>Helmholtz has proved that in the atmosphere strata of different
-    densities come at regular intervals <span class="pagenum" id="Page_437">437</span>to be contiguous one above
-    the other, and thus to beget conditions favorable to the formation
-    of aërial waves, sometimes so large as to set the lower regions of
-    air into violent commotion and thereby generate the so-called gusty
-    weather. He has summarized as follows some of the important conclusions
-    of his dynamic analysis.<a id="FNanchor_78" href="#Footnote_78" class="fnanchor">[78]</a></p>
-
-  <p>“As soon as a lighter fluid lies above a denser one with well-defined
-    boundary, then evidently the conditions exist at this boundary for
-    the origin and regular propagation of waves, such as we are familiar
-    with on the surface of water. This case of waves, as ordinarily
-    observed on the boundary surfaces between water and air, is only to be
-    distinguished from the system of waves that may exist between different
-    strata of air, in that in the former the difference of density of the
-    two fluids is much greater than in the latter case. It appeared to me
-    of interest to investigate what other differences result from this in
-    the phenomena of air waves and water waves.</p>
-
-  <p>“It appears to me not doubtful that such systems of waves occur with
-    remarkable frequency at the bounding surfaces of strata of air of
-    different densities, even although in most cases they remain invisible
-    to us. Evidently we see them only when the lower stratum is so nearly
-    saturated with aqueous vapor that the summit of the wave, within which
-    the pressure is less, begins to form a haze. Then there appear streaky,
-    parallel trains of clouds of very different breadths, occasionally
-    stretching over the broad surface of the sky in regular patterns.
-    Moreover, it seems to me probable that this, which we thus observe
-    under special conditions that have rather the character of exceptional
-    cases, is present <span class="pagenum" id="Page_438">438</span>in innumerable other cases when we do not see it.</p>
-
-  <p>“The calculations performed by me show, further, that for the observed
-    velocities of the wind there may be formed in the atmosphere not only
-    small waves, but also those whose wave lengths are many kilometers
-    which, when they approach the earth’s surface to within an altitude
-    of one or several kilometers, set the lower strata of air into
-    violent motion and must bring about the so-called gusty weather. The
-    peculiarity of such weather (as I look at it) consists in this, that
-    gusts of wind often accompanied by rain are repeated at the same place,
-    many times a day, at nearly equal intervals and nearly uniform order of
-    succession.”</p>
-
-  <p>Commandant Le Clement de Saint-Marcq has drawn some interesting
-    conclusions from the hypothesis that an ordinary wind consists of a
-    uniform current on which is superposed periodic motions in the wind’s
-    main direction and also at right angles thereto. But he has not
-    established his hypothesis by adequate observations. He assumes the
-    pulsations to be simple harmonic motions, which of course they would be
-    if they were plane compressional waves; but at the same time he shows
-    that the fluctuations are too large to be compressional waves, with the
-    concurrent slight variations of the barometric pressure.</p>
-
-  <p>It is still a question whether the pulsations of the natural wind be
-    harmonic. If so, the speed records should be sine curves, and the to
-    and fro acceleration of any mass of moving air should be variable for
-    any given pulsation. But the few records available show in many parts a
-    constant acceleration of the wind speed throughout a particular swell
-    or lull of velocity, indicating that the pulsations are not generally
-    simple harmonic ones.</p>
-
-  <p><span class="pagenum" id="Page_439">439</span></p>
-
-  <p>In scanning the wind-speed records published by Langley, so many
-    instances of uniform wind acceleration are noticed that one naturally
-    inquires whether the rate of gain of velocity be sufficient to sustain
-    in soaring flight an aëroplane or bird held to the wind solely by
-    its inertia, as Langley believed to be possible. The total forward
-    resistance of a well-formed aërial glider, or bird, may be taken as
-    one eighth of its weight; hence, if poised stationary in its normal
-    attitude of flight, it will just be sustained by a direct head wind
-    having a horizontal acceleration of one eighth that of gravity, or
-    four feet per second. Now, the most favorable parts of the record here
-    shown (<a href="#Fig_58">Fig. 58</a>) exhibit nowhere an acceleration so great as four feet
-    per second, and on the average far less than that, as may be proved
-    by sealing the diagram. Hence, the wind here recorded was wholly
-    inadequate to support by its pulsative force either bird or man. But
-    as this record is a fair representative of all those published by Dr.
-    Langley, it follows that such pulsations can at best merely aid in
-    soaring when happily and adroitly encountered; but that they cannot
-    fully sustain soaring at any level, much less during ascensional flight
-    to great altitudes, or migrational flight to vast distances. It still
-    remains, therefore, to ascertain what kind of aërial currents are
-    adequate to sustain those marvelous feats of soaring on passive pinions
-    which for ages have been the delight and wonder of all keen observers,
-    and which are of such enduring interest to mankind. This investigation,
-    however, appertains more particularly to the science of applied
-    aërodynamics.</p>
-
-  <hr class="page" />
-  <div class="chapter" >
-    <span class="pagenum" id="Page_441">441</span>
-    <h2 class="xlarge">APPENDICES</h2>
-  </div>
-
-  <hr class="page" />
-  <div class="chapter" id="appendix_I">
-    <span class="pagenum" id="Page_443">443</span>
-    <h3>APPENDIX I</h3>
-    <span class="small">STRESS IN A VACUUM BALLOON<a id="FNanchor_79" href="#Footnote_79" class="fnanchor">[79]</a></span>
-  </div>
-
-  <div class="center large mb2"><i>By A. F. Zahm</i></div>
-
-  <p><span class="smcap">As</span> inventors frequently propose the construction of a vacuum balloon,
-    to secure buoyancy without the use of gas, it may be desirable to
-    estimate the strength of material required to resist crushing, say in a
-    spherical balloon.</p>
-
-  <p>The unit stress in the wall of a thin, hollow, spherical balloon
-    subject to uniform hydrostatic pressure, which is prevented from
-    buckling, is given by equating the total stress on a diametral section
-    of the shell to the total hydrostatic pressure across a diametral
-    section of the sphere, thus:</p>
-
-  <div class="center">2π<i>rtS</i> = π<i>pr<sup>2</sup></i></div>
-
-  <p class="noindent">in which <i>S</i> may be the stress in pounds per square inch, <i>p</i> the
-    resultant hydrostatic pressure in pounds per square inch, <i>r</i> the
-    radius of the sphere, <i>t</i> the wall thickness.</p>
-
-  <p>The greatest allowable mass of the shell is found by equating it to the
-    mass of the displaced air, thus:</p>
-
-  <div class="center">4π<i>r</i><sup>2</sup><i>t</i>ς<sub>1</sub> = 4π<i>r</i><sup>3</sup>ς<sub>2</sub>/3</div>
-
-  <p class="noindent">in which ς<sub>1</sub> is the density of the wall material, ς<sub>2</sub> the density
-    of the atmosphere outside.</p>
-
-  <p><span class="pagenum" id="Page_444">444</span></p>
-
-  <p>Now, assuming <i>p</i> = 15, ς<sub>1</sub>/ς<sub>2</sub> = 6,000, for steel and air, the
-    equations give:</p>
-
-  <div class="center"><i>S</i> = 3<i>p</i>ς<sub>1</sub>/2ς<sub>2</sub> = 45 × 6,000/2 = 135,000 pounds</div>
-
-  <p class="noindent">per square inch as the stress in a steel vacuum balloon.</p>
-
-  <p>For aluminum ς<sub>1</sub> is less, but the permissible value of <i>S</i> is also
-    less in about the same proportion.</p>
-
-  <p>The last equation shows that for a given material and atmospheric
-    environment, the stress in the shell or wall of the spherical balloon
-    is independent of the radius of the surface. It is also well known
-    that the stress is less for the sphere than for any other surface.
-    Hence, no surface can be constructed in which <i>S</i> will be less than
-    3<i>p</i>ς<sub>1</sub>/2ς<sub>2</sub>. The argument is easily seen to apply to a partial
-    vacuum balloon, since a balloon of one nth vacuum will float a cover of
-    but one nth the mass and strength.</p>
-
-  <p>The above result was obtained on the assumption that the shell was
-    prevented from buckling. As a matter of fact, it would buckle long
-    before the crushing stress could be attained. We must conclude,
-    therefore, that while a vacuum balloon has alluring features, the
-    materials of engineering are not strong enough to favor such a
-    structure. Perhaps it is nearer the truth to say that such a project is
-    visionary, with the materials now available.</p>
-
-  <hr class="tb" />
-
-  <p>A like argument applies to the balloon reservoir in which it has
-    been proposed to compress the surplus gas taken from a balloon hull
-    on expansion of its contents by change of level or temperature. If a
-    given mass of gas obeying Boyle’s law be pumped into a receiver of
-    given shape and mass, the resultant stress in the receiver wall will be
-    independent of the size. Hence the material of the proposed reservoir,
-    if expanded to the size of the hull itself,<span class="pagenum" id="Page_445">445</span> will weigh the same, and
-    suffer the same increment of unit stress, for a given mass increment of
-    gas. Hence, instead of pumping the above-mentioned gas surplus from the
-    hull into the reservoir, this latter may be discarded and its mass of
-    material spread over the hull itself. This argument applies only if the
-    shapes of hull and reservoir be equally effective, as, for example, if
-    both be cylindrical.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="appendix_II">
-    <span class="pagenum" id="Page_446">446</span>
-    <h3>APPENDIX II</h3>
-    <span class="small">AËRONAUTIC LETTERS OF BENJAMIN FRANKLIN</span>
-  </div>
-
-  <div class="right small"><span class="smcap">Passy</span>, Aug. 30, 1783.</div>
-
-  <p class="mt0"><span class="smcap">On</span> Wednesday, the 27th instant, the new aërostatic Experiment, invented
-    by Messrs. Montgolfier of Annonay, was repeated by M. Charles,
-    Professor of experimental Philosophy at Paris.</p>
-
-  <p>A hollow Globe 12 feet Diameter was formed of what is called in England
-    Oiled Silk, here Taffetas gommé, the Silk being impregnated with a
-    Solution of Gum elastic in Linseed Oil, as he said. The Parts were
-    sewed together while wet with the Gum, and some of it was afterwards
-    passed over the Seam, to render it as tight as possible.</p>
-
-  <p>It was afterwards filled with inflammable Air that is produced by
-    pouring Oil of Vitriol upon Filings of Iron, when it was found to have
-    a tendency upwards so strong as to be capable of lifting a Weight of 39
-    Pounds, exclusive of its own Weight which was 25 lbs and the Weight of
-    the Air contain’d.</p>
-
-  <p>It was brought early in the morning to the Champ de Mars, a Field in
-    which Reviews are sometimes made, lying between the military School and
-    the River. There it was held down by a Cord till 5 in the afternoon,
-    when it was to let loose. Care was taken before the Hour to replace
-    what Portion had been lost, of the inflammable Air, or of its Force, by
-    injecting more.</p>
-
-  <p>It is supposed that not less than 50,000 People<span class="pagenum" id="Page_447">447</span> were assembled to see
-    the Experiment, The Champ de Mars being surrounded by multitudes, and
-    vast Numbers on the opposite Side of the River.</p>
-
-  <p>At 5 O’clock Notice was given to the Spectators by the Firing of two
-    Cannon, that the Cord was about to be cut. And presently the Globe was
-    seen to rise, and that as fast as a Body of 12 feet Diameter, with a
-    force only of 39 Pounds, could be suppos’d to remove the resisting Air
-    out of its Way. There was some Wind, but not very strong. A little
-    Rain had wet it, so that it shone, and made an agreeable appearance.
-    It diminished in Apparent Magnitude as it rose, till it enter’d the
-    Clouds, when it seem’d to me scarce bigger than an Orange, and soon
-    after became invisible, the Clouds concealing it.</p>
-
-  <p>The multitude separated, all well satisfied and delighted with the
-    Success of the Experiment, and amusing one another with discourses of
-    the various uses it may possibly be apply’d to, among which many were
-    very extravagant. But possibly it may pave the Way to some Discoveries
-    in Natural Philosophy of which at present we have no conception.</p>
-
-  <p>A Note secur’d from the Weather had been affix’d to the Globe,
-    signifying the Time &amp; Place of its Departure, and praying those who
-    might happen to find it, to send an account of its state to certain
-    Persons at Paris. No News was learned of it till the next Day, when
-    information was received that it fell a little after 6 o’clock, at
-    Gonesse, a Place about four Leagues Distance, and that it was rent
-    open, and some say had ice in it. It is suppos’d to have burst by the
-    Elasticity of the contain’d Air when no longer compress’d by so heavy
-    an Atmosphere.</p>
-
-  <p>One of 38 feet Diameter is preparing by Mr. Montgolfier himself, at the
-    Expence of the Academy,<span class="pagenum" id="Page_448">448</span> which is to go up in a few days. I am told it
-    is constructed of Linen &amp; Paper, and is to be filled with different
-    Air, not yet made public, but cheaper than that produc’d by the Oil of
-    Vitriol, of which 200 Paris Pints were consum’d in filling the other.</p>
-
-  <p>It is said that for some Days after its being fill’d the Ball was found
-    to lose an eighth Part of its Force of Levity in 24 Hours; Whether this
-    was from Imperfection in the Tightness of the Ball, or a Change in the
-    Nature of the Air, Experiments may easily discover....</p>
-
-  <p>M. Montgolfier’s Air to fill the Globe has hitherto been kept secret;
-    some suppose it to be only common Air heated by passing thro’ the Flame
-    of burning Straw, and thereby extreamly rarefied. If so, its Levity
-    will soon be deminish’d by Condensation, when it comes into the cooler
-    Region above....</p>
-
-  <p>P. S. I just now learned that some observers say, the Ball was 150
-    Seconds in rising, from the cutting of the Cord till hid in the Clouds;
-    that its height was then about 500 Toises, but, being moved out of
-    the Perpendicular by the Wind, it had made a Slant so as to form a
-    Triangle, whose base on the Earth was about 200 Toises. It is said the
-    Country People who saw it fall were frightened, conceiv’d from its
-    bounding a little, when it touched the Ground, that there was some
-    living Animal in it, and attack’d with Stones and Knives, so that it
-    was much mangled; but it is now brought to Town and will be repair’d.</p>
-
-  <p>The great one of M. Montgolfier is to go up, as is said, from
-    Versailles, in about 8 or 10 days. It is not a Globe but of a different
-    Form, more convenient for penetrating the Air.</p>
-
-  <p>It contains 50,000 cubic Feet, and is supposed to have Force of Levity
-    equal to 1,500 pounds weight. A Philosopher here, M. Pilâtre du Rozier,
-    has seriously <span class="pagenum" id="Page_449">449</span>apply’d to the Academy for leave to go up with it, in
-    order to make some experiments. He was complimented on his Zeal and
-    Courage for the Promotion of Science, but advis’d to wait till the
-    management of these Balls was made by Experience more certain &amp; safe.
-    They say the filling of it in Montgolfier’s Way will not cost more
-    than half a Crown. One is talk’d of to be 110 feet Diameter. Several
-    gentlemen have ordered small ones to be made for their Amusement.
-    One has ordered four of 15 feet Diameter each; I know not with what
-    Purpose; but such is the present Enthusiasm for promoting and improving
-    this Discovery, that probably we shall soon make considerable Progress
-    in the art of constructing and using the Machines.</p>
-
-  <p>Among the Pleasanteries Conversation produces on this subject, some
-    suppose Flying to be now invented, and that since Men may be supported
-    in the Air, nothing is wanted but some light handy instrument to give
-    and direct Motion. Some think Progressive Motion on the Earth may
-    be advanc’d by it, and that a Running Footman or a Horse slung and
-    suspended under such a Globe so as to have no more of Weight pressing
-    the Earth with their Feet, then Perhaps 8 or 10 pounds, might with a
-    fair Wind run in a straight Line across Countries as fast as that Wind,
-    and over Hedges, Ditches &amp; even Waters. It has been even fancied that
-    in time People will keep such Globes anchored in the Air, to which by
-    Pullies they may draw up Game to be preserved in the Cool &amp; Water to be
-    frozen when Ice is wanted. And that to get Money, it will be contriv’d
-    to give People an extensive View of the Country, by running them up in
-    an Elbow Chair a Mile high for a Guinea, &amp;c., &amp;c.</p>
-
-  <p class="right">
-    <span class="pagenum" id="Page_450">450</span><span class="smcap">B. Franklin.</span><br />
-    <br />
-    <span class="smcap">Passy</span>, Nov. 22d, 1783.<br />
-  </p>
-
-  <p>... Enclosed is a copy of the Proces verbal taken of the Experiment
-    yesterday in the Garden of the Queen’s Palace la Muette, where the
-    Dauphin now resides, which being near my House I was present. This
-    Paper was drawn up hastily, and may in some Places appear to you
-    obscure; therefore I shall add a few explanatory Observations.</p>
-
-  <p>This Balloon was larger than that which went up from Versailles and
-    carried the Sheep, &amp;c. Its bottom was open, and in the middle of the
-    Opening was fixed a kind of Basket Grate, in which Faggots and Sheaves
-    of Straw were burnt. The Air rarefied in passing thro’ this Flame rose
-    in the Balloon, swell’d out its sides, and Fill’d it.</p>
-
-  <p>The Persons who were plac’d in the Gallery made of Wicker, and attached
-    to the Outside near the Bottom, had each of them a Port thro’ which
-    they could pass Sheaves of Straw into the Grate to keep up the Flame,
-    &amp; thereby keep the Balloon full. When it went over our Heads, we could
-    see the Fire which was very considerable. As the Flame slackens, the
-    rarefied Air cools and condenses, the Bulk of the Balloon diminishes
-    and it begins to descend. If those in the Gallery see it likely to
-    descend in an improper Place, they can by throwing on more Straw, &amp;
-    renewing the Flame, make it rise again, and the Wind carries it farther.</p>
-
-  <p>One of these courageous Philosophers, the Marquis d’Arlandes, did me
-    the honour to call upon me in the Evening after the Experiment, with
-    Mr. Montgolfier, the very ingenious Inventor. I was happy to see him
-    safe. He informed me that they lit gently, without the least Shock, and
-    the Balloon was very little damaged.</p>
-
-  <p>This method of filling the Balloon with hot Air is cheap and
-    expeditious, and it is supposed may be<span class="pagenum" id="Page_451">451</span> sufficient for certain
-    purposes, such as elevating an Engineer to take a view of an Enemy’s
-    Army, Works, &amp;c., conveying Intelligence into, or out of a besieged
-    Town, giving Signals to distant places, or the like.</p>
-
-  <p>The other method of filling a Balloon with permanently elastic
-    inflammable Air, and then closing it is a tedious Operation, and
-    very expensive; Yet we are to have one of that kind sent up in a few
-    days. It is a Globe of 26 feet diameter. The Gores that compose it
-    are red and white Silk, so that it makes a beautiful appearance. A
-    very handsome triumphal Car will be suspended to it, in which Messrs.
-    Roberts, two Brothers, very ingenious Men, who have made it in concert
-    with Mr. Charles, propose to go up. There is room in this Car for a
-    little Table to be placed between them, on which they can write and
-    keep their journal, that is, take Notes of everything they observe, the
-    State of their Thermometer, Barometer, Hygrometer, &amp;c., which they will
-    have more leisure to do than the others, having no fire to take care
-    of. They say they have a contrivance which will enable them to descend
-    at Pleasure. I know not what it is. But the Expence of this machine,
-    Filling included, will exceed, it is said, 10,000 Livres.</p>
-
-  <p>This Balloon of only 26 feet diameter, being filled with Air ten times
-    lighter than common Air, will carry up a greater Weight than the other,
-    which tho’ vastly bigger, was filled with an Air that could scarcely be
-    more than twice as light. Thus the great Bulk of one of these Machines,
-    with the short duration of its Power, &amp; the great Expence of filling
-    the other will prevent the Inventions being of so much Use as some may
-    expect, till Chemistry can invent a cheaper light Air producible with
-    more Expedition.</p>
-
-  <p><span class="pagenum" id="Page_452">452</span></p>
-
-  <p>But the Emulation between the two Parties running high, the Improvement
-    in the Construction and Management of the Balloons had already made
-    a rapid Progress; and one cannot say how far it may go. A few Months
-    since the idea of Witches riding thro’ the Air upon a Broomstick, and
-    that of Philosophers upon a Bag of Smoke, would have appeared equally
-    impossible and ridiculous.</p>
-
-  <p>These Machines must always be subject to be driven by the Winds.
-    Perhaps Mechanic Art may find easy means to give them progressive
-    Motion in a Calm, and to slant them a little in the Wind.</p>
-
-  <p>I am sorry this Experiment is totally neglected in England, where
-    mechanic Genius is so strong. I wish I could see the same Emulation
-    between the two Nations as I see between the two Parties here. Your
-    Philosophy seems to be too bashful. In this Country we are not so
-    much afraid of being laught at. If we do a foolish thing, we are the
-    first to laugh at it ourselves, and are almost as much pleased with
-    a Bon Mot or a Chanson, that ridicules well the Disappointment of a
-    Project, as we might have been with its Success. It does not seem to me
-    a good reason to decline prosecuting a new Experiment which apparently
-    increases the power of a Man over Matter, till we can see to what use
-    that power can be applied. When we have learnt to manage it, we may
-    hope some time or other to find Uses for it, as men have done for
-    Magnetism and Electricity, of which the first Experiments were mere
-    Matters of Amusement.</p>
-
-  <p>This Experience is by no means a trifling one. It may be attended with
-    important Consequences that no one can foresee. We should not suffer
-    Pride to prevent our progress in Science.</p>
-
-  <p>Beings of a Rank and Nature far superior to ours have not disdained
-    to amuse themselves with<span class="pagenum" id="Page_453">453</span> making and launching Balloons, otherwise we
-    should never have enjoyed the Light of those glorious objects that rule
-    our Day &amp; Night, nor have had the Pleasure of riding round the Sun
-    ourselves upon the Balloon we now inhabit.</p>
-
-  <p class="right">
-    <span class="smcap">B. Franklin.</span><br />
-    <br />
-    <span class="smcap">Passy</span>, Dec. 1, 1783.<br />
-  </p>
-
-  <p>In mine of yesterday I promised to give you an account of Messrs.
-    Charles &amp; Roberts’ Experiment, which was to have been made this Day,
-    and at which I intended to be present. Being a little indispos’d, &amp;
-    the Air cool, and the Ground damp, I declin’d going into the Garden
-    of the Tuilleries where the Balloon was plac’d, not knowing how long
-    I might be oblig’d to wait there before it was ready to depart; and
-    chose to stay in my Carriage near the Statue of Louis XV, from whence I
-    could well see it rise, &amp; have an extensive View of the Region of Air
-    thro’ which, as the Wind sat, it was likely to pass. The Morning was
-    foggy, but about one o’clock the Air became tolerably clear; to the
-    great satisfaction of spectators, who were infinite. Notice having been
-    given of the intended Experiment several days before in the Papers,
-    so that all Paris was out, either about the Tuilleries, on the Quays
-    &amp; Bridges, in the Fields, the Streets, at the Windows, or on the Tops
-    of Houses, besides the inhabitants of all the Towns &amp; Villages of the
-    Environs. Never before was a philosophical Experiment so magnificently
-    attended. Some Guns were fired to give Notice that the departure of
-    the great Balloon was near, and a small one was discharg’d which went
-    to an amazing height, there being but little Wind to make it deviate
-    from its perpendicular Course, and at length the Sight of it was lost.
-    Means were used, I am told, to prevent the great Balloon’s rising so
-    high as might endanger <span class="pagenum" id="Page_454">454</span>its Bursting. Several Bags of Sand were taken
-    on board before the Cord that held it down was cut, and the whole
-    Weight being then too much to be lifted, such a Quantity was discharg’d
-    as to permit its Rising slowly. Thus it would sooner arrive at that
-    Region where it would be in equilibrio with the surrounding Air, and
-    by discharging more Sand afterwards, it might go higher if desired.
-    Between One &amp; Two o’Clock, all Eyes were gratified with seeing it
-    rise majestically from among the Trees and ascend gradually above the
-    Buildings, a most beautiful Spectacle! When it was about 200 feet high,
-    the brave Adventurers held out and wav’d a little white Pennant, on
-    both sides their Car, to salute the Spectators, who return’d loud Claps
-    of Applause. The Wind was very little, so that the Object, tho’ moving
-    to the Northward, continued long in View; and it was a great while
-    before the admiring People began to disperse. The persons embark’d
-    were Mr. Charles, Professor of Experimental Philosophy, &amp; zealous
-    Promotor of that Science; and one of the Messieurs Robert, the very
-    ingenious Constructors of the Machine. When it arrived at its height,
-    which I suppose might be 3 or 400 Toises, it appeared to have only
-    horizontal Motion. I had a Pocket Glass, with which I follow’d it,
-    till I lost Sight first of the Men, then of the Car, and when I last
-    saw the Balloon, it appear’d no bigger than a Walnut. I write this at
-    7 in the evening. What became of them is not yet known here. I hope
-    they descended by Day-light, so as to see and avoid falling among
-    Trees or on Houses, and that the Experience was completed without any
-    mischievous Accident, which the Novelty of it &amp; the want of Experience
-    might well occasion. I am the more anxious for the Event, because I am
-    not well informed of the Means provided for letting themselves gently<span class="pagenum" id="Page_455">455</span>
-    down, and the Loss of these very ingenious Men would not only be a
-    Discouragement to the Progress of the Art, but be a sensible Loss to
-    Science and Society.</p>
-
-  <p>Tuesday Morning, December 2,—I am reliev’d from my Anxiety by hearing
-    that the Adventurers descended well near l’Isle Adam, before Sunset.
-    This Place is near 7 Leagues from Paris. Had the Wind blown fresh, they
-    might have gone much farther.</p>
-
-  <p>P.S. Tuesday Evening ... I hear farther that the Travellers had perfect
-    Command of the Carriage, descending as they pleas’d by letting some of
-    the inflammable Air escape, and rising again by discharging some Sand;
-    that they descended over a Field so low as to talk with Labourers in
-    passing and mounted again to pass a Hill. The little Balloon falling at
-    Vincennes shows that mounting higher it met with a Current of Air in a
-    contrary Direction; an Observation that may be of use to future aërial
-    Voyagers.</p>
-
-  <p class="right">
-    <span class="smcap">B. Franklin.</span><br />
-  </p>
-
-  <hr class="page" />
-  <div class="chapter" id="appendix_III">
-    <span class="pagenum" id="Page_456">456</span>
-    <h3>APPENDIX III</h3>
-    <span class="small">SUCCESSFUL MILITARY DIRIGIBLE BALLOONS</span>
-  </div>
-
-  <div class="smcap center mb2">France</div>
-
-  <div class="center"><i>The Clément-Bayard II</i><a id="FNanchor_80" href="#Footnote_80" class="fnanchor">[80]</a></div>
-
-  <p><span class="smcap">The</span> <i>Clément-Bayard II</i> may be classed among the airships usually
-    called “flexible.” The shape of its hull is preserved not by any rigid
-    framing, but by internal gas pressure maintained by ballonets fed by
-    ventilating fans. Moreover, the suspension which binds envelope and car
-    together as one solid is composed wholly of flexible elements, without
-    any rigid intermediary structure.</p>
-
-  <p>The general plan, then, of the craft comprises three prominent
-    features, well marked and distinct in character:</p>
-
-  <p>(<i>a</i>) The fish-shaped envelope with major section well forward, a form
-    favorable to both speed and stability.</p>
-
-  <p>(<i>b</i>) The trussed girderlike car whose length allows the load to be
-    distributed over the hull, thus preserving its nicety of outline.
-    The most minute and technical and mechanical details were studied
-    for eighteen months by M. Clément and his devoted collaborator, the
-    engineer Sabathier. The girder car, as will be seen presently, is
-    particularly well designed to serve as car, sustainer and stiffener. No
-    stabilizing device is attached to the envelope; all are <span class="pagenum" id="Page_457">457</span>fixed to the
-    car, on which is mounted also the complete propulsion plant.</p>
-
-  <p>(<i>c</i>) The suspension which binds the buoyant envelope to the car serves
-    no other purpose. Note also the ingenious arrangement of two motors
-    and two propellers, forming two independent systems, yet unitable
-    under certain conditions. The placement of the propellers, rudders and
-    stabilizing surfaces well above the bottom of the car, insures them
-    against dangerous contact on landing, or while maneuvering near the
-    ground.</p>
-
-  <p>The envelope is of rubberized Continental cloth. Its volume is 7,000
-    cubic meters, length 76.5 meters and major diameter 13.22 meters, or
-    an elongation of 5.76 diameters. Inside the gas envelope is an air bag
-    of 2,200 cubic meters. It is divided into two compartments, <i>Q</i> and
-    <i>Q´</i>, which can be filled with air together or separately through the
-    air duct, <i>Q</i>, joined to a blower, <i>P</i>, run by the two motors, or by
-    hand when so desired. The balloon proper comprises two gas valves, <i>R</i>.
-    Each compartment of the ballonet has one air valve, <i>S</i>. The valves of
-    the type Clément-Bayard-Chauvière are automatic. Their construction is
-    so perfect that for the first time in France, at least on a balloon of
-    so large bulk, the blower runs continuously in constant communication
-    with the ballonet, the pressure in the envelope remaining invariable,
-    due to the regular play of the valves, which yield at the pressure for
-    which they are set. They may also be Worked by hand from the pilot’s
-    bridge in case of emergency. The envelope has on its upper side three
-    ripping seams, one in the middle, the others toward either end. These
-    rip panels can be worked together or separately, and permit the rapid
-    deflation of the balloon.</p>
-
-  <p>The long car is attached to the hull by hempen duck feet fastened to
-    a bolt rope running along the<span class="pagenum" id="Page_458">458</span> envelope below the equator; these duck
-    feet terminate below in steel suspension cables fixed to the car. Below
-    the principal bolt rope are others to which are fastened the duck
-    feet of the oblique cords, which assure the perfect solidarity of the
-    envelope and car. The steel cable sustainers have an ingenious patented
-    regulating windlass. The girder car consists of a latticed girder,
-    built of steel tubes united with cast-iron joints and steel-tie wires.
-    Its whole length is 45 meters, of which 14.5 meters constitute the car
-    proper. It is divided into segments which are easily demountable, thus
-    rendering it easily transportable by truck or railway. The forward
-    segment, <i>A</i>, tapers toward the front to a sharp point and is of
-    triangular cross-section. The mid segment, <i>B</i>, constituting the car,
-    has a quadrangular section of variable size. The rear segment, <i>D</i>, is
-    of triangular section, diminishing progressively toward the rear, which
-    rises to a sort of tail supporting the empennage and the direction
-    rudders. The entire girder car when resting on the ground is supported
-    by two pneumatic shock absorbers, <i>U</i>, <i>U</i>, projecting from its floor.</p>
-
-  <p>The car proper comprises three parts: in front, the motor and machine
-    room, 2.5 meters wide; in the middle, the elevated bridge, <i>N</i>, for
-    the pilot and his aide; in the rear, the passenger cabin, 8 meters
-    long, 1.3 meters wide and 2 meters high for the observers and wireless
-    telegraphy plant. The two reservoirs of essence, <i>M</i>, <i>m</i>, are placed
-    above the passenger about the center of pressure. The blower <i>P</i>, for
-    the ballonets, and the guide ropes <i>T</i>, are placed above the pilot’s
-    bridge.</p>
-
-  <p>In the motor room are symmetrically arranged two Bayard-Clément
-    engines, <i>G G</i>, separated enough to allow free passage between them.
-    Each motor is elastically supported to obviate vibrations, and connects
-    with the transmission shaft by a variable speed<span class="pagenum" id="Page_459">459</span> gear. The engines
-    can be run separately or together by a connecting sprocket chain, and
-    develop 100 to 130 horse-power each. The cooling of each motor is
-    effected by an aluminum radiator, <i>L L</i>, of large surface.</p>
-
-  <p>The Chauvière propellers, <i>K K</i>, six feet in diameter, are driven by
-    shafting and gear wheels at a normal speed of 250 rotations per minute.
-    A special recording device serves to show their thrust at each instant,
-    as also the torque of the motors.</p>
-
-  <p>The pilot, standing on the bridge where he enjoys a clear view, has
-    immediate charge of the vessel’s movements. Before him are the various
-    controls which he must operate, and the divers indicators which he must
-    consult. These are the direction wheel, the manometers, the aneroid
-    and registering barometers, the clinometer, the blower control to
-    regulate the amount and distribution of pressure, the elevating-rudder
-    wheel, the spark control, the ripping cord, the release string of the
-    guide-rope, and the system of transmitting orders to the mechanicians
-    whereby he can control the engines and the blowers which furnish air to
-    the radiator and ballonet.</p>
-
-  <p>The direction and poise of the vessel in flight are controlled by the
-    rudders and empennage at the rear, and its altitude from minute to
-    minute is governed by the elevating biplane <i>E´</i>, of 30 square meters
-    above the car in the mid region of the vessel.</p>
-
-  <h4>The <i>Patrie</i><a id="FNanchor_81" href="#Footnote_81" class="fnanchor">[81]</a></h4>
-
-  <p>The <i>Patrie</i>, the third of its type, was first operated in 1906. The
-    gas bag of the first balloon was built by Surcouf at Billancourt,
-    Paris. The mechan<span class="pagenum" id="Page_460">460</span>ical part was built at the Lebaudy Sugar Refinery.
-    Since then the gas bags have been built at the Lebaudy balloon shed at
-    Moisson, near Paris, under the direction of their aëronaut, Juchmes.
-    The gas bag of the <i>Patrie</i> was 197 feet long with a maximum diameter
-    of 33 feet, 9 inches, situated about 2/5 of the length from the front;
-    volume 111,250 cubic feet; length approximately six diameters. This
-    relation, together with the cigar shape, is in accordance with the
-    plans of Colonel Renard’s dirigible, built and operated in France in
-    1884; the same general shape and proportions being found in the Ville
-    de Paris.</p>
-
-  <p>The first Lebaudy was pointed at the rear, which is generally admitted
-    to be the proper shape for the least resistance, but to maintain
-    stability it was found necessary to put a horizontal and vertical plane
-    there, so that it had to be made an ellipsoid of revolution to give
-    attachment for these planes.</p>
-
-  <p>The ballonet for air had a capacity of 22,958 cubic feet or about 1/5
-    of the total volume. This is calculated to permit reaching a height of
-    about one mile and to be able to return to the earth, keeping the gas
-    bag always rigid. To descend from a height of one mile, gas would be
-    released by the valve, then air pumped into the ballonet to keep the
-    gas bag rigid, these two operations being carried on alternately. On
-    reaching the ground from the height of one mile, the air would be at
-    the middle of the lower part of the gas bag and would not entirely fill
-    the ballonet. To prevent the air from rolling from one end to the other
-    when the air ship pitches, thus producing instability, the ballonet
-    was divided into three compartments by impermeable cloth partitions.
-    Numerous small holes were pierced in these partitions, through which
-    the air finally reached the two end compartments.</p>
-
-  <p>In September, 1907, the <i>Patrie</i> was enlarged by<span class="pagenum" id="Page_461">461</span> 17,660 cubic feet
-    by the addition of a cylindrical section at the maximum diameter,
-    increasing the length but not the maximum diameter.</p>
-
-  <p><i>The Gas Bag.</i>—The gas bag is cut in panels; the material is a rubber
-    cloth made by the Continental Tire Company at Hanover, Germany. It
-    consists of four layers arranged as follows:</p>
-
-  <table summary="Gas bag layers">
-    <tbody>
-      <tr class="small">
-        <th>&nbsp;</th>
-        <th>Weight oz. per<br />square yard.</th>
-      </tr>
-      <tr>
-        <td><i>a.</i> Outer layer of cotton cloth covered with lead chromate</td>
-        <td class="pl5">2.5</td>
-      </tr>
-      <tr>
-        <td><i>b.</i> Layer of vulcanized rubber</td>
-        <td class="pl5">2.5</td>
-      </tr>
-      <tr>
-        <td><i>c.</i> Layer of cotton cloth</td>
-        <td class="pl5">2.5</td>
-      </tr>
-      <tr>
-        <td><i>d.</i> Inner layer of vulcanized rubber</td>
-        <td class="pl5">2.21</td>
-      </tr>
-      <tr>
-        <td>&nbsp;</td>
-        <td>&mdash;&mdash;&mdash;</td>
-      </tr>
-      <tr>
-        <td class="pl5">&nbsp;&nbsp;&nbsp;Total weight</td>
-        <td class="pl5">9.71</td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>A strip of this cloth one foot wide tears at a tension of about 934
-    pounds. A pressure of about one inch of water can be maintained in the
-    gas bag without danger. The lead chromate on the outside is to prevent
-    the entrance of the actinic rays of the sun, which would cause the
-    rubber to deteriorate. The heavy layer of rubber is to prevent the
-    leaking of the gas. The inner layer of rubber is merely to prevent
-    deterioration of the cloth by impurities in the gas. This material
-    has the warp of the two layers of cotton cloth running in the same
-    direction and is called straight thread. The material in the ballonet
-    weighs only about 7¾ ounces per square yard, and has a strength of
-    about 336 pounds per running foot. When the <i>Patrie</i> was enlarged in
-    September, 1907, the specifications of the material allowed a maximum
-    weight of 10 ounces per square yard, a minimum strength of 907 pounds
-    per running foot, and a loss of 5.1 cubic inches of hydrogen per square
-    yard in twenty-four hours at a pressure of 1.18 inches of water. Bands
-    of cloth are pasted over the seams inside and out with a solution of
-    rubber to prevent leaking through the stitches.</p>
-
-  <p><span class="pagenum" id="Page_462">462</span></p>
-
-  <p><i>Suspension.</i>—One of the characteristics of the <i>Patrie</i> is the “short”
-    suspension. The weight of the car is distributed over only about 70
-    feet of the length of the gas bag. To do this, an elliptical-shaped
-    frame of nickel-steel tubes is attached to the bottom of the gas
-    bag; steel cables run from this down to the car. A small hemp net
-    is attached to the gas bag by means of short wooden cross-pieces,
-    or toggles, which are let into holes in a strong canvas band which
-    is sewed directly on the gas bag. The metal frame, or platform, is
-    attached to this net by means of toggles, so that it can be quickly
-    removed in dismounting the air ship for transportation. The frame can
-    also be taken apart, 28 steel cables about 0.2 inches in diameter run
-    from the frame down to the car, and are arranged in triangles. Due
-    to the impossibility of deforming a triangle, rigidity is maintained
-    between the car and gas bag.</p>
-
-  <p>The objection to the “short” suspension of the <i>Patrie</i> is the
-    deformation of the gas bag. A distinct curve can be seen in the middle.</p>
-
-  <p><i>The Car.</i>—The car is made of nickel-steel tubes (12 per cent nickel).
-    This metal gives the greatest strength for minimum weight. The car is
-    boat-shaped, about 16 feet long, about 5 feet wide and 2½ feet high.
-    About 11 feet separate the car from the gas bag. To prevent any chance
-    of the fire from the engine communicating with the hydrogen, the steel
-    framework under the gas bag is covered with a noncombustible material.</p>
-
-  <p>The pilot stands at the front of the car, the engine is in the
-    middle, the engineer at the rear. Provision is made for mounting a
-    telephotographic apparatus, and for a 100-candle-power acetylene
-    searchlight. A strong pyramidal structure of steel is built under the
-    car, pointing downward. In landing the point comes to the ground first
-    and this protects<span class="pagenum" id="Page_463">463</span> the car, and especially the propellers, from being
-    damaged. The car is covered to reduce air resistance. It is so low,
-    however, that part of the equipment and most of the bodies of those
-    inside are exposed, so that the total resistance of the car is large.</p>
-
-  <p><i>The Motor.</i>—The first Lebaudy had a 40-horse-power Daimler-Mercedes
-    benzine motor. The <i>Patrie</i> was driven by a 60 to 70-horse-power
-    4-cylinder Panhard and Levassor benzine motor, making 1,000 r. p. m.</p>
-
-  <p><i>The Propellers.</i>—There are two steel propellers 8½ feet in diameter
-    (two blades each) placed at each side of the engine, this giving the
-    shortest and most economical transmission. To avoid any tendency to
-    twist the car, the propellers turn in opposite directions. They are
-    “high speed,” making 1,000 to 1,200 r. p. m.</p>
-
-  <p>The gasoline tank is placed under the car inside the pyramidal frame.
-    The gasoline is forced up to the motor by air compression. The exhaust
-    is under the rear of the car pointing down and is covered with a metal
-    gauze to prevent flames coming out. The fan which drives the air into
-    the ballonet is run by the motor, but a dynamo is also provided so
-    that the fan can always be kept running even if the motor stops. This
-    is very essential as the pressure must be maintained inside the gas
-    bag so that the latter will remain rigid and keep its form. There are
-    five valves in all, part automatic and part both automatic and also
-    controlled from the car with cords. The valves in the ballonet open
-    automatically at less pressure than the gas valves, so that when the
-    gas expands all the air is driven out of the ballonet before there is
-    any loss of gas. The ballonet valves open at a pressure of about O.78
-    inches of water, the gas valves at about 2 inches.</p>
-
-  <p><i>Stability.</i>—Vertical stability is maintained by<span class="pagenum" id="Page_464">464</span> means of fixed
-    horizontal planes. One having a surface of 150 square feet is attached
-    at the rear of the gas bag and due to its distance from the center of
-    gravity is very efficient. The elliptical frame attached under the gas
-    bag has an area of 1,055 square feet, but due to its proximity to the
-    center of gravity, has little effect on the stability. Just behind
-    the elliptical frame is an arrangement similar to the feathering of
-    an arrow. It consists of a horizontal plane of 150 square feet, and a
-    vertical plane of 113 square feet. To maintain horizontal stability,
-    that is, to enable the air ship to move forward in a straight line
-    without veering to the sides, fixed vertical planes are used. One runs
-    from the center to the rear of the elliptical frame and has an area of
-    108 square feet.</p>
-
-  <p>In addition to the vertical surface of 113 square feet at the rear of
-    the elliptical frame, there is a fixed plane of 150 square feet at the
-    rear of the gas bag. To fasten the two perpendicular planes at the
-    rear of this gas bag, cloth flaps are sewed directly on the gas bag.
-    Nickel-steel tubes are placed in the flaps, which are then laced over
-    the tubes. With these tubes as a base, a light tube and wire framework
-    is attached and waterproof cloth laced on this framework. Additional
-    braces run from one surface to the other and from each surface to the
-    gas bag. The rudder is at the rear under the gas bag. It has about 150
-    square feet and is balanced.</p>
-
-  <p>A movable horizontal plane near the center of gravity, above the
-    car, is used to produce rising or descending motion, or to prevent
-    an involuntary rising or falling of the air ship due to expansion or
-    contraction of the gas or to other causes. After the adoption of this
-    movable horizontal plane, the loss of gas and ballast was reduced to a
-    minimum. Ballast is carried in 10- and 20-pound sandbags. A<span class="pagenum" id="Page_465">465</span> pipe runs
-    through the bottom of the car from which the ballast is thrown.</p>
-
-  <p>There are two long guide-ropes, one attached at the front of the
-    elliptical frame and the other on the car. On landing, the one in front
-    is seized first so as to hold the air ship with the head to the wind.
-    The motor may then be stopped and the descent made by pulling down on
-    both guide-ropes. A heavy rope 22 feet long, weighing 110 pounds, is
-    attached at the end of a 164-foot guide-rope. This can be dropped out
-    on landing to prevent coming to the ground too rapidly. The equipment
-    of the car includes a “siren” speaking trumpet, carrier pigeons, iron
-    pins and a rope for anchoring the air ship, reserve supply of fuel and
-    water, and fire extinguisher.</p>
-
-  <p>After being enlarged in September, 1907, the <i>Patrie</i> made a number of
-    long trips at an altitude of 2,500 to 3,000 feet. In November, 1907,
-    she went from Paris to Verdun, near the German frontier, a distance of
-    about 175 miles, in about 7 hours, carrying four persons. This trip was
-    made in a light wind blowing from the northeast. Her course was east,
-    so that the wind was unfavorable. On Friday, November 20, 1907, during
-    a flight near Verdun, the motor stopped due to difficulty with the
-    carburetor. The air ship drifted with the wind to a village about 10
-    miles away, where she was safely landed. The carburetor was repaired on
-    the 20th. Soon after, a strong wind came up and tore loose some of the
-    iron pickets with which it was anchored. This allowed the air ship to
-    swing broadside to the wind; it then tilted over on the side far enough
-    to let some of the ballast bags fall out. The 150 or 200 soldiers who
-    were holding the ropes were pulled along the ground until directed by
-    the officer in charge to let go. After being released, it rose and was
-    carried by the wind across the north of France, the English<span class="pagenum" id="Page_466">466</span> Channel
-    and into the north of Ireland. It struck the earth there, breaking off
-    one of the propellers, and then drifted to sea.</p>
-
-  <h4>The <i>République</i></h4>
-
-  <p>This is the latest of the French military dirigible balloons, and
-    differs but slightly from its predecessor, the <i>Patrie</i>. The volume has
-    been increased by about 2,000 cubic feet. The length has been reduced
-    to 200 feet and the maximum diameter increased to 35½ feet. The shape
-    of the gas bag accounts for the 2,000 additional cubic feet of volume.
-    The motor and propeller are as in the <i>Patrie</i>. The total lifting
-    capacity is 9,000 pounds, of which 2,700 pounds are available for
-    passengers, fuel, ballast, instruments, etc. Its best performance was a
-    125-mile flight made in 6½ hours against an unfavorable wind.</p>
-
-  <p>The material for the gas bag of the new air ship was furnished by the
-    Continental Tire Company. It is made up as follows:</p>
-
-  <table summary="Gas bag layers">
-    <tbody>
-      <tr class="small">
-        <th>&nbsp;</th>
-        <th>Weight oz. per<br />square yard.</th>
-      </tr>
-      <tr>
-        <td>Outer yellow cotton layer</td>
-        <td class="tdr"><div>3.25</div></td>
-      </tr>
-      <tr>
-        <td>Layer of vulcanized rubber</td>
-        <td class="tdr"><div>3.25</div></td>
-      </tr>
-      <tr>
-        <td>Layer of cotton cloth</td>
-        <td class="tdr"><div>3.25</div></td>
-      </tr>
-      <tr>
-        <td>Inner layer of rubber</td>
-        <td class="tdr"><div>0.73</div></td>
-      </tr>
-      <tr>
-        <td>&nbsp;</td>
-        <td class="tdr"><div>&mdash;&mdash;&mdash;</div></td>
-      </tr>
-      <tr>
-        <td class="pl5">&nbsp;&nbsp;&nbsp;Total weight</td>
-        <td class="tdr"><div>10.48</div></td>
-      </tr>
-    </tbody>
-  </table>
-
-  <p>It is interesting to note the changes which this type has undergone
-    since the first one was built. The <i>Jaune</i>, constructed in 1902–3, was
-    pointed at the rear and had no stability plane there; later it was
-    rounded off at the rear and a fixed horizontal plane attached. Finally
-    a fixed vertical plane was added. The gas bag has been increased in
-    capacity from 80,670 cubic feet to about 131,000 cubic feet. The
-    manufacturers have been able to increase the<span class="pagenum" id="Page_467">467</span> strength of the material
-    of which the gas bag is made, without materially increasing the weight.
-    The rudder has been altered somewhat in form. It was first pivoted on
-    its front edge, but later on a vertical axis, somewhat to the rear of
-    this edge. With the increase in size, has come an increase in carrying
-    capacity and, consequently, a greater speed and more widely extended
-    field of action.</p>
-
-  <h4><i>Ville de Paris</i></h4>
-
-  <p>This air ship was constructed for Mr. Deutsch de la Meurthe, of
-    Paris, who has done a great deal to encourage aërial navigation. The
-    first <i>Ville de Paris</i> was built in 1902, on plans drawn by Tatin,
-    a French aëronautical engineer. It was not a success. Its successor
-    was built in 1906, on plans of Surcouf, an aëronautical engineer and
-    balloon builder. The gas bag was built at his works in Billancourt,
-    the mechanical part at the Voisin shop, also in Billancourt. The plans
-    are based on those of Colonel Renard’s air ship, the <i>France</i>, built
-    in 1884, and the <i>Ville de Paris</i> resembles the older air ship in many
-    particulars. In September, 1907, Mr. Deutsch offered the use of his air
-    ship to the French Government. The offer was accepted, but delivery was
-    not to be made except in case of war or emergency. When the <i>Patrie</i>
-    was lost in November, 1907, the military authorities immediately took
-    over the Deutsch air ship.</p>
-
-  <p><i>Gas Bag.</i>—The gas bag is 200 feet long for a maximum diameter of
-    34½ feet, giving a length of about 6 diameters, as in the <i>France</i>
-    and the <i>Patrie</i>. Volume, 112,847 cubic feet; maximum diameter at
-    about ⅜ of the distance from the front, approximately, as in the
-    <i>Patrie</i>. The middle section is cylindrical with conical sections in
-    front and rear. At<span class="pagenum" id="Page_468">468</span> the extreme rear is a cylindrical section with
-    eight smaller cylinders attached to it. The ballonet has a volume of
-    21,192 cubic feet or about ⅕ of the volume, the same proportion found
-    in the <i>Patrie</i>. The ballonet is divided into three compartments from
-    front to rear. The division walls are of permeable cloth, and are not
-    fastened to the bottom so that when the middle compartment fills with
-    air, and the ballonet rises, the division walls are lifted up from
-    the bottom of the gas bag, and there is free communication between
-    the three compartments. The gas bag is made up of a series of strips
-    of perpendicular to a meridian line. These strips run around the
-    bag, their ends meeting on the under meridian. This is known as the
-    “barchistode” method of cutting out the material, and has the advantage
-    of bringing the seams parallel to the line of greatest tension. They
-    are therefore more likely to remain tight and not allow the escape
-    of gas. The disadvantage lies in the fact that there is a loss of
-    33⅓ per cent of material in cutting. The material was furnished by
-    the Continental Tire Company, and has approximately the same tensile
-    strength and weight as that used in the <i>Patrie</i>. It differs from the
-    other in one important feature—it is diagonal thread, that is, the warp
-    of the outer layer of cotton cloth makes an angle of 45 degrees with
-    the warp of the inner layer of cotton cloth. The result is to localize
-    a rip or tear in the material. A tear in the straight thread material
-    will continue along the warp, or the weave, until it reaches a seam.</p>
-
-  <p><i>Valves.</i>—There are five in all, made of steel, about fourteen inches
-    in diameter; one on the top connected to the car by a cord, operated by
-    hand only; two near the rear underneath. These are automatic but can
-    be operated by hand from the car. Two ballonet valves directly under
-    the middle are<span class="pagenum" id="Page_469">469</span> automatic and are also operated from the car by hand.
-    The ballonet valves open automatically at a pressure of 2/3 inches of
-    water; the gas valves open at a higher pressure.</p>
-
-  <p><i>Suspension.</i>—This air ship has the “long” suspension. That is, the
-    weight is distributed along practically the entire length of the gas
-    bag. A doubled band of heavy canvas is sewn with six rows of stitches
-    along the side of the gas bag. Hemp ropes running into steel cables
-    transmit most of the weight of the car to these two canvas bands and
-    thus to the gas bag. On both sides and below these first bands are
-    two more. Lines run from these to points half way between the gas
-    bag and the car, then radiate from these points to different points
-    of attachment on the car. This gives the triangular or nondeformable
-    system of suspension, which is necessary in order to have the car and
-    gas bag rigidly attached to each other. With this “long” suspension,
-    the <i>Ville de Paris</i> does not have the deformation so noticeable in the
-    gas bag of the <i>Patrie</i>.</p>
-
-  <p><i>The Car.</i>—This is in the form of a trestle. It is built of wood with
-    aluminum joints and O.12 inch wire tension members. It is 115 feet
-    long, nearly 7 feet high at the middle and a little over 5½ feet wide
-    at the middle. It weighs 660 pounds and is considered unnecessarily
-    large and heavy. The engine and engineer are well to the front, the
-    aëronaut with steering wheels is about at the center of gravity.</p>
-
-  <p><i>Motor.</i>—The motor is a 70 to 75-horse-power <i>Argus</i>, and is
-    exceptionally heavy.</p>
-
-  <p><i>Propeller.</i>—The propeller is placed at the front end of the car. It
-    thus has the advantage of working in undisturbed air; the disadvantage
-    is the long transmission and difficulty in attaching the propeller
-    rigidly. It has two blades and is 19.68 feet long with a pitch of
-    26.24 feet. The blades are of cedar<span class="pagenum" id="Page_470">470</span> with a steel arm. The propeller
-    makes a maximum of 250 turns per minute when the engine is making 900
-    revolutions. Its great diameter and width compensate for its small
-    speed.</p>
-
-  <p><i>Stability.</i>—This is maintained entirely by the cylinders at the rear.
-    Counting the larger one to which the smaller ones are attached, there
-    are five, arranged side by side corresponding to the horizontal planes
-    of the <i>Patrie</i>, and five vertical ones corresponding to the <i>Patrie’s</i>
-    vertical planes. The volume of the small cylinders is so calculated
-    that the gas in them is just sufficient to lift their weight, so they
-    neither increase nor decrease the ascensional force of the whole. The
-    horizontal projection of these cylinders is 1,076 square feet. The
-    center of this projection is 72 feet from the center of gravity of the
-    gas. The great objection to this method of obtaining stability, is the
-    air resistance due to these cylinders, and consequent loss of speed.
-    The stability of the <i>Ville de Paris</i> in a vertical plane is said to be
-    superior to that of the <i>Patrie</i>, due to the fact that the stability
-    planes of the latter do not always remain rigid. The independent
-    velocity of the <i>Ville de Paris</i> probably never exceeded 25 miles an
-    hour.</p>
-
-  <p><i>The Rudder.</i>—The rudder has a double surface of 150 square feet placed
-    at the rear end of the car, 72 feet from the center of gravity. It is
-    not balanced, but is inclined slightly to the rear so that its weight
-    would make it point directly to the rear if the steering gear should
-    break. Two pairs of movable horizontal planes, one at the rear of the
-    car having 43 square feet, and one at the center of gravity (as on the
-    <i>Patrie</i>) having 86 square feet, serve to drive the air ship up or down
-    without losing gas or ballast.</p>
-
-  <p><i>Guide-Ropes.</i>—A 400-foot guide-rope is attached<span class="pagenum" id="Page_471">471</span> at the front end of
-    the car. A 230-foot guide-rope is attached to the car at the center of
-    gravity.</p>
-
-  <p>About thirty men are required to maneuver the <i>Ville de Paris</i> on the
-    ground. The pilot has three steering wheels, one for the rudder and
-    two for the movable horizontal planes. The instruments used are an
-    aneroid barometer, a registering barometer giving heights up to 1,600
-    feet, and an ordinary dynamometer, which can be connected either with
-    the gas bag or ballonet by turning a valve. A double column of water
-    is also connected to the tube to act as a check on the dynamometer.
-    Due to the vibration of the car caused by the motor, these instruments
-    are suspended by rubber attachments. Even with this arrangement, it is
-    necessary to steady the aneroid barometer with the hand in order to
-    read it. The vibration prevents the use of the statoscope.</p>
-
-  <h4><span class="smcap">Germany</span></h4>
-
-  <p>Three different types of air ships are being developed in Germany. The
-    <i>Gross</i> is the design of Major Von Gross, who commands the Balloon
-    Battalion at Tegel near Berlin. The <i>Parseval</i> is being developed by
-    Major Von Parseval, a retired German officer, and the <i>Zeppelin</i> is the
-    design of Count Zeppelin, also a retired officer of the German Army.</p>
-
-  <h4>The <i>Gross</i></h4>
-
-  <p>The first air ship of this type made its first ascension on July 23,
-    1907. The mechanical part was built at Siemen’s Electrical Works in
-    Berlin; the gas bag by the Riedinger firm in Augsburg.</p>
-
-  <p><i>Gas Bag.</i>—The gas bag is made of rubber cloth furnished by the
-    Continental Tire Company similar<span class="pagenum" id="Page_472">472</span> to that used in the <i>Ville de Paris</i>.
-    It is diagonal-thread, but there is no inner layer of rubber, as they
-    do not fear damage from impurities in the hydrogen gas. Length, 131¼
-    feet; maximum diameter about 39⅓ feet; volume, 63,576 cubic feet;
-    the elongation is about 3⅓. The form is cylindrical with spherical
-    cones at the ends, the whole being symmetrical.</p>
-
-  <p><i>Suspension.</i>—The suspension is practically the same as that of the
-    <i>Patrie</i>. A steel and aluminum frame is attached to the lower part of
-    the gas bag, and the car is suspended on this by steel cables. The
-    objection to this system is even more apparent in the <i>Gross</i> than in
-    the <i>Patrie</i>. A marked dip along the upper meridian of the gas bag
-    shows plainly the deformation.</p>
-
-  <p><i>The Car.</i>—The car is boat-shaped like that of the <i>Patrie</i>. It is
-    suspended thirteen feet below the gas bag.</p>
-
-  <p><i>Motor.</i>—The motor is a 20- to 24-horse-power, 4-cylinder
-    Daimler-Mercedes.</p>
-
-  <p><i>Propellers.</i>—There are two propellers 8³/₁₀ foot in diameter, each
-    having two blades. They are placed one on each side, but well up under
-    the gas bag near the center of resistance. The transmission is by belt.
-    The propellers make 800 r. p. m.</p>
-
-  <p><i>Stability.</i>—The same system, with planes, is used in the <i>Gross</i> as
-    in the <i>Patrie</i>, but it is not nearly so well developed. At the rear
-    of the rigid frame, attached to the gas bag, are two fixed horizontal
-    planes, one on each side. A fixed vertical plane runs down from between
-    these horizontal planes, and is terminated at the rear by the rudder.
-    A fixed horizontal plane is attached on the rear of the bags as in the
-    <i>Patrie</i>. The method of attachment is the same, but the plane is put on
-    before inflation in the <i>Gross</i> air ship, afterwards in the <i>Patrie</i>.
-    The stability of the <i>Gross</i> air ship in a vertical plane<span class="pagenum" id="Page_473">473</span> is reported
-    to be very good, but it is said to veer considerably in attempting to
-    steer a straight course.</p>
-
-  <p>The many points of resemblance between this dirigible and the Lebaudy
-    type are worthy of notice. The suspension or means of maintaining
-    stability, and the disposition for driving are in general the same. As
-    first built, the <i>Gross</i> had a volume of 14,128 cubic feet less than
-    at present, and there was no horizontal plane at the rear of the gas
-    bag. Its maximum speed is probably fifteen miles per hour. As a result
-    of his experiments of 1907, Major Von Gross has this year produced a
-    perfected air ship, built on the same lines as his first, but with
-    greatly increased volume and dimensions. The latest one has a volume of
-    176,000 cubic feet, is driven by two 75-horse-power Daimler motors, and
-    has a speed of 27 miles per hour.</p>
-
-  <p>On September 11th of this year, the <i>Gross</i> air ship left Berlin at
-    10.25 <span class="smcap">p.m.</span>, carrying four passengers, and returned the next
-    day at 11.30 <span class="smcap">a.m.</span>, having covered 176 miles in the period of a
-    little over 13 hours. This is the longest trip, both in point of time
-    and distance, ever made by any air ship returning to the starting point.</p>
-
-  <h4>The <i>Parseval</i></h4>
-
-  <p>The <i>Parseval</i> air ship is owned and controlled by the Society for the
-    Study of Motor Balloons. This organization, composed of capitalists,
-    was formed practically at the command of the emperor, who is very much
-    interested in aërial navigation. The society has a capital of 1,000,000
-    marks, owns the <i>Parseval</i> patents and is ready to construct air ships
-    of the <i>Von Parseval</i> type. The present air ship was constructed by the
-    Riedinger firm at Augsburg, and<span class="pagenum" id="Page_474">474</span> is operated from the balloon house of
-    this society at Tegel, adjoining the military balloon house.</p>
-
-  <p>The gas bag is similar in construction to that of the <i>Drachen</i>
-    balloon, used by the army for captive work. Volume, 113,000 cubic
-    feet; length, 190 feet; maximum diameter, 30½ feet. It is cylindrical
-    in shape, rounded at the front and pointed at the rear. The material
-    was furnished by the Continental Tire Company. It is diagonal-thread,
-    weighing about 11³/₁₀ ounces per square yard and having a strength of
-    about 940 pounds per running foot. Its inner surface is covered with a
-    layer of rubber.</p>
-
-  <p><i>Ballonets.</i>—There are two ballonets, one at each end, each having a
-    capacity of 10,596 cubic feet. The material in the ballonet weighs
-    about 8¼ ounces per square yard, the cotton layers being lighter than
-    in the material for the gas bag. Air is pumped into the rear ballonet
-    before leaving the ground, so that the air ship operates with the front
-    end inclined upward. The air striking underneath exerts an upward
-    pressure, as on an aëroplane, and thus adds to its lifting capacity.
-    Air is pumped into the ballonets from a fan operated by the motor.
-    A complex valve, just under the middle of the gas bag, enables the
-    engineer to drive air into either, or both ballonets. The valves also
-    act automatically and release air from the ballonets at a pressure of
-    about 0.9 inches of water.</p>
-
-  <p>In the middle of the top of the gas bag is a valve for releasing the
-    gas. It can be operated from the car, and open automatically at a
-    pressure of about 2 inches of water. Near the two ends and on opposite
-    sides are two rip strips controlled from the car by the cords.</p>
-
-  <p><i>Suspension.</i>—The suspension is one of the characteristics of the air
-    ships, and is protected by patents. The car has four trolleys, two on
-    each side,<span class="pagenum" id="Page_475">475</span> which run on two steel cables. The car can run backwards
-    and forwards on these cables, thus changing its position with relation
-    to the gas bag. This is called “loose” suspension. Its object is to
-    allow the car to take up, automatically, variations in thrust due to
-    the motor, and variations in resistance due to the air. Ramifications
-    of hemp rope from these steel cables are sewed onto a canvas strip,
-    which in turn is sewed onto the gas bag. This part of the suspension is
-    the same as in the <i>Drachen</i> balloon. The weight is distributed over
-    the entire length of the gas bag.</p>
-
-  <p><i>The Car.</i>—The car is 16.4 feet long and is built of steel tubes and
-    wire. It is large enough to hold the motor and three men, though four
-    or five may be taken.</p>
-
-  <p><i>Motor.</i>—The motor is a 110-horse-power Daimler-Mercedes. Sufficient
-    gasoline is carried for a run of twelve hours.</p>
-
-  <p><i>Propeller.</i>—The propeller, like the suspension, is peculiar to this
-    air ship and is protected by patents. It has four cloth blades which
-    hang limp when not turning. When the motor is running, these blades,
-    which are carefully weighed with lead at certain points, assume the
-    proper position due to the various forces acting. The diameter is 13¾
-    feet. The propeller is placed above the rear of the car near the center
-    of resistance. Shaft transmission is used. The propeller makes 500
-    r. p. m. to 1,000 of the motor. There is a space of 6½ feet from the
-    propeller blades to the gas bag, the bottom of the car being about 30
-    feet from the gas bag. This propeller has the advantage of being very
-    light. Its position, so far from the engine, necessarily incurs a great
-    loss of power in transmission.</p>
-
-  <p>The steering wheel at the front of the car has a spring device for
-    locking it in any position.</p>
-
-  <p><span class="pagenum" id="Page_476">476</span></p>
-
-  <p>The 1908 model No. 1 of this air ship was constructed for the purpose
-    of selling it to the government. Among other requirements is a 12-hour
-    flight without landing, and a sufficient speed to maneuver against a
-    22-mile wind. A third and larger air ship of this type is now under
-    construction.</p>
-
-  <h4><span class="smcap">United States</span></h4>
-
-  <p class="center"><i>Signal Corps Dirigible No. 1</i></p>
-
-  <p>Due to the lack of funds, the United States Government has not been
-    able to undertake the construction of an air ship sufficiently large
-    and powerful to compete with those of European nations. However,
-    specifications were sent out last January for an air ship not over 120
-    feet long and capable of making 20 miles per hour. Contract was awarded
-    to Capt. Thomas S. Baldwin, who delivered an air ship last August to
-    the Signal Corps, the description of which follows:</p>
-
-  <p><i>Gas Bag.</i>—The gas bag is spindle shaped, 96 feet long, maximum
-    diameter, 19 feet 6 inches, with a volume of 20,000 cubic feet. A
-    ballonet for air is provided inside the gas bag, and has a volume of
-    2,800 cubic feet. The material for the gas bag is made of two layers of
-    Japanese silk, with a layer of vulcanized rubber between.</p>
-
-  <p><i>Car.</i>—The car is made of spruce, and is 66 feet long, 2½ feet wide and
-    2½ feet high.</p>
-
-  <p><i>Motor.</i>—The motor is a 20-horse-power water-cooled Curtiss make.</p>
-
-  <p><i>Propeller.</i>—The propeller is at the front end of the car, and is
-    connected to the engine by a steel shaft. It is built of spruce, has
-    a diameter of 10 feet, 8 inches, with a pitch of 11 feet, and turns
-    at<span class="pagenum" id="Page_477">477</span> the rate of 450 r. p. m. A fixed vertical surface is provided at
-    the rear end of the car to minimize veering, and a horizontal surface
-    attached to the vertical rudder at the rear tends to minimize pitching.
-    A double horizontal surface controlled by a lever and attached to the
-    car in front of the engine, serves to control the vertical motion and
-    also to minimize pitching.</p>
-
-  <p>The position of the car very near to the gas bag, is one of the
-    features of the Government dirigible. This reduces the length and
-    consequently the resistance of the suspension, and places the propeller
-    thrust near the center of resistance.</p>
-
-  <p>The total lifting power of the air ship is 1,350 pounds of which
-    500 pounds are available for passengers, ballast, fuel, etc. At its
-    official trials a speed of 19.61 miles per hour was attained over a
-    measured course and an endurance run lasting two hours, during which
-    seventy per cent of the maximum speed was maintained.</p>
-
-  <p><i>Dirigible No. 1</i>, as this air ship has been named, has already served
-    a very important purpose in initiating officers of the Signal Corps
-    in the construction and operation of a dirigible balloon. With the
-    experience now acquired, the United States Government is in a position
-    to proceed with the construction and operation of an air ship worthy of
-    comparison with any now in existence, but any efforts in this direction
-    must await the action of Congress in providing the necessary funds.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="appendix_IV">
-    <span class="pagenum" id="Page_478">478</span>
-    <h3>APPENDIX IV</h3>
-    <span class="small">THE RELATIONS OF WEIGHT, SPEED AND POWER OF FLYERS<a id="FNanchor_82" href="#Footnote_82" class="fnanchor">[82]</a></span>
-  </div>
-
-  <div class="center"><i>By Wilbur and Orville Wright</i></div>
-
-  <p><span class="smcap">The</span> flyer of 1903 carried a four-cylinder gasoline motor of four-inch
-    bore and four-inch stroke. Complete with magneto, radiators, tanks,
-    water, fuel, etc., the motor weighed a little over 200 pounds, and at
-    1,200 revolutions per minute developed 16 horse power for the first 15
-    seconds after starting. After a minute or two the power did not exceed
-    13 or 14 horse power. At 1,020 revolutions per minute—the speed of the
-    motor in the flights at Kitty Hawk on the 17th of December, 1903—it
-    developed about 12 horse power.</p>
-
-  <p>The flyer of 1904 was equipped with a motor similar to the first, but
-    of 1/8-inch larger bore. This engine at 1,500 revolutions per minute
-    developed 24 horse power for the first 15 seconds, but only 16 to 17
-    horse power after a few minutes run. Complete with water, fuel and
-    other accessories, it weighed 240 pounds.</p>
-
-  <p>The same engine with a few modifications in the oiling device and the
-    carburetor, was used in all the flights of 1905. A test of its power
-    made soon after the flights of October, 1905, revealed a gain of 3
-    horse power over tests made just before mounting <span class="pagenum" id="Page_479">479</span>it on the flyer
-    in 1904. This gain is attributed to the increased smoothness of the
-    cylinders and pistons produced by wear. The small output of these
-    engines was due to lack of experience in building gasoline motors.</p>
-
-  <p>During the past year further improvements have been made, and our
-    latest engines of four-inch bore and four-inch stroke produce about 25
-    horse power continuously. The improvement in the reliability of the
-    motor has been even more marked, so that now flights of long distances
-    can be attempted without danger of failure on account of the stopping
-    of the motor.</p>
-
-  <p>A comparison of the flyers of 1903, 1904 and 1905 show some interesting
-    facts. The flyer of 1903 weighed, complete with operator, 745 pounds.
-    Its longest flight was of 59 seconds duration, with a speed of 30 miles
-    an hour and an expenditure of 12 horse power. The flyer of 1904 weighed
-    about 900 pounds, including a load of 70 pounds in iron bars. A speed
-    of more than 34 miles an hour was maintained for a distance of three
-    miles with an expenditure of 17 horse power. The flyer of 1905 weighed,
-    including load, 925 pounds. With an expenditure of 19 to 20 horse power
-    it traveled over 24 miles at a speed of more than 38 miles an hour. The
-    flights of 1904 and 1905 would have been slightly faster had they been
-    made in a straight line, as were those of 1903.</p>
-
-  <p>In 1903, 62 pounds per horse power were carried at a speed of 30 miles
-    an hour; in 1904, 53 pounds, at 34 miles an hour; and in 1905, 46
-    pounds at 38 miles an hour. It will be noted that the weight carried
-    per horse power is almost exactly in inverse ratio to the speed, as
-    theory demands—the higher the speed, the smaller the weight carried per
-    horse power.</p>
-
-  <p><span class="pagenum" id="Page_480">480</span></p>
-
-  <p>Since flyers can be built with approximately the same dynamic
-    efficiency for all speeds up to 60 miles an hour, a flyer designed to
-    carry a total weight of 745 pounds at 20 miles an hour would require
-    only 8 horse power or two thirds of the power necessary for 30 miles an
-    hour. At 60 miles 24 horse power would be necessary—twice that required
-    to carry the same weight at 30 miles an hour. At 120 miles an hour 60
-    to 75 horse power would probably be necessary, and the weight carried
-    per horse power would be only 10 or 12 pounds. At such high speed
-    the resistance of the operator’s body and the engine is a formidable
-    factor, consuming 64 times as much horse power as at 30 miles an hour.
-    At speeds below 60 miles an hour this resistance is almost negligible.</p>
-
-  <p>It is evident that the limits of speed have not as yet been closely
-    approached in the flyers already built, and that in the matter of
-    distance, the possibilities are even more encouraging. Even in the
-    existing state of the art it is easy to design a practical and durable
-    flyer that will carry an operator and supplies of fuel for a flight of
-    over 500 miles at a speed of 50 miles an hour.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="appendix_V">
-    <span class="pagenum" id="Page_481">481</span>
-    <h3>APPENDIX V</h3>
-    <span class="small">CURTISS’S EXPERIMENTS IN RISING FROM THE WATER<a id="FNanchor_83" href="#Footnote_83" class="fnanchor">[83]</a></span>
-  </div>
-
-  <p><span class="smcap">During</span> the past two years Glenn H. Curtiss, who, more than any other
-    experimenter, has been given to developing the aëroplane for various
-    uses, has experimented with floats for his biplane that would enable
-    it to rise from the surface of the water. Something over a year ago he
-    succeeded in developing a speed of about twenty miles an hour on the
-    water, but this was insufficient to rise from the surface.</p>
-
-  <p>At the beginning of the new year Mr. Curtiss moved to the Pacific Coast
-    and set about endeavoring to develop suitable floats which would make
-    it possible for his machine to rise from the surface of the water.
-    These experiments have been carried on at San Diego, where Mr. Curtiss
-    is instructing several naval and military officers in the art of flying.</p>
-
-  <p>In his first experiments on the Pacific Coast Mr. Curtiss followed
-    the successful experiments of this sort made by M. Henri Fabre at
-    Marseilles, France, about a year ago, as far as the design of his
-    floats was concerned. He constructed one large float six feet wide,
-    five feet from front to rear, and one foot thick at its central point,
-    and placed this under the center of the machine. The bottom of this
-    float was<span class="pagenum" id="Page_482">482</span> perfectly flat and arranged at an incline of ten or twelve
-    degrees. Some distance forward of the main float, at about the position
-    of the front wheel in the land machine, another float six feet wide,
-    by one foot from front to rear, and six inches deep, was placed; while
-    at the extreme front end of the machine, on a special outrigger, was
-    mounted a small elevating hydroplane six feet wide by eight inches
-    in a fore-and-aft direction, and one and one-half inches thick. This
-    hydroplane was fixed at an angle of about twenty-five degrees and was
-    intended to lift the front part of the machine. A spray shield was
-    fitted back of it, as shown in the diagram, <a href="#Page_333">page 333</a>.</p>
-
-  <p>The first experiments were made with these new floats on January 26th
-    last; and although they made a considerable disturbance in the water,
-    especially at low speed, the aviator was enabled to get up a speed on
-    the surface of about forty-five miles an hour. He found that at as low
-    a rate as ten miles the hydroplanes (which normally were submerged)
-    rose to the surface, while as the speed increased only the rear edges
-    of the two main planes were required to support the machine. The
-    aëroplane readily attained sufficient speed to rise in the air, for
-    as the speed increased and the floats emerged from the water, the
-    head resistance of the floats diminished and there was only the skin
-    friction of the water on a few inches of the rear edge of these floats,
-    plus the air resistance, to be overcome.</p>
-
-  <p>At the first try-out, while traveling over the water at high speed, Mr.
-    Curtiss found himself suddenly nearing the shore, and to avoid running
-    aground he turned his horizontal rudder sharply upward, with the
-    result that the machine rose from the water with perfect ease. He soon
-    alighted again, and in the second flight he made a circle and remained
-    in the air a minute and twenty-one seconds.<span class="pagenum" id="Page_483">483</span>
-    Two other experimental flights were made the first day, and on
-    January 27th he made a three-and-one-half-minute flight and stated,
-    upon alighting, that he found no difficulty in remaining aloft as long
-    as he pleased. The machine showed a speed of fifty miles an hour in the
-    air as against forty-five miles an hour when skimming over the surface
-    of the water.</p>
-
-  <hr class="page" />
-  <div id="Plate_XXXII" class="center"><b>PLATE XXXII.</b></div>
-
-  <div class="figcenter">
-    <img src="images/i_563a.jpg" width="600" height="225" alt="" />
-    <div class="captionp">CURTISS STARTING FROM THE WATER.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_563b.jpg" width="600" height="221" alt="" />
-    <div class="captionp">CURTISS BIPLANE FOR LAND AND WATER.</div>
-  </div>
-
-  <div class="figcenter">
-    <img src="images/i_563c.jpg" width="600" height="224" alt="" />
-    <div class="captionp">CURTISS TRIPLANE RISEN FROM THE WATER.</div>
-  </div>
-
-  <p>Not satisfied with the several floats with which he had attained
-    his first success in rising from the water, Mr. Curtiss immediately
-    constructed a single float twelve feet long by two feet in width
-    and twelve inches deep. This float is built of wood and resembles a
-    flat-bottomed boat or scow, the top being covered with canvas to keep
-    the water from getting in. Three feet from the front end the bottom
-    is curved upward forming a bow the full width of the float, while at
-    the same distance from the rear the float slants downward in a similar
-    manner.</p>
-
-  <p>This single float is placed under the aëroplane in such a position that
-    the main weight of the machine and aviator is slightly to the rear of
-    the center of the float, which causes the latter to incline upward
-    slightly and thus gives the necessary angle for hydroplaning on the
-    surface of the water. The weight of this new float is but fifty pounds,
-    or less than half as much as that of the two floats that were used
-    before.</p>
-
-  <p>The paint was barely dry on the new float before Mr. Curtiss had it
-    fitted to his machine and gave it a trial. This was done on February
-    1st and the trial was thoroughly successful. The machine ran over the
-    surface of the water with very much less disturbance than before and
-    rose in the air readily. A glance at the photographs showing the new
-    and the old floats in action will give one an excellent idea of the
-    much less commotion caused by the single <span class="pagenum" id="Page_484">484</span>scow-shaped float. Besides
-    being much more compact and creating less disturbance, this float or
-    scow can be used for carrying articles or a passenger.</p>
-
-  <p>In order to keep the aëroplane from tilting to one side or the other,
-    an inclined stick four feet long and three inches wide, to which is
-    attached on its upper side an inflated rubber tube, is fastened to the
-    front edge of the lower plane at each end. By the use of these props
-    the aëroplane does not tip readily when skimming along the surface,
-    even though the scow-shaped float used is but two feet in width.</p>
-
-  <p>After meeting with success with his new float, Mr. Curtiss, on February
-    17th, made more flights with the motor and propeller placed at the
-    front of his biplane and with his seat placed at the rear of the main
-    planes. The chief of these flights was one which he made from North
-    Island, where he is experimenting, over San Diego harbor to the cruiser
-    <i>Pennsylvania</i>. He alighted upon the surface close beside the cruiser
-    and his aëroplane was hauled up beside the warship and placed on her
-    deck.</p>
-
-  <p>After a short visit on the cruiser the aviator was again lowered to the
-    surface in his machine. A sailor started the engine, and Mr. Curtiss
-    flew back to his starting point in short order. The naval authorities
-    were greatly pleased with his demonstration and it is probable that the
-    Navy Department will purchase one of these machines in the near future
-    and continue the instruction of its officers.</p>
-
-  <p>After increasing the surface of his biplane Mr. Curtiss, on February
-    24th, took up one of his naval pupils, Lieutenant T. G. Ellyson, as
-    a passenger. He made a flight of one and one-half miles, rising to a
-    height of one hundred feet and flying as slowly as twenty-five miles an
-    hour, or as fast as fifty miles an hour, at will. Lieutenant Ellyson
-    was seated on the<span class="pagenum" id="Page_485">485</span> pontoon below the aëroplane. He could look down
-    in the water and see bottom at a depth of twenty-five feet, and he
-    believes submarines can be easily located by flying over the water.
-    The slow speed at which it is possible to fly will make the biplane
-    especially useful for bomb dropping. As we go to press Mr. Curtiss is
-    about to try his machine fitted with wheels and floats as well.</p>
-
-  <hr class="page" />
-  <div class="chapter" id="index">
-    <span class="pagenum" id="Page_487">487</span>
-    <h3>INDEX</h3>
-  </div>
-  <hr class="short" />
-
-  <ul>
-    <li>Abbe, Cleveland, <a href="#Page_200">200</a>, <a href="#Page_437">437</a>.</li>
-    <li>Acosta, <a href="#Page_10">10</a>.</li>
-    <li>Ader, C. F., <a href="#Page_222">222–226</a>.</li>
-    <li>Aërial Experiment Association, <a href="#Page_264">264–267</a>, <a href="#Page_305">305</a>.</li>
-    <li>Aëro Club of America, <a href="#Page_243">243</a>, <a href="#Page_244">244</a>, <a href="#Page_322">322</a>, <a href="#Page_323">323</a>.</li>
-    <li class="sub">of France, <a href="#Page_106">106</a>, <a href="#Page_256">256</a>, <a href="#Page_258">258</a>, <a href="#Page_259">259</a>, <a href="#Page_301">301</a>.</li>
-    <li class="sub">of Great Britain, <a href="#Page_287">287</a>.</li>
-    <li>Aëro Corporation Limited, <a href="#Page_322">322</a>.</li>
-    <li>Aërodrome, <a href="#Page_111">111</a>, <a href="#Page_194">194</a>, <a href="#Page_240">240</a>, <a href="#Page_292">292</a>.</li>
-    <li>Aëronat, <a href="#Page_126">126</a>.</li>
-    <li>Aëronautic meteorology, <a href="#Page_347">347</a> <i>et seq.</i></li>
-    <li>Aëronautic Society of New York, <a href="#Page_284">284</a>.</li>
-    <li><i>Aëronautical Annual</i>, <a href="#Page_215">215</a>, <a href="#Page_227">227</a>, <a href="#Page_427">427</a>.</li>
-    <li><i>Aëronautics</i>, <a href="#Page_252">252</a>.</li>
-    <li><i>Aërophile</i>, <a href="#Page_130">130</a>, <a href="#Page_166">166</a>, <a href="#Page_340">340</a>.</li>
-    <li>Aëroplanes, Ader’s, <a href="#Page_222">222–226</a>.</li>
-    <li class="sub">advances in, in 1909, <a href="#Page_283">283</a>, <a href="#Page_284">284</a>.</li>
-    <li class="sub">Aërial Experiment Association’s, <a href="#Page_264">264–267</a>.</li>
-    <li class="sub"><i>Antoinette</i>, <a href="#Page_288">288</a>, <a href="#Page_289">289</a>, <a href="#Page_320">320</a>, <a href="#Page_324">324</a>.</li>
-    <li class="sub">Blériot’s, <a href="#Page_267">267–270</a>, <a href="#Page_286">286</a>, <a href="#Page_287">287</a>, <a href="#Page_290">290–292</a>,
-      <a href="#Page_299">299</a>, <a href="#Page_300">300</a>, <a href="#Page_309">309</a>.</li>
-    <li class="sub">Bréguet’s, <a href="#Page_313">313</a>.</li>
-    <li class="sub">Chanute and Herring’s, <a href="#Page_218">218–221</a>.</li>
-    <li class="sub">Cody’s, <a href="#Page_305">305</a>.</li>
-    <li class="sub">competitive flying of, <a href="#Page_283">283</a> <i>et seq.</i></li>
-    <li class="sub">cost of, <a href="#Page_342">342</a>.</li>
-    <li class="sub">Curtiss’, <a href="#Page_264">264–266</a>, <a href="#Page_284">284–286</a>, <a href="#Page_294">294–300</a>, <a href="#Page_316">316</a>,
-      <a href="#Page_317">317</a>, <a href="#Page_322">322</a>, <a href="#Page_333">333</a>.</li>
-    <li class="sub">Delagrange’s flights with, <a href="#Page_261">261–263</a>.</li>
-    <li class="sub"><i>Demoiselle</i>, <a href="#Page_324">324</a>.</li>
-    <li class="sub">Deperdussin’s, <a href="#Page_399">399</a>.</li>
-    <li class="sub">earliest public flight of, <a href="#Page_257">257</a>.</li>
-    <li class="sub">Esnault-Pélterie’s, <a href="#Page_304">304</a>, <a href="#Page_314">314</a>, <a href="#Page_337">337</a>.</li>
-    <li class="sub">Etrich’s, <a href="#Page_335">335</a>, <a href="#Page_336">336</a>.</li>
-    <li class="sub">Fabre’s, <a href="#Page_332">332</a>, <a href="#Page_335">335</a>.</li>
-    <li class="sub">Farman’s, Henri, <a href="#Page_259">259–264</a>, <a href="#Page_298">298</a>, <a href="#Page_303">303</a>, <a href="#Page_305">305</a>,
-      <a href="#Page_321">321</a>.</li>
-    <li class="sub">Farman’s, Maurice, <a href="#Page_305">305</a>, <a href="#Page_311">311</a>.</li>
-    <li class="sub">first tour in, <a href="#Page_268">268–270</a>.</li>
-    <li class="sub">first town-to-town flight in, <a href="#Page_264">264</a>.</li>
-    <li class="sub">Grade’s, <a href="#Page_304">304</a>.</li>
-    <li class="sub">Hanriot’s, <a href="#Page_339">339</a>.</li>
-    <li class="sub">Herring’s compressed air, <a href="#Page_221">221</a>, <a href="#Page_222">222</a>.</li>
-    <li class="sub">impossibility of, <a href="#Page_12">12</a>.</li>
-    <li class="sub">Langley’s, <a href="#Page_239">239–243</a>.</li>
-    <li class="sub">launching of, <a href="#Page_202">202</a>.</li>
-    <li class="sub">Le Bris’, <a href="#Page_203">203–205</a>.</li>
-    <li class="sub">Lilienthal’s, <a href="#Page_207">207–209</a>.</li>
-    <li class="sub">Mattullath’s, <a href="#Page_235">235–239</a>.</li>
-    <li class="sub">Maxim’s, <a href="#Page_226">226–228</a>.</li>
-    <li class="sub">model, <a href="#Page_173">173</a> <i>et seq.</i></li>
-    <li class="sub">Montgomery’s, <a href="#Page_251">251–255</a>, <a href="#Page_282">282</a>.</li>
-    <li class="sub">Mouillard’s, <a href="#Page_207">207–209</a>.</li>
-    <li class="sub">Nieuport’s, <a href="#Page_339">339</a>.</li>
-    <li class="sub"><span class="pagenum" id="Page_488">488</span>nineteenth century, <a href="#Page_202">202</a> <i>et seq.</i></li>
-    <li class="sub">Paulhan’s, <a href="#Page_324">324</a>, <a href="#Page_325">325</a>.</li>
-    <li class="sub">Pilcher’s, <a href="#Page_216">216–218</a>.</li>
-    <li class="sub">public flying, <a href="#Page_256">256</a> <i>et seq.</i></li>
-    <li class="sub">reliability of, <a href="#Page_341">341</a>.</li>
-    <li class="sub">Santos-Dumont’s, <a href="#Page_256">256–258</a>, <a href="#Page_303">303</a>, <a href="#Page_324">324</a>.</li>
-    <li class="sub">stability of, <a href="#Page_232">232–234</a>.</li>
-    <li class="sub">stable and powerful, <a href="#Page_235">235</a> <i>et seq.</i></li>
-    <li class="sub">Tellier’s, <a href="#Page_312">312</a>.</li>
-    <li class="sub">utility of, <a href="#Page_341">341</a>.</li>
-    <li class="sub">Voisin’s, <a href="#Page_259">259</a>, <a href="#Page_267">267</a>, <a href="#Page_313">313</a>.</li>
-    <li class="sub">Wright brothers’, <a href="#Page_245">245–249</a>, <a href="#Page_270">270–282</a>, <a href="#Page_309">309</a>,
-      <a href="#Page_324">324</a>, <a href="#Page_326">326</a>, <a href="#Page_329">329</a>.</li>
-    <li class="sub">Zahm’s system of control of, <a href="#Page_229">229–231</a>.</li>
-    <li>Aërostal, <a href="#Page_22">22</a>.</li>
-    <li>Æschylus, <a href="#Page_29">29</a>.</li>
-    <li>Agobard, <a href="#Page_22">22</a>.</li>
-    <li>Ailerons, <a href="#Page_286">286</a>.</li>
-    <li>Air bag, <a href="#Page_83">83</a>.</li>
-    <li>Air friction, <a href="#Page_238">238</a>, <a href="#Page_239">239</a>.</li>
-    <li>Airscout, <a href="#Page_11">11</a>, <a href="#Page_12">12</a>.</li>
-    <li>Allen, Gen. James, <a href="#Page_271">271</a>.</li>
-    <li>Alps, Chavez’s flight across, <a href="#Page_318">318</a>, <a href="#Page_319">319</a>.</li>
-    <li>Altitude records, <a href="#Page_307">307–309</a>.</li>
-    <li><i>American Engineer and Railway Journal</i>, <a href="#Page_229">229</a>.</li>
-    <li>American military dirigible, <a href="#Page_138">138</a>.</li>
-    <li><i>Antoinette</i> monoplane, <a href="#Page_288">288</a>, <a href="#Page_289">289</a>, <a href="#Page_309">309</a>,
-      <a href="#Page_320">320</a>, <a href="#Page_324">324</a>, <a href="#Page_340">340</a>.</li>
-    <li>Archdeacon, Ernest, <a href="#Page_256">256</a>.</li>
-    <li>Archibald, Douglass, <a href="#Page_77">77</a>.</li>
-    <li>Archytas of Tarentum, <a href="#Page_198">198</a>.</li>
-    <li>Arlandes, Marquis de, <a href="#Page_38">38–42</a>.</li>
-    <li>Ascending trend of wind, <a href="#Page_211">211</a>.</li>
-    <li>Assman, Professor, <a href="#Page_72">72</a>.</li>
-    <li>Astra Society, <a href="#Page_120">120</a>, <a href="#Page_123">123</a>, <a href="#Page_124">124</a>.</li>
-    <li>Atmosphere, composition of, <a href="#Page_348">348–350</a>.</li>
-    <li class="sub">cyclones, tornadoes, waterspouts, <a href="#Page_394">394</a> <i>et seq.</i></li>
-    <li class="sub">general circulation of, <a href="#Page_376">376–380</a>.</li>
-    <li class="sub">general properties of, <a href="#Page_347">347</a> <i>et seq.</i></li>
-    <li class="sub">permanent and periodic winds, <a href="#Page_376">376</a> <i>et seq.</i></li>
-    <li class="sub">temperature and pressure, <a href="#Page_363">363</a> <i>et seq.</i></li>
-    <li class="sub">thunderstorms, windgusts, <a href="#Page_422">422</a> <i>et seq.</i></li>
-    <li>Aubrun, Emile, <a href="#Page_331">331</a>.</li>
-    <li>Audemars, <a href="#Page_324">324</a>.</li>
-    <li>Automobile Club of France, <a href="#Page_321">321</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Bacon, Roger, <a href="#Page_20">20</a>.</li>
-    <li>Balance, complete dynamical, <a href="#Page_234">234</a>.</li>
-    <li>Baldwin, F. W., <a href="#Page_264">264</a>, <a href="#Page_266">266</a>.</li>
-    <li class="sub">Thomas S., <a href="#Page_138">138</a>.</li>
-    <li>Ballonets, <a href="#Page_95">95</a>.</li>
-    <li><i>Ballons sondes</i>, <a href="#Page_72">72</a>.</li>
-
-    <li>Balloon, dirigible:</li>
-    <li class="sub2">Baumgarten and Wölfert’s, <a href="#Page_99">99</a>.</li>
-    <li class="sub2"><i>Belgique</i>, <a href="#Page_129">129</a>.</li>
-    <li class="sub2">Blanchard’s, <a href="#Page_79">79</a>, <a href="#Page_80">80</a>.</li>
-    <li class="sub2">British and American, <a href="#Page_130">130</a>, <a href="#Page_131">131</a>.</li>
-    <li class="sub2"><i>Clément-Bayard I</i>, <a href="#Page_123">123</a>.</li>
-    <li class="sub2"><i>Clément-Bayard II</i>, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>, <a href="#Page_133">133</a>.</li>
-    <li class="sub2">combined with aëroplane, <a href="#Page_123">123</a>.</li>
-    <li class="sub2"><i>Colonel Renard</i>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>.</li>
-    <li class="sub2">development of rigid, <a href="#Page_145">145</a> <i>et seq.</i></li>
-    <li class="sub2">Dupuy de Lome’s, <a href="#Page_19">19</a>, <a href="#Page_92">92</a>, <a href="#Page_93">93</a>.</li>
-    <li class="sub2">early experiments with Zeppelin, <a href="#Page_147">147–150</a>.</li>
-    <li class="sub2">early gasoline driven, <a href="#Page_10">10</a> <i>et seq.</i></li>
-    <li class="sub2">electric, <a href="#Page_92">92–97</a>.</li>
-    <li class="sub2"><span class="pagenum" id="Page_489">489</span><i>España</i>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>,
-      <a href="#Page_127">127</a>.</li>
-    <li class="sub2">first designs for, <a href="#Page_78">78–86</a>.</li>
-    <li class="sub2">general design of <i>Zeppelin</i>, <a href="#Page_146">146</a>, <a href="#Page_147">147</a>.</li>
-    <li class="sub2">German aërial fleet, <a href="#Page_141">141</a>, <a href="#Page_142">142</a>.</li>
-    <li class="sub2">German nonrigid, <a href="#Page_138">138</a>.</li>
-    <li class="sub2">Giffard’s, <a href="#Page_90">90</a>, <a href="#Page_91">91</a>, <a href="#Page_98">98</a>.</li>
-    <li class="sub2">Gross type of, <a href="#Page_138">138</a>, <a href="#Page_139">139</a>, <a href="#Page_140">140</a>,
-      <a href="#Page_471">471–473</a>.</li>
-    <li class="sub2">Hänlein’s, <a href="#Page_98">98</a>.</li>
-    <li class="sub2">Hopkinson’s suggestion for, <a href="#Page_84">84</a>.</li>
-    <li class="sub2">Italian, <a href="#Page_130">130</a>.</li>
-    <li class="sub2"><i>Jaune</i>, <a href="#Page_115">115</a>, <a href="#Page_116">116</a>.</li>
-    <li class="sub2">Jefferson’s suggestion for, <a href="#Page_84">84</a>.</li>
-    <li class="sub2">Jullien’s model, <a href="#Page_88">88</a>.</li>
-    <li class="sub2"><i>Lebaudy</i>, <a href="#Page_116">116</a>, <a href="#Page_117">117</a>.</li>
-    <li class="sub2">Lebaudy’s, <a href="#Page_115">115–120</a>, <a href="#Page_134">134–137</a>.</li>
-    <li class="sub2"><i>Liberté</i>, <a href="#Page_120">120</a>.</li>
-    <li class="sub2">maneuvers at Cologne, <a href="#Page_143">143</a>, <a href="#Page_144">144</a>.</li>
-    <li class="sub2">Meusnier’s designs for, <a href="#Page_85">85</a>, <a href="#Page_86">86</a>.</li>
-    <li class="sub2">Miolan and Janinet’s, <a href="#Page_81">81</a>.</li>
-    <li class="sub2"><i>Morning Post</i>, <a href="#Page_134">134</a>.</li>
-    <li class="sub2">muscular driven, <a href="#Page_80">80</a>, <a href="#Page_82">82</a>, <a href="#Page_85">85</a>,
-      <a href="#Page_92">92</a>.</li>
-    <li class="sub2">Parseval type of, <a href="#Page_138">138</a>, <a href="#Page_139">139</a>, <a href="#Page_140">140–143</a>,
-      <a href="#Page_473">473–476</a>.</li>
-    <li class="sub2"><i>Patrie</i>, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>.</li>
-    <li class="sub2">Porter’s, <a href="#Page_86">86</a>, <a href="#Page_87">87</a>.</li>
-    <li class="sub2">practical development of nonrigid, <a href="#Page_115">115</a> <i>et seq.</i></li>
-    <li class="sub2">practical speed of, <a href="#Page_101">101</a>.</li>
-    <li class="sub2">Renard and Krebs’, <a href="#Page_93">93–97</a>.</li>
-    <li class="sub2"><i>Republique</i>, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>,
-      <a href="#Page_466">466</a>.</li>
-    <li class="sub2">Robert’s, <a href="#Page_81">81</a>, <a href="#Page_82">82</a>, <a href="#Page_83">83</a>.</li>
-    <li class="sub2"><i>Russie</i>, <a href="#Page_120">120</a>.</li>
-    <li class="sub2">Santos-Dumont’s, <a href="#Page_102">102–114</a>.</li>
-    <li class="sub2">Schwartz’s, <a href="#Page_99">99</a>, <a href="#Page_100">100</a>.</li>
-    <li class="sub2">steam, <a href="#Page_87">87</a>, <a href="#Page_89">89</a>.</li>
-    <li class="sub2">successful military, <a href="#Page_456">456</a>.</li>
-    <li class="sub2">two systems of, <a href="#Page_101">101</a>.</li>
-    <li class="sub2">types of, <a href="#Page_122">122</a>.</li>
-    <li class="sub2"><i>U. S. Military I</i>, <a href="#Page_138">138</a>, <a href="#Page_476">476</a>, <a href="#Page_477">477</a>.</li>
-    <li class="sub2"><i>Ville de Nancy</i>, <a href="#Page_124">124</a>, <a href="#Page_125">125</a>.</li>
-    <li class="sub2"><i>Ville de Paris</i>, <a href="#Page_120">120–123</a>, <a href="#Page_467">467–471</a>.</li>
-    <li class="sub2">voyage of across English channel, <a href="#Page_132">132</a>, <a href="#Page_136">136</a>, <a href="#Page_137">137</a>.</li>
-    <li class="sub2">in <i>Zeppelin</i>, <a href="#Page_153">153–156</a>.</li>
-    <li class="sub2"><i>Zeppelin IV</i>, explosion, <a href="#Page_157">157</a>, <a href="#Page_158">158</a>.</li>
-    <li class="sub2"><i>Zeppelin</i> passenger service, <a href="#Page_167">167–169</a>.</li>
-    <li class="sub2"><i>Zeppelin</i> type of, <a href="#Page_145">145–169</a>.</li>
-    <li class="sub2"><i>Zodiac</i> type of, <a href="#Page_127">127</a>, <a href="#Page_128">128</a>, <a href="#Page_129">129</a>.</li>
-    <li class="sub">passive:</li>
-    <li class="sub2">cabinet for lofty ascents in, <a href="#Page_71">71</a>, <a href="#Page_72">72</a>.</li>
-    <li class="sub2">Charles’ passenger, <a href="#Page_42">42</a>, <a href="#Page_43">43</a>.</li>
-    <li class="sub2">cruise of, from London to Weilburg, <a href="#Page_54">54</a>.</li>
-    <li class="sub2">dragon fire-inflated, <a href="#Page_20">20</a>.</li>
-    <li class="sub2">earliest conceptions of, <a href="#Page_18">18</a>, <a href="#Page_29">29</a>.</li>
-    <li class="sub2">earliest experiments with, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>, <a href="#Page_32">32</a>.</li>
-    <li class="sub2">early history of, <a href="#Page_29">29</a> <i>et seq.</i></li>
-    <li class="sub2">first coal gas, <a href="#Page_54">54</a>.</li>
-    <li class="sub2">first human passengers in, <a href="#Page_38">38</a>.</li>
-    <li class="sub2">first hydrogen, <a href="#Page_35">35</a>.</li>
-    <li class="sub2">first passengers in, <a href="#Page_37">37</a>.</li>
-    <li class="sub2">first scientific ascension in, <a href="#Page_44">44</a>, <a href="#Page_45">45</a>.</li>
-    <li class="sub2">Glashier’s observations in, <a href="#Page_64">64–70</a>.</li>
-    <li class="sub2">highest ascent of, <a href="#Page_69">69</a>, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>, <a href="#Page_72">72</a>.</li>
-    <li class="sub2">instruments and adjuncts to, <a href="#Page_76">76</a>, <a href="#Page_77">77</a>.</li>
-    <li class="sub2">largest hot air, <a href="#Page_48">48–50</a>.</li>
-    <li class="sub2"><span class="pagenum" id="Page_490">490</span>largest gas, <a href="#Page_70">70</a>, <a href="#Page_71">71</a>.</li>
-    <li class="sub2">longest voyage of, <a href="#Page_74">74</a>.</li>
-    <li class="sub2">modern spherical, <a href="#Page_75">75</a>.</li>
-    <li class="sub2">Nadar’s <i>Geant</i>, <a href="#Page_60">60</a>, <a href="#Page_61">61</a>.</li>
-    <li class="sub2">practical development of, <a href="#Page_54">54</a> <i>et seq</i>.</li>
-    <li class="sub2">principle of, <a href="#Page_18">18</a>.</li>
-    <li class="sub2">public inauguration of, <a href="#Page_33">33</a>, <a href="#Page_34">34</a>.</li>
-    <li class="sub2">recent improvements in, <a href="#Page_76">76</a>, <a href="#Page_77">77</a>.</li>
-    <li class="sub2">ripping panel of, <a href="#Page_74">74</a>, <a href="#Page_75">75</a>.</li>
-    <li class="sub2">sounding and pilot, <a href="#Page_72">72</a>.</li>
-    <li class="sub2">voyage across the Atlantic in, <a href="#Page_74">74</a>, <a href="#Page_75">75</a>.</li>
-    <li class="sub3">across the English channel in, <a href="#Page_50">50</a>, <a href="#Page_52">52</a>.</li>
-    <li class="sub3">Paris to Meaux in, <a href="#Page_61">61</a>, <a href="#Page_62">62</a>.</li>
-    <li class="sub3">Paris to Nienburg in, <a href="#Page_62">62</a>, <a href="#Page_63">63</a>.</li>
-    <li>Balsan, <a href="#Page_74">74</a>.</li>
-    <li>Baltimore aviation meet, <a href="#Page_319">319</a>.</li>
-    <li><i>Baltimore Sun</i>, <a href="#Page_319">319</a>.</li>
-    <li>Barometric pressure, <a href="#Page_363">363</a> <i>et seq.</i></li>
-    <li class="sub">distribution of, <a href="#Page_370">370–374</a>.</li>
-    <li class="sub">gradient of, <a href="#Page_370">370</a>.</li>
-    <li class="sub">high and low areas of, <a href="#Page_372">372</a>.</li>
-    <li class="sub">hygrometric features of, <a href="#Page_373">373</a>.</li>
-    <li class="sub">mechanical features of, <a href="#Page_373">373</a>, <a href="#Page_374">374</a>.</li>
-    <li class="sub">modifying conditions of, <a href="#Page_371">371</a>, <a href="#Page_373">373</a>.</li>
-    <li class="sub">surfaces and lines of equal, <a href="#Page_370">370</a>, <a href="#Page_371">371</a>.</li>
-    <li>Basenach, <a href="#Page_138">138</a>.</li>
-    <li>Baumgarten, <a href="#Page_99">99</a>.</li>
-    <li><i>Belgique</i>, the, <a href="#Page_129">129</a>.</li>
-    <li>Bell, A. G., <a href="#Page_194">194</a>, <a href="#Page_244">244</a>, <a href="#Page_264">264–267</a>.</li>
-    <li>Bell, Mrs. A. G., <a href="#Page_264">264</a>.</li>
-    <li>Belmont Park, <a href="#Page_310">310</a>, <a href="#Page_322">322</a>.</li>
-    <li>Bennett international contests, <a href="#Page_75">75</a>, <a href="#Page_292">292–301</a>, <a href="#Page_325">325</a>,
-      <a href="#Page_326">326</a>.</li>
-    <li>Berson, Professor, <a href="#Page_70">70</a>.</li>
-    <li>Betheny Plain, <a href="#Page_292">292</a>.</li>
-    <li>Bielovucic, Jean, <a href="#Page_313">313</a>.</li>
-    <li>Bigelow, Professor, <a href="#Page_412">412</a>, <a href="#Page_413">413</a>.</li>
-    <li>Biplane, <a href="#Page_174">174</a>, <a href="#Page_220">220</a>.</li>
-    <li>Birds, armed against airships, <a href="#Page_11">11</a>.</li>
-    <li class="sub">as men carriers, <a href="#Page_10">10</a>, <a href="#Page_11">11</a>, <a href="#Page_12">12</a>.</li>
-    <li class="sub">major limit of, <a href="#Page_11">11</a>, <a href="#Page_12">12</a>.</li>
-    <li>Bishop, Cortlandt Field, <a href="#Page_285">285</a>.</li>
-    <li>Black, <a href="#Page_29">29</a>.</li>
-    <li>Blanchard, <a href="#Page_15">15</a>, <a href="#Page_16">16</a>, <a href="#Page_18">18</a>, <a href="#Page_50">50</a>,
-      <a href="#Page_79">79</a>, <a href="#Page_80">80</a>.</li>
-    <li>Blériot, Louis, <a href="#Page_267">267–270</a>, <a href="#Page_286">286</a>, <a href="#Page_287">287</a>, <a href="#Page_290">290–292</a>,
-      <a href="#Page_299">299–300</a>, <a href="#Page_380">380–382</a>.</li>
-    <li>Bréguet, Louis, <a href="#Page_313">313</a>.</li>
-    <li>Brookins, Walter, <a href="#Page_309">309</a>, <a href="#Page_326">326</a>.</li>
-    <li>Brown, D. S., <a href="#Page_193">193</a>.</li>
-    <li>Bubbles, soap and varnish, <a href="#Page_30">30</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Calm belts, <a href="#Page_381">381</a>.</li>
-    <li>Cammerman, Lieutenant, <a href="#Page_314">314</a>.</li>
-    <li>Cardan, <a href="#Page_10">10</a>.</li>
-    <li>Catapult, <a href="#Page_240">240</a>, <a href="#Page_338">338</a>.</li>
-    <li>Cavallo, <a href="#Page_30">30</a>, <a href="#Page_31">31</a>.</li>
-    <li>Cavendish, <a href="#Page_29">29</a>.</li>
-    <li>Cayley, Sir George, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>.</li>
-    <li>Chanute, Octave, <a href="#Page_15">15</a>, <a href="#Page_181">181</a>, <a href="#Page_218">218–221</a>, <a href="#Page_245">245</a>,
-      <a href="#Page_250">250</a>, <a href="#Page_256">256</a>, <a href="#Page_260">260</a>.</li>
-    <li>Charles, <a href="#Page_35">35</a>.</li>
-    <li><i>Charlière</i>, <a href="#Page_42">42</a>.</li>
-    <li><i>Chauvière</i>, <a href="#Page_125">125</a>, <a href="#Page_136">136</a>, <a href="#Page_331">331</a>, <a href="#Page_339">339</a>.</li>
-    <li>Chavez, George, <a href="#Page_318">318</a>, <a href="#Page_319">319</a>.</li>
-    <li><i>Circuit de l’Est</i>, <a href="#Page_339">339</a>, <a href="#Page_331">331</a>.</li>
-    <li><i>Clément-Bayard</i>, the, <a href="#Page_123">123</a>, <a href="#Page_131">131–133</a>, <a href="#Page_456">456–459</a>.</li>
-    <li>Cody, S. F., <a href="#Page_305">305</a>.</li>
-    <li><i>Colonel Renard</i>, the, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>.</li>
-    <li><i>Compagnie General Transaerienne</i>, <a href="#Page_124">124</a>.</li>
-    <li>Control, three rudder system of, <a href="#Page_229">229–331</a>.</li>
-    <li>Coulomb, <a href="#Page_17">17</a>, <a href="#Page_18">18</a>.</li>
-    <li><i>Country Life</i>, <a href="#Page_321">321</a>.</li>
-    <li>Coxwell, <a href="#Page_64">64–70</a>.</li>
-    <li><span class="pagenum" id="Page_491">491</span>Critical temperature and pressure, <a href="#Page_351">351</a>.</li>
-    <li>Cross-country records, <a href="#Page_311">311–314</a>.</li>
-    <li>Curtiss, Glenn H., <a href="#Page_138">138</a>, <a href="#Page_264">264–266</a>, <a href="#Page_282">282</a>, <a href="#Page_284">284–286</a>,
-      <a href="#Page_294">294–300</a>, <a href="#Page_316">316</a>, <a href="#Page_317">317</a>, <a href="#Page_322">322</a>,
-      <a href="#Page_323">323</a>, <a href="#Page_481">481</a> <i>et seq.</i></li>
-    <li>Cyclone, frequency of, <a href="#Page_403">403</a>, <a href="#Page_404">404</a>.</li>
-    <li class="sub">motions and pressures in, <a href="#Page_395">395</a>, <a href="#Page_400">400</a>.</li>
-    <li class="sub">motive power of, <a href="#Page_395">395</a>.</li>
-    <li class="sub">nature of, <a href="#Page_394">394</a>.</li>
-    <li class="sub">progression of, <a href="#Page_401">401–403</a>.</li>
-    <li class="sub">stationary, <a href="#Page_403">403</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Daedalus, <a href="#Page_3">3</a>, <a href="#Page_4">4</a>, <a href="#Page_5">5</a>, <a href="#Page_6">6</a>.</li>
-    <li><i>Daily Mail</i>, London, <a href="#Page_314">314</a>.</li>
-    <li>Daimler engine, <a href="#Page_99">99</a>, <a href="#Page_150">150</a>.</li>
-    <li>Dante, J. B., <a href="#Page_13">13</a>, <a href="#Page_14">14</a>.</li>
-    <li>Dauberck, Dr. W., <a href="#Page_403">403</a>.</li>
-    <li>Da Vinci, <a href="#Page_8">8</a>, <a href="#Page_9">9</a>.</li>
-    <li>De Bacqueville, <a href="#Page_13">13</a>, <a href="#Page_14">14</a>.</li>
-    <li>Delagrange, Leon, <a href="#Page_261">261–263</a>.</li>
-    <li>Delcourt, Dupuis, <a href="#Page_100">100</a>.</li>
-    <li>De Laland, <a href="#Page_16">16</a>, <a href="#Page_18">18</a>.</li>
-    <li>De Lesseps, Count, <a href="#Page_327">327</a>, <a href="#Page_328">328</a>.</li>
-    <li>De Lome, Dupuis, <a href="#Page_91">91</a>, <a href="#Page_92">92</a>, <a href="#Page_93">93</a>.</li>
-    <li><i>Demoiselle</i> monoplanes, <a href="#Page_324">324</a>.</li>
-    <li>Déperdussin, <a href="#Page_339">339</a>.</li>
-    <li>Deutsche de la Meurthe, 120 259.</li>
-    <li>Dew point, <a href="#Page_358">358</a>.</li>
-    <li>Dientsbach, Carl, <a href="#Page_vii">vii</a>, <a href="#Page_164">164</a>.</li>
-    <li>Distance records, <a href="#Page_311">311–314</a>.</li>
-    <li>Doldrums, <a href="#Page_381">381</a>.</li>
-    <li>Doubleday, Page &amp; Co., <a href="#Page_478">478</a>.</li>
-    <li>Drift, defined, <a href="#Page_186">186</a>.</li>
-    <li>Dubonnet, <a href="#Page_312">312</a>.</li>
-    <li>Du Cros, Arthur, <a href="#Page_131">131</a>.</li>
-    <li>Dutrieu, Helene, <a href="#Page_321">321</a>.</li>
-    <li>Dynamic flyers, <a href="#Page_174">174</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Endurance records, <a href="#Page_311">311–314</a>.</li>
-    <li>Engine, Daimler, <a href="#Page_99">99</a>, <a href="#Page_150">150</a>, <a href="#Page_163">163</a>.</li>
-    <li class="sub">Gnome, <a href="#Page_312">312</a>.</li>
-    <li class="sub">Körting, <a href="#Page_139">139</a>.</li>
-    <li class="sub">Mercedes, <a href="#Page_140">140</a>.</li>
-    <li class="sub">Panhard-Levassor, <a href="#Page_136">136</a>.</li>
-    <li class="sub">Rénault, <a href="#Page_311">311</a>.</li>
-    <li class="sub">Vivinus, <a href="#Page_129">129</a>.</li>
-    <li><i>Engineering News</i>, <a href="#Page_435">435</a>.</li>
-    <li>English Channel flights, <a href="#Page_50">50–53</a>, <a href="#Page_56">56</a>, <a href="#Page_137">137</a>,
-      <a href="#Page_289">289–292</a>.</li>
-    <li>English military dirigibles, <a href="#Page_130">130–137</a>.</li>
-    <li><i>Eole</i>, <a href="#Page_223">223</a>.</li>
-    <li>Equator of balloon, <a href="#Page_76">76</a>.</li>
-    <li>Equilibrium, of angels, <a href="#Page_7">7</a>, <a href="#Page_8">8</a>.</li>
-    <li>Esnault-Pélterie, Robert, <a href="#Page_304">304</a>, <a href="#Page_314">314</a>, <a href="#Page_337">337</a>,
-      <a href="#Page_340">340</a>.</li>
-    <li><i>España</i>, the, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>, <a href="#Page_127">127</a>.</li>
-    <li>Espy, <a href="#Page_419">419</a>, <a href="#Page_420">420</a>.</li>
-    <li>Etrich, Igo, <a href="#Page_335">335</a>, <a href="#Page_336">336</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Fabre, <a href="#Page_332">332–335</a>.</li>
-    <li>Farman, Henri, <a href="#Page_259">259–264</a>, <a href="#Page_298">298</a>, <a href="#Page_303">303</a>, <a href="#Page_305">305</a>,
-      <a href="#Page_321">321</a>.</li>
-    <li class="sub">Maurice, <a href="#Page_305">305</a>, <a href="#Page_311">311</a>.</li>
-    <li>Federation Aëronautique International, <a href="#Page_322">322</a>, <a href="#Page_323">323</a>.</li>
-    <li>Fequant, Lieutenant, <a href="#Page_312">312</a>.</li>
-    <li>Ferber, Captain, <a href="#Page_256">256</a>.</li>
-    <li>Ferrel, W., <a href="#Page_356">356</a>, <a href="#Page_376">376–379</a>, <a href="#Page_397">397</a>, <a href="#Page_413">413</a>,
-      <a href="#Page_436">436</a>.</li>
-    <li>Fin, <a href="#Page_229">229</a>.</li>
-    <li><i>Flesselle</i>, the, <a href="#Page_48">48</a>, <a href="#Page_49">49</a>, <a href="#Page_50">50</a>.</li>
-    <li>Flexible balloons, <a href="#Page_122">122</a>, <a href="#Page_123">123</a>.</li>
-    <li>Fluctuating winds, <a href="#Page_427">427–439</a>.</li>
-    <li class="sub">cause of, <a href="#Page_436">436–438</a>.</li>
-    <li class="sub">impact of, <a href="#Page_435">435</a>, <a href="#Page_436">436</a>.</li>
-    <li>Flying machine, impossibility of, <a href="#Page_12">12</a>, <a href="#Page_17">17</a>.</li>
-    <li>Flying machine models, <a href="#Page_173">173</a> <i>et seq.</i></li>
-    <li class="sub">Abbe’s proposed, <a href="#Page_200">200</a>.</li>
-    <li class="sub">Cayley’s aërial glider, <a href="#Page_181">181</a>, <a href="#Page_182">182</a>.</li>
-    <li class="sub">Da Vinci’s helicopter, <a href="#Page_175">175</a>.</li>
-    <li class="sub">Da Vinci’s parachute, <a href="#Page_177">177</a>, <a href="#Page_178">178</a>.</li>
-    <li class="sub"><span class="pagenum" id="Page_492">492</span>Forlanini’s helicopter, <a href="#Page_200">200</a>.</li>
-    <li class="sub">Garnerin’s parachute, <a href="#Page_179">179</a>.</li>
-    <li class="sub">Hargrave’s, <a href="#Page_190">190</a>, <a href="#Page_191">191</a>.</li>
-    <li class="sub">Helicopter, <a href="#Page_198">198–201</a>.</li>
-    <li class="sub">Henson’s aëroplane, <a href="#Page_182">182–184</a>.</li>
-    <li class="sub">Henson and Stringfellow’s, <a href="#Page_184">184</a>, <a href="#Page_185">185</a>, <a href="#Page_187">187</a>.</li>
-    <li class="sub">Langley’s, <a href="#Page_192">192–197</a>.</li>
-    <li class="sub">Launoy and Bienvenu’s, <a href="#Page_198">198</a>, <a href="#Page_199">199</a>.</li>
-    <li class="sub">Lenormand’s parachute, <a href="#Page_177">177</a>, <a href="#Page_178">178</a>.</li>
-    <li class="sub">Paper traveling parachutes, <a href="#Page_180">180</a>, <a href="#Page_181">181</a>.</li>
-    <li class="sub">Penaud’s toy, <a href="#Page_188">188</a>.</li>
-    <li class="sub">Phillips’ aëroplane, <a href="#Page_191">191</a>, <a href="#Page_192">192</a>.</li>
-    <li class="sub">Phillips’ helicopter, <a href="#Page_199">199</a>.</li>
-    <li class="sub">Tatin’s aëroplane, <a href="#Page_189">189</a>.</li>
-    <li class="sub">Veranzio’s parachute, <a href="#Page_177">177</a>, <a href="#Page_178">178</a>.</li>
-    <li class="sub">Wenham’s aëroplane, <a href="#Page_185">185</a>, <a href="#Page_186">186</a>.</li>
-    <li class="sub">Zanonia Macrocarpa, <a href="#Page_180">180</a>.</li>
-    <li>Forbes, A. Holland, <a href="#Page_6">6</a>.</li>
-    <li>Forlanini, Professor, <a href="#Page_200">200</a>.</li>
-    <li>Fort Myer flights, <a href="#Page_138">138</a>, <a href="#Page_272">272</a>, <a href="#Page_275">275–281</a>.</li>
-    <li>Foulois, Lieutenant Benjamin, <a href="#Page_278">278</a>.</li>
-    <li><i>France</i>, the, <a href="#Page_93">93–97</a>.</li>
-    <li>Franklin, Benjamin, <a href="#Page_48">48</a>, <a href="#Page_446">446</a>.</li>
-    <li>Free air, composition of, <a href="#Page_349">349</a>.</li>
-    <li class="sub">conditions of precipitation in, <a href="#Page_351">351</a>, <a href="#Page_352">352</a>.</li>
-    <li class="sub">critical points of constituents of, <a href="#Page_351">351</a>.</li>
-    <li class="sub">dynamical properties of dry, <a href="#Page_353">353</a>, <a href="#Page_356">356</a>.</li>
-    <li class="sub">friction of, <a href="#Page_239">239</a>.</li>
-    <li class="sub">humidity and density of, <a href="#Page_358">358–361</a>.</li>
-    <li class="sub">kinds of expansion of, <a href="#Page_361">361</a>, <a href="#Page_362">362</a>.</li>
-    <li class="sub">properties of moist, <a href="#Page_357">357</a>, <a href="#Page_361">361</a>.</li>
-    <li>French Academy, <a href="#Page_17">17</a>, <a href="#Page_35">35</a>.</li>
-    <li>French dirigibles, <a href="#Page_88">88–129</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Garnerin, Jacques, <a href="#Page_179">179</a>.</li>
-    <li>Garros, <a href="#Page_324">324</a>.</li>
-    <li>Gasnier, Réné, <a href="#Page_340">340</a>.</li>
-    <li>German Airship Society, <a href="#Page_166">166</a>, <a href="#Page_167">167</a>.</li>
-    <li>German dirigibles, <a href="#Page_138">138–169</a>.</li>
-    <li>Giffard, Henri, <a href="#Page_71">71</a>, <a href="#Page_88">88</a>, <a href="#Page_89">89</a>, <a href="#Page_90">90</a>,
-      <a href="#Page_91">91</a>.</li>
-    <li>Glaisher, James, <a href="#Page_68">68–70</a>.</li>
-    <li>Gliding machines, <a href="#Page_203">203–221</a>, <a href="#Page_245">245–248</a>.</li>
-    <li>Gnome engine, <a href="#Page_312">312</a>, <a href="#Page_331">331</a>, <a href="#Page_340">340</a>.</li>
-    <li>Godard, <a href="#Page_62">62</a>, <a href="#Page_74">74</a>, <a href="#Page_129">129</a>.</li>
-    <li>Gold-beater skin balloons, <a href="#Page_30">30</a>, <a href="#Page_88">88</a>.</li>
-    <li>Grade, <a href="#Page_314">314</a>.</li>
-    <li>Grahame-White, Claude, <a href="#Page_315">315</a>, <a href="#Page_316">316</a>, <a href="#Page_319">319</a>, <a href="#Page_325">325</a>,
-      <a href="#Page_327">327</a>, <a href="#Page_328">328</a>.</li>
-    <li>Gravitational stability, <a href="#Page_233">233</a>.</li>
-    <li>Green, Charles, <a href="#Page_54">54</a>.</li>
-    <li>Gross, Major von, <a href="#Page_138">138</a>.</li>
-    <li>Gross dirigibles, <a href="#Page_138">138</a>, <a href="#Page_139">139</a>, <a href="#Page_140">140</a>.</li>
-    <li>Guide rope, or drag rope, <a href="#Page_56">56</a>, <a href="#Page_76">76</a>, <a href="#Page_111">111</a>, <a href="#Page_114">114</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Hailstorms and hailstones, <a href="#Page_415">415–419</a>.</li>
-    <li>Hamilton, C. K., <a href="#Page_313">313</a>.</li>
-    <li>Hammer, W. J., <a href="#Page_vii">vii</a>.</li>
-    <li>Hangar, <a href="#Page_126">126</a>.</li>
-    <li>Hänlein, <a href="#Page_98">98</a>, <a href="#Page_99">99</a>.</li>
-    <li>Hann, <a href="#Page_365">365</a>.</li>
-    <li>Hanriot, <a href="#Page_339">339</a>.</li>
-    <li>Hargrave, Lawrence, <a href="#Page_190">190</a>, <a href="#Page_191">191</a>, <a href="#Page_250">250</a>, <a href="#Page_260">260</a>,
-      <a href="#Page_339">339</a>.</li>
-    <li>Harmon, Clifford B., <a href="#Page_321">321</a>.</li>
-    <li>Hawley, A. R., <a href="#Page_75">75</a>.</li>
-    <li>Hazen, Prof. H. A., <a href="#Page_435">435</a>.</li>
-    <li>Hearne, <a href="#Page_131">131</a>, <a href="#Page_228">228</a>.</li>
-    <li>Helicopters, <a href="#Page_198">198–201</a>.</li>
-    <li>Helmholtz, Prof. Ludvig von, <a href="#Page_436">436–438</a>.</li>
-    <li>Henson, <a href="#Page_182">182–184</a>.</li>
-    <li>Herring, A. M., <a href="#Page_218">218–222</a>, <a href="#Page_245">245</a>, <a href="#Page_271">271</a>.</li>
-    <li>Holland, Robert, <a href="#Page_54">54</a>.</li>
-    <li><span class="pagenum" id="Page_493">493</span>Hopkinson, Francis, <a href="#Page_84">84</a>.</li>
-    <li>Horner, <a href="#Page_414">414</a>.</li>
-    <li>Hoxsey, Arch, <a href="#Page_309">309</a>, <a href="#Page_324">324</a>.</li>
-    <li>Huffaker, E. C., <a href="#Page_247">247</a>.</li>
-    <li>Hull, best forms of, <a href="#Page_88">88</a>, <a href="#Page_97">97</a>, <a href="#Page_98">98</a>, <a href="#Page_113">113</a>.</li>
-    <li class="sub">stiffening of, by internal pressure, <a href="#Page_83">83</a>, <a href="#Page_86">86</a>.</li>
-    <li>Humidity, absolute, <a href="#Page_359">359</a>.</li>
-    <li class="sub">percentage of, <a href="#Page_358">358</a>.</li>
-    <li>Humphreys, Dr. W. J., <a href="#Page_vii">vii</a>, <a href="#Page_349">349</a>, <a href="#Page_370">370</a>.</li>
-    <li>Hydro-aëroplanes, <a href="#Page_332">332–334</a>, <a href="#Page_481">481</a> <i>et seq.</i></li>
-    <li>Hydrogen balloon, invention of, <a href="#Page_29">29–31</a>, <a href="#Page_35">35</a>.</li>
-    <li class="sub">first ascent of, <a href="#Page_36">36</a>.</li>
-    <li>Hydrogen bubbles, <a href="#Page_29">29</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Icarus, <a href="#Page_3">3</a>, <a href="#Page_4">4</a>, <a href="#Page_5">5</a>.</li>
-    <li>Ice, launching from, <a href="#Page_265">265</a>.</li>
-    <li>Indian seed parachute, <a href="#Page_180">180</a>.</li>
-    <li>Inherent stability, <a href="#Page_229">229</a>.</li>
-    <li>Insolation, effect on density of air, <a href="#Page_364">364</a>.</li>
-    <li class="sub">quantity of, received, <a href="#Page_364">364–366</a>.</li>
-    <li>Isobaric lines and surfaces, <a href="#Page_371">371</a>.</li>
-    <li>Isothermal lines, surfaces, <a href="#Page_366">366</a>, <a href="#Page_367">367</a>.</li>
-    <li>Isothermal layer, <a href="#Page_370">370</a>.</li>
-    <li>Italian Aviation Society, <a href="#Page_318">318</a>.</li>
-    <li>Italian military dirigibles, <a href="#Page_130">130</a>.</li>
-    <li>&nbsp;</li>
-
-    <li><i>Jaune</i>, the, <a href="#Page_115">115</a>, <a href="#Page_116">116</a>.</li>
-    <li>Jefferson, Thomas, <a href="#Page_84">84</a>.</li>
-    <li>Jeffries, <a href="#Page_50">50</a>.</li>
-    <li>Johnstone, Ralph, <a href="#Page_309">309</a>, <a href="#Page_324">324</a>, <a href="#Page_329">329</a>.</li>
-    <li>Jullien, <a href="#Page_88">88</a>.</li>
-    <li>Julliot, Henri, <a href="#Page_115">115</a>, <a href="#Page_134">134</a>, <a href="#Page_136">136</a>.</li>
-    <li><i>June Bug</i>, the, <a href="#Page_266">266</a>, <a href="#Page_267">267</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Kai Kaoos, <a href="#Page_8">8</a>, <a href="#Page_9">9</a>, <a href="#Page_10">10</a>.</li>
-    <li>Kapferer, H., <a href="#Page_120">120</a>, <a href="#Page_294">294</a>.</li>
-    <li>Keel surface, <a href="#Page_120">120</a>.</li>
-    <li>Kinet, Daniel, <a href="#Page_312">312</a>.</li>
-    <li>Kinetic stability, <a href="#Page_233">233</a>.</li>
-    <li>Kite balloon, <a href="#Page_77">77</a>.</li>
-    <li>Körting, <a href="#Page_139">139</a>.</li>
-    <li>Krebs, Captain, <a href="#Page_93">93–97</a>.</li>
-    <li>Kress, Wilhelm, <a href="#Page_214">214</a>.</li>
-    <li>&nbsp;</li>
-
-    <li><i>La Belgique</i>, <a href="#Page_129">129</a>.</li>
-    <li><i>La España</i>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>, <a href="#Page_127">127</a>.</li>
-    <li><i>La Flesselle</i>, <a href="#Page_48">48</a>, <a href="#Page_49">49</a>, <a href="#Page_50">50</a>.</li>
-    <li><i>La France</i>, <a href="#Page_93">93–97</a>.</li>
-    <li>Lahm, Lieutenant Frank P., <a href="#Page_272">272</a>, <a href="#Page_277">277</a>.</li>
-    <li><i>La Liberté</i>, <a href="#Page_120">120</a>.</li>
-    <li>Lambert, Count de, <a href="#Page_273">273</a>, <a href="#Page_302">302</a>.</li>
-    <li>Lana, <a href="#Page_23">23</a>, <a href="#Page_24">24</a>.</li>
-    <li><i>La Nature</i>, <a href="#Page_312">312</a>.</li>
-    <li>Land-and-sea breezes, <a href="#Page_392">392</a>.</li>
-    <li>Landelle, G. de la, <a href="#Page_203">203</a>.</li>
-    <li>Langley, S. P., <a href="#Page_187">187</a>, <a href="#Page_192">192–197</a>, <a href="#Page_211">211</a>, <a href="#Page_231">231</a>,
-      <a href="#Page_232">232</a>, <a href="#Page_239">239–245</a>, <a href="#Page_251">251</a>, <a href="#Page_427">427</a>,
-      <a href="#Page_433">433</a>, <a href="#Page_434">434</a>, <a href="#Page_439">439</a>.</li>
-    <li><i>La Patrie</i>, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>, <a href="#Page_459">459–465</a>.</li>
-    <li><i>La République</i>, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>.</li>
-    <li><i>La Russie</i>, <a href="#Page_120">120</a>.</li>
-    <li>Latent heat of condensation, <a href="#Page_364">364</a>.</li>
-    <li>Lateral balance of aëroplane, <a href="#Page_229">229–231</a>.</li>
-    <li>Latham, Hubert, <a href="#Page_283">283</a>, <a href="#Page_288">288–290</a>, <a href="#Page_291">291</a>, <a href="#Page_319">319</a>,
-      <a href="#Page_320">320</a>, <a href="#Page_324">324</a>.</li>
-    <li>Launching an aëroplane, <a href="#Page_202">202</a>, <a href="#Page_230">230</a>, <a href="#Page_256">256</a>, <a href="#Page_258">258</a>,
-      <a href="#Page_259">259</a>, <a href="#Page_265">265</a>.</li>
-    <li>Launching methods, <a href="#Page_202">202</a>, <a href="#Page_240">240</a>, <a href="#Page_258">258</a>, <a href="#Page_259">259</a>,
-      <a href="#Page_265">265</a>.</li>
-    <li>Launoy and Bienvenu, <a href="#Page_198">198</a>, <a href="#Page_199">199</a>.</li>
-    <li>Laurens, <a href="#Page_314">314</a>.</li>
-    <li><i>La Ville de Paris</i>, <a href="#Page_120">120–123</a>.</li>
-    <li><i>Lebaudy</i>, the, <a href="#Page_116">116</a>, <a href="#Page_117">117</a>.</li>
-    <li>Le Blanc, Alfred, <a href="#Page_273">273</a>, <a href="#Page_290">290</a>, <a href="#Page_310">310</a>, <a href="#Page_313">313</a>,
-      <a href="#Page_326">326</a>, <a href="#Page_331">331</a>.</li>
-    <li><span class="pagenum" id="Page_494">494</span><i>Le Clément-Bayard</i>, <a href="#Page_123">123</a>, <a href="#Page_131">131–133</a>,
-      <a href="#Page_456">456–459</a>.</li>
-    <li><i>Le Colonel Renard</i>, <a href="#Page_124">124</a>, <a href="#Page_126">126</a>.</li>
-    <li>Lefebvre, <a href="#Page_293">293</a>.</li>
-    <li>Leganeaux, U. G., <a href="#Page_311">311</a>, <a href="#Page_319">319</a>.</li>
-    <li>Lenormand, Sebastien, <a href="#Page_177">177</a>, <a href="#Page_178">178</a>.</li>
-    <li>Levino, A. S., <a href="#Page_vii">vii</a>.</li>
-    <li>Lift, defined, <a href="#Page_186">186</a>.</li>
-    <li>Lilienthal, Otto, <a href="#Page_210">210–216</a>, <a href="#Page_250">250</a>.</li>
-    <li><i>London Daily Mail</i>, <a href="#Page_289">289</a>.</li>
-    <li>Loomis, <a href="#Page_402">402</a>, <a href="#Page_414">414</a>.</li>
-    <li>Lord Rayleigh, <a href="#Page_6">6</a>, <a href="#Page_427">427</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>McCurdy, J. A. D., <a href="#Page_264">264</a>.</li>
-    <li>MacMechen, <a href="#Page_164">164</a>.</li>
-    <li>Madison, James, <a href="#Page_84">84</a>.</li>
-    <li>Malecot, <a href="#Page_123">123</a>.</li>
-    <li>Maloney, D., <a href="#Page_251">251–255</a>.</li>
-    <li>Manley, Charles M., <a href="#Page_242">242</a>, <a href="#Page_245">245</a>, <a href="#Page_251">251</a>, <a href="#Page_285">285</a>.</li>
-    <li>Marconnet, Captain, <a href="#Page_312">312</a>.</li>
-    <li>Marey, Professor, <a href="#Page_427">427</a>.</li>
-    <li>Marvin, Prof. C. F., <a href="#Page_435">435</a>.</li>
-    <li>Mason, Monck, <a href="#Page_55">55</a>.</li>
-    <li>Mattullath, Hugo, <a href="#Page_231">231</a>, <a href="#Page_235">235–239</a>.</li>
-    <li>Maxim, Sir Hiram S., <a href="#Page_226">226–228</a>, <a href="#Page_245">245</a>.</li>
-    <li>Mendoza, <a href="#Page_19">19</a>.</li>
-    <li>Mercedes, <a href="#Page_140">140</a>.</li>
-    <li><i>Meteorological Journal</i>, <a href="#Page_435">435</a>.</li>
-    <li>Meusnier, General, <a href="#Page_85">85</a>, <a href="#Page_86">86</a>.</li>
-    <li>Michelin prize, <a href="#Page_273">273</a>, <a href="#Page_303">303</a>, <a href="#Page_311">311</a>, <a href="#Page_314">314</a>,
-      <a href="#Page_321">321</a>.</li>
-    <li>Milton, <a href="#Page_7">7</a>.</li>
-    <li>Moisant, John, <a href="#Page_31">31</a>, <a href="#Page_328">328</a>.</li>
-    <li>Monaco, Prince of, <a href="#Page_111">111</a>.</li>
-    <li>Monge, Marey, <a href="#Page_100">100</a>.</li>
-    <li>Monoplane, <a href="#Page_174">174</a>.</li>
-    <li>Monsoons, <a href="#Page_385">385–391</a>.</li>
-    <li>Montgolfier, <a href="#Page_29">29</a>, <a href="#Page_37">37</a>, <a href="#Page_50">50</a>.</li>
-    <li><i>Montgolfière</i>, <a href="#Page_42">42</a>.</li>
-    <li>Montgomery, Prof. J. J., <a href="#Page_251">251–255</a>, <a href="#Page_282">282</a>, <a href="#Page_339">339</a>.</li>
-    <li>Moore, Willis L., <a href="#Page_349">349</a>, <a href="#Page_405">405</a>, <a href="#Page_422">422</a>.</li>
-    <li>Morane, <a href="#Page_310">310</a>.</li>
-    <li><i>Morning Post</i>, <a href="#Page_131">131</a>, <a href="#Page_134">134–137</a>.</li>
-    <li>Motors, <a href="#Page_340">340</a>.</li>
-    <li class="sub">Antoinette, <a href="#Page_254">254</a>, <a href="#Page_258">258</a>.</li>
-    <li class="sub">Clément-Bayard, <a href="#Page_458">458</a>.</li>
-    <li class="sub">Daimler, <a href="#Page_99">99</a>, <a href="#Page_150">150</a>, <a href="#Page_163">163</a>.</li>
-    <li class="sub">Electrical, <a href="#Page_92">92</a>, <a href="#Page_95">95</a>.</li>
-    <li class="sub">Gnome, <a href="#Page_312">312</a>.</li>
-    <li class="sub">Körting, <a href="#Page_139">139</a>.</li>
-    <li class="sub">Mercedes, <a href="#Page_140">140</a>.</li>
-    <li class="sub">Panhard-Levassor, <a href="#Page_136">136</a>.</li>
-    <li class="sub">Rénault, <a href="#Page_311">311</a>.</li>
-    <li class="sub">steam, <a href="#Page_228">228</a>, <a href="#Page_234">234</a>.</li>
-    <li class="sub">Vivinus, <a href="#Page_129">129</a>.</li>
-    <li>Mouillard, L. P., <a href="#Page_206">206–209</a>.</li>
-    <li>Mountain-and-valley winds, <a href="#Page_293">293</a>.</li>
-    <li>Munn &amp; Co., <a href="#Page_481">481</a>.</li>
-    <li>Muscular flight, <a href="#Page_3">3–7</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Nadar’s balloon, the <i>Geant</i>, <a href="#Page_60">60</a>.</li>
-    <li><i>Nassau, Great Balloon of</i>, <a href="#Page_55">55</a>.</li>
-    <li><i>Nature</i>, <a href="#Page_217">217</a>, <a href="#Page_427">427</a>.</li>
-    <li>Nieuport, <a href="#Page_339">339</a>.</li>
-    <li>Northcliffe, Lord, <a href="#Page_305">305</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Olieslaegers, Jan, <a href="#Page_311">311</a>.</li>
-    <li>Orthopters, <a href="#Page_174">174</a>.</li>
-    <li>Ovid, <a href="#Page_3">3</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Panhard-Levassor, <a href="#Page_136">136</a>.</li>
-    <li>Parachutes, <a href="#Page_176">176–81</a>.</li>
-    <li>Parseval dirigibles, <a href="#Page_138">138</a>, <a href="#Page_140">140–143</a>.</li>
-    <li>Parseval, Major von, <a href="#Page_77">77</a>, <a href="#Page_138">138</a>.</li>
-    <li>Passive fliers, <a href="#Page_174">174</a>.</li>
-    <li><i>Patrie</i>, the, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>, <a href="#Page_459">459–465</a>.</li>
-    <li>Paulhan, Louis, <a href="#Page_284">284</a>, <a href="#Page_293">293–296</a>, <a href="#Page_305">305</a>, <a href="#Page_311">311</a>,
-      <a href="#Page_315">315</a>, <a href="#Page_316">316</a>, <a href="#Page_317">317</a>, <a href="#Page_324">324</a>,
-      <a href="#Page_325">325</a>.</li>
-    <li>Peltier, H., <a href="#Page_456">456</a>.</li>
-    <li>Pénaud, A., <a href="#Page_188">188</a>.</li>
-    <li>Pendular stability, <a href="#Page_233">233</a>.</li>
-    <li><i>Philadelphia Ledger</i>, the, <a href="#Page_313">313</a>.</li>
-    <li>Phillips, Horatio, <a href="#Page_191">191</a>, <a href="#Page_192">192</a>, <a href="#Page_199">199</a>.</li>
-    <li>Picardie military maneuvers, <a href="#Page_131">131</a>.</li>
-    <li><span class="pagenum" id="Page_495">495</span>Pilcher, <a href="#Page_216">216–218</a>, <a href="#Page_246">246</a>.</li>
-    <li>Polignac, Marquis de, <a href="#Page_301">301</a>.</li>
-    <li>Porter, Rufus, <a href="#Page_86">86</a>, <a href="#Page_87">87</a>.</li>
-    <li>Post, Augustus, <a href="#Page_6">6</a>, <a href="#Page_75">75</a>.</li>
-    <li>Power expended in flight, <a href="#Page_6">6</a>, <a href="#Page_7">7</a>.</li>
-    <li>Power flyers, <a href="#Page_174">174</a>.</li>
-    <li>Pressure, critical, <a href="#Page_351">351</a>.</li>
-    <li>atmospheric, <a href="#Page_370">370–374</a>.</li>
-    <li><i>Preussen</i>, the, <a href="#Page_70">70</a>.</li>
-    <li>Projectile stability, <a href="#Page_232">232</a>.</li>
-    <li>Propeller, Chauvière, <a href="#Page_125">125</a>, <a href="#Page_136">136</a>.</li>
-    <li>Puy de Dome, <a href="#Page_314">314</a>.</li>
-    <li>Pylons, <a href="#Page_292">292</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Rayleigh, Lord, <a href="#Page_6">6</a>, <a href="#Page_427">427</a>.</li>
-    <li>Records, aëroplane,</li>
-    <li class="sub">altitude, <a href="#Page_307">307–309</a>.</li>
-    <li class="sub">cross-country, <a href="#Page_311">311–314</a>.</li>
-    <li class="sub">distance, <a href="#Page_311">311</a>.</li>
-    <li class="sub">duration, <a href="#Page_311">311–314</a>.</li>
-    <li class="sub">load, <a href="#Page_311">311–314</a>.</li>
-    <li class="sub">speed, <a href="#Page_310">310–311</a>.</li>
-    <li><i>Red Wing</i>, <a href="#Page_265">265</a>, <a href="#Page_266">266</a>.</li>
-    <li>Relative humidity, <a href="#Page_358">358</a>.</li>
-    <li>Renard, Captain, <a href="#Page_93">93–97</a>, <a href="#Page_210">210</a>.</li>
-    <li><i>République</i>, the, <a href="#Page_115">115</a>, <a href="#Page_118">118</a>, <a href="#Page_119">119</a>.</li>
-    <li>Reye, Dr., <a href="#Page_414">414</a>.</li>
-    <li>Rheims aviation contests, <a href="#Page_292">292–301</a>.</li>
-    <li>Riedinger, August, <a href="#Page_140">140</a>.</li>
-    <li>Rigid balloons, <a href="#Page_122">122</a>.</li>
-    <li>Robert, <a href="#Page_42">42</a>, <a href="#Page_45">45</a>, <a href="#Page_81">81</a>, <a href="#Page_82">82</a>,
-      <a href="#Page_83">83</a>.</li>
-    <li>Roc, <a href="#Page_11">11</a>.</li>
-    <li>Rolls, Hon. C. S., <a href="#Page_321">321</a>.</li>
-    <li>Romain, <a href="#Page_52">52</a>.</li>
-    <li>Rotch, A. Lawrence, <a href="#Page_380">380–382</a>.</li>
-    <li>Rougier, <a href="#Page_302">302</a>.</li>
-    <li>Rozier, Pilâtre de, <a href="#Page_38">38</a>, <a href="#Page_52">52</a>.</li>
-    <li>Rudders, aëroplane, <a href="#Page_245">245</a>, <a href="#Page_246">246</a>.</li>
-    <li class="sub">three-torque, <a href="#Page_229">229–231</a>, <a href="#Page_247">247</a>, <a href="#Page_248">248</a>.</li>
-    <li>Ruskin, John, <a href="#Page_7">7</a>.</li>
-    <li><i>Russie</i>, the, <a href="#Page_120">120</a>.</li>
-    <li>Ryan, Allan A., <a href="#Page_327">327</a>.</li>
-    <li>Thomas F., <a href="#Page_327">327</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Sabathier, <a href="#Page_131">131</a>, <a href="#Page_132">132</a>.</li>
-    <li>Saddle bird, <a href="#Page_8">8</a>.</li>
-    <li>Saint-Marcq, Com. Le Clément, <a href="#Page_438">438</a>.</li>
-    <li>Sandt, Emile, <a href="#Page_153">153</a>.</li>
-    <li>Santos-Dumont, Alberto, <a href="#Page_102">102–114</a>, <a href="#Page_303">303</a>, <a href="#Page_324">324</a>,
-      <a href="#Page_356">356–359</a>.</li>
-    <li>Saturation, <a href="#Page_358">358</a>.</li>
-    <li>Scaliger, <a href="#Page_10">10</a>.</li>
-    <li>Schottus, <a href="#Page_19">19</a>.</li>
-    <li>Schwartz, <a href="#Page_99">99</a>, <a href="#Page_100">100</a>.</li>
-    <li><i>Scientific American</i>, <a href="#Page_86">86</a>, <a href="#Page_153">153</a>, <a href="#Page_443">443</a>,
-      <a href="#Page_481">481</a>.</li>
-    <li>Screw, da Vinci’s, <a href="#Page_176">176</a>.</li>
-    <li class="sub">metal, <a href="#Page_340">340</a>.</li>
-    <li class="sub">radial-arm, <a href="#Page_129">129</a>, <a href="#Page_242">242</a>, <a href="#Page_340">340</a>.</li>
-    <li class="sub">wooden, <a href="#Page_339">339</a>.</li>
-    <li>Selfridge, Lieutenant T., <a href="#Page_264">264</a>, <a href="#Page_265">265</a>.</li>
-    <li><i>Signal Corps Dirigible No. 1</i>, <a href="#Page_138">138</a>, <a href="#Page_476">476</a>, <a href="#Page_477">477</a>.</li>
-    <li>Signal Corps, U. S., <a href="#Page_vi">vi</a>, <a href="#Page_271">271</a>, <a href="#Page_272">272</a>, <a href="#Page_276">276–281</a>.</li>
-    <li>Signal Service, U. S., <a href="#Page_417">417–419</a>.</li>
-    <li>Sigsfeld, Captain von, <a href="#Page_77">77</a>.</li>
-    <li><i>Silver Dart</i>, <a href="#Page_305">305</a>.</li>
-    <li>Skin-friction, <a href="#Page_238">238</a>, <a href="#Page_239">239</a>.</li>
-    <li>Soaring, early attempts at, <a href="#Page_13">13</a>.</li>
-    <li class="sub">winds helpful to, <a href="#Page_303">303</a>, <a href="#Page_393">393</a>, <a href="#Page_403">403</a>,
-      <a href="#Page_431">431</a>, <a href="#Page_425">425–459</a>.</li>
-    <li>Society for the Study of Motor Air Ships, <a href="#Page_138">138</a>.</li>
-    <li>Sommer, Roger, <a href="#Page_284">284</a>, <a href="#Page_293">293</a>.</li>
-    <li>Sopwith, Thomas, <a href="#Page_314">314</a>.</li>
-    <li>Speed records, <a href="#Page_310">310</a>, <a href="#Page_311">311</a>.</li>
-    <li>Spratt, G. A., <a href="#Page_247">247</a>.</li>
-    <li>Squier, Major George Owen, <a href="#Page_279">279</a>, <a href="#Page_459">459</a>.</li>
-    <li>St. Louis tornado, <a href="#Page_412">412</a>, <a href="#Page_413">413</a>.</li>
-    <li>Stabilizing planes, <a href="#Page_86">86</a>.</li>
-    <li>Stability and steadiness, artificial, <a href="#Page_229">229–231</a>.</li>
-    <li class="sub">automatic, <a href="#Page_218">218</a>, <a href="#Page_220">220</a>, <a href="#Page_229">229</a>.</li>
-    <li class="sub">three-axial, <a href="#Page_229">229</a>, <a href="#Page_234">234</a>.</li>
-    <li>Statoscope, <a href="#Page_76">76</a>.</li>
-    <li><span class="pagenum" id="Page_496">496</span>Statue of Liberty Prize, <a href="#Page_325">325</a>.</li>
-    <li>Stringfellow, <a href="#Page_184">184</a>, <a href="#Page_185">185</a>, <a href="#Page_187">187</a>.</li>
-    <li>Surcouf, <a href="#Page_115">115</a>.</li>
-    <li>Süring, Dr., <a href="#Page_70">70</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Tabuteau, Maurice, <a href="#Page_311">311</a>.</li>
-    <li>Tasso, <a href="#Page_3">3</a>.</li>
-    <li>Tatin, Victor, <a href="#Page_189">189</a>.</li>
-    <li>Tellier monoplane, <a href="#Page_312">312</a>.</li>
-    <li>Temperature, critical, <a href="#Page_351">351</a>.</li>
-    <li class="sub">distribution of, <a href="#Page_366">366–370</a>.</li>
-    <li class="sub">gradient, <a href="#Page_367">367</a>.</li>
-    <li class="sub">vertical gradient, <a href="#Page_367">367–369</a>.</li>
-    <li>Temperature of the air, <a href="#Page_363">363</a> <i>et seq.</i></li>
-    <li>Teisserenc de Bort, <a href="#Page_380">380–382</a>.</li>
-    <li><i>The New York Times</i>, <a href="#Page_313">313</a>.</li>
-    <li>Three-rudder principle, <a href="#Page_229">229–232</a>.</li>
-    <li>Thunderstorms, genesis and propagation of, <a href="#Page_423">423</a>, <a href="#Page_424">424</a>.</li>
-    <li class="sub">nature of, <a href="#Page_422">422</a> <i>et seq.</i></li>
-    <li>Tidswell, Ella, <a href="#Page_216">216</a>.</li>
-    <li>Tissandier, Gaston, <a href="#Page_273">273</a>, <a href="#Page_283">283</a>, <a href="#Page_293">293</a>.</li>
-    <li>Tornadoes, bursting of, <a href="#Page_419">419–420</a> <i>et seq.</i></li>
-    <li class="sub">destructive power of, 409, <a href="#Page_410">410</a>.</li>
-    <li class="sub">dry, <a href="#Page_420">420</a>, <a href="#Page_421">421</a>.</li>
-    <li class="sub">dynamics of, <a href="#Page_406">406–409</a>.</li>
-    <li class="sub">genesis of, <a href="#Page_405">405–406</a>.</li>
-    <li class="sub">hail and snow, <a href="#Page_415">415–419</a>.</li>
-    <li class="sub">misty, <a href="#Page_411">411</a> <i>et seq.</i></li>
-    <li class="sub">nature of, <a href="#Page_404">404</a>.</li>
-    <li class="sub">sections of, <a href="#Page_409">409–417</a>.</li>
-    <li>Tractional balance, <a href="#Page_254">254</a>.</li>
-    <li>Trade-winds and antitrade, <a href="#Page_380">380–383</a>.</li>
-    <li>Transatlantic voyages, <a href="#Page_74">74</a>, <a href="#Page_75">75</a>, <a href="#Page_381">381</a>,
-      <a href="#Page_383">383</a>.</li>
-    <li>Triplanes, <a href="#Page_175">175</a>.</li>
-    <li>Types of flyers, <a href="#Page_174">174</a>.</li>
-    <li class="sub">balloons, <a href="#Page_122">122</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>United States Signal Corps, <a href="#Page_vi">vi</a>, <a href="#Page_271">271</a>, <a href="#Page_272">272</a>, <a href="#Page_276">276–281</a>.</li>
-    <li>United States War Department, <a href="#Page_138">138</a>, <a href="#Page_196">196</a>, <a href="#Page_271">271</a>,
-      <a href="#Page_272">272</a>, <a href="#Page_275">275–281</a>.</li>
-    <li>United States Weather Bureau, <a href="#Page_vi">vi</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Vacuum balloon, <a href="#Page_18">18</a>, <a href="#Page_24">24</a>, <a href="#Page_25">25</a>, <a href="#Page_443">443–445</a>.</li>
-    <li>Van der Born, <a href="#Page_312">312</a>.</li>
-    <li>Varnish bubbles, <a href="#Page_30">30</a>.</li>
-    <li>Vaulx, Count de la, <a href="#Page_74">74</a>, <a href="#Page_127">127</a>, <a href="#Page_129">129</a>.</li>
-    <li>Veranzio, Fauste, <a href="#Page_177">177</a>.</li>
-    <li><i>Ville de Nancy</i>, the, <a href="#Page_124">124</a>, <a href="#Page_125">125</a>.</li>
-    <li><i>Ville de Paris</i>, the, <a href="#Page_120">120–123</a>.</li>
-    <li>Vivinus, <a href="#Page_129">129</a>.</li>
-    <li>Voisin, <a href="#Page_259">259</a>, <a href="#Page_267">267</a>, <a href="#Page_313">313</a>.</li>
-    <li>Von Bezold, <a href="#Page_424">424</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Waterspouts, analysis of St. Louis, <a href="#Page_412">412</a>, <a href="#Page_413">413</a>.</li>
-    <li class="sub">nature of, <a href="#Page_411">411</a> <i>et seq.</i></li>
-    <li>Weiller prize, <a href="#Page_314">314</a>.</li>
-    <li>Wellman, Walter, <a href="#Page_25">25</a>, <a href="#Page_75">75</a>, <a href="#Page_383">383</a>.</li>
-    <li>Wenham, <a href="#Page_185">185</a>, <a href="#Page_186">186</a>, <a href="#Page_245">245</a>.</li>
-    <li>Weyman, <a href="#Page_314">314</a>, <a href="#Page_331">331</a>.</li>
-    <li><i>White Wing</i>, the, <a href="#Page_266">266</a>.</li>
-    <li>Wilkins, <a href="#Page_10">10</a>.</li>
-    <li>Winans, Ross, <a href="#Page_320">320</a>.</li>
-    <li>Wind gusts, distribution of, <a href="#Page_425">425</a>, <a href="#Page_426">426</a>.</li>
-    <li class="sub">energy of, <a href="#Page_435">435</a>, <a href="#Page_436">436</a>.</li>
-    <li class="sub">instrumental study of, <a href="#Page_427">427–459</a>.</li>
-    <li class="sub">nature of, <a href="#Page_425">425</a> <i>et seq.</i></li>
-    <li class="sub">soaring value of, <a href="#Page_426">426</a>, <a href="#Page_427">427</a>, <a href="#Page_439">439</a>.</li>
-    <li class="sub">sustaining force of, <a href="#Page_426">426</a>.</li>
-    <li>Winds, ascending trend of, <a href="#Page_211">211</a>.</li>
-    <li class="sub">cause of periodic, <a href="#Page_383">383</a>.</li>
-    <li class="sub">cyclonic, <a href="#Page_394">394</a> <i>et seq.</i></li>
-    <li class="sub">diurnal, <a href="#Page_392">392–393</a>.</li>
-    <li class="sub">dry whirl, <a href="#Page_420">420</a>, <a href="#Page_421">421</a>.</li>
-    <li class="sub">fluctuations of, <a href="#Page_427">427–439</a>.</li>
-    <li class="sub">general cause of, <a href="#Page_363">363</a>, <a href="#Page_364">364</a>.</li>
-    <li class="sub">kinds of permanent, <a href="#Page_380">380</a>.</li>
-    <li class="sub"><span class="pagenum" id="Page_497">497</span>kinds of periodic, <a href="#Page_383">383</a>.</li>
-    <li class="sub">monsoon, <a href="#Page_385">385</a>, <a href="#Page_391">391</a>.</li>
-    <li class="sub">nonperiodic, <a href="#Page_394">394</a> <i>et seq.</i></li>
-    <li class="sub">nonvortical, <a href="#Page_422">422</a> <i>et seq.</i></li>
-    <li class="sub">permanent and periodic, <a href="#Page_376">376</a> <i>et seq.</i></li>
-    <li class="sub">prevailing westerlies, <a href="#Page_380">380</a>, <a href="#Page_382">382</a>, <a href="#Page_383">383</a>.</li>
-    <li class="sub">trade-winds and antitrade, <a href="#Page_380">380</a>, <a href="#Page_381">381</a>.</li>
-    <li class="sub">useful for voyages, <a href="#Page_381">381</a>, <a href="#Page_383">383</a>.</li>
-    <li class="sub">in soaring, <a href="#Page_303">303</a>, <a href="#Page_393">393</a>, <a href="#Page_403">403</a>, <a href="#Page_421">421</a>,
-      <a href="#Page_425">425–439</a>.</li>
-    <li>Wise, John, <a href="#Page_73">73</a>, <a href="#Page_74">74</a>, <a href="#Page_383">383</a>, <a href="#Page_415">415</a>,
-      <a href="#Page_416">416</a>.</li>
-    <li>Wölfert, <a href="#Page_99">99</a>.</li>
-    <li><i>World</i>, the New York, <a href="#Page_313">313</a>, <a href="#Page_316">316</a>.</li>
-    <li>Wright brothers, <a href="#Page_245">245–251</a>, <a href="#Page_270">270–282</a>, <a href="#Page_309">309</a>, <a href="#Page_324">324</a>,
-      <a href="#Page_326">326</a>, <a href="#Page_329">329</a>, <a href="#Page_338">338</a>, <a href="#Page_478">478</a>.</li>
-    <li>Wynmalen, Henri, <a href="#Page_321">321</a>.</li>
-    <li>&nbsp;</li>
-
-    <li>Zahm, <a href="#Page_30">30</a>, <a href="#Page_97">97</a>, <a href="#Page_113">113</a>, <a href="#Page_221">221</a>,
-      <a href="#Page_229">229–231</a>, <a href="#Page_239">239</a>, <a href="#Page_245">245</a>, <a href="#Page_334">334</a>,
-      <a href="#Page_427">427–432</a>, <a href="#Page_443">443</a>.</li>
-    <li>Zanonia Macrocarpa, <a href="#Page_180">180</a>.</li>
-    <li>Zeppelin, Count Ferdinand von, <a href="#Page_102">102</a>.</li>
-    <li>Zeppelin Airship Construction Co., <a href="#Page_158">158</a>, <a href="#Page_161">161</a>.</li>
-    <li>Zeppelin dirigibles, <a href="#Page_145">145</a>, <a href="#Page_169">169</a>.</li>
-    <li>Zodiac balloons, <a href="#Page_127">127</a>, <a href="#Page_128">128</a>, <a href="#Page_129">129</a>.</li>
-  </ul>
-
-  <div class="footnotes">
-    <h4>FOOTNOTES:</h4>
-
-    <div class="footnote">
-      <p><a id="Footnote_1" href="#FNanchor_1"><span class="label">[1]</span></a> With apologies to the California professor who will ride
-        on wings worked by muscular force alone.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_2" href="#FNanchor_2"><span class="label">[2]</span></a> Mr. A. Holland Forbes and Mr. Augustus Post, in the
-        international balloon race of 1908, used a balloon having too long a
-        neck, thus causing such pressure at its top as to burst the bag. A
-        dreadful plunge ensued, landing them on a house, but without injury,
-        as the netting and collapsed bag dampened their speed of fall. It is
-        reported that they crashed through the skylight, and that the lady of
-        the house regretted not being there to receive them.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_3" href="#FNanchor_3"><span class="label">[3]</span></a> <i>Mechanical Principles of Flight.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_4" href="#FNanchor_4"><span class="label">[4]</span></a> The reader may like to know that the basis of so much
-        confidence was that ancient Euclidean theorem connecting the surfaces
-        and volumes of similar figures with certain powers of their homologous
-        linear dimensions.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_5" href="#FNanchor_5"><span class="label">[5]</span></a> The writer has made hydrogen-inflated varnish bubbles
-        a foot in diameter which ascended swiftly to the ceiling; also,
-        air-inflated varnish bubbles a foot and a half in diameter which lasted
-        an hour. These, if suitably heated, may be made to ascend; but this
-        experiment is more difficult.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_6" href="#FNanchor_6"><span class="label">[6]</span></a> Both had studied science in college. Stephen was
-        an accomplished architect; Joseph, the author of many important
-        inventions, among others the common lamp chimney, the hydraulic press,
-        etc.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_7" href="#FNanchor_7"><span class="label">[7]</span></a> A long patch on the balloon that can be ripped open for
-        the sudden release of gas.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_8" href="#FNanchor_8"><span class="label">[8]</span></a> The equator of such a balloon is its horizontal great
-        circle.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_9" href="#FNanchor_9"><span class="label">[9]</span></a> A similar suggestion was made by Thomas Jefferson in a
-        letter to Prof. James Madison, and dated from Paris in 1785: “I went
-        some time ago to see a machine which offers something new. A man had
-        applied to a light boat a very large screw, the thread of which was
-        a thin plate, two feet broad, applied by its edge spirally around a
-        small axis. It somewhat resembled a bottle brush, if you will suppose
-        the hairs of the bottle brush joining together, and forming a spiral
-        plane. This, turned on its axis in the air, carried the vessel across
-        the Seine. It is, in fact a screw which takes hold of the air and draws
-        itself along by it; losing, indeed, much of its effort by the yielding
-        nature of the body it lays hold of to pull itself on by. I think it may
-        be applied in the water with much greater effect and to very useful
-        purposes. Perhaps it may be used also for the balloon.”</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_10" href="#FNanchor_10"><span class="label">[10]</span></a> <i>La Navigation Aerienne</i>, Gaston Tissandier.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_11" href="#FNanchor_11"><span class="label">[11]</span></a> The motive power equals the product of the speed and
-        resistance. But in the assumed case, the speed is doubled and the
-        resistance quadrupled; hence, the power required is eightfold.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_12" href="#FNanchor_12"><span class="label">[12]</span></a> Santos-Dumont, <i>My Airships</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_13" href="#FNanchor_13"><span class="label">[13]</span></a> m<sup>3</sup> signifies cubic meters. One cubic meter equals
-        35.3166 cubic feet.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_14" href="#FNanchor_14"><span class="label">[14]</span></a> Hangar, an airship harbor, or garage.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_15" href="#FNanchor_15"><span class="label">[15]</span></a> Aëronat, an airship of the lighter-than-air kind.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_16" href="#FNanchor_16"><span class="label">[16]</span></a> Hearne, <i>Airships in Peace and War</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_17" href="#FNanchor_17"><span class="label">[17]</span></a> <i>Over Sea by Air-Ship</i>, MacMechen and Dienstbach, <i>The
-          Century</i>, May, 1910.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_18" href="#FNanchor_18"><span class="label">[18]</span></a> A mathematical argument against this device is presented
-        in Appendix I.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_19" href="#FNanchor_19"><span class="label">[19]</span></a> It is commonly reported by navigators that the albatross
-        “sports in the tempest” on unbeating pinions; but it may be questioned
-        whether any bird can make headway against the swiftest winds.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_20" href="#FNanchor_20"><span class="label">[20]</span></a> The “drift” and “lift” are the components of surface
-        wind-pressure respectively in the direction of flight and at right
-        angles to it.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_21" href="#FNanchor_21"><span class="label">[21]</span></a> The tandem monoplane, or two lifting planes arranged in
-        tandem, was invented by D. S. Brown and exhibited to the Aëronautical
-        Society of Great Britain in 1873.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_22" href="#FNanchor_22"><span class="label">[22]</span></a> This gasoline aëroplane model was previously tested in
-        private many times, both with single surface wings, and with superposed
-        surfaces.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_23" href="#FNanchor_23"><span class="label">[23]</span></a> Abbe, <i>Helicopters for Aërial Research</i>, <i>Aëronautics</i>,
-        Feb. 1909.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_24" href="#FNanchor_24"><span class="label">[24]</span></a> <i>L’Empire de l’Air.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_25" href="#FNanchor_25"><span class="label">[25]</span></a> <i>Progress in Flying Machines</i>, Chanute.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_26" href="#FNanchor_26"><span class="label">[26]</span></a> The air rises with increased temperature, hence with
-        increased volume displacement, thus causing the wind in general to have
-        a slightly ascending trend.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_27" href="#FNanchor_27"><span class="label">[27]</span></a> <i>Aëronautical Annual, 1897.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_28" href="#FNanchor_28"><span class="label">[28]</span></a> Ella Tidswell, <i>The Aëronautical Journal</i>, July, 1909.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_29" href="#FNanchor_29"><span class="label">[29]</span></a> W. J. S. Lockyer, <i>Nature</i>, August 12, 1897.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_30" href="#FNanchor_30"><span class="label">[30]</span></a> Wenham used superposed planes, Stringfellow superposed
-        planes trussed by vertical rods and diagonal wires, Phillips,
-        Lilienthal and Hargrave superposed arched surfaces.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_31" href="#FNanchor_31"><span class="label">[31]</span></a> See <i>Aëronautic Annual</i>, 1896.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_32" href="#FNanchor_32"><span class="label">[32]</span></a> <i>Aërial Warfare</i>, Hearne, p. 77.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_33" href="#FNanchor_33"><span class="label">[33]</span></a> Published by the <i>American Engineer and Railway Journal.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_34" href="#FNanchor_34"><span class="label">[34]</span></a> This kind of automatic stability may be called inherent
-        stability.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_35" href="#FNanchor_35"><span class="label">[35]</span></a> Models embodying the above devices had been made and
-        flown by the writer some years previously; but aside from these it is
-        obvious that a Phillips’s aëroplane and other kinds can be effectively
-        controlled in flight by the above-proposed three-torque system.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_36" href="#FNanchor_36"><span class="label">[36]</span></a> This idea was later materialized in Langley’s gasoline
-        biplane.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_37" href="#FNanchor_37"><span class="label">[37]</span></a> The means for balancing here suggested in italics was
-        claimed some years later in Mr. Hugo Mattullath’s patent application in
-        which the inventor had the assistance of the present writer.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_38" href="#FNanchor_38"><span class="label">[38]</span></a> A nearly equivalent vertical surface was used in Dr.
-        Langley’s large “aërodrome.” It was a wind-vane rudder placed well
-        below and to the rear of the centroid, to be used in turning corners.
-        The pressure on this rudder would tilt the aëroplane toward the center
-        of curvature of the path, and turn it about the vertical axis, but
-        would conspire with the centrifugal force. If placed above and forward,
-        it would give the desired moments, but oppose the centrifugal force.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_39" href="#FNanchor_39"><span class="label">[39]</span></a> He died of apoplexy, January 31, 1902.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_40" href="#FNanchor_40"><span class="label">[40]</span></a> The first flights were to be made from the water.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_41" href="#FNanchor_41"><span class="label">[41]</span></a> It can be shown that the angle of flight requiring the
-        least motive power is that which makes the wing resistance, or drift,
-        three fourths of the entire resistance to progression.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_42" href="#FNanchor_42"><span class="label">[42]</span></a> <i>Atmospheric Resistance on Even Surfaces</i>, by A. F. Zahm,
-        <i>Phil. Soc. Washington</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_43" href="#FNanchor_43"><span class="label">[43]</span></a> The term “aërodrome” is now commonly applied to an
-        aviation field.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_44" href="#FNanchor_44"><span class="label">[44]</span></a> On August 25, 1909, Louis Paulhan, in the aviation
-        contest at Rheims, flew 82 miles in 2 hours, 43 minutes and 24 seconds,
-        preserving his lateral balance without the aid of torsion-wing
-        mechanism and in a turbulent atmosphere.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_45" href="#FNanchor_45"><span class="label">[45]</span></a> <i>Aërial Locomotion</i>, A. G. Bell, Washington Academy of
-        Science, March 4, 1907.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_46" href="#FNanchor_46"><span class="label">[46]</span></a> The Wrights in 1910 adopted the rear horizontal and
-        vertical rudder, thus returning to the design of their predecessors.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_47" href="#FNanchor_47"><span class="label">[47]</span></a> On July 18, 1905.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_48" href="#FNanchor_48"><span class="label">[48]</span></a> These glides were abandoned as too dangerous and
-        roundabout, in favor of direct tentative flights with a motor.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_49" href="#FNanchor_49"><span class="label">[49]</span></a> Falling weights pulling a cord that accelerates the
-        aëroplane at starting.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_50" href="#FNanchor_50"><span class="label">[50]</span></a> <i>Present Status of Military Aëronautics</i>, <i>Journal of the
-          American Society of American Engineers</i>, December, 1908.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_51" href="#FNanchor_51"><span class="label">[51]</span></a> On September 18, 1906, Montgomery received a U. S.
-        patent on an aëroplane having curved wings and three-rudder control,
-        the Wright brothers having on May 22, 1906, received a patent on an
-        aëroplane having normally flat wings and three-rudder control.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_52" href="#FNanchor_52"><span class="label">[52]</span></a> The daring aviator escaped without a scratch, but his
-        propeller and running gear were damaged slightly.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_53" href="#FNanchor_53"><span class="label">[53]</span></a> This was an official record, but Brookins had flown 4939
-        feet high, at Indianapolis, on June 17th.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_54" href="#FNanchor_54"><span class="label">[54]</span></a> This record was made with an uncalibrated barograph, and
-        hence was unofficial and unaccepted as a world’s record.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_55" href="#FNanchor_55"><span class="label">[55]</span></a> The present writer, in his paper quoted on page 229,
-        pointed out the equilibrative and steadying quality of torsionally
-        elastic wings, and some years previously had proved this by gliding
-        models having sustainers with flexible rear margins.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_56" href="#FNanchor_56"><span class="label">[56]</span></a> The whole water vapor in the atmosphere of our latitude
-        in summer is equivalent to about one inch of rainfall.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_57" href="#FNanchor_57"><span class="label">[57]</span></a> Computed by W. J. Humphreys for Moore’s <i>Descriptive
-          Meteorology</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_58" href="#FNanchor_58"><span class="label">[58]</span></a> Ferrel, <i>Popular Treatise on Winds</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_59" href="#FNanchor_59"><span class="label">[59]</span></a> Solar radiation received by the earth.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_60" href="#FNanchor_60"><span class="label">[60]</span></a> W. J. Humphreys, <i>Astro. Phys. Journ.</i>, January, 1909.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_61" href="#FNanchor_61"><span class="label">[61]</span></a> An isobar is a line of intersection of an isobaric
-        surface with a water level surface at any altitude.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_62" href="#FNanchor_62"><span class="label">[62]</span></a> <i>A Popular Treatise on the Winds.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_63" href="#FNanchor_63"><span class="label">[63]</span></a> <i>The Conquest of the Air.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_64" href="#FNanchor_64"><span class="label">[64]</span></a> By this current John Wise, in 1870, and Walter Wellman,
-        in 1910, proposed to voyage across the Atlantic; Wise in a free
-        balloon, Wellman in a motor balloon with drag rope. See pp. 74, 75.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_65" href="#FNanchor_65"><span class="label">[65]</span></a> It is reported that once during the month of August the
-        rainfall totaled thirty-two feet; and it is believed that the annual
-        fall exceeds fifty feet.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_66" href="#FNanchor_66"><span class="label">[66]</span></a> The “eye” is most noticeable at sea, where the cyclones
-        are more symmetrical, and particularly in lower latitudes, where they
-        are more concentrated.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_67" href="#FNanchor_67"><span class="label">[67]</span></a> The destructive one that visited Galveston in 1900 is a
-        well-known example.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_68" href="#FNanchor_68"><span class="label">[68]</span></a> <i>Contributions to Meteorology.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_69" href="#FNanchor_69"><span class="label">[69]</span></a> Dr. W. Dauberck, <i>Met. Zeitschrift</i>, April, 1866.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_70" href="#FNanchor_70"><span class="label">[70]</span></a> Moore’s <i>Meteorology</i>, p. 164.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_71" href="#FNanchor_71"><span class="label">[71]</span></a> Von Bezold, on the <i>Thermodynamics of the Atmosphere</i>.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_72" href="#FNanchor_72"><span class="label">[72]</span></a> Chanute, <i>Aeronautical Annual</i>, 1897, p. 101.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_73" href="#FNanchor_73"><span class="label">[73]</span></a> <i>Nature</i>, April 5, 1883.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_74" href="#FNanchor_74"><span class="label">[74]</span></a> <i>Vol des Oiseaux.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_75" href="#FNanchor_75"><span class="label">[75]</span></a> <i>Internal Work of the Wind.</i></p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_76" href="#FNanchor_76"><span class="label">[76]</span></a> <i>Engineering News</i>, December 13, 1890.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_77" href="#FNanchor_77"><span class="label">[77]</span></a> <i>Meteorological Journal</i>, November, 1891.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_78" href="#FNanchor_78"><span class="label">[78]</span></a> On <i>Atmospheric Movements</i> (Abbe’s translation).</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_79" href="#FNanchor_79"><span class="label">[79]</span></a> From <i>Scientific American</i>, March 13, 1909, by permission
-        of Munn &amp; Co.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_80" href="#FNanchor_80"><span class="label">[80]</span></a> For a fuller account of this fine airship see H.
-        Peltier’s article in <i>L’Aérophile</i>, December 1, 1910.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_81" href="#FNanchor_81"><span class="label">[81]</span></a> This description and the following are from <i>Present
-          Status of Military Aëronautics</i>, by Major G. O. Squier.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_82" href="#FNanchor_82"><span class="label">[82]</span></a> From <i>Navigating the Air</i>, by permission of Doubleday,
-        Page &amp; Co.</p>
-    </div>
-
-    <div class="footnote">
-      <p><a id="Footnote_83" href="#FNanchor_83"><span class="label">[83]</span></a> From <i>Scientific American</i> of March 4, 1911, by
-        permission of Munn &amp; Co.</p>
-    </div>
-  </div>
-
-  <div class="transnote mt10">
-    <p class="large"><b>Transcriber’s Notes:</b></p>
-    <p>Redundant title page has been removed.</p>
-    <p>Blank pages have been removed.</p>
-    <p>Silently corrected typographical errors.</p>
-  </div>
-
-
-
-
-
-
-
-
-<pre>
-
-
-
-
-
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