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+The Project Gutenberg EBook of Scientific American Supplement, No. 433,
+April 19, 1884, by Various
+
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+Title: Scientific American Supplement, No. 433, April 19, 1884
+
+Author: Various
+
+Release Date: October, 2005 [EBook #9076]
+[Yes, we are more than one year ahead of schedule]
+[This file was first posted on September 3, 2003]
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+Edition: 10
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+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THE PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN SUP., NO. 433 ***
+
+
+
+
+Produced by J. Niehof, D. Kretz, J. Sutherland, and Distributed Proofreaders
+
+
+
+
+[Illustration]
+
+
+
+
+SCIENTIFIC AMERICAN SUPPLEMENT NO. 433
+
+
+
+
+NEW YORK, APRIL 19, 1884
+
+Scientific American Supplement. Vol. XVII, No. 433.
+
+Scientific American established 1845
+
+Scientific American Supplement, $5 a year.
+
+Scientific American and Supplement, $7 a year.
+
+
+       *       *       *       *       *
+
+TABLE OF CONTENTS.
+
+I.    CHEMISTRY, METALLURGY, ETC.--New Analogy between
+      Solids, Liquids, and Gases.
+
+      Hydrogen Amalgam.
+
+      Treatment of Ores by Electrolysis.--By M. KILIANI.
+
+II.   ENGINEERING, AND MECHANICS.--Electric Railway at Vienna.--With
+      engraving.
+
+      Instruction in Mechanical Engineering.--Technical and trade
+      education.--A course of study sketched out.--By Prof. R.H.
+      THURSTON.
+
+      Improved Double Boiler.--3 figures.
+
+      The Gardner Machine Gun.--With three engravings showing the
+      single barrel, two barrel, and five barrel guns.
+
+      Climbing Tricycles.
+
+      Submarine Explorations.--Voyage of the Talisman.--The Thibaudier
+      sounding apparatus.--With map, diagrams, and engravings.
+
+      Jamieson's Cable Grapnel.--With engraving.
+
+      A Threaded Set Collar.
+
+III.  TECHNOLOGY.--Wretched Boiler Making.
+
+      Pneumatic Malting.--With full description of the most improved
+      methods and apparatus.--Numerous figures.
+
+      Reducing and Enlarging Plaster Casts.
+
+      Stripping the Film from Gelatine Negatives.
+
+IV.   ELECTRICITY.--Non-sparking Key.
+
+      New Instruments for Measuring Electric Currents and Electromotive
+      Force.--By MESSRS. K.E. CROMPTON and GISBERT
+      KAPP.--Paper read before the Society of Telegraph Engineers.--With
+      several engravings.
+
+      When Does the Electric Shock Become Fatal?
+
+V.    ART AND ARCHÆOLOGY.--Robert Cauer's Statute of Lorelei.--With
+      engraving.
+
+      The Pyramids of Meroe.--With engraving.
+
+VI.   ASTRONOMY AND METEOROLOGY.--The Red Sky.--Cause of
+      the same explained by the Department of Meteorology.
+
+      A Theory of Cometary Phenomena.
+
+      On Comets.--By FURMAN LEAMING, M.D.
+
+VII.  NATURAL HISTORY.--The Prolificness of the Oyster.
+
+      Coarse Food for Pigs.
+
+VIII. BOTANY, HORTICULTURE, ETC.--Forms of Ivy.--With
+      several engravings.
+
+      Propagating Roses.
+
+      A Few of the Best Inulas.--With engraving.
+
+      Fruit Growing.--By P.H. FOSTER.
+
+IX.   MEDICINE, HYGIENE, ETC.--A People without Consumption,
+      and Some Account of Their Country, the Cumberland Tableland.
+      --By E.M. WIGHT.
+
+      The Treatment of Habitual Constipation.
+
+X.    MISCELLANEOUS.--The French Scientific Station at Cape Horn.
+
+XI.   BIOGRAPHY.--The Late Maori Chief, Mete Kingi.--With portrait.
+
+       *       *       *       *       *
+
+
+
+
+THE FRENCH SCIENTIFIC STATION AT CAPE HORN.
+
+
+In 1875 Lieutenant Weyprecht of the Austrian navy called the attention
+of scientific men to the desirability of having an organized and
+continual system of hourly meteorological and magnetic observations
+around the poles. In 1879 the first conference of what was termed the
+International Polar Congress was held at Hamburg. Delegates from eight
+nations were present--Germany, Austria, Denmark, France, Holland,
+Norway, Russia, and Sweden.
+
+The congress then settled upon a programme whose features were: 1. To
+establish general principles and fixed laws in regard to the pressure
+of the atmosphere, the distribution and variation of temperature,
+atmospheric currents, climatic characteristics. 2. To assist the
+prediction of the course and occurrence of storms. 3. To assist the
+study of the disturbances of the magnetic elements and their relations
+to the auroral light and sun spots. 4. To study the distribution of
+the magnetic force and its secular and other changes. 5. To study the
+distribution of heat and submarine currents in the polar regions. 6. To
+obtain certain dimensions in accord with recent methods. Finally, to
+collect observations and specimens in the domain of zoology, botany,
+geology, etc.
+
+The representatives of the various nations had several conferences
+later, and by the 1st of May, 1881, there were sufficient subscribers to
+justify the establishment of eight Arctic stations.
+
+France entered actively in this work later, and its first expedition was
+to Orange Bay and Cape Horn, under the surveillance and direction of
+the Academy of Sciences, Paris, and responsible to the Secretary of the
+Navy. On the 6th of September, 1882, this scientific corps established
+itself in Orange Bay, near Cape Horn, and energetically began its
+serious labors, and by October 22 the greater part of their preliminary
+preparations was completed, comprising the erection of a magnetic
+observatory, an astronomic observatory, a room for the determination of
+the carbonic anhydride of the air, another for the sea register, and
+a bridge 92 feet long, photographic laboratory, barometer room, and
+buildings for the men, food, and appurtenances, together with a
+laboratory of natural history.
+
+In short, in spite of persistent rains and the difficulties of the
+situation, from September 8 to October 22 they erected an establishment
+of which the different parts, fastened, as it were, to the flank of a
+steep hill, covered 450 square meters (4,823 square feet), and rested
+upon 200 wooden piles.
+
+From September 26, 1882, to September 1, 1883, night and day
+uninterruptedly, a watch was kept, in which the officers took part, so
+that the observations might be regularly made and recorded. Every four
+hours a series of direct magnetic and meteorological observations was
+made, from hour to hour meteorological notes were taken, the rise and
+fall of the sea recorded, and these were frequently multiplied by
+observations every quarter of an hour; the longitude and latitude were
+exactly determined, a number of additions to the catalogue of the fixed
+stars for the southern heavens made, and numerous specimens in natural
+history collected.
+
+The apparatus employed by the expedition for the registration of the
+magnetic elements was devised by M. Mascart, by which the variations
+of the three elements are inscribed upon a sheet of paper covered with
+gelatine bromide, inclination, vertical and horizontal components, with
+a certainty which is shown by the 330 diurnal curves brought back from
+the Cape.
+
+The register proper is composed of a clock and a photographic frame
+which descends its entire length in twenty-four hours, thus causing the
+sensitized paper to pass behind a horizontal window upon which falls the
+light reflected by the mirrors of the magnetic instruments. One of those
+mirrors is fixed, and gives a line of reference; the other is attached
+to the magnetic bar, whose slightest movements it reproduces upon the
+sensitized paper. The moments when direct observations were taken were
+carefully recorded. The magnetic _pavilion_ was made of wood and copper,
+placed at about fifty-three feet from the dwellings or camp, near the
+sea, against a wooded hill which shaded it completely; the interior
+was covered with felt upon all its sides, in order to avoid as much as
+possible the varying temperatures.
+
+The diurnal amplitude of the declination increased uniformly from the
+time of their arrival in September up to December, when it obtained
+its maximum of 7'40", then diminished to June, when it is no more than
+2'20"; from this it increased up to the day of departure. The maximum
+declination takes place toward 1 P.M., the minimum at 8:50 A.M. The
+night maxima and minima are not clearly shown except in the southern
+winter.
+
+The mean diurnal curve brings into prominence the constant diminution
+of the declination and the much greater importance of the perturbations
+during the summer months. These means, combined with the 300 absolute
+determinations, give 4' as the annual change of the declination.
+
+M. Mascart's apparatus proved to be wonderfully useful in recording the
+rapid and slight perturbations of the magnet. Comparisons between the
+magnetic and atmospheric perturbations gave no result. There was,
+however, little stormy weather and no auroral displays. This latter
+phenomenon, according to the English missionaries, is rarely observed in
+Tierra del Fuego.
+
+The electrometer used at the Cape was founded upon the principle
+developed by Sir William Thomson. The atmospheric electricity is
+gathered up by means of a thin thread of water, which flows from a
+large brass reservoir furnished with a metallic tube 6.5 feet long. The
+reservoir is placed upon glass supports isolated by sulphuric acid, and
+is connected to the electrometer by a thread of metal which enters a
+glass vessel containing sulphuric acid; into the same vessel enters a
+platinum wire coming from the aluminum needle. Only 3,000 observations
+were given by the photographic register, due to the fact that the
+instruments were not fully protected against constant wet and cold.
+
+Besides these observations direct observations of the magnetometer were
+made, and the absolute determination of the elements of terrestrial
+magnetism attempted.
+
+On the 17th of November, 1882, a severe magnetic disturbance occurred,
+lasting from 12 M. until 3 P.M., which in three hours changed the
+declination 42'. The same perturbation was felt in Europe, and the
+comparison of the observations in the two hemispheres will prove
+instructive.
+
+       *       *       *       *       *
+
+
+
+
+THE ELECTRIC RAILWAY AT VIENNA.
+
+
+The total length of this railway, which extended from the Eiskeller in
+the Schwimmschul-Allee to the northern entrance of the Rotunda, was
+1528.3 meters; the gauge was 1 meter, and 60 per cent. of the length
+consisted of tangents, the remaining 40 per cent. being mostly curves
+of 250 meters radius. The gradients, three in number, were very small,
+averaging about 1:750.
+
+Two generating dynamos were used, which were coupled in parallel
+circuit, but in such a manner that the difference of potential in both
+machines remained the same at all times. This was accomplished by the
+well known method of coupling introduced by Siemens and Halske, in which
+the current of one machine excites the field of the other.
+
+Although the railroad was not built with a view of obtaining a high
+efficiency, an electro-motive force of only 150 volts being used, a
+mechanical efficiency of 50 per cent. was nevertheless obtained, both
+with one generator and one car with thirty passengers, as well as with
+two generators and two cars with sixty passengers; while with two
+generators and three cars (two of them having motors) the same result
+was shown.
+
+[Illustration: THE ELECTRIC RAILWAY AT VIENNA.]
+
+The curves obtained by the apparatus that recorded the current showed
+very plainly the action within the machines when the cars were started
+or set in motion; at first, the current rose rapidly to a very high
+figure, and then declined gradually to a fixed point, which corresponded
+to the regular rate of speed. The tractive power, therefore, increases
+rapidly to a value far exceeding the frictional resistances, but this
+surplus energy serves to increase the velocity, and disappears as soon
+as a uniform velocity is reached.
+
+The average speed, both with one and three cars, was 30 kilometers per
+hour.--_Zeitsch. f. Elektrotechnik_.
+
+       *       *       *       *       *
+
+
+
+
+INSTRUCTION IN MECHANICAL ENGINEERING.
+
+By Professor R. H. THURSTON.
+
+
+The writer has often been asked by correspondents interested in
+the matter of technical and trade education to outline a course of
+instruction in mechanical engineering, such as would represent his
+idea of a tolerably complete system of preparation for entrance into
+practice. The synopsis given at the end of this article was prepared
+in the spring of 1871, when the writer was on duty at the U.S. Naval
+Academy, as Assistant Professor of Natural and Experimental Philosophy,
+and, being printed, was submitted to nearly all of the then leading
+mechanical engineers of the United States, for criticism, and with a
+request that they would suggest such alterations and improvements as
+might seem to them best. The result was general approval of the course,
+substantially as here written. This outline was soon after proposed as a
+basis for the course of instruction adopted at the Stevens Institute of
+Technology, at Hoboken, to which institution the writer was at about
+that time called. He takes pleasure in accepting a suggestion that its
+publication in the SCIENTIFIC AMERICAN would be of some advantage to
+many who are interested in the subject.
+
+The course here sketched, as will be evident on examination, includes
+not only the usual preparatory studies pursued in schools of mechanical
+engineering, but also advanced courses, such as can only be taught in
+special schools, and only there when an unusual amount of time can be
+given to the professional branches, or when post graduate courses can be
+given supplementary to the general course. The complete course, as here
+planned, is not taught in any existing school, so far as the writer is
+aware. In his own lecture room the principal subjects, and especially
+those of the first part of the work, are presented with tolerable
+thoroughness; but many of the less essential portions are necessarily
+greatly abridged. As time can be found for the extension of the course,
+and as students come forward better prepared for their work, the earlier
+part of the subject is more and more completely developed, and the
+advanced portions are taken up in greater and greater detail, each year
+giving opportunity to advance beyond the limits set during the preceding
+year.
+
+Some parts of this scheme are evidently introductory to advanced courses
+of study which are to be taken up by specialists, each one being adapted
+to the special instruction of a class of students who, while pursuing
+it, do not usually take up the other and parallel courses. Thus, a
+course of instruction in Railroad Engineering, a course in Marine
+Engineering, or a course of study in the engineering of textile
+manufactures, may be arranged to follow the general course, and the
+student will enter upon one or another of these advanced courses as his
+talents, interests, or personal inclinations may dictate. At the Stevens
+Institute of Technology, two such courses--Electrical and Marine
+Engineering--are now organized as supplementary of the general course,
+and are pursued by all students taking the degree of Mechanical
+Engineer. These courses, as there given, however, are not fairly
+representative of the idea of the writer, as above expressed, since the
+time available in general course is far too limited to permit them to be
+developed beyond the elements, or to be made, in the true sense of the
+term, advanced professional courses. Such advanced courses as the writer
+has proposed must be far more extended, and should occupy the whole
+attention of the student for the time. Such courses should be given in
+separate departments under the direction of a General Director of the
+professional courses, who should be competent to determine the extent of
+each, and to prevent the encroachment of the one upon another; but they
+should each be under the immediate charge of a specialist capable
+of giving instruction in the branch assigned to him, in both the
+theoretical and purely scientific, and the practical and constructive
+sides of the work. Every such school should be organized in such a
+manner that one mind, familiar with the theory and the practice of the
+professional branches taught, should be charged with the duty of giving
+general direction to the policy of the institution and of directing
+the several lines of work confided to specialists in the different
+departments. It is only by careful and complete organization in this, as
+in every business, that the best work can be done at least expense in
+time and capital.
+
+In this course of instruction in Mechanical Engineering it will be
+observed that the writer has incorporated the scheme of a workshop
+course. This is done, not at all with the idea that a school of
+mechanical engineering is to be regarded as a "trade school," but that
+every engineer should have some acquaintance with the tools and the
+methods of work upon which the success of his own work is so largely
+dependent. If the mechanical engineer can acquire such knowledge in the
+more complete course of instruction of the trade school, either before
+or after his attendance at the technical school, it will be greatly to
+his advantage. The technical school has, however, a distinct field; and
+its province is not to be confounded with that of the trade school.
+The former is devoted to instruction in the theory and practice of a
+profession which calls for service upon the men from the latter--which
+makes demand upon a hundred trades--in the prosecution of its designs.
+The latter teaches, simply, the practical methods of either of the
+trades subsidiary to the several branches of engineering, with only so
+much of science as is essential to the intelligent use of the tools and
+the successful application of the methods of work of the trade taught.
+The distinction between the two departments of education, both of which
+are of comparatively modern date, is not always appreciated in the
+United States, although always observed in those countries of Europe
+in which technical and trade education have been longest pursued as
+essential branches of popular instruction. Throughout France and
+Germany, every large town has its trade schools, in which the trades
+most generally pursued in the place are systematically taught; and every
+large city has its technical school, in which the several professions
+allied to engineering are studied with special development of those to
+which the conditions prevailing at the place give most prominence and
+local importance.
+
+A course of trade instruction, as the writer would organize it, would
+consist, first, in the teaching of the apprentice the use of the tools
+of his trade, the nature of its materials, and the construction and
+operation of the machinery employed in its prosecution. He would next be
+taught how to shape the simpler geometrical forms in the materials of
+his trade, getting out a straight prism, a cylinder, a pyramid, or a
+sphere, of such size and form as may be convenient; getting lines and
+planes at right angles, or working to miter; practicing the working of
+his "job" to definite size, and to the forms given by drawings, which
+drawings should be made by the apprentice himself. When he is able to
+do good work of this kind, he should attempt larger work, and the
+construction of parts of structures involving exact fitting and special
+manipulations. The course, finally, should conclude with exercises in
+the construction and erection of complete structures and in the making
+of peculiar details, such as are regarded by the average workman
+as remarkable "_tours de force_." The trade school usually gives
+instruction in the common school branches of education, and especially
+in drawing, free-hand and mechanical, carrying them as far as the
+successful prosecution of the trade requires. The higher mathematics,
+and advanced courses in physics and chemistry, always taught in schools
+of engineering, are not taught in the trade school, as a rule; although
+introduced into those larger schools of this class in which the aim is
+to train managers and proprietors, as well as workmen. This is done in
+many European schools.
+
+As is seen above, the course of instruction in mechanical engineering
+includes some trade education. The engineer is dependent upon the
+machinist, the founder, the patternmaker, and other workers at the
+trades, for the proper construction of the machinery and structures
+designed by him. He is himself, in so far as he is an engineer, a
+designer of constructions, not a constructor. He often combines,
+however, the functions of the engineer, the builder, the manufacturer,
+and the dealer, in his own person. No man can carry on, successfully,
+any business in which he is not at home in every detail, and in which he
+cannot instruct every subordinate, and cannot show every person employed
+by him precisely what is wanted, and how the desired result can be best
+attained. The engineer must, therefore, learn, as soon and as thoroughly
+as possible, enough of the details of every art and trade, subsidiary
+to his own department of engineering, to enable him to direct, with
+intelligence and confidence, every operation that contributes to the
+success of his work. The school of engineering should therefore be so
+organized that the young engineer may be taught the elements of every
+trade which is likely to find important application in his professional
+work. It cannot be expected that time can be given him to make himself
+an expert workman, or to acquire the special knowledge of details and
+the thousand and one useful devices which are an important part of the
+stock in trade of the skilled workman; but he may very quickly learn
+enough to facilitate his own work greatly, and to enable him to learn
+still more, with rapidity and ease, during his later professional life.
+He must also, usually, learn the essential elements and principles of
+each of several trades, and must study their relations to his work, and
+the limitations of his methods of design and construction which they
+always, to a greater or less extent, cause by their own practical or
+economical limitations. He will find that his designs, his methods of
+construction, and of fitting up and erecting, must always be planned
+with an intelligent regard to the exigencies of the shop, as well as to
+the aspect of the commercial side of every operation. This extension of
+trade education for the engineer into several trades, instead of its
+restriction to a single trade, as is the case in the regular trade
+school, still further limits the range of his instruction in each. With
+unusual talent for manipulation, he may acquire considerable knowledge
+of all the subsidiary trades in a wonderfully short space of time, if he
+is carefully handled by his instructors, who must evidently be experts,
+each in his own trade. Even the average man who goes into such schools,
+following his natural bent, may do well in the shop course, under good
+arrangements as to time and character of instruction. If a man has not a
+natural inclination for the business, and a natural aptitude for it, he
+will make a great mistake if he goes into such a school with the hope of
+doing creditable work, or of later attaining any desirable position in
+the profession.
+
+The course of instruction, at the Stevens Institute of Technology,
+includes instruction in the trades to the extent above indicated. The
+original plan, as given below, included such a course of trade education
+for the engineer; but it was not at once introduced. The funds
+available from an endowment fund crippled by the levying of an enormous
+"succession tax" by the United States government and by the cost of
+needed apparatus and of unanticipated expenses, in buildings and in
+organization, were insufficient to permit the complete organization
+of this department. A few tools were gathered together; but skilled
+mechanics could not be employed to take up the work of instruction in
+the several courses. Little could therefore be done for several years in
+this direction. In 1875 the writer organized a "mechanical laboratory,"
+with the purpose of attaining several very important objects: the
+prosecution of scientific research in the various departments of
+engineering work; the creation of an organization that should give
+students an opportunity to learn the methods of research most usefully
+employed in such investigations; the assistance of members of the
+profession, and business organizations in the attempt to solve such
+questions, involving scientific research, as are continually arising in
+the course of business; the employment of students who had done
+good work in their college course, when they so desire, in work of
+investigation with a view to giving them such knowledge of this peculiar
+line of work as should make them capable of directing such operations
+elsewhere; and finally, but not least important of all, to secure, by
+earning money in commercial work of this kind, the funds needed to carry
+on those departments of the course in engineering that had been, up
+to that time, less thoroughly organized than seemed desirable. This
+"laboratory" was organized in 1875, the funds needed being obtained
+by drawing upon loans offered by friends of the movement and by the
+"Director."
+
+It was not until the year 1878, therefore, that it became possible to
+attempt the organization of the shop course; and it was then only by the
+writer assuming personal responsibility for its expenses that the plan
+could be entered upon. As then organized--in the autumn of 1878--a
+superintendent of the workshop had general direction of the trade
+department of the school. He was instructed to submit to the writer
+plans, in detail, for a regular course of shop instruction, and was
+given as assistants a skilled mechanic of unusual experience and
+ability, whose compensation was paid from the mechanical laboratory
+funds, and guaranteed by the writer personally, and another aid whose
+services were paid for partly by the Institute and partly as above. The
+pay of the superintendent was similarly assured. This scheme had been
+barely entered upon when the illness of the writer compelled him to
+temporarily give up his work, and the direction of the new organization
+fell into other hands, although the department was carried on, as above,
+for a year or more after this event occurred.
+
+The plan did not fall through; the course of instruction was
+incorporated into the college course, and its success was finally
+assured by the growth of the school and a corresponding growth of its
+income, and, especially, by the liberality of President Morton, who met
+expenses to the amount of many thousands of dollars by drawing upon his
+own bank account. The department was by him completely organized, with
+an energetic head, and needed support was given in funds and by a force
+of skilled instructors. This school is now in successful operation.
+This course now also includes the systematic instruction of students in
+experimental work, and the objects sought by the writer in the creation
+of a "mechanical laboratory" are thus more fully attained than they
+could have possibly been otherwise. It is to be hoped that, at
+some future time, when the splendid bequest of Mr. Stevens may be
+supplemented by gifts from other equally philanthropic and intelligent
+friends of technical education, among the alumni of the school and
+others, this germ of a trade school maybe developed into a complete
+institution for instruction in the arts and trades of engineering, and
+may thus be rendered vastly more useful by meeting the great want, in
+this locality, of a real trade school, as well as fill the requirements
+of the establishment of which it forms a part, by giving such trade
+education as the engineer needs and can get time to acquire.
+
+The establishment of advanced courses of special instruction in
+the principal branches of mechanical engineering may, if properly
+"dovetailed" into the organization, be made a means of somewhat
+relieving the pressure that must be expected to be felt in the attempt
+to carry out such a course as is outlined below. The post-graduate
+or other special departments of instruction, in which, for example,
+railroad engineering, marine engineering, and the engineering of cotton,
+woolen, or silk manufactures, are to be taught, may be so organized that
+some of the lectures of the general course may be transferred to them,
+and the instructors in the latter course thus relieved, while the
+subjects so taught, being treated by specialists, may be developed more
+efficiently and more economically.
+
+Outlines of these advanced courses, as well as of the courses in trade
+instruction comprehended in the full scheme of mechanical engineering
+courses laid out by the writer a dozen years ago, and as since recast,
+might be here given, but their presentation would occupy too much space,
+and they are for the present omitted.
+
+The course of instruction in this branch of engineering, at the Stevens
+Institute of Technology, is supplemented by "Inspection Tours," which
+are undertaken by the graduating class toward the close of the last
+year, under the guidance of their instructors, in which expeditions they
+make the round of the leading shops in the country, within a radius of
+several hundred miles, often, and thus get an idea of what is meant by
+real business, and obtain some notion of the extent of the field of work
+into which they are about to enter, as well as of the importance of
+that work and the standing of their profession among the others of the
+learned professions with which that of engineering has now come to be
+classed.
+
+At the close of the course of instruction, as originally proposed, and
+as now carried out, the student prepares a "graduating thesis," in which
+he is expected to show good evidence that he has profited well by the
+opportunities which have been given him to secure a good professional
+education. These theses are papers of, usually, considerable extent, and
+are written upon subjects chosen by the student himself, either with or
+without consultation with the instructor. The most valuable of
+these productions are those which present the results of original
+investigations of problems arising in practice or scientific research
+in lines bearing upon the work of the engineer. In many cases, the
+work thus done has been found to be of very great value, supplying
+information greatly needed in certain departments, and which had
+previously been entirely wanting, or only partially and unsatisfactorily
+given by authorities. Other theses of great value present a systematic
+outline of existing knowledge of some subject which had never before
+been brought into useful form, or made in any way accessible to the
+practitioner. In nearly all cases, the student is led to make the
+investigation by the bent of his own mind, or by the desire to do work
+that may be of service to him in the practice of his profession. All
+theses are expected to be made complete and satisfactory to the head
+of department of Engineering before his signature is appended to the
+diploma which is finally issued to the graduating student. These
+preliminaries being completed, and the examinations having been reported
+as in all respects satisfactory, the degree of Mechanical Engineer is
+conferred upon the aspirant, and he is thus formally inducted into the
+ranks of the profession.
+
+
+COURSE OF INSTRUCTION IN MECHANICAL ENGINEERING.
+
+
+Robert H. Thurston--July, 1871.
+
+I.
+
+MATERIALS USED IN ENGINEERING.--Classification, Origin, and Preparation
+(where not given in course of Technical Chemistry), Uses, Cost.
+
+_Strength and Elasticity_.--Theory (with experimental illustrations),
+reviewed, and tensile, transverse and torsional resistance determined.
+
+_Forms_ of greatest strength determined. _Testing_ materials.
+
+_Applications_.--Foundations, Framing in wood and metal.
+
+FRICTION.--Discussion from Rational Mechanics, reviewed and extended.
+
+_Lubricants_ treated with materials above.
+
+Experimental determination of "coefficients of friction."
+
+II.
+
+TOOLS.--Forms for working wood and metals. Principles involved in their
+use.
+
+Principles of pattern making, moulding, smith and machinists' work so
+far as they modify design.
+
+Exercises in Workshops in mechanical manipulation.
+
+Estimates of _cost_ (stock and labor).
+
+MACHINERY AND MILL WORK.--Theory of machines. Construction. Kinematics
+applied. Stresses, calculated and traced. Work of machines. Selection
+of materials for the several parts. Determination of _proportions_ of
+details, and of _forms_ as modified by difficulties of construction.
+
+Regulators, Dynamometers, Pneumatic and Hydraulic machinery. Determining
+_moduli_ of machines.
+
+POWER, transmission by gearing, belting, water, compressed air, etc.
+
+LOADS, transportation.
+
+III.
+
+HISTORY AND PRESENT FORMS OF THE PRIME MOVERS.
+
+_Windmills_, their theory, construction, and application.
+
+_Water Wheels_. Theory, construction, application, testing, and
+comparison of principal types.
+
+_Air, Gas, and Electric Engines_, similarly treated.
+
+STEAM ENGINES.--Classification. [Marine (merchant) Engine assumed as
+representative type.] Theory. Construction, including general design,
+form and proportion of details.
+
+_Boilers_ similarly considered. Estimates of _cost_.
+
+_Comparison_ of principal types of Engines and Boilers. Management and
+repairing. Testing and recording performance.
+
+IV.
+
+MOTORS APPLIED to Mills. Estimation of required power and of _cost_.
+
+Railroads. Study of Railroad machinery.
+
+Ships. Structure of Iron Ships and rudiments of Naval architecture and
+Ship propulsion.
+
+PLANNING Machine shops, Boiler shops, Foundries, and manufactories of
+textile fabrics. Estimating _cost_.
+
+LECTURES BY EXPERTS.
+
+GENERAL SUMMARY of principal facts, and natural laws, upon the thorough
+knowledge of which successful practice is based; and general _resume_
+of principles of business which must be familiar to the practicing
+engineer.
+
+V.
+
+GRADUATING THESES.
+
+GRADUATION.
+
+Accompanying the above are courses of instruction in higher mathematics,
+graphics, physics, chemistry, and the modern languages and literatures.
+
+       *       *       *       *       *
+
+
+
+
+IMPROVED DOUBLE BOILER.
+
+
+The operation of boiling substances under pressure with more or less
+dilute sulphuric or sulphurous acid forms a necessary stage of several
+important manufactures, such as the production of paper from wood, the
+extraction of sugar, etc. A serious difficulty attending this process
+arises from the destructive action of the acid upon the boiler or
+chamber in which the operation is carried on, and as this vessel, which
+is generally of large dimensions, is exposed to considerable pressures,
+it is necessarily constructed of iron or some other sufficiently
+resisting metal. An ingenious method of avoiding this difficulty has
+been devised, we believe in Germany, and has been put into practice with
+a certain amount of success. It consists in lining the iron boiler with
+a covering of lead, caused by fusion to unite firmly to the walls of the
+boiler, and thus to protect it from the action of the acid. No trouble,
+it is stated, is found to arise from the difference in expansion of the
+two metals, which, moreover, adhere fairly well; but, on the other hand,
+we believe it does actually occur that the repairs to this lead lining
+are numerous, tedious, and costly of execution, so that the system can
+scarcely be regarded as meeting the requirements of the manufacturer.
+It is to secure all the advantages possessed by a lead-lined vessel,
+without the drawback of frequent and expensive repairs, that the
+digester, of which we annex illustrations, has been devised by Mr.
+George Knowles, of Billiter House, Billiter Street. It consists of a
+closed iron cylindrical vessel suitable for boiling under pressure, and
+containing a second vessel open at the top, and of such a diameter as to
+leave an annular space between it and the walls of the outer shell. This
+inner receiver, which may be made of lead, glass, pottery, or any
+other suitable material, contains the substance to be treated and the
+sulphurous acid or other solution in which it is to be boiled. The
+annular space between the two vessels is filled with water to the same
+level as the solution in the receiver, and the latter is provided with
+suitable pipes or coils, in which steam is caused to circulate for
+the purpose of raising the solution of the desired temperature, and
+effecting the digesting process. At the same time any steam generated
+collects in the upper part of the boiler, and maintains an equal
+pressure within the whole apparatus. Figs. 1 to 3 show the arrangement
+clearly. Within the boiler, a, is placed the receiver, b, of pottery,
+lead, or other material, leaving an annular space between it and the
+boiler; this space is filled with water. The receiver, b, is furnished
+with a series of pipes, in which steam or hot water circulates, to heat
+the charge to the desired temperature. These pipes may be arranged
+either in coils, as shown at d, Fig. 1, or vertically at d, Fig. 3. The
+latter are provided with inner return pipes, so that any condensed water
+accumulating at the bottom may be forced up the inner pipes by the
+steam pressure and escape at the top. The vessel is charged through the
+manhole, e, and the hopper, c, provided with a perforated cover, and is
+discharged at the bottom by the valve, f, shown in Figs. 2 and 3. The
+upper part of the boiler serves as a steam dome, and the pressure on the
+liquid in the receiver and on the water in the annular space is thereby
+maintained uniform. The necessary fittings for showing the pressure
+in the vessel, water level indicator, safety valve, cocks for testing
+solutions, etc., are of course added to the apparatus, but are not
+indicated in the drawing. The arrangement appears to us to possess
+considerable merit, and we shall refer to it again on another occasion,
+after experiments have been made to test its efficiency.--_Engineering_.
+
+[Illustration: IMPROVED DOUBLE BOILER.]
+
+       *       *       *       *       *
+
+
+
+
+THE GARDNER MACHINE GUN.
+
+
+[Illustration: FIG. 1.--SINGLE BARREL GARDNER MACHINE GUN.]
+
+The mechanism by which the various functions of loading, firing, and
+extracting are performed is contained in a rectangular gun metal case,
+varying in dimensions with the number of barrels in the arm. In the
+single barrel gun the size of this case is 14 inches in length, 5½
+inches in depth, and 2½ inches in width. The top of the box is hinged,
+so that easy access can be had to the mechanism, which consists of a
+lock, the cartridge carrier, and the devices for actuating them. In the
+multiple barrel guns, the frames which, with the transverse bar at the
+end, hold the barrels in place, form the sides of the mechanism chamber,
+in the front end of which the barrels are screwed. The mechanism is
+actuated by a cam shaft worked by a hand crank on one side of the
+chamber. By this means the locks are driven backward and forward,
+the latter motion forcing the cartridges into place, and the former
+withdrawing the empty cartridge case after firing. The extractor hook
+pivoted to the lock plunger rises, as the lock advances, over the rim of
+the case, but is rigid as the lock is withdrawn, so that the action is
+a positive one. The cartridges, which are contained in a suitable
+frame attached to the forward part of the breech chamber, pass through
+openings in the top plate of the latter, an efficient distribution being
+secured by means of a valve having a transverse motion. Each cartridge
+as it falls is brought into the axis of the barrel and the plunger,
+while the advance motion of the lock forces them into position. In the
+five-barrel gun illustrated by Fig. 3 the cartridge feeder contains 100
+cartridges, in five Vertical rows of 20 cartridges each, and these are
+kept supplied, when firing, from supplementary holders. Fig. 1 shows the
+portable rest manufactured by the Gardner Gun Company. It consists of
+two wrought iron tubes, placed at right angles to each other; the front
+bar can be easily unlocked, and placed in line with the trail bar, from
+which project two arms, each provided with a screw that serves for the
+lateral adjustment of the gun. These screws are so arranged as to allow
+for an oscillating motion of the gun through any distance up to 15 deg.
+The tripod mounting, used for naval as well as land purposes, is shown
+in Fig. 2, which illustrates the two barrel gun complete. The five
+barrel gun, Fig. 3, is shown mounted on a similar tripod. The length of
+this weapon over all is 53.5 inches, the barrels (Henry system) are 33
+inches long, with seven grooves of a uniform twist of one turn in 22
+inches.
+
+[Illustration: Fig. 2.--TWO BARREL GARDNER GUN.]
+
+Gardener's five barrel gun in the course of one of the trials fired
+16,754 rounds with only 24 jams, and in rapid firing reached a maximum
+of 330 shots in 30 seconds. The two barrel gun fired 6,929 rounds
+without any jam; the last 3,000 being in 11 minutes 39 seconds, without
+any cleaning or oiling.--_Engineering_.
+
+[Illustration: Fig. 3.--FIVE BARREL GARDNER GUN.]
+
+       *       *       *       *       *
+
+
+
+
+CLIMBING TRICYCLES.
+
+
+The cycle trade is one which has been developed with great rapidity
+within the last ten years, and, like all new industries, has called
+forth a considerable amount of ingenuity and skill on the part of those
+engaged in it. We cannot help thinking, however, that much of this
+ingenuity has been misplaced, and that instead of striving after new
+forms involving considerable complication and weight, it would have
+been better and more profitable if manufacturers had moderated their
+aspirations, and aimed at greater simplicity of design; for it must
+be remembered that cyclists are, as a rule, without the slightest
+mechanical knowledge, while the machines themselves are subject to very
+hard usage and considerable wear and tear in traveling over the
+ordinary roads in this country. We refer, of course, more especially to
+tricycles, which in one form or another are fast taking the place of
+bicycles, and which promise to assume an important position in every
+day locomotion. Hitherto one of the chief objections to the use of the
+tricycle has been the great difficulty experienced in climbing hills, a
+very slight ascent being sufficient to tax the powers of the rider to
+such an extent as to induce if not compel him in most instances to
+dismount and wheel his machine along by hand until more favorable ground
+is reached. To obviate this inconvenience many makers have introduced
+some arrangement of gearing speeds of two powers giving the necessary
+variation for traveling up hill and on the level. We noticed, however,
+one machine at the exhibition which seemed to give all that could be
+desired without any gearing or chains at all. This was a direct action
+tricycle shown by the National Cycle Company, of Coventry, in which the
+pressure from the foot is made to bear directly upon the main axle, and
+so transmitted without loss to the driving wheels on each side, the
+position of the rider being arranged so that just sufficient load is
+allowed to fall on the back wheel as to obtain certainty in steerage.
+The weight of this machine is much less than when gearing is used, and
+the friction is also considerably reduced, trials with the dynamometer
+having shown that on a level, smooth road, a pull of 1 lb. readily
+moved it, while with a rider in the seat 4 lb. was sufficient. On this
+tricycle any ordinary hill can, it is stated, be ascended with great
+ease, and as a proof of its power it was exhibited at the Stanley show
+climbing over a piece of wood 8 in. high, without any momentum whatever.
+We understand that at the works at Coventry a flight of stairs has been
+erected, and that no difficulty is experienced in ascending them on one
+of these machines.--_The Engineer_.
+
+       *       *       *       *       *
+
+
+
+
+SUBMARINE EXPLORATIONS.
+
+VOYAGE OF THE TALISMAN.
+
+
+It was but a few years ago that the idea was prevalent that the seas at
+great depths were immense solitudes where life exhibited itself under no
+form, and where an eternal night reigned. To-day, thanks to expeditions
+undertaken for the purpose of exploring the abysses of the ocean, we
+know that life manifests itself abundantly over the bottom, and that
+at a depth of five and six thousand meters light is distributed by
+innumerable phosphorescent animals. Different nations have endeavored to
+rival each other in the effort to effect these important discoveries,
+and several scientific missions have been sent to different points of
+the globe by the English and American governments. The French likewise
+have entered with enthusiasm upon this new line of research, and for
+four consecutive years, thanks to the devoted aid of the ministry of the
+marine, savants have been enabled to take passage in government vessels
+that were especially arranged for making submarine explorations.
+
+[Illustration: THE FRENCH SCIENTIFIC STEAMER TALISMAN.]
+
+The first French exploration, which was an experimental trip, was made
+in 1880 by the Travailleur in the Gulf of Gascogne. Its unhoped
+for results had so great an importance that the following year the
+government decided to continue its researches, and the Travailleur was
+again put at the disposal of Mr. Alph. Milne Edwards and the commission
+over which he presided. Mr. Edwards traversed the Gulf of Gascogne,
+visited the coast of Portugal, crossed the Strait of Gibraltar, and
+explored a great portion of the Mediterranean. In 1882 the same vessel
+undertook a third mission to the Atlantic Ocean, and as far as to the
+Canary Islands. The Travailleur, however, being a side-wheel advice-boat
+designed for doing service at the port of Rochefort, presented none
+of those qualities that are requisite for performing voyages that are
+necessarily of long duration. The quantity of coal that could be stored
+away in her bunkers was consumed in a week, and, after that, she could
+not sail far from the points where it was possible for her to coal up
+again. So after her return Mr. Edwards made a request for a ship that
+was larger, a good sailer, and that was capable of carrying with it a
+sufficient supply of fuel for remaining a long time at sea, and that
+was adapted to submarine researches. The Commission indorsed this
+application, and the Minister of Instruction received it and transmitted
+it to Admiral Jauréguiberry--the Minister of the Marine--who at once
+gave orders that the Talisman should be fitted up and put in commission
+for the new dredging expedition. This vessel, under command of Captain
+Parfait, who the preceding year had occupied the same position on the
+Travailleur, left the port of Rochefort on the 1st of June, 1883, having
+on board Mr. Milne Edwards and the scientific commission that had been
+appointed by the Minister of Public Instruction. The Talisman explored
+the coasts of Portugal and Morocco, visited the Canary and Cape Verd
+Islands, traversed the Sea of Sargasso, and, after a stay of some time
+at the Azores, returned to France, after exploring on its way the Gulf
+of Gascogne (Fig.).
+
+[Illustration: FIG.1.--CHART OF THE TALISMAN'S VOYAGE.]
+
+The magnificent collections in natural history that were collected
+on this cruise, and during those of preceding years made by the
+Travailleur, are, in a few days, to be exhibited at the Museum of
+Natural History. We think we shall be doing a service to the readers of
+this journal, in giving them some details as to the organization of the
+Talisman expedition as well as to the manner in which the dredgings were
+performed.
+
+[Illustration: FIG.2.--PLAN OF THE VESSEL.]
+
+The vessel, as shown by her plan in Fig. 2, had to undergo important
+alterations for the cruise that she was to undertake. Her deck was
+almost completely freed from artillery, since this would have encumbered
+her too much. Immediately behind the bridge, in the center of the
+vessel, there were placed two windlasses, one, A, to the right, and the
+other, B, to the left (Fig. 2). These machines, whose mode of operation
+will be explained further along, were to serve for raising and lowering
+the fishing apparatus. A little further back there were constructed
+two cabins, G and HH. The first of these was designed to serve as a
+laboratory, and the second was arranged as quarters for the members of
+the mission.
+
+The sounding apparatus, the Brothergood engine for actuating it, and the
+electric light apparatus were placed upon the bridge. The operating
+of the sounding line and of the electric light was therefore entirely
+independent of that of the dredges. On the foremast, at a height of
+about two meters, there was placed a crane, F, which was capable of
+moving according to a horizontal plane. Its apex, as may be seen from
+the plan of the boat, was capable of projecting beyond the sides of the
+ship, to the left and right. To this apex was fixed a pulley over which
+ran the cable that supported the dredges or bag-nets, which latter were
+thus carried over the boat's sides.
+
+[Illustration: FIG.3.--DIAGRAM OF THE THIBAUDIER SOUNDING APPARATUS.]
+
+The preliminary operation in every submarine exploration consists in
+exactly determining the depth of the sea immediately beneath the vessel.
+To effect this object different sounding apparatus have been proposed.
+As the trials that were made of these had shown that each of them
+possessed quite grave defects, Mr. Thibaudier, an engineer of the navy,
+installed on board the Talisman last year a new sounding apparatus which
+had been constructed according to directions of his and which have given
+results that are marvelous. The apparatus automatically registers the
+number of meters of wire that is paid out, and as soon as the sounding
+lead touches bottom, it at once stops of itself. This apparatus is shown
+in Fig. 4, and a diagram of it is given in Fig. 3, so that its operation
+may be better understood. The Thibaudier sounding apparatus consists of
+a pulley, P (Fig. 3), over which is wound 10,000 meters of steel wire
+one millimeter in diameter. From this pulley, the wire runs over a
+pulley, B, exactly one meter in circumference; from thence it runs to a
+carriage, A, which is movable along wooden shears, runs up over a fixed
+pulley, K, and reaches the sounding lead, S, after traversing a guide,
+g, where there is a small sheave upon which it can bear, whatever be the
+inclination of the boat. The wheel, B, carries upon its axle an endless
+screw that sets in motion two toothed wheels that indicate the number
+of revolutions that it is making. One of these marks the units and the
+other the hundredths (Fig. 5). This last is graduated up to 10,000
+meters. As every revolution of the wheel, B, corresponds to one meter,
+the number indicated by the counter represents the depth. Upon the axle
+of the winding pulley there is a break pulley, p. The brake, f, is
+maneuvered by a lever, L, at whose extremity there is a cord, C, which
+is made fast to the carriage, A. When, during the motions due to
+rolling, the tension of the steel wire that supports the lead diminishes
+or increases, the carriage slightly rises or falls, and, during these
+motions, acts more or less upon the brake and consequently regulates the
+velocity with which the wire unwinds. When the lead touches bottom, the
+wire, being suddenly relieved from all weight (which is sometimes as
+much as 70 kilos), instantly stops.
+
+[Illustration: FIG. 4.--GENERAL VIEW OF THE SOUNDING APPARATUS IN THE
+"TALISMAN:"]
+
+The maneuver of this apparatus may be readily understood. The apparatus
+and its weights are arranged in the interior of the vessel. A man bears
+upon the lever, L (Fig. 3), and the counter is set at zero. All being
+thus arranged, the man lets go of the break, and the unwinding then
+proceeds until the lead has touched bottom. During the operation of
+sounding, the boat is kept immovable by means of its engine, so that the
+wire shall remain as vertical as possible. The bottom being reached, the
+unwinding suddenly ceases, and there is nothing further to do but read
+the indication given by the differential counter, this giving the depth.
+
+[Illustration: FIG. 5.--APPARATUS FOR MEASURING THE LENGTH OF THE WIRE
+PAID OUT.]
+
+Near the winding pulley, there is a small auxiliary engine, M, which
+is then geared with the axle of the said pulley, and which raises the
+sounding apparatus that has been freed from its weight by a method that
+will be described further along.
+
+We have endeavored in Fig. 4 to show the aspect of the bridge at the
+moment when a sounding was about being made. From this engraving (made
+from a photograph) our readers may obtain a clear idea of the Thibaudier
+sounding apparatus, and understand how the wheel over which the wire
+runs is set in motion by the Brothergood engine.--_La Nature_.
+
+       *       *       *       *       *
+
+
+
+
+CABLE GRAPNEL.
+
+
+Some improvements have recently been made by Mr. Alexander Glegg and the
+inventor in the well-known Jamieson grapnel used for raising submerged
+submarine cables. The chief feature of the grapnel is that the flukes,
+being jointed at the socket, bend back against a spring when they catch
+a rock, until the grapnel clears the obstruction, but allow the cable
+to run home to the crutch between the fluke and base, as shown in the
+figures. In the older form the cable was liable to get jammed, and cut
+between the fixed toe or fluke and the longer fluke jointed into it.
+This is now avoided by embracing the short fluke within the longer one.
+The shank, formerly screwed into the boss, is now pushed through and
+kept up against the collar of the boss, by the volute spring, which at
+the same time presses back the hinged flukes after being displaced by
+a rock. The shank can now freely swivel round, whereas before it was
+rigidly fixed. The toes or flukes are now made of soft cast steel, which
+can be straightened if bent, and the boss is made of cast steel or
+gun-metal.
+
+[Illustration: JAMIESON'S GRAPNEL.]
+
+       *       *       *       *       *
+
+
+
+
+WRETCHED BOILERMAKING.
+
+
+_To the Editor of the Scientific American_:
+
+As long as I have been a reader of the SCIENTIFIC AMERICAN I have been
+pleased with the manner in which you investigate and explain the cause
+of any boiler explosion which comes to your knowledge; and I have
+rejoiced when you heaped merited censure upon the fraudulent
+boilermaker. In your paper in December last you copied a short article
+on "Conscience in Boilermaking," in which the writer, after speaking
+of the tricks of the boilermaker in using thinner iron for the center
+sheets than for the others, and in "upsetting" the edges of the plates
+to make them appear thicker, goes on to say: "We call attention to this,
+because the discovery of such practice has made serious trouble between
+the boilermaker and the steam user. We would not believe that there were
+men so blind to the duties and obligations which rest upon them as
+to resort to such practice, but the careful inspector finds all such
+defects, and in time we come to know whose work is carefully and
+honestly done, and whose is open to suspicion. In States and cities
+where inspection laws are in force that give the methods and rules by
+which the safe working pressure of a boiler is calculated, there is no
+alternative except to follow the rules; and if certain requirements
+regarding construction are a part of the law, there is no authority or
+right to depart from it, and yet there are boilermakers who try to force
+their boilers into such localities when their work is not up to the
+requirements of the law."
+
+Now, if some boilermakers are so dishonest as to try and impose upon the
+locomotive engineer, who they know will carefully examine every part of
+his boiler, and who is able to detect any flaw, it is not to be expected
+that the farmer will escape. Nor does he. The great number of explosions
+of boilers used in thrashing and in other farm work proves that there
+are boilermakers who "force their boilers into such localities
+when their work is not up to the requirements of the law." And the
+boilermaker, if he be dishonest, is doubly tempted if the broad width of
+a continent intervenes between him and the farmer for whom his work is
+intended, and if in the place where the boiler is to be used there are
+no inspection laws in force. The farmer who lives many miles from a
+city, and who has no means of testing any boiler he may purchase,
+is wholly at the mercy of the boilermaker, and must run it until it
+explodes or time proves it to have been honestly made. Then, again,
+there are boilermakers who, although making boilers of good iron and of
+the proper thickness, finish them off so badly that the farmer is put to
+great inconvenience and expense to put them in working order. Two years
+ago I purchased a straw-burning engine and boiler made by an Eastern
+firm. Before it had run ten days the boiler began to leak at the
+saddle-bolt holes. The engineer tightened the nuts as far as possible,
+but could not stop the leaks, which at last became so bad that we had to
+stop work and take the engine to the shop. Upon taking off the saddle
+and taking out the bolts it was discovered that they were too small for
+the holes in the boiler, and that they had been wrapped with candle wick
+and white lead to make them fill the holes, and that a light washer had
+been put on each bolt between the head and the inside of the boiler.
+This washer kept the lead in its place, and prevented the boiler from
+showing a leak when first fired up. The water pipes in the fire-box soon
+gave out and became utterly useless. Upon inquiring of the patentee of
+this straw-burning device, who was supposed to have put it in my boiler,
+he stated that he had had nothing to do with it, but that it was put in
+by the firm selling these engines, and "as cheaply as possible." Before
+I got this boiler and engine in fair running order I had spent hundreds
+of dollars and had to do entirely away with the water grates.
+
+Last summer, needing another tharshing engine, I was induced to buy
+one of the same make as my old one, but with a different straw-burning
+device. The firm who sold it to me agreed that it should have none of
+the faults of the old one. Well, I got it, and, upon hauling it out to
+my ranch, and getting up steam, I found it to be much worse than the
+first one I had bought. The boiler leaked at nearly every hole where
+a tap had been screwed into it. It took an engineer, a boilermaker, a
+blacksmith, and a fireman several days to get it in shape so that we
+could use it at all; and after we did start up, the boilermaker had
+to be sent for several times to stop new leaks that were continually
+showing themselves.
+
+I send you by this mail for your inspection one of the saddle bolts and
+one of the bolts taken out of the piston, and also the certificates of
+the engineer, boilermaker, and machinist who repaired the boiler. In
+justice to my fellow-farmers I ought to publish these certificates and
+the names of these boilermakers to the world, but, for the present at
+least, I refrain from so doing. These boilermakers will see this article
+and they will know, if the public does not, for whom it is intended. If
+it has the effect of making them exercise more care in the construction
+and fitting up of their engines and boilers, I have not written in vain.
+
+D. FREEMAN.
+
+Los Angeles, Cal., March 7,1884.
+
+[The two bolts and the certificates above referred to accompany the
+letter of Mr. Freeman. We can only wonder how it was that, after having
+been treated as he relates in the first instance, he should have had any
+further business with parties who would send out such boilers, for the
+testimony of the engineer and workmen make the case even stronger than
+Mr. Freeman has put it.--ED.]
+
+       *       *       *       *       *
+
+
+
+
+A THREADED SET COLLAR.
+
+
+There are cases where a long screw must be rotated with a traversing nut
+or other threaded piece traveling on its thread a limited and variable
+distance. At one time the threaded nut or piece may be required to
+go almost the entire length of the screw, and at another time a much
+shorter traverse would be required. In many instances the use of side
+check nuts is inconvenient, and in some it is impossible. One way of
+utilizing the nut as a set collar is to drill through its side for a set
+screw, place it on its screw, pour a little melted Babbitt metal, or
+drop a short, cold plug of it into the hole, tap the hole, and the tap
+will force the Babbitt into the threads.
+
+Insert the set screw, and when it acts on the Babbitt metal it will
+force it with great friction on to the thread without injuring the
+thread; and when the set screw tension is released, the nut turns
+freely. A similar and perhaps a better result may be obtained by
+slotting the hole through the nut as though for the reception of a key.
+Secure a key (preferably of the same material as the nut) by slight
+upsetting at its ends, and then thread the nut, key, and all. Place
+a set screw through the nut over the threaded key, and the job is
+complete.
+
+       *       *       *       *       *
+
+
+
+
+PNEUMATIC MALTING.
+
+
+The lethargy in the malting trade, and in all matters relating to
+malting processes, induced by two centuries of restrictive legislation,
+is being gradually shaken off by the malting industry under the new law.
+For many years nearly all improvements in malting processes originated
+abroad, as numberless Acts of Parliament fettered every process and the
+use of every implement requisite in a malt-house in this country. The
+entire removal of these legislative restrictions gives an opportunity
+for improved processes, which promises to open up a considerable
+field for engineering work, and to develop a very backward art by the
+application of scientific principles. The present time is, therefore,
+one of more material change than malting has ever experienced.
+
+[Illustration: PNEUMATIC MALTING AT TROYES. Fig. 1.]
+
+Of the numerous improvements effected in the past few years, those made
+by M. Galland in France, and more recently by M. Saladin, are by far the
+most prominent. M. Galland originated what is known as the pneumatic
+system eight or nine years ago. This system is carried out at the
+Maxéville brewery, near Nancy.
+
+[Illustration: PNEUMATIC MALTING AT TROYES. Fig. 2.]
+
+Since that time further improvements have been made by M. Galland; but
+more recently great advances have been made in the system by M.
+Saladin. He has developed the practice of the leading principle, and in
+conjunction with Mr. H. Stopes, of London, has added improved kilns and
+various mechanical apparatus for performing the work previously done by
+hand. He has also devised a very ingenious machine for cooling the moist
+air by which the process is carried on.
+
+[Illustration: FIG. 4.--ECHANGEUR AND TURNING MACHINE.]
+
+At the recent Brewery Exhibition, some of the machinery used in these
+new maltings was shown in action by Messrs. H. Stopes & Co., together
+with drawings of a malting constructed at Troyes for M. Bonnette under
+M. Saladin's instructions. This malting is the third constructed for the
+same firm, the others being at Nancy. That at Troyes we now illustrate.
+We will not occupy space by a general description of the pneumatic
+system, one great feature in which is the continuous manufacture of malt
+throughout the year instead of only from five to eight months of the
+year, as it will be gathered from the following description of the
+Troyes malting:
+
+[Illustration: FIG. 5.--ECHANGEUR, AXIAL SECTION.]
+
+In our engravings, Figs. 1, 2, and 3, the letter A indicates the
+germinating cases; B, Saladin's patent turning screws; C A, air
+channels; D, passages; E R, main driving shafts; e, pulleys; F, metal
+recesses to fit turning screws; G, elevators; H, trap doors; I, air
+channels; J, openings to growing floor for air; K S, engines and fan
+room; L N, fans, supply and exhaust; T, boiler; U, chimney; f, well. The
+capacity of the malting is 130 qr. malt every day. This is equivalent to
+an English house of 520 qr. steep. The whole space occupied is the area
+necessary for kilns, malt and barley stores, engine and boiler house,
+and fans. No additional area is required for germinating floors, as ten
+germinating cases, A, are placed in the basement below the kilns and
+stores. The building is of brick, with the internal walls below the
+ground line resting upon cast iron columns and rolled joists. The
+germinating cases, A A, are of iron; the bottoms are double. One of
+perforated plate is placed 6 inches above the bottom. These plates admit
+of draining the corn if the germinating case is used as a steeping
+cistern also. Their chief object is, however to admit of ready
+circulation of the air by the means presently to be described. Large
+channels, A a, serve as drains for moisture and to convey the air to or
+from the growing corn. Between each case is a passage, D, enabling the
+maltster to have free access to the corn at all points.
+
+[Illustration: FIG. 6.--ECHANGEUR TRANSVERSE SECTION.]
+
+With the exception of the driving shaft, E, all the machinery is in
+duplicate, so that the possibility is remote of any breakdown that would
+seriously affect the working of the house. This is necessary, as should
+the fans, L N, be stopped for twenty-four hours the corn germinating
+at a depth exceeding 30 inches would heat and impair its vitality. The
+boilers, T, and engines, S, are of the common type of 20 horse power
+nominal. The fans, L N, are the Farcot patent, illustrated a short time
+since in our pages. The lower floors of the kilns are provided with
+the Schlemmer patent mechanical turners. The turners, Fig. 4, in the
+germinating cases are Saladin's patent.
+
+[Illustration: FIG. 7.--ECHANGEUR, SECTIONAL PLAN.]
+
+The germination of the grain is effected by means of cool moist air
+provided by the fan described and the cooler and moistener--Figs. 5, 6,
+and 7, herewith--known as an _echangeur_. As the germinating grain has
+a depth of from 30 inches to 40 inches some pressure is required, and
+mechanical means are necessary for efficient and economical turning.
+The _echangeur_ is a very ingenious application of the well understood
+rapidity of evaporation of any liquid when spread out in very thin
+layers over large surfaces and exposed to a current of air. It consists
+of a cylinder, or series of cylinders, of increasing diameter, placed
+one within another. Each consists of finely perforated sheet iron. They
+are placed in a trough of water, just sufficiently immersed to insure
+complete wetting. When rotated at a slow speed, the surfaces of all the
+cylinders are kept just wetted. A volume of air is either driven or
+drawn through, as may be required for any particular purpose. In the
+model malting, as shown at Fig. 4, taken from that shown at the Brewery
+Exhibition, the air was driven through the _echangeur_ and thence
+through the germinating barley. Here or as employed in the malting
+illustrated, the air in its passage comes first into contact with the
+moistened cylinders, and if hot and dry it becomes moist and cool, for
+the constant evaporation upon the cylinders has a very considerable
+refrigerating effect.
+
+This was well known to the Egyptians over four thousand years ago, and
+the porous bottle--_gergeleh_--of Esnch has been made until the present
+day, to keep the drinking water cool and fresh. The _echangeur_ is
+like a gigantic gergeleh, and by increasing the size and number of the
+cylinders, and causing the water in the moistening trough to circulate,
+any volume of air can be wetted to the saturation limit corresponding to
+its temperature. It will be seen that this apparatus gives the maltster
+complete control of the humidity and heat as well as volume of the air
+driven through germinating corn.
+
+[Illustration: Fig. 8.]
+
+The turning apparatus is shown by Fig. 4, and consists, as will be seen,
+of a cylindrical frame provided with rollers which run on rails at the
+edge of the germinating cases. It is carried to and fro from either end
+of the case by compensating rope gearing which at the same time gives
+motion to the gearing actuating the turning screws. These screws do not
+quite touch the bottom of the germinating case, but are provided with a
+pair of small brushes, as shown in the annexed engraving, Fig. 8, which
+just skim it. The apparatus shown has but three of these screws, but the
+cases are generally made wide enough for six. The kilns are double,
+each possessing two floors, and worked upon the Stopes' system. The
+construction of the furnaces is of the ordinary French pattern. The
+arrangement of the house permits of great regularity in working. Every
+day 130 qrs. of barley is screened, sorted, cleaned, and passed into a
+steeping cistern. When sufficiently steeped it runs through piping into
+the germinating case, which, in the natural order of working, is empty.
+Here it forms the couch. When it is desirable to open couch a small
+amount of air is forced through the grain by opening the trap door
+connected with the main air channel. This furnishes the growing corn
+with oxygen, removes the carbonic acid gas, and regulates temperatures
+of the mass of grain. Later the Saladin turner is put in motion about
+every eight to twelve hours. The screws in rotating upon their axes are
+slowly propelled horizontally. They thus effectually turn the grain and
+leave it perfectly smooth. This turning prevents matting of the roots,
+the regulation of temperature and exposure to air being effected
+by means of the cold air from the _echangeur_. When the grain is
+sufficiently grown it is elevated to the kilns. For forty hours it
+remains upon the top floor. It is then dropped upon the bottom floor, a
+further charge of green corn following upon the top floor. The benefit
+is mutual. The bottom floor is maintained at an even temperature, being
+virtually plunged in an air bath; free radiation of heat is prevented;
+the top surface of the malt is necessarily nearly as warm as that next
+the wires, which in its turn is subject to lower heats than would be
+necessary if free radiation from the surface was allowed. The top floor
+is by the intervention of the layer of malt between it and the fire
+prevented it from coming into direct contact with heat of a dangerous
+and damaging degree. The same heat which is used to dry one floor, and
+in an ordinary kiln passes at once into the air as waste, is the best
+possible description of heat, namely, very slightly moistened heated
+air, to remove the moisture from the second layer of malt at a low
+temperature. It is of vital importance to retain this green malt at a
+low heat so long as any percentage of moisture exceeding, say, 15 per
+cent, is retained by the corn.
+
+The regulation of temperature is shown by the diagrams, Figs. 9 and 10:
+
+[Illustration: Fig. 9.]
+
+[Illustration: Fig. 10.]
+
+The distribution of the heated air in the kiln is rarely as uniform as
+is supposed, the temperature of the malt on drying floor being very
+different at different parts. In illustration of this, the following may
+be taken from a statement by Mr. Stopes of the results of an examination
+of the temperatures at different parts of a drying floor in a kiln in
+Norfolk: "A malting steeping 105 qr. every four days has a kiln 75
+feet by 36 feet; an average drying area of under 26 feet per qr. The
+consequent depth of green malt when loaded is over 10 inches. The total
+area of air inlets is less than 27 feet super. The air outlet exceeds
+117 feet, a ratio of 13 to 3. The capacity of head room equals 44,550
+feet cube. The area of each tile is 144 inches, with 546 holes, giving
+an effective air area of some 32 inches. The ratio of non-effective
+metallic surface to air space is thus 9 to 2." The Casella anemometer
+gave no indications at several points, and fluctuating up and down
+draughts were observable at many others, especially at two corners and
+along the center. "The strongest upward draught pulsated with the gusts
+of wind and ranged from 30 feet to 54 feet per minute, a down draught of
+equal intensity occurring at intervals at the same spot, notwithstanding
+the fact that the air was rushing in at the inlets below the floor at
+the high velocity of 785 feet per minute. The temperatures of the drying
+malt and superimposed air consequent upon the conditions thus indicated
+were naturally as follows: At B, the place supposed to be hottest: Heat
+of malt touching tiles, 216 deg.; heat of malt 1 inch above tiles, 167
+deg.; heat of malt 3 inches above tiles 154 deg.; heat of malt 4 inches
+above tiles, 152 deg.; heat of malt 5 inches above tiles, 142 deg.; heat
+of malt on surface, 112 deg. At A, the place supposed to be coldest:
+Heat of malt next tiles, 174 deg.; heat of malt 2 inches above tiles,
+143 deg.; heat of malt 4 inches above tiles, 135 deg.; heat of malt on
+surface, 104 deg.; the heat of the air 3 feet above tiles, 84 deg.; the
+heat of the air 5 feet above tiles, 82 deg. Fig. 9 shows the temperature
+at twenty-six points close to the tiles, taken with twelve registered
+and accurate thermometers in the space of fifteen minutes." These and
+other similar tests have led to the conclusion that the best malt drying
+cannot be done on a single floor.
+
+Fig. 10 is a similar diagram showing the temperatures on a drying floor
+of kiln at Poole, Dorset, altered to Stopes' system of drying. The
+temperature at different depths of the drying grain was as follows: Malt
+at surface of tiles, 142 deg.; malt at 1 inch above tiles, 142 deg.;
+malt at 2 inches above tiles, 142 deg.; malt at 4 inches above tiles,
+141 deg.; malt on surface, 140 deg.
+
+The advantages of the Saladin system over that hitherto working in
+Britain are numerous, and are thus enumerated by Messrs. Stopes & Co.
+who are agents for M. Saladin: The area occupied by the building does
+not equal one-third of that otherwise required. The actual growing-floor
+space is only about one-seventh, and the number of workmen is ruled
+necessarily by the size of the house, but on an average is reduced
+two-thirds; but the employment of much more power is necessary, and the
+power is used at more frequent intervals. The use of plant and premises
+is continuous, the processes of malting being equally well performed
+during the summer months. The further advantage of this is that brewers
+secure entire uniformity in age of malt. By the English system the
+stocks of finished malt necessarily fluctuate largely. All grain is
+subjected to the same conditions of surrounding air, exposure, and
+temperature. The volume of air supplied to the germinating corn is
+entirely under control, as are also its temperature and humidity. When
+germination is arrested and the green malt is drying, the double kilns
+insure control of the temperatures of the corn in the kilns. The
+infrequency of turning the germinating grain benefits the growth of the
+roots and the development of the plumule, besides saving much labor. No
+grains are crushed or damaged by the feet or shovels of workmen. The air
+supplied to the corn can be inexpensively freed from disease germs
+and impurities. The capital needed for malting can be reduced by the
+diminished cost of installation, and the reduced stocks of malt on hand.
+The quality of the malt made is considerably improved. The percentages
+of acidity are much reduced. The stability of the beer is increased,
+and a greater percentage of the extractive matter of the barley is
+obtainable by the brewer.--_The Engineer_.
+
+       *       *       *       *       *
+
+
+
+
+NON-SPARKING KEY.
+
+
+Profs. Ayrton and Perry lately described and exhibited before the
+Physical Society their new ammeters and voltmeters, also a non-sparking
+key. The well known ammeters and voltmeters of the authors used for
+electric light work are now constructed so as to dispense with
+a constant, and give the readings in amperes and volts without
+calculation. This is effected by constructing the instruments so
+that there is a falling off in the controlling magnetic field, and a
+considerable increase in the deflecting magnetic field. The deflections
+are thus made proportional to the current or E.M.F. measured. The
+ingenious device of a core or soft iron pole-piece, adjustable between
+the poles of the horseshoe magnet, is used for this purpose. By means of
+an ammeter and voltmeter used conjointly, the resistance of part of the
+circuit, say a lamp or heated wire, can be got by Ohm's law. Profs.
+Ayrton and Perry's non-sparking key is designed to prevent sparking with
+large currents. It acts by introducing a series of resistance coils
+determined experimentally one after the other in circuit, thereby
+cutting off the spark.
+
+       *       *       *       *       *
+
+
+
+
+NEW INSTRUMENTS FOR MEASURING ELECTRIC CURRENTS AND ELECTRO-MOTIVE
+FORCE.
+
+By Messrs. R. E. CROMPTON and GISBERT KAPP.
+
+[Footnote: Paper read before the Society of Telegraph Engineers, 14th
+February, 1884.]
+
+
+In consequence of the rapid development of that part of electrical
+science which may be termed "heavy electrical engineering," reliable
+measuring instruments specially suitable for the large currents
+employed in lighting and transmission of energy have become an absolute
+necessity. As usual, demand has stimulated supply, and many ingenious
+and useful instruments have been invented, the manufacture of which
+forms at the present day an important industry. Mr. Shoolbred, in a
+paper which he recently read before this Society, gave a full and
+interesting account of the labors of our predecessors in this field.
+To-day we add to the list then given a class of instruments invented by
+us, examples of which are now before you on the table. We have preferred
+to call them current and potential indicators in preference to meters,
+considering that the latter term, or rather termination, ought to be
+applied rather to integrating instruments, which the necessities of
+electric lighting, we believe, will soon bring into extensive use. The
+principal aim in the design of these indicators has been to obtain
+instruments which will not alter their calibration in consequence of
+external disturbing forces. If this object can be attained, then it will
+be possible to divide the scale of each instrument directly into amperes
+or volts, as the cause may be, and thus avoid the use of a coefficient
+of calibration by which the deflection has to be multiplied. This is an
+important consideration when it is remembered that in many cases
+these instruments have to be used by unskilled workmen, to whom a
+multiplication involving the use of demical fractions is a tedious and
+in some cases even an impossible task.
+
+[Illustration: FIG. 1. FIG. 2.]
+
+All measurements are comparative. We measure weights or forces by
+comparison with some generally known and accepted unit standard
+weights, lengths, areas, and volumes, by comparison with a unit length,
+resistance by a standard ohm, and so forth. In the same way currents
+could be measured by comparison with a standard current: but this
+would be a troublesome process, not only on account of the apparatus
+necessary, but also because it would be a matter of some difficulty to
+have a standard current always ready for use. In general, measurement
+by direct comparison with a standard unit is discarded for the more
+indirect method of measuring not the current itself, but its chemical,
+mechanical, or magnetic effect. The chemical method is very accurate if
+a proper density of current through the surface of the electrodes be
+used,[1] but since it requires a considerable time, and, above all, an
+absolutely constant current, its use is almost entirely restricted
+to laboratory work and to the calibration of other instruments. For
+practical ready use, instruments employing the mechanical or magnetic
+effect of the current are alone suitable. We weigh, so to speak, the
+current against the force of a magnet, of a spring, or of gravity.
+The measurement will be exact if the thing against which we weigh or
+counterbalance the current itself retains its original standard value.
+Where permanent magnets or springs are used as a balancing force, this
+condition of constancy in our weights and measures is not always fully
+maintained, and to make matters worse, there is no visible sign by which
+a change, should it have occurred, can be readily detected. A spring
+may have been overstrained or a steel magnet may have become weakened
+without showing the least alteration in outward appearance. To overcome
+this difficulty, the obvious remedy is not to use springs or steel
+magnets at all, but to substitute for these some other force which
+should be either absolutely constant, such as the force of gravity, or
+at least should, vary only within narrow limits, and this in accordance
+with a definite law. This latter condition can be fulfilled by the
+employment of electro-magnets.
+
+[Footnote 1: According to recent experiments made by Dr. Hammerl, the
+density of current in a copper voltameter should be half an ampere per
+square inch of surface.]
+
+[Illustration: FIG 3.]
+
+To imitate with an electro magnet as nearly as possible a permanent
+magnet, so that the former can be used to replace the latter, it is
+necessary that the magnetism in the iron core should remain constant.
+This could, of course, be done by exciting the electro magnet with a
+constant current from a separate source. (In a recent note to the Paris
+Academy of Science, M.E. Ducretet described a galvanometer with steel
+magnet, which is surrounded by an exciting coil. When recalibration
+appears necessary, a known standard current from large Daniell cells is
+sent through this coil during a certain time, and thus the magnet is
+brought back to its original degree of saturation. M. Ducretet also
+mentions the use of a soft iron bar instead of a steel magnet, in which
+case the current from the Daniell cells must be kept on during the time
+an observation is taken.) But such a system would appear to be too
+complicated for ready use. Moreover, some sort of indicator would be
+required by which we could make sure that the exciting current has the
+normal strength.
+
+[Illustration: FIG 4.]
+
+The plan we adopt is to excite the electro magnet by the whole or a part
+of the current which is to be measured. Since this current varies, the
+power exciting the core of the electro magnet must also vary; and since
+we require the core to have as nearly as possible a permanent magnetic
+force, we are brought face to face with the question, whether an electro
+magnet can be constructed that has a constant moment under varying
+exciting currents. This question has been answered by the well known
+experiments of Jacobi, Dub, Mueller, Weber, and others. To get an
+absolutely constant magnetic moment, is not possible, but between
+certain limits we can get a very near approximation to constancy.
+
+[Illustration]
+
+The relation between exciting power and magnetic moment is very
+complicated, depending not only on the dimensions and shape of the core
+and the manner of winding, but also on the chemical constitution of the
+iron of the core. It is not possible, or at least it has hitherto not
+been found possible, to embody all these various elements into an exact
+mathematical formula, which would give the magnetic moment as a function
+of the exciting current; but the above mentioned experiments have shown
+that within certain limits, and in the neighborhood of the point of
+saturation, the relation between the two is that of an arc to its
+geometrical tangent. It will be seen that for large angles the arc
+increases much slower than the tangent; that is, for strongly excited
+cores, a very large increase of the exciting current will produce only
+a slight increase of magnetic moment. If Mueller's formula were correct
+for all currents, absolute saturation could only be reached with an
+infinite current. Whether this be the case or not, it is certain that
+the greater the exciting current the less will a variation in it affect
+the magnetic moment of the core. To imitate as nearly as possible
+permanent steel magnets, it is therefore necessary to use electro
+magnets, the cores of which are easily saturated. The core should be
+thin and long and of the horseshoe type; the amount of wire wound round
+it should be large in comparison with the size of the core.
+
+[Illustration]
+
+Here is a magnet partly wound which was used in one of our earliest
+experiments, but which was a failure on account of having far too much
+mass in the core in comparison with the amount of copper wire wound
+round it. Since then we have greatly diminished the iron and increased
+the copper. The cores of the instruments on the table are composed of
+two or three No. 18 b.w.g. charcoal iron wires, and are wound with one
+layer of 0'120 inch wire in the case of the current indicators, and
+eighteen layers of 0.0139 inch wire in the case of the potential
+indicator. If from the diagram, Fig. 1, we plot a curve the abscissae of
+which represent exciting current, and the ordinates magnetic moment of
+the soft iron core, we find that a considerable portion of the curve
+is almost a straight and only slightly inclined line. If it, were a
+horizontal straight line the core would be absolutely saturated, but
+such as it is, it answers the purpose sufficiently well, for with a
+variation of exciting current from 10 to 100 amperes the magnetic moment
+varies but slightly. If a small soft iron or magnetic steel needle, _n
+s_, be suspended between the poles, S N, of an electro magnet of such
+proportions as described above, and the current, after exciting the
+electro magnet, _e e_, be lead round the coils, DD, it will be found
+that for all currents between 10 and 100 amperes the needle, _n
+s_, shows a definite deflection for each current. Here we have a
+galvanometer with permanent calibration. In this case the deflection of
+the needle will not strictly follow the law of tangents, because the
+directing power of the electro magnet is not absolutely constant; but
+whatever the exact ratio between deflection and current may be, it must
+always remain the same, and to each angle of deflection corresponds one
+definite strength of current.
+
+[Illustration]
+
+The force with which the electro magnet tends to keep the needle in its
+zero position, that is, in line with the poles, S N, is due partly to
+the magnetism of the core, which is nearly constant, and partly to the
+magnetic influence of the coils, _ee_, themselves, which is, of course,
+simply proportional to the current. The total magnetic force acting on
+the needle is, therefore, represented by the sum of these two forces,
+and consequently not nearly so constant as might be desired in order to
+get a good imitation of a tangent galvanometer with a permanent magnet.
+In the diagram, Fig. 2, the curve, O A B, represents the magnetic moment
+of the iron core, the straight line, ODE, that of the exciting coils per
+se, and the dotted line, O F M, the sum of the two, obtained by adding
+for every current, O C, the respective ordinates, CD and C A.
+
+  CF = CD + CA
+
+The rise of this curve shows that the force which tends to bring the
+needle back to its zero position increases with the current, though at a
+slower ratio than the deflecting force of the current. It follows from
+this that for large currents the increment in the angle of deflection is
+comparatively small, and the divisions on the scale whereon the current
+is to be read off would come too near together to allow accurate
+readings to be taken. In other words, the range of accurate reading in
+an instrument so constructed would only be limited. But it is very easy
+to eliminate the magnetic effect of the coils of the electro magnet on
+the needle, by introducing an opposite magnetic effect, so that only
+that part of the force remains which belongs to the soft iron core
+proper. One way of doing this is by surrounding the needle with a coil,
+the plane of which is at right angles to the line, S N, and coupling
+this coil in series with the deflecting coil, D D. If the proportions
+of this transverse coil and the direction of the current through it
+be properly chosen, its magnetic effect can be made to exactly
+counterbalance that of the exciting coils, _e e_, without perceptibly
+weakening the magnetism of the iron core. But instead of employing two
+coils, one parallel and the other transversely to the zero position of
+the needle, we can obtain the same result in a more simple manner with
+one coil only, if this be placed at such an angle that its magnetic
+effect can be substituted for the combined effects of the two coils. In
+other words, we set the deflecting coil, D D, at a certain angle to the
+zero position of the needle.
+
+A similar arrangement, though not precisely for the same purpose, has
+already been suggested and tried by Messrs. Deprez, Carpentier, Ayrton,
+and Perry, in galvanometers with permanent steel magnets. If the coil,
+D D, be so placed, the deflecting force which now acts obliquely can be
+considered as the resultant of two forces, one acting at right angles to
+the line, S N, as in an ordinary galvanometer, and the other parallel to
+this line, but in a sense opposed to the action of the electro magnet
+and its exciting coils. If the angle of obliquity be so chosen that this
+latter component exactly equals the magnetic effect of the exciting
+coils _per se_, an equality which holds good for all currents, then we
+shall have an almost perfect imitation of a tangent galvanometer with
+permanent magnets. But we can go a step further than this; we can
+overbalance the exciting coils by setting the deflecting coil at a
+greater angle than necessary for the mere elimination of the former, and
+thus attain that an increase of current results in a slight weakening of
+the field in which the needle swings, thus allowing the increment of the
+angle of deflection to be comparatively large even for large currents.
+In this way it is possible to obtain a more evenly divided scale than
+in the case when the deflection follows the law of tangents, as in an
+ordinary tangent galvanometer. This principle of overbalancing the
+exciting coils is shown on diagram, Fig. 2. The straight line, O G,
+represents the magnetic effect on the needle of that component of the
+deflecting force which is parallel, but in sense opposed to S N;
+as mentioned above, the magnetic effect of the exciting coils is
+represented by the straight line, O E. The combined effect of these two
+forces on the needle is represented by the line, O K, the ordinates
+of which must be deducted from those of the curve, O A B, in order to
+obtain the total directing force due to each current. This is shown by
+the curve, O P Q, shown in a thick full line. This curve shows how
+the directing force or strength of field in which the needle swings
+decreases with an increasing current. That this does actually take place
+can easily be proved by experiment.
+
+Fig. 4 shows two curves; the one drawn in a full line is obtained
+by plotting the deflection in degrees of the needle of a potential
+indicator as abscissae, and the corresponding electromotive forces
+measured simultaneously on a standard instrument as ordinates; the
+dotted line shows what this curve would be with an ordinary tangent
+galvanometer.
+
+The needle of the potential indicator is mounted at the lower end of
+a steel axle, to the upper end of which is fastened a light aluminum
+pointer, whereby the deflection of the needle can be read off on a scale
+divided directly into volts. The scale is placed within a circular dial
+plate with glass cover, giving sufficient room for the pointer to swing
+all round, and the needle is placed within a central tube fitting it
+closely, which acts as a damper and so makes the instrument almost
+dead beat. Tube and dial are in one casting. The electro magnet is of
+horseshoe form fastened to a central tubular stand, which also serves
+to support the two deflecting coils, one on either side of it. The tube
+within which the magnetic needle swings is inserted into the stand,
+which is bored out to the external diameter of the tube. The electro
+magnet and deflecting coils are wound with from 50 to 100 ohms of fine
+insulated copper wire, and an additional resistance coil of from 450
+to 900 ohms of German silver is added, which can, however, be short
+circuited by depressing a key when the instrument has to be used for
+reading low electromotive forces. In this case the indication of the
+pointer must be divided by ten. If a current be sent through the
+instrument the wrong way, the needle turns through an angle of 180°, and
+thus brings the pointer to the side of the dial opposite to where the
+scale is. In this position no reading can be taken, and to facilitate
+the sending of the current in the right direction a commutator is added,
+and the same is so coupled up that when the pointer stands over the
+scale the handle on the commutator points to the positive terminal
+screw. There is a limit of electromotive force below which the indicator
+fails to give reliable readings. For instance, an instrument wound with
+100 ohms of copper wire and 900 ohms of German silver can be used for
+electromotive forces varying between 300 and 3 volts, but would not be
+reliable for measuring less than 3 volts.
+
+For very exact measurements the instrument should be placed north and
+south, in the same position in which it was calibrated. Two different
+patterns of current indicators are on the table; one with double needles
+suspended on a point in the way compass magnets are suspended, the other
+with one lozenge shaped needle mounted on an axle and pivoted on jewels,
+in every way similar to the needle of the potential indicator first
+described.
+
+For measurements of currents from 10 amperes upward, there is no need
+to employ a complete coil as the deflecting agent; one half-coil or one
+strip passing close under the needle gives sufficient deflecting force,
+and thus the construction of the instrument is rendered extremely
+simple. The current, after entering at one of the flat electrodes,
+splits in two parts, each part passing round the winding of an electro
+magnet of horseshoe form, the similar poles of both magnets pointing
+toward each other and toward the needle. After traversing the winding,
+the current unites again, and passes through a metal strip close under
+the needle, and finally out of the instrument by the other electrode,
+which lies close under that at which the current entered, but is
+insulated from it by a sheet of fiber. The metal strip is set at an
+angle, to balance or overbalance, as may be preferred, the magnetic
+influence of the exciting coils. The effect of this overbalancing is
+shown in Fig. 5, where the full curve represents the current as a
+function of the deflection--obtained by comparison with a standard
+instrument--and the dotted curve shows what that relation between
+deflection and current would be if the law of tangents held good for
+these instruments. It will be seen that, about the middle of the scale,
+the dotted line coincides nearly with the full line, while at the
+extreme end of the scale the dotted line is higher. From this follows,
+that if we compare our indicator from which this curve was taken with
+any form of tangent instrument showing an equal angle of deflection at
+the medium reading, it will be seen that the needle of our indicator
+will be deflected to a greater angle at high readings than that of the
+tangent galvanometer. Consequently, the divisions on the scale will
+be widest apart in our instruments, which greatly facilitates high
+readings.
+
+       *       *       *       *       *
+
+
+
+
+SECONDARY BATTERIES.
+
+
+The Consolidated Electric Light Company has now completed the secondary
+battery which has for some time engaged the attention of its officers,
+and their regular manufacture and use for electric lighting stations
+have been fairly entered upon. Among other places to which the batteries
+have been sent and put into work is Colchester, where the company
+has for some time had an installation at work, chiefly employing
+incandescent lamps. The battery consists of lead electrodes, anode and
+cathode being of the same character. They are constructed of narrow
+ribbons of lead, each element being made from long lengths of the ribbon
+about or nearly 0.20 in. width, rolled together into a flat cake like
+rolls of narrow webbing, as illustrated by the annexed diagram, Fig.
+1, the greater part of the ribbon being very thin and flat; but
+intermediate thicker ribbons are also employed, as in Fig. 2, this
+thicker ribbon being corrugated as shown, and affording passage room
+for the circulation of the electrolyte. From four to eight coils of the
+plain ribbons are between every pair of corrugated ribbons. They are
+wound up together tightly, and pressed into the nearly rectangular form
+shown. The bar for suspending the coil plates so made in the cells is
+soldered to the coil. The object of this construction is of course to
+obtain large lead surface, and of course a much larger surface is so
+obtained than could be practically obtained from plain lead plates in
+the same compass. A battery thus made may be seen at the offices of the
+company, 110 Cannon Street.
+
+[Illustration: FIG. 1. FIG. 2.]
+
+A very ingenious device for cutting the battery out of circuit when
+charged as much as is thought desirable is used by the company. In a
+cell is an element which has a determined lower capacity than those in
+the rest of the battery. Over this element is placed a gas-tight chamber
+in which is a diaphgram, this diaphragm being of very flexible material
+placed in the cover of the box of cells. When charging has proceeded as
+long as is desirable, or proceeds too fast, hydrogen is evolved, and
+this collecting in the chamber referred to acts upon the diaphragm, and
+by means of a rod connected thereto, switches the current, which is
+supplied to an electro-magnet and by which circuit is made through the
+medium of mercury contacts. The object, of this is to save the
+battery from destruction by over-charging or charging by too large a
+current.--_The Engineer_.
+
+       *       *       *       *       *
+
+
+
+
+ACETYLENE FROM IODOFORM.
+
+
+P. CAZENEUVE publishes in the _Comptes Rendus_ a new method for the
+preparation of acetylene, which consists in mixing iodoform intimately
+with moist and finely divided silver. An abundant evolution of acetylene
+takes place without heating. The reaction is represented by the
+following formula: 2CHI_{3} + 6Ag = C_{2}H_{2} + 6 AgI. The
+decomposition of the iodoform is hastened if the silver is mixed with
+finely divided copper, such as can be obtained by precipitating it from
+its sulphate by means of zinc.
+
+Cazeneuve also observed that most metals which have any affinity for
+iodine will decompose iodoform in the presence of water, forming
+acetylene and an iodide of the metal. By the use of zinc he obtained a
+liquid having a pleasant ethereal odor, and a gas mixture that contained
+besides acetylene an iodine compound which burned with a purple-edged,
+fawn-colored flame.
+
+       *       *       *       *       *
+
+
+
+
+WHEN DOES AN ELECTRICAL SHOCK BECOME FATAL?
+
+
+In this age of electricity and electric wires carrying currents of
+various intensity, the question of danger arising from contact with them
+has caused considerable discussion. An examination into the facts as
+they exist may therefore enlighten some who are at present in the dark.
+
+To begin with, we often hear the question asked--why is it that certain
+wires carrying very large currents give very little shock, whereas
+others, with very small currents, may prove fatal to those coming in
+contact with them? The answer to this is--that the shock a person
+experiences does not depend upon the current _flowing in the wires_, but
+upon the current _diverted from them_ and _flowing through the body_.
+
+The muscular contraction due to a galvanic current, which was first
+observed in the frog, gives a good illustration of the fact that it
+requires only a very minute current to flow through the muscles in order
+to contract them. Thus the simple contact of pieces of zinc and copper
+with the nerves generated current sufficient to excite the muscles--a
+current which would require a delicate galvanometer for its detection.
+What is true of the muscles of the frog holds good also for the human
+muscles; they too are very susceptible to the passage of a current.
+
+In order to determine the current which proves fatal we need only to
+apply the formula which expresses Ohm's law, viz., C=E/R, or the current
+(ampere) equals the electromotive force (volt) divided by the resistance
+(ohm).
+
+According to the committee of Parliament investigation, the
+electromotive force dangerous to life is about 300 volts; this then is
+the quantity, E, in the formula. There remains now only to determine the
+resistance in ohms which the body offers to the passage of the current.
+In order to obtain this, a series of measurements under different
+conditions were made. On account of the nature of the experiment a high
+resistance Thomson reflecting galvanometer was used, with the following
+results.
+
+When the hands had been wiped perfectly dry, the resistance of the body
+was about 30,000 ohms; with the hands perspiring ordinarily it fell to
+10,000 ohms; whereas when they were dripping wet it was as low as 7,000
+ohms. Our readers can judge this resistance best when we state that the
+Atlantic cable offers a resistance of 8,000 ohms.
+
+Taking an ordinary condition of the body, with the hands perspiring as
+usual, we would have the resistance equal to 10,000 ohms. Applying the
+two known quantities in the formula, we get:
+
+  C = (300 / 10,000) - (1 / 33.333+)
+
+This means, therefore, that when the electromotive force or potential is
+great enough to send a current of 1/33 ampere through the body, fatal
+results will ensue. This current is so minute that it would deposit only
+about 6 _grains_ of copper in _one hour_, a grain being 1/7,000 of a
+pound.
+
+Let us now compare these figures with some actual cases, taking as
+an example a system of incandescent lighting. In these systems the
+difference of potential between any two points of the circuit outside of
+the lamps does not exceed 150 volts. Taking this figure, therefore, it
+will be seen that under no circumstances can the shock received from
+touching these wires become dangerous--not even by touching the
+terminals of the dynamo itself; because in neither case can a current be
+driven through the body, sufficient to cause an excessive contraction of
+the muscles.
+
+In a system of arc lighting, however, we have to deal with entirely
+different conditions; for, while in the incandescent system the adding
+of a lamp, which diminishes the resistance, requires no increase of
+electromotive force, the contrary is the case in the arc light system.
+Here every additional lamp added to the circuit means an increase in
+resistance, and consequent increase in electromotive force or potential.
+Taking for example a well known system of arc lighting, we find that the
+lamps require individually an electromotive force of 40 volts with a
+current of 10 amperes. In other words, the difference in potential at
+the two terminals of every such lamp is 40 volts. Consequently, if the
+circuit were touched in two places, including between them only one
+lamp, no injurious effects would ensue. If we touch the circuit so as
+to include two lamps between us, the effect would be greater, since the
+potential between those two points is 2 x 40 volts. We might continue
+in this manner touching the circuit until we had included about 7 or
+8 lamps, when the shock would become fatal, since the point would be
+reached at which the difference of potential is great enough to send a
+dangerous current through the body.
+
+Up to this point we have assumed that, while touching two points in the
+wire, the rest of the circuit is perfectly insulated, so that no current
+can leak, in other words, that the circuit is nowhere "grounded." If
+this is not the case we may, under suitable conditions, receive a
+shock by touching only _one_ point of the wire. This becomes clear
+by considering the current to leak from another spot of different
+potential, to pass through the ground and into the body; thus, on
+touching the wire the body virtually makes a connection between the
+two points of the circuit. In clear dry weather such leaks are
+insignificant; but in damp and rainy weather, and with poor insulation,
+they may rise to such a point at which it would be dangerous to touch
+the circuit even with one hand, the leaks being sometimes so great as
+to cause the lamps to burn in a fitful, desultory manner, and to go out
+entirely.
+
+There is still another factor which enters into the discussion of the
+danger of electric light wires. This must be looked for in the fact that
+the physiological effects are greatest at the moment of the opening or
+the closing of the circuit; or in a closed circuit they are the more
+marked when the flow of current stops and starts, or diminishes and
+increases. In dynamo electric machines the current is not absolutely
+continuous or uniform, since the coils on the armature being separated a
+distance cause a slight break or diminution of the current between each.
+This break is so short that it does not interfere with the practical
+work for lighting; in some constructions, nevertheless, the distances
+apart is so great that, while not interfering with light, its effects
+upon the muscles are greatly increased over those of other constructions
+which give a more uniform current.
+
+All these statements might lead to the conclusion that arc light wires
+are dangerous under any circumstances; but this is not the case. The
+first and only requisite is, that they be perfectly insulated. When thus
+protected accidents from them are impossible, and all mishaps that have
+occurred through them can be traced directly to the lack of insulation.
+Nevertheless, we would warn our readers against experimenting upon arc
+wires by actual trial, because unforeseen conditions might lead to
+disagreeable results.
+
+       *       *       *       *       *
+
+
+
+
+ROBERT CAUER'S STATUE OF LORELEI.
+
+
+The statue of Lorelei, the mythical siren of the Rhine, represented in
+the annexed cut, which is taken from the _Illustrirte Zeitung_, was
+modeled by Robert Cauer, of Kreuglach on the Rhine. He was born at
+Dresden in 1831, and is the son of the well-known sculptor Emil Cauer,
+and a brother of the sculptor Karl Cauer.
+
+[Illustration: LORELEI STATUE BY ROBERT CAUER.]
+
+       *       *       *       *       *
+
+
+
+
+REDUCING AND ENLARGING PLASTER CASTS.
+
+
+Ordinary casts taken in plaster vary somewhat, owing to the shrinkage of
+the plaster; but it has hitherto not been possible to regulate this
+so as to produce any desired change and yet preserve the proportions.
+Hoeger, of Gmuend, has, however, recently devised an ingenious method
+for making copies in any material, either reduced or enlarged, without
+distortion.
+
+The original is first surrounded with a case or frame of sheet metal or
+other suitable material, and a negative cast is taken with some elastic
+material, if there are undercuts; the inventor uses agar-agar. The usual
+negative or mould having been obtained as usual, he prepares a gelatine
+mass resembling the hektograph mass, by soaking the gelatine first, then
+melting it and adding enough of any inorganic powdered substance to give
+it some stability. This is poured into the mould, which is previously
+moistened with glycerine to prevent adhesion. When cold, the gelatine
+cast is taken from the mould, and is, of course, the same size as the
+original. If the copy is to be reduced, this gelatine cast is put in
+strong alcohol and left entirely covered with it. It then begins to
+shrink and contract with the greatest uniformity. When the desired
+reduction has taken place, the cast is removed from its bath. From
+this reduced copy a cast is taken as usual. As there is a limit to the
+shrinkage of the gelatine cast, when a considerable reduction is desired
+the operation is repeated by making a plaster mould from the reduced
+copy, and from this a second gelatine cast is taken and likewise
+immersed in alcohol and shrunk. It is claimed that even when repeated
+there is no sacrifice of the sharpness of the original.
+
+When the copy is to be enlarged instead of reduced, the gelatine cast is
+put in a cold water bath, instead of alcohol. After it has swollen as
+much as it will, the plaster mould is made as before. For enlarging,
+the mould could also be made of some slightly soluble mass, and then by
+filling it with water the cavity would grow larger, but it would not
+give so sharp a copy.
+
+       *       *       *       *       *
+
+
+
+
+STRIPPING THE FILM FROM GELATINE NEGATIVES.
+
+
+We have frequent inquiries as to the best means of removing a
+gelatino-bromide negative from its glass support so that it can be used
+either as a direct or reversed negative, and it does not appear to be
+very generally known that about two years ago Mr. Plener described a
+method which answers well under all circumstances, whether a substratum
+has been used or not.
+
+If a negative is immersed in extremely dilute hydrofluoric acid
+contained in an ebonite dish, say half a teaspoonful to half a pint of
+water, the film very soon becomes loosened, and floats off the glass,
+this circumstance being due to the solvent action which the acid
+exercises upon the surface of the plate as soon as it has penetrated the
+film. If the floating film be now caught upon a plate which has been
+slightly waxed, and it is allowed to dry on this plate, it will become
+quite flat and free from wrinkles. To wax the plate, it should be held
+before the fire until it is moderately hot, after which it is rubbed
+over with a lump of wax, and the excess is polished off with a piece
+of flannel. When the film is dry, it will leave the waxed glass
+immediately, if one corner is lifted by means of a penknife. The film
+will become somewhat enlarged during the above-described operation; but,
+by taking suitable precautions, this enlargement may be avoided. It is
+also convenient to prepare the hydrofluoric acid extemporaneously by the
+action of sulphuric acid on fluoride of sodium; and, in many cases, it
+is advisable to thicken up the film by an additional layer of gelatine.
+
+The following directions embody these points. The negative, which must
+be unvarnished, is leveled, and covered with a layer of warm gelatine
+solution (one in eight) about as thick as a sixpence. This done, and
+the gelatine set, the plate is immersed in alcohol for a few minutes
+in order to remove the greater part of the water from the gelatinous
+stratum. The next step is to allow the plate to remain for five or six
+minutes in a cold mixture of one part of sulphuric acid with twelve
+parts of water, and in the mean time two parts of sodium fluoride are
+dissolved in one hundred parts of water, an ebonite tray being used. A
+volume of the dilute sulphuric acid equal to about one-fourth of the
+fluoride solution is next added from the first dish, and the plate
+is then transferred to the second dish, when the film soon becomes
+liberated. When this is the case, it is placed once more in the dilute
+sulphuric acid. After a few seconds it is rinsed in water, and laid on a
+sheet of waxed glass, complete contact being established by means of a
+squeegee, and the edges are clamped down by means of strips of wood held
+in position by American clips or string. All excess of sulphuric acid
+may now be removed by soaking the plate in methylated alcohol, after
+which it is dried. It is as well to add a few drops of ammonia to the
+last quantity of alcohol used.
+
+The plate bearing the film negative is now placed in a warm locality,
+under which circumstances a few hours will suffice for the complete
+drying of the pellicular negative, after which it may be detached
+with the greatest ease by lifting the edges with the point of a
+penknife.--_Photo. News_.
+
+       *       *       *       *       *
+
+
+
+
+NEW ANALOGY BETWEEN SOLIDS, LIQUIDS, AND GASES,
+
+By W. SPRING.
+
+
+The author asks in the first place, What is the cause of the different
+specific gravities of one and the same metal according as it has been
+cast, rolled, drawn into wire, or hammered? Does the difference observed
+prove a real condensation of the matter under the action of pressure, or
+is it merely due to the expulsion by pressure of gases which have been
+occluded when the ingot was cast? According to well-known researches,
+metals such as platinum, gold, silver, and copper, which have
+been proved to occlude gases on fusion, and to let them escape,
+_incompletely_, on solidification, are precisely those which are
+most increased in their specific gravity by pressure. The author has
+submitted to pressures of about 20,000 atmospheres metals which possess
+this property, either not at all, or to a very trifling extent, and he
+finds that though a first pressure produces a slight permanent increase
+of density, its repetition makes little difference. Their density is
+found to have reached a maximum. Hence the density of solids, like that
+of liquids, is only really modified by temperature. Pressure effects
+no permanent condensation of solid bodies, except they are capable of
+assuming an allotropic condition of greater density. The author's former
+researches tend to show that solid matter, in suitable conditions of
+temperature, takes the state corresponding to the volume which it is
+compelled to occupy. Hence there is an analogy between the allotropic
+states of certain solids and the different states of aggregation of
+matter. Possibly the different forms of matter may be due to a single
+cause--polymerization. The limit of elasticity of a solid body is the
+critical moment when the matter begins to flow under the action of the
+pressure to which it is submitted, just as, e.g., ice at or below 0° may
+be liquefied by strong pressure. A brittle body is simply one which does
+not possess the property of flowing under the action of pressure.
+
+       *       *       *       *       *
+
+
+
+
+HYDROGEN AMALGAM.
+
+
+Hydrogen, although a gas, is recognized by chemists as a metal, and when
+combined with any solid metal--as in the case known to electricians as
+the polarization of a negative element,--the compound may correctly be
+termed an alloy; while any compound of hydrogen with the fluid metal
+mercury may with equal correctness be termed an amalgam of hydrogen, or
+"hydrogen amalgam." The efforts of many chemists and mining engineers
+have for many years been devoted to a search for some effective and
+economical means for preventing the "sickening" of mercury and its
+consequent "flouring" and loss. Some sixteen or more years ago,
+Professor Crookes, F.R.S., discovered and, after a series of
+experiments, patented the use of an amalgam of the metal sodium for this
+purpose. He made the amalgam in a concentrated form, and it was added
+in various proportions to the mercury used for gold amalgamation. Water
+becoming present, it will readily be understood that the sodium, in
+being converted into the hydrate (KHO) of that metal, caused a rapid
+evolution of hydrogen. The hydrogen thus evolved was the excess over a
+certain proportion which enters into combination with the mercury. While
+the mercury retained the charge of hydrogen, the "quickness" of the
+fluid metal was preserved; but upon the loss of the hydrogen the
+"quickness" ceased, and the mercury was acted upon by the injurious
+components contained in the ore.
+
+Since the introduction of the sodium amalgam, many attempts have been
+made, more especially in America, to overcome the tendency of mercury to
+"sicken" and lose its "quickness." The greater number of these efforts
+have been made by the use of electricity as the active agent in
+attaining this end; but such efforts have been generally of a crude and
+unscientific character. Latterly Mr. Barker, of the Electro-amalgamator
+Company, Limited, has introduced a system--already detailed in these
+pages--by which the mercury is "quickened." In his method the running
+water passing over the tables, or other apparatus of a similar
+character, is used as the electrolyte. In this arrangement, the mercury
+being the cathode, plates or wires of copper constituting anodes are
+brought into contact with the water passing over the mercury in each
+"riffle." Both the cathode and the anodes are, of course, maintained in
+contact with the poles of a suitable source of electrical supply. The
+current then passes from the copper anode through the running water
+to the mercury cathode, and so on to the negative pole of the
+electro-motor. As a consequence of this arrangement, hydrogen is evolved
+from the water, and has the effect of reducing any oxide or other
+detrimental compound of the metal; in other words, it "quickens" and
+prevents "sickening" of the fluid metal, and consequent "flouring" and
+loss. While the hydrogen is evolved at the cathode, oxygen enters into
+combination with the copper constituting the anodes. This to some extent
+impairs the conductivity of the circuit.
+
+The latest process, however, is that of Mr. Bernard C. Molloy, M.P.,
+which we have already characterized as highly scientific and effective,
+the production of a suitable amalgam being obtained under the most
+economical and simple conditions. This process has the advantage of
+producing not only a hydrogen amalgam, but also at will an amalgam of
+hydrogen combined with any metal electro-positive to this latter. Thus
+hydrogen potassium or hydrogen sodium can be obtained, as will be seen
+by the following description.
+
+Mr. Molloy's effort appears to have been, in the first place, directed
+to a system which could be adapted to any existing apparatus, and in
+certain cases where water was scarce, to avoid altogether the use of
+that, in some districts, rare commodity. For the purpose of explanation
+we select an ordinary amalgamating table fitted with mercury riffles.
+The surface of the table is in no way interfered with or disturbed. The
+bed of the riffle, however, is constructed of some porous material, such
+as leather, non-resinous wood, or cement, which serves as the diaphragm
+upon which the mercury rests, and separates the fluid metal from the
+electrolyte beneath. Running the full length of the table is a thin
+layer of sand, supported and pressing against the diaphragm, and lying
+in this sand is the anode, formed preferably of lead. A peroxide of
+that metal is formed by the action of the currents, and may be readily
+reduced for use over and over again after working for from one to three
+months. The peroxide of lead, as is well known, is a conductor of
+electricity, and this fact constitutes an important advantage in the
+working of the process. The thin layer of sand is saturated with an
+electrolyte, such as dilute sulphuric acid (H_{2}SO_{4} + 20H_{2}O)
+to give a simple hydrogen amalgam; (Na_{2}SO_{4} + xH_{2}O) to give a
+hydrogen sodium amalgam; or (K_{2}SO_{4} + xH_{2}O) to give a hydrogen
+potassium amalgam. Numerous other electrolytes constituted by acids,
+alkalies, and salts can be used to form an amalgam permanently
+maintained in a condition of "quickness" and freed from all liability
+to "sicken," whatever the components of the ore may be. The mercury
+is connected with the negative pole of the voltaic battery or other
+electro-motor, and the lead made with the positive pole of the same
+source. When the current passes there is formed according to the nature
+of the electrolyte, a hydrogen amalgam, or an amalgam of hydrogen with a
+metal electro-positive to hydrogen. The electrolyte, which, it will be
+understood, is distinct and apart from the body of water passing over
+the table, will last almost indefinitely, there being no consumption of
+any of its constituents, excepting hydrogen and oxygen from the water
+of solution. The quantity of acid or saline material contained in the
+electrolyte is so very small that there can be no difficulty in finding
+a supply in any district. The question of the supply of electricity is
+one which in many mining districts involves considerations of practical
+importance, since a large supply would necessitate water or steam power.
+It has been found that two cells having an electromotive force of about
+two volts each will in this process suffice; if preferred, however,
+a very small dynamo machine can be used. In connection with the
+electro-motive force it is requisite to use, it may be observed that an
+amalgam of sodium containing only a small quantity of this metal would,
+when constituting a positive element in conjunction with a lead negative
+and on an aqueous electrolyte, give an opposing electro-motive force of
+less than three volts. Such an amalgam could therefore be obtained under
+an electro-motive force of about four volts. The electrical resistance
+in the circuit constituted by the apparatus being very small, no
+electrical power is wasted. When water constitutes the electrolyte, as
+in Barker's system, then the electro-motive force required to obtain a
+given current would be very much greater than that above specified.
+The conditions assured under this process appear to be all that can
+be required, while the amalgams obtained are those most calculated to
+preserve the "quickness" and prevent the "sickening" of the mercury.
+
+Mr. Molloy has designed a special form of amalgamating machine to be
+used in conjunction with the above process, and with or without the aid
+of water. By the employment of this machine, each particle of the ore
+is slowly rolled in the quickened mercury for from fifteen to thirty or
+more seconds.
+
+When the extent of the gold and silver mining industries is considered,
+and when it is borne in mind that a considerable percentage of the
+precious metal present in the ore is, in the ordinary process of
+extraction, lost through defective amalgamation--due to insufficient
+contact with the mercury or to a total absence of contact, as in the
+case of float gold--it is obvious that the introduction of any system
+obviating such loss is a matter of very great importance to those who
+are interested in the above mentioned industries. We expect shortly to
+hear of the practical introduction on a large scale of Mr. Molloy's
+process, and we look forward with interest to the results which may be
+obtained from it.--_The Engineer_.
+
+       *       *       *       *       *
+
+
+
+
+TREATMENT OF ORES BY ELECTROLYSIS.
+
+By M. KILIANI.
+
+
+The author lays down general principles for electrolytic metallurgy.
+Ores must be distinguished as good and bad conductors; the former
+may serve directly as anodes, and are easily oxidized by the
+electro-negative radicals formed at their contact, and dissolve readily
+in the electrolyte. The bad conductors have to be placed in contact
+with a conducting anode, formed of an inoxidizable substance, such as
+platinum, manganese peroxide, or coke. In laboratory experiments a good
+conducting ore is electrolyzed by suspension from a platinum wire in
+connection with the source of electricity, and is then immersed in the
+bath. On an industrial scale the ore, coarsely broken up, is placed in
+one of the compartments of a trough divided by a diaphragm.
+
+On the fragments of the ore which extend up outside of the electrolytic
+bath is laid a plate of copper connected with the positive wire. Care
+must be taken that this plate does not plunge into the bath, otherwise
+the current would not traverse the ore at all. The cathode is preferably
+formed of the same metal which is to be obtained. The bath should
+not contain organic acids. In practice the common mineral acids are
+employed, or their salts, selecting by preference a salt of the metal
+which is to be isolated. It is convenient to pass the current through
+the greatest possible number of small decomposition troughs, taking care
+that the resistance in each is not too great. With a current of one and
+the same intensity we obtain in n troughs n times as much metal as in a
+single one. To keep down the resistance of the circuit we employ poles
+of a large surface, i.e., plenty of ore and baths which are as good
+conductors as possible.
+
+The state in which the metal is deposited at the negative pole depends
+on the secondary actions undergone by the electrolyte, and especially of
+the escape of gas. This is a function of the _density_, of the current,
+i.e., the proportion of its intensity to the surface of the cathode. If
+the density is too great there is an escape of hydrogen, and the metal
+is deposited in a spongy condition. If the density of the current falls
+below a certain minimum, an oxide is deposited in place of metal. The
+electrolytic treatment of ores often renders it possible to separate
+the different metals which may be present. These are deposited in
+succession, and are sharply separated if the electromotive power is not
+too great.
+
+1. _Zinc_.--The zinciferous compounds--calamine, blende, and zinc
+ash--are all poor conductors. They are first dissolved, and the salts
+obtained are electrolyzed, employing anodes of coke. Blende should be
+roasted before it is dissolved. The electrolytic bath should be as
+concentrated as possible to avoid sponginess of the metal and an escape
+of hydrogen. In a saturated solution the formation of hydrogen decreases
+as the density of the current augments.
+
+2. _Lead_.--Galena is a good conductor, and may be directly
+electrolyzed. The best bath is a solution of lead nitrate. The
+arborescent crystallizations extend rapidly, and must be broken from
+time to time to prevent the formation of a metallic connection between
+the anode and the cathode. The sulphur of the galena falls to the bottom
+of the bath, and may be separated from the gangue by solution in carbon
+disulphide.
+
+3. _Copper_.--Native copper sulphide, though a good conductor, cannot
+be directly electrolyzed en account of the presence of iron sulphide,
+whence iron would be deposited along with the copper. The copper pyrites
+are roasted, dissolved in dilute sulphuric acid, and the liquid thus
+obtained is submitted to electrolysis.
+
+       *       *       *       *       *
+
+
+
+
+A PEOPLE WITHOUT CONSUMPTION, AND SOME ACCOUNT OF THEIR COUNTRY--THE
+CUMBERLAND TABLELAND.
+
+By E. M. WIGHT, M.D., Chattanooga, Tenn., Late Professor of Diseases
+of the Chest and State Medicine, Medical Department University of
+Tennessee; Late Member of the Tennessee State Board of Health, and
+ex-President of the Tennessee State Medical Society.
+
+
+During the ten years that I have practiced medicine in the neighborhood
+of the Cumberland Tablelands, I have often heard it said that the
+people on the mountains never had consumption. Occasionally a traveling
+newspaper correspondent from the North found his way down through the
+Cumberlands, and wrote back filled with admiration for their grandeur,
+their climate, their healthfulness, and almost invariably stated that
+consumption was never known upon these mountains, excepting brought
+there by some person foreign to the soil, who, if he came soon enough,
+usually recovered. Similar information came to me in such a variety of
+ways and number of instances, that I determined some four years ago,
+when the attempt to get a State Board of Health organized was first
+discussed by a few medical men of our State, that I would make an
+investigation of this matter. These observations have extended over that
+whole time, and have been made with great care and as much accuracy
+as possible, and to my own astonishment and delight, I have become
+convinced that pulmonary consumption does not exist among the people
+native and resident to the Tablelands of the Cumberland Mountains.
+
+In the performance of the work which has enabled me to arrive at this
+conclusion, I have had the generous assistance of more than twenty
+physicians, who have been many years in practice in the vicinity of
+these mountains. Their knowledge of the diseases which had occurred
+there extended over a, period of more than forty years. Some of these
+physicians have reported the knowledge of the occurrence of deaths from
+consumption on the Tablelands, but when carefully inquired into they
+have invariably found that the person dying was not a native of the
+mountains, but, a sojourner in search of health. In answer to the
+question: "How many cases of pulmonary consumption have you known to
+occur on Walden's Ridge, among the people native to the mountains?"
+eleven physicians say, "Not one." All of these have been engaged in
+practice there more than three years, four of them more than ten years,
+one of them more than twenty, and one of them more than forty years. All
+the physicians of whom inquiries have been made are now residents, or
+have been, of the valleys contiguous to Walden's Ridge, and know the
+mountain people well. Four other physicians in answer to the same
+question say, that they have known from one to four cases, numbering
+eleven in all, but had not ascertained whether five of them were born
+and raised on the mountains or not. The names and place of death of all
+these cases were given, and I have traced their history and found that
+but three of them were "natives," or had lived there more than five
+years, and that one of these was 57 years of age when she died, and had
+suffered from cancer for three years before her death. The two others
+died within six months after returning home from long service in the
+army, where both contracted their disease.
+
+All these investigations have been made with more particular reference
+to that part of the Cumberlands known as Walden's Ridge than to the
+mountains as a whole. This ridge is of equal elevation and of very
+similar character to the main Cumberland range in the southern part of
+Tennessee, northwest Georgia, and northwest Alabama, and what is true of
+this particular part of the great Cumberland table is, in the main, true
+of the remainder.
+
+Sequatchee Valley lies between Walden's Ridge and what is commonly known
+in that neighborhood as the Cumberland Mountains, and separates it from
+the main range for a distance of about one hundred miles, from the
+Tennessee River below Chattanooga to Grassy Cove, well up toward the
+center line of the State. Grassy Cove is a small basin valley, which
+was described to me there as a "sag in the mountains," just above the
+Sequatchee Valley proper. It is here that the Sequatchee River rises,
+and flowing under the belt of hills which unites the ridge and the main
+range, for two miles or more, rises again at the head of Sequatchee
+Valley. Above Grassy Cove the mountains unite and hold their union
+firmly on their way north as far as our State reaches.
+
+Topographically considered as a whole, the Cumberland range has its
+southern terminus in Alabama, and its northern in Pennsylvania. It
+is almost wholly composed of coal-bearing rocks, resting on Devonian
+strata, which are visible in many places in the valleys.
+
+But a small portion of the Cumberland lies above a plane of 2,000 feet.
+Walden's Ridge and Lookout Mountain vary in height from 2,000 to 2,500
+feet.
+
+North of Grassy Cove, after the ridges are united, the variation from
+2,000 feet is but little throughout the remainder of the State, and
+the general character of the table changes but little. The great and
+important difference is in the climate, the winters being much more
+severe in these mountains in the northern part of the State than in the
+southern, and the summers much more liable to sudden changes of weather.
+Scott, Fentress, and Morgan counties comprise this portion of the table,
+and these have not been included in my examination, excepting as to
+general features.
+
+In all our southern country, and I may say in our whole country, there
+is no other large extent of elevated territory which offers mankind
+a pleasant living place, a comfortable climate--none too cold or too
+hot--and productive lands. We have east of the upper waters of the great
+Tennessee River, in our State, and in North Carolina and Georgia, the
+great Blue Ridge range of mountains, known as the Unaka, or Smoky,
+Chilhowee, Great and Little Frog, Nantahala, etc., all belonging to the
+same family of hills. This chain has the same general course as the
+Cumberlands. It is a much bolder range of mountains, but it is vastly
+less inhabitable, productive, or convenient of access. The winters there
+are severely cold, and the nights in summer are too cold and damp for
+health and comfort, as I know by personal experience of two summers on
+Nantahala River. But the trout fishing is beyond comparison, and that
+is one inducement of great value for a stout consumptive _who is a good
+fellow_. These mountains are much more broken up into branches, peaks,
+and spurs than the Cumberlands. They afford no table terrritory of
+any extent. There are some excellent places there for hot summer
+visits--Ashville, Warm Springs, Franklin, and others.
+
+The Cumberland Mountains, as a whole, are flat, in broad level spaces,
+broken only by the "divides," or "gulfs," as they are called by the
+inhabitants, where the streams flow out into the valleys.
+
+Walden's Ridge, of which we come now to speak particularly, is the best
+located of any part of the Cumberlands as a place for living. From the
+separation of this ridge from the main range of Grassy Cove to its
+southern terminus at the Tennessee River, it maintains a remarkably
+uniform character in every particular. From it access to commerce is
+easy, having the Tennessee River and the new (now building) Cincinnati
+Southern Railroad skirting its entire length on the east. It rises very
+abruptly from both the Tennessee and Sequatchee Valleys, being from
+1,200 to 1,500 feet higher than the valleys on each side. Looking from
+below, on the Tennessee Valley side, the whole extent of the ridge
+appears securely walled in at the top by a continuous perpendicular wall
+of sandstone, from 100 to 200 feet high; and from the Sequatchee side
+the appearance is very similar, excepting that the wall is not so
+continuous, and of less height.
+
+The top of the ridge is one level stretch of plain, broken only by the
+"gulfs" before mentioned and an occasional prominent sandstone wall or
+bowlder. The width on top is, I should judge, 6 or 7 miles. The soil is
+of uniform character, light, sandy, and less productive for the ordinary
+crops of the Tennessee farmer than the soil of the lowlands. The grape,
+apple, and potato grow to perfection, better than in the valleys, and
+are all never failing crops; so with rye and buckwheat. Corn grows
+well, very well in selected spots, and where the land is made rich
+by cultivation. The grasses are rich and luxuriant, even in the wild
+forests, and when cultivated, the appearance is that of the rich farms
+of the Ohio or Connecticut Rivers, only here they are green and growing
+the greater part of the year; so much so that sheep, and in the mild
+winters the young cattle, live by the wild grasses of the forests the
+whole year. The great stock raisers of the Sequatchee and Tennessee
+Valleys make this the summer pasture for their cattle, and drive them to
+their own farms and barns or to market in winter. The whole Cumberland
+table, with the exception of that small part which is under cultivation,
+is one great free, open pasture for all the cattle of the valleys.
+Thousands of cattle graze there whose owners never pay a dollar for
+pasturage or own an acre of the range, though, as a rule, most of the
+well-to-do stock farmers in the valleys own more or less mountain lands.
+These lands have, until quite recently, been begging purchasers at from
+12½ to 25 cents per acre in large tracts of 10,000 acres and upward, and
+perhaps the same could be said of the present time, leaving out choice
+tracts and easily accessible places, which are held at from 50 cents to
+$2 per acre, wooded virgin lands.
+
+The forest growth of Walden's Ridge is almost entirely oak and chestnut.
+Hickory, perhaps, comes next in frequency, and pine after. There is but
+little undergrowth, and where the forests have never been molested there
+are but few small trees. This is due to the annual fires which occur
+every autumn, or some time in winter, almost without exception, and
+overrun the whole ridge. It does not rage like a prairie fire. Its
+progress is usually slow, the material consumed being only the dry
+forest leaves and grasses. The one thing essential to its progress is
+these dry leaves, hence it cannot march into the clearings. Nearly all
+the small shrubs are killed by these fires, otherwise they are harmless,
+and are greatly valued by the stock men for the help they render in the
+growth of the wild grasses. The free circulation of air through these
+great unbroken forests is certainly much facilitated by these fires,
+since they destroy every year what would soon become impediments. The
+destruction of this undergrowth leaves the woods open, and the lands are
+mainly so level that a carriage may be driven for miles, regardless of
+roads, through the forests in every direction.
+
+The shrubs about the fields and places where the forests have
+been interrupted by civilization and other causes are blackberry,
+huckleberry, raspberry, sumac, and their usual neighbors, with the
+azalia, laurel, and rhododendron on the slopes and in the shade of the
+cliffs.
+
+The kinds of wild grasses, I regret to say, I have not noted, and the
+same of the rich and varied display of wild flowers.
+
+The whole ridge is well supplied with clean, soft running water, even
+in the driest of the season. There are no marshes, swamps, or bogs, no
+still water--not even a "puddle" for long--for the soil is of such a
+character, that surface water quickly filters away into the sands and
+mingles with the streams in the gulfs. Springs of mineral water are
+abundant everywhere. Probably there is not a square mile of Walden's
+Ridge which does not furnish chalybeate water abundantly. Sulphur
+springs with Epsom salts in combination are nearly as common.
+
+The entire extent of Walden's Ridge is underlaid with veins of coal, and
+iron ore is plentiful, especially in the foot hills. The coal and iron
+are successfully mined in many places on the eastern slope; on the
+western they are nearly untouched for the want of transportation. I find
+that the impression prevails that the minerals of the Cumberlands are
+largely controlled by land agents and speculators. This is only true as
+applied to a very small part of the whole, not more than 1 per cent. The
+mineral ownership remains with the lands almost entirely.
+
+The prevailing winds on Walden's Ridge are from the southwest; northers
+and northeasters are of rare occurrence. One old lady who had resided
+there for forty years, in answer to my query upon this subject, said:
+"Nine days out of ten, the year round, I can smell Alabama in the air."
+This was the usual testimony of the residents. Winds of great velocity
+never occur there. In summer there is always an evening breeze,
+commencing at 4 to 6 o'clock, and continuing until after sunrise
+the next morning. In times of rain, clouds hang low over the ridge
+occasionally, but they never have fogs there.
+
+The range of the thermometer is less on the Tablelands than in the
+adjacent valleys. I have had access to the carefully taken observations
+of the Lookout Mountain Educational Institute, such published accounts
+as have been made by Professor Safford, State Geologist, Mr. Killebrew,
+the thorough and painstaking private record of Captain John P. Long,
+of Chattanooga, and many more of less length of time. From all these I
+deduce the fact that the summer days are seven or eight degrees cooler
+on the mountains than in the Tennessee Valley at Chattanooga, and five
+or six degrees cooler than in the Sequatchee Valley, as far up as Dunlay
+and Pikeville. The nights on the table are cooler than in the lower
+lands by several more degrees than the days; how much I have thus far
+not been able to state. The late fall months, the winter, and early
+spring are not so much colder than the valleys as the summer months, the
+difference between the average temperature of the mountains and valleys
+being at that time four or five degrees less than in the summer. There
+is no record of so hot a day ever having occurred on the Cumberladd
+Mountains as to cause mercury to run so high as 95° F., or so cold a day
+as to cause it to run so low as 10° below zero.
+
+In the average winter the ground rarely freezes to a greater depth than
+2 or 3 inches, and it remains frozen but a few days at a time. Ice has
+been known to form 8 inches thick, but in ordinary winters, 3 or 4
+is the maximum. Snow falls every winter, more or less, and sometimes
+remains for a week. Old people have a remembrance of a foot of snow
+which lasted for a week.
+
+Walden's Ridge has a total population of a little more than 4,000,
+scattered over 600 square miles of surface. The number of dwellings is
+about 800. Ninety per cent. of these are log houses; 70 per cent. of
+them are without glass windows; light being furnished through the
+doorways, always open in the daytime, the shuttered window openings, and
+the open spaces between the logs of the walls. Less than 2 per cent. of
+these houses have plastered walls or ceilings, and less than 5 per cent.
+have ceiled walls or ceilings. About 20 per cent. of them are fairly
+well chinked with clay between the logs, the remainder being but
+indifferently built in that particular. Fully 90 per cent. of these
+abodes admit of free access of air at all times of day and night,
+through the floors beneath as well as the walls and roof above. It is
+the custom of the people to guard against the coldest of days and nights
+by hanging bed clothes against the walls, and many good housewives have
+a supply of tidy drapery which they keep alone for this purpose.
+
+Wood, always at hand, is the only fuel in use. The whole heating
+apparatus consists in one large open fireplace, built of stone,
+communicating with a large chimney outside the house at one end, and
+frequently scarcely as high as the one story building which supports it.
+This chimney is constructed in such a manner as to be a great ventilator
+of the whole room, quite sufficient, it would be thought, if there were
+no other means of ventilation. It is usually made of stone at the
+base, and that part above the fire is of sticks laid upon one another,
+cobhouse fashion, and plastered over inside and between with similar
+clay as that with which the house walls are chinked.
+
+Very few of these houses are more than one story high. They are all
+covered with long split oak shingles--the people there call them
+"boards"--rifted from the trunks of selected trees. There is no
+sheathing on the roof beneath these shingles. They are nailed down upon
+the flat hewn poles running across the rafters, at convenient distances.
+Looking up through the many openings in the roof in one of these house,
+one would think that this would be but poor protection against rain, but
+they rarely leak.
+
+Not one family in fifty is provided with a cooking stove. They bake
+their bread in flat iron kettles, with iron covers, covered with hot
+coals and ashes. These they call ovens. The meat is fried, with only the
+exception of when accompanied by "turnip greens."
+
+The question, "What is the principal food of the people who live on
+these mountains?" has been asked by me several hundred times. The
+almost invariable answer has been, "Corn bread, bacon, and coffee."
+Occasionally biscuits and game have been mentioned in the answers. All
+food is eaten hot. Coffee is usually an accompaniment of all three
+meals, and is drunk without cream and often without sugar. Some families
+eat beef and mutton for one or two of the colder months in the year on
+rare occasions, though beef is commonly considered "onfit to go
+upon," as I was told upon several occasions, and mutton sustains less
+reputation. Chickens are used for food while they are young and tender
+enough to fry, on occasions of quarterly meetings, visits of "kinfolks"
+or the "preachers" and the traveling doctors. Fat young lambs are plenty
+in many settlements from March to October, and can be had at fifty cents
+each, but I could not learn that one was ever eaten.
+
+A large majority of the adult population use tobacco in some shape--the
+men by chewing or smoking, the women by smoking or dipping snuff. They
+never have dyspepsia, nor do they ever get flesh, after they pass out of
+childhood, though nearly all the children are ruddy in appearance, and
+well rounded with fat.
+
+One physical type prevails among the people in middle life, and carries
+along into old age but little change; and old age is common there.
+Nearly every house has its old man or old woman, or both. Everybody,
+father and mother, and frequently grandfather and grandmother, is still
+on hand, looking as brisk and moving about as lively as the newer
+generations. After they pass their forty years, they never seem to
+grow any older for the next twenty or thirty, and the grandfathers and
+grandmothers can scarcely be selected, by comparison, from their own
+children and grandchildren. The men are taller than the average, and
+the women, relatively, taller than the men. They are all thin featured,
+bright eyed, long haired, sharp looking people, with every appearance of
+strength and power of endurance.
+
+I think the men who live on Walden's Ridge can safely challenge the
+world as walkers--aborigines and all; and unless the challenge should be
+accepted by their own women folks, I feel quite sure they would "win the
+boots." They go everywhere on foot, and never seem to tire.
+
+Nearly all the people of the Tablelands are employed in the pursuits of
+agriculture. Very few of them seem to be hard workers. The men are all
+great lovers of the forest sports, much given to the good, reliable, old
+fashioned long rifles. The women and children are much employed in out
+door occupations, and live a great portion of their time in the open
+air. The clothing of all classes is scanty. The use of woolen fabrics
+for underwear has not yet been introduced, and coarse cotton domestic
+is the universal shirting, and cotton jeans, or cotton and wool mixed,
+constitute the staple for outer wearing apparel. The men wear shoes
+throughout the year much more commonly than boots. They never wear
+gloves, mittens, scarfs, or overcoats, and they scorn umbrellas.
+Probably this whole 4,000 people do not possess two dozen umbrellas or
+twice as many overcoats. The women go about home with bare feet a great
+part of the summer. They never wear corsets or other lacing.
+
+I have learned by careful inquiry that very few of the people of the
+Ridge have ever had the diseases of childhood. Scarlet fever I could
+hear of in but two places, and I suppose that not one person in fifty
+has had it. Whooping cough and measles have occurred but rarely, and the
+large majority have not yet experienced the realities of either. Very
+few people there have ever been vaccinated, nor has smallpox ever
+prevailed. Typhoid, typhus, and intermittent fevers are unknown. In the
+great rage of typhoid fever which took place ten or twelve years ago in
+the Tennessee and Sequatchee Valleys, not a single case occurred on the
+Mountains, as I have been informed by physicians who were engaged in
+practice in the neighborhood at the time. Diphtheria has never found a
+victim there; so of croup. Nobody has nasal catarrh there, and a cough
+or a cold is exceedingly rare.
+
+I have said that these observations refer more particularly to Walden's
+Ridge than to the Cumberland Tablelands in our State as a whole. This
+ridge was chosen by me for this examination, mainly for the reason of
+its convenience, but partly owing to its being more generally settled
+than any other equal portion of the table which lies in Tennessee.
+Lookout Mountain is not as well located; it is on the wrong side of the
+Tennessee River, and but a few acres of it belong in this State. Sand
+Mountain is altogether out of the State, but it is perhaps nearer like
+Walden's Ridge in its physical features than Lookout. That part of the
+Cumberlands west of Sequatchee Valley is Walden's Ridge in duplicate,
+excepting that it is further west, and nearer the Middle Tennessee
+basin. There are some small towns, villages of miners, and summer
+resorts there, which interferes with that evenness of the distribution
+of population which Walden's Ridge has, rendering it more liable to
+visitations of epidemic and contagious diseases. The tablelands north
+of the center line of the State, above Grassy Cove, are very similar
+to Walden's Ridge, as far up as Kentucky, with the exception before
+mentioned--that of climate--it being from one to ten degrees colder in
+winter.
+
+This whole Cumberland Table is no small country. It comprises territory
+enough to make a good sized State. At present, it is almost one great
+wilderness, in many particulars as unknown as the Black Hills. It is
+coming into the world now, and will be well known in a few years. The
+great city of Cincinnati has determined to build a railroad through
+the very center of this great table in the north part of the State,
+connecting with Chattanooga in the southern part. This road is nearly
+bored through, and in another year or two the Cumberland Tablelands in
+Tennessee will be much heard of at home and abroad.
+
+It seems to me this country has merits. It is located in the latitude of
+mild climate; not so far south as to be scorched by the hot summer sun,
+or visited by the great life destroying epidemics; not so far north as
+to meet the severe and lengthened winters.
+
+Climate, we know, is a fixture; it has a government; it has rules; the
+weather may change, but climate does not; it is a permanent out-door
+affair, and what is true of to-day was true centuries ago, and will
+be true forever, in the measure of any practical scope, at least. The
+people of the world are beginning to know that the greatest destroyer of
+human life has its remedy in climate.
+
+Mr. Lombard, in his famous exhibit in relation to the prevalence of
+consumption among the people of different occupations, circumstances of
+life, and place of dwelling, gives the lowest number of deaths from this
+cause to those who live in the open air. He found the people who lived
+most in the open air, as would be readily conjectured, in the mild
+latitudes, not in the countries of hot sands or cold snows.
+
+[The above article, in regard to which we have noticed frequent
+allusions in many of our exchanges, all erroneously attributing it to
+_Dr. Wright_, of Tennessee, and for which we have received repeated
+requests quite recently, was read by the lamented Dr. E.M. Wight at
+the 43d annual meeting of the Tennessee State Medical Society, held
+at Nashville, April 4, 5, and 6, 1876. Its distinguished and talented
+author will long be remembered as one of the most active, earnest, and
+zealous members of the State Society. At this meeting he also read a
+very admirable paper on "The Microscopic Appearance of the Blood in
+Syphilis," and prepared the report of the Committee on State Board
+of Health, to which report may be ascribed the honor of securing the
+necessary legislation organizing the Board. A true, upright, honest man,
+an earnest, devoted and zealous physician, universally esteemed and
+beloved by all who knew him; himself the subject of tuberculosis, dying
+in the prime of a brilliant manhood. He had but few equals in the
+glorious profession he honored and loved so well.
+
+From a careful reading of his paper, we find that he describes a large
+area of territory, free, absolutely free, from subsoil moisture, a
+climate mild and equable, a soil capable of producing nearly everything
+necessary for the comfortable maintenance of human life, surroundings
+that tempt, nay, compel the greatest possible amount of open air
+life. His description is exceedingly accurate of a plain, primitive,
+simple-minded people with but few wants, many of the virtues and few
+of the vices of humanity. With their surroundings, soil, climate,
+residence, and mode of living, need we be surprised that "there is
+a people," or a land "free from consumption"?--ED.]--_Southern
+Practitioner_.
+
+       *       *       *       *       *
+
+
+
+
+THE TREATMENT OF HABITUAL CONSTIPATION.
+
+
+Dr. F.P. Atkinson thus writes in the _Practitioner_, January, 1884: I
+suppose there is no derangement of the system we are more frequently
+called upon to treat than habitual constipation; and though all kinds of
+medicines are suggested for its relief, they rarely produce more than
+temporary benefit--and it is difficult to see how the result can well be
+otherwise, while the root of the evil remains untouched. Now by far the
+more numerous subjects of this disorder are women; and as they do not
+seem to know that regularity is essential to the performance of every
+one of nature's operations, they appoint no stated times for trying to
+get the bowels relieved, but trust to receiving intimation when the
+rectal accumulation and distension can be borne no longer. This method
+of action may and does answer fairly well for a time; but nature
+gradually gets upset, the sensation of the lower bowel becomes blunted,
+and at last it ceases to respond to the ordinary stimulus. Then
+aperients are regularly resorted to, and although these act fairly
+well for a time, they gradually have to be increased in strength
+and frequency. Now, as regards the treatment, the first thing to be
+accomplished is of course to get the rectum well relieved; the next,
+to get the actions to take place at fixed times; and lastly, it is
+necessary to get more tone imparted to the muscular tissue of the
+bowels, so that the regularity of action may be helped and also
+maintained. In order, then, to get the bowels relieved in the first
+instance, it is well to give five grains of both compound colocynth and
+compound rhubarb pill at bed-time (this rarely requires to be repeated),
+then to take a tumblerful of cold water the next morning on waking, and
+repeat it regularly at the same time each day. Should the bowels remain
+sluggish for some time, the same quantity of water may be taken daily
+before each meal. Supposing no action takes place on rising or shortly
+after, a small injection of warm water may be resorted to. After each
+movement of the bowels, a small hand-ball syringeful of _cold_ water
+should be thrown into the rectum and retained. A soup plateful of coarse
+oatmeal porridge (made with water and taken according to the Scotch
+method, viz., by filling half the spoon with the hot porridge and the
+other with cold milk) each night at bed-time, or even every night and
+morning for a time, is often a very great help. But above all things,
+it is necessary for the patient to _try_ and get relief at a certain
+_fixed_ time regularly every day. If these directions are strictly
+carried out in their entirety, the evil, even if it has been of long
+standing, will generally be corrected, and the patient will improve in
+health and appearance. Of course where the constipation results from
+exhaustion of the nervous system (such, for instance, as is brought
+about by self-abuse), the special cause has to be taken into
+consideration, and such treatment adopted as is suited to the particular
+necessities of the case.
+
+       *       *       *       *       *
+
+
+
+
+THE PYRAMIDS OF MEROE.
+
+
+About fifty miles from the mouth of the Atbara, and, of course, on the
+eastern bank of the Nile, stand the pyramids of Meroe. They consist
+of three groups, and there are, in all, about eighty pyramids. The
+presumption is that they represent the old sepulchers of the kings of
+Meroe. Candance, Queen of the Ethiopians, mentioned in Acts, chap.
+viii., v. 27, is supposed to have belonged to Meroe, that being the name
+also of the capital, which is understood to have been somewhere not far
+distant from the sepulchers. These pyramids of Meroe possess one marked
+feature, distinguishing them from the pyramids of Egypt proper--that is,
+they have an external doorway or porch. As there is no entrance to the
+pyramid at these porticoes, it is quite possible that they were temples
+for worship or making offerings to the dead. By comparing them with
+the pyramids of Ghizeh, it will be seen that they are also taller in
+proportion to their base. Another important point in these porches
+or temples is the existence of the arch; and that, too, an arch in
+principle, with a keystone.--_Illustrated London News_.
+
+[Illustration: THE PYRAMIDS OF MEROE, ON THE NILE.]
+
+       *       *       *       *       *
+
+
+
+
+THE PROLIFICNESS OF THE OYSTER.
+
+
+In an article by Prof. Karl Mobius on "The Oyster and Oyster Culture,"
+reproduced in the recently issued report of the U. S. Commissioner of
+Fish and Fisheries, the author says:
+
+A mature egg-bearing oyster lays about one million of eggs, so that
+during the breeding season there are upon our oyster beds at least
+2,200,000,000,000 young oysters, which surely would suffice to transform
+the entire extent of the sea-flats into an unbroken oyster bed; for if
+such a number of young oysters should be distributed over a surface 74
+kilometers long by 22 broad, 1,351 oysters would be allotted to every
+square meter. But this sum of 2,200,000,000,000 young oysters is
+undoubtedly less than that in reality hatched out, for not only do those
+full-grown oysters which are over six years of age spawn, but they begin
+to propagate during their second or third year, although it is true that
+the young ones have fewer eggs than those which are fully developed. At
+a very moderate estimation, the total number of three to six year old
+oysters which lie upon our beds will produce three hundred billions of
+eggs. This number added to that produced by the five millions of full
+grown oysters would give for every square meter of surface not merely
+1,351 young oysters, but at least 1,535. In order to determine how
+many eggs oysters produce, they must be examined during their spawning
+season. This begins upon the Schleswig-Holstein beds in the middle of
+June, and lasts until the end of August or beginning of September. The
+spawning oyster does not allow its ripe eggs to fall into the water, as
+do many other mollusks, but retains them in the so-called beard, the
+mantle, and gill-plates until they become little swimming animals. The
+eggs are white, and cover the mantle and gill-plates as a semi-fluid,
+cream-like mass. As soon as they leave the generative organs the
+development of the germ begins. The entire yolk-mass of the egg divides
+into cells, and these cells form a hollow, sphere-like body, in which an
+intestinal canal arises by the invagination of one side. Very soon the
+beginnings of the shell appear along the right and left sides of the
+back of the embryo, and not long afterward a ciliated pad, the velum, is
+formed along the under side. This velum can be thrust out from between
+the valves of the shell at the will of the young animal, and used by the
+motion of its cilia as an organ for driving food to the mouth, or
+in swimming as a rudder. During these transformations the original
+cream-white color of the germ changes into pale gray, and finally into a
+deep bluish-gray color. At this time they have a long oval outline, and
+are from 0.15 to 0.18 of a millimeter in breadth. Over 300,000 can find
+room upon a square centimeter of surface. If an oyster in which the
+embryos are in this condition is opened, there will be found upon its
+beard a slimy coating thickly loaded with grayish-blue granules. These
+granules are the embryo oysters, if a drop of the granular slime be
+placed in a dish with pure sea water, the young animals will soon
+separate from the mass, and spread swimming through the entire water.
+When the embryos are at this stage their number may be estimated in the
+following manner: The whole mass of embryos is carefully scraped from
+the beard of the mother oyster by means of a small hair brush. The whole
+mass is then weighed, and afterward a small portion of the mass. This
+small portion is then diluted with water or spirits of wine, and the
+embryos portioned out into a number of small glass dishes, so that they
+can be placed under the microscope and counted. Thus, knowing the weight
+of the small portion and the number of embryos in it by count, we can
+estimate the total number of embryos from the weight of the entire mass,
+which is also known. In this manner I estimated the number of embryos
+in each of five full grown Schleswig-Holstein oysters caught in August,
+1869, and found that the average number was 1,012,956.
+
+Notwithstanding this great fecundity, but an extremely small proportion
+of the young oysters produced during the course of the summer arrive
+at maturity, 421 only out of 500,000,000 escaping destruction. The
+immolation of a vast number of young germs is the means by which nature
+secures to a few germs the certainty of arriving at maturity. In order
+to render the ideas of germ-fecundity and productiveness more easily
+understood, Prof. Mobius makes the following comparison between the
+oyster and man:
+
+According to Wappaus, for every 1,000 men there are 347 births.
+According to Bockh, out of every 1,000 men born 554 arrive at maturity,
+that is, live to be twenty years or more of age; thus, on an average,
+347 children are produced from 554 mature men, or 626 children from
+1,000 mature men. Since 1,000 full-grown oysters produce 440,000,000 of
+germs, then the germ fecundity of the oyster is to the germ fecundity of
+man as 440,000,000 to 6.26, or as 7,028,754 to 1. On the other hand, the
+number which arrive at maturity is 579,002 times as great with mankind
+as with the oyster; for of 1,000 human embryos brought into the world
+554 arrive at maturity, or of 440,000,000 newly born 243,760,000 would
+live to grow up, while of 440,000,000 young oysters only 421 ever become
+capable of propagating their species. The proportion is then 421 to
+243,760,000, or as 1 to 579,002. I am fully persuaded that these figures
+represent the number of oysters which arrive at maturity more favorably
+than is really the case, since from every thousand of full grown oysters
+it is certain that, on an average, more than 440,000,000 young are
+produced.
+
+       *       *       *       *       *
+
+
+
+
+RED SKY.
+
+
+The beautiful red sky which has been so frequent of late, morning as
+well as evening, has excited much comment. The comment, however, has
+consisted more of description, statement of fact, theory, and wonder as
+to cause, rather than as to satisfactory explanation.
+
+Facts in the case which would reveal the secret of this beautiful
+display of nature are not complete and numerous enough at present to
+establish the cause of this phenomenon on a sure basis; yet enough
+facts, it would seem, have been obtained to satisfy the strong mind
+capable of bridging over a wide expanse.
+
+Facts in an argument are like piers to a bridge-the more we have of
+them, c. p., the more substantial the structure. When the facts are
+_legion_, the structure becomes a causeway, and there is no need of
+argument.
+
+Argument is a bridge--the fewer the facts, the more the necessity for
+the bridge; the less the facts, the more argument necessary to connect
+the few we have, and the more skill is required to make substantial
+connecting links between the few solid piers (facts) that exist.
+
+One of the queer things in connection with this is, the public have
+looked chiefly, if not wholly, to the astronomers for an explanation
+of this phenomenon, when it is not their special province to explain
+matters in this department of nature.
+
+The explanation belongs to the department of meteorology, and not to
+astronomy. But the fact of having looked to the astronomers shows how
+little the world knows of meteorology and how few meteorologists
+there are able, ready, and willing to rise and explain in face of the
+opposition of the public, who seem to think that the explanation must
+necessarily belong to astronomy. Astronomy proper deals with the
+position of the earth in space and its relation to the other heavenly
+bodies, whether suns, fixed stars, planets, satellites, comets, or other
+bodies in the vast space about us. Meteorology deals with the atmosphere
+of the globe, in all its forms. Astronomy could be studied in the early
+ages; its grand facts were not wholly dependent upon the advanced
+condition of the mechanic arts; it could be studied even without the aid
+of telescopes, though telescopes have added much to its advancement.
+Meteorology, on the contrary, depended on the advancement of the arts
+and sciences; they must first be perfected ere we could know much about
+this branch of science. To one unfamiliar with the advancement and
+perfection of meteorology within the past ten years, this statement
+may seem strange, yet it is an undisputable fact that, prior to the
+establishment of the daily weather reports, the knowledge on this
+subject amounted to very little, and was not even worthy of being
+designated a science. Prior to the advent of the weather map the world
+was in absolute ignorance of the laws governing the atmosphere. Sure, we
+had had large volumes on the laws of storms, but the later revelations
+leave them shelved high and dry on the shores and as useless as a wreck
+in a similar condition; with the daily weather map before us we have no
+need to even open these huge volumes; they are completely circumvented,
+and only negative in value--to show how little was known of the subject
+without the full and complete facts daily collected and spread before us
+on the map published by the Weather Bureau.
+
+In order to understand the color of our sky, we must understand the
+subject which is so immediately connected with it and its creation.
+
+The earth is a sphere in space; generally speaking, it is composed of
+land and water. These are two factors; the heat that it derives from
+the sun forms a third factor; the three--land, water, and heat--are
+essential to life, at least the higher conditions of life which
+culminate in man. The old physical geography taught us this much, but
+it was not able to go further and tell us why it was cold or warm
+independent of the seasons; it could not explain why it was at times as
+warm, and even warmer, half-way to the pole than at the equator; why it
+was at times very warm in the extreme northeast while very cold in
+the Southern States; cold in the northwest when it was warm in the
+northeast, and warm in the northwest when cold all along the upper
+Atlantic seaboard; it could not forewarn us of storms. These and a
+host of other facts, which the weather map makes as plain as astronomy
+demonstrates that Jupiter is a planet, the new revelation, through the
+instrumentality of the perfected telegraph system, makes exceedingly
+plain to us if we will but seek the easily obtained information.
+
+The principal revelations of the weather map are the facts in regard to
+the areas of high and low barometer, and the influence they exert upon
+the climate of the globe.
+
+These conditions--high and low barometer--move on general lines from the
+west towards the east, or towards the rising sun, and around the world
+in irregular belts. The centers of low barometer are various distances
+apart, from a thousand to two thousand and even more miles apart--call
+the average about two thousand miles.
+
+The clouds are formed from the moisture present by the action of the
+sun's heat. The direction of the wind is from the area of high barometer
+to that of low. The nearer the winds approach the center of "low" (low
+barometer), the more they partake of the lines of the volute curve, or
+curve of the sea shell or water in a whirlpool. High barometer is the
+atmospheric hill; low barometer is the atmospheric valley. But time at
+present will not permit more than these general statements; a close
+study of the weather map for a season will reveal the beautiful minor
+details.
+
+To the reader it may seem a long way round, yet in order to fully
+understand the nature of the atmosphere which surrounds our globe we
+must pay due attention to these newly discovered physical laws.
+
+The red sky which was so noticeable, in the fall of 1883, the
+astronomers have told us was due to "meteoric dust" which was produced
+by the volcanic eruption on the island of Java, August 27, 1883.
+
+This "meteoric dust" they say combined with the atmosphere, followed it
+around the earth, and caused the beautiful redness of the sky at morning
+and evening. For one, I do not believe dust of any description in the
+atmosphere would produce such an effect.
+
+There is nothing luminous, transparent, or delicate about dust. Dust
+would not remain in the atmosphere for months, it would settle in a very
+short time, and if thick enough in the atmosphere to obstruct the light
+of the sun it would be visible, discernible, to the eye, and manifest
+on the face of nature. Years ago, before the age of the weather map, we
+might have thought that the atmosphere followed the surface of the earth
+like the water on a grindstone, but it does not. As already seen, the
+wind is from the area of high barometer to that of low, and there are
+many of these "low centers."
+
+From the best calculation we can make at present, there would be at
+least some six centers on an average between the center of the United
+States and the island of Java. In addition to this there would also be
+a number of belts of "low" centers, which would complicate the thing
+threefold at least. At all these different centers the winds would be
+blowing from all points of the compass at the same time. Such winds
+would not be apt to bring the "meteoric dust" from Java to the United
+States, either in an easterly or westerly direction. But, it is said,
+"dust" has been gathered.
+
+How high from the surface of the ground has this _dust_ been
+gathered--at what elevation?
+
+There is undoubtedly a little dust in the air most of the time, but I do
+not think that it extends very high. Where it would be the highest and
+most perceptible would be on the arid plans of Africa and Asia, when
+the _simoom_ is passing, or in the track of a tornado. But from the
+multiplicity of these storm centers and the varied winds they would
+produce even this dust could not travel from Java to America.
+
+Again, all clouds, no matter how high or how low, are affected by the
+low centers, as the movement of clouds prove, and travel from the "high"
+to the "low," from and to all points of the compass. High authority
+gives the heights of the clouds as follows: lower clouds, 16,000 feet;
+upper clouds, 23,000 feet.
+
+As all clouds, from the highest to the lowest, are affected by the
+centers as above referred to, it follows that if this "meteoric dust"
+follows the earth around, as it would have to do in order to make good
+this theory, it would have to travel suspended in the atmosphere above
+the upper clouds, or at a height of more than 23,000 feet, or at an
+elevation of over four miles!
+
+Now, is it reasonable to believe that dust, however fine, will remain in
+the atmosphere at that elevation for over six months?
+
+As a side argument it is suggested that the smoke of the burning woods,
+or few years ago in Michigan, caused as peculiar condition of the
+atmosphere. This extensive fire was on a day when the area of low
+barometer was on a high line of latitude and passing to the eastward.
+This naturally took the smoke, which is far lighter than dust, along
+with it. It mingled with the muggy condition of an extensive "low," and
+produced a yellowness of the atmosphere. This however was of only a few
+hours' duration, and was only visible in favorable localities.
+
+Here again we see the advantage of the weather maps; but for this map we
+would never have been able to have satisfactorily explained the peculiar
+phenomenon produced by the great Michigan fire.
+
+If the delicate redness of the sky is not caused by dust, what is it
+caused by?
+
+But for the weather map, I think we should still be in the dark in
+regard to it.
+
+In the first place, this redness is nothing new, only the conditions
+are more favorable sometimes than at others. It has always existed and
+always will exist, independent of earthquakes, volcanoes, etc. Nature
+is ever changing; the movements of the atmosphere more resemble the
+kaleidoscope than any thing else.
+
+The summer and fall of 1883, the movements of "high" (high barometer)
+over the United States were quite central and extensive, causing this
+peculiar phenomenon over a wide extent of territory.
+
+We have no information of the condition of the barometer over the other
+part of the world; we speak move particularly of the United States; yet
+if certain conditions produce certain effects here, it is quite safe to
+say that the same effects are produced by the same cause elsewhere.
+
+As now well established by the map, the surface wind is from the area
+of high barometer to that of low--from the atmospheric hill to the
+atmospheric valley.
+
+The tendency of this is to free "high" of all clouds and moisture; but
+then it is impossible to free "high" entirely of moisture; a little
+will remain, and it is just this little, which is highly rarefied, that
+produces the result. We look around us and above, we see little or no
+evidence of evaporation, yet it is the while going on. When the sun is
+immediately below the horizon, where it will shine horizontally through
+the mass of light, suspended moisture, the delicate presence of vapor
+heretofore unnoticed is revealed. The action of the sun's rays is the
+same as when illuminating a well formed cloud--it is an embodiment
+of the same principle, but the material is much more expanded. The
+particles of suspended moisture are very fine, few and far between,
+therefore the effect of the light upon it is more diffused and
+transparent. It is much like looking through a piece of window glass
+flatwise and endwise; flatwise we do not perceive any color; endwise,
+from seeing through a greater mass, the glass has a very perceptible
+green color.
+
+We see the same idea also in the rising and setting sun and moon. On
+a clear, cloudless night, when nothing seems to interfere with the
+brightness of the stars, we cannot, by looking upward, perceive any
+moisture present in the atmosphere; but if we cast our eyes to the
+horizon, whereby we see through the mass of atmosphere endwise, as it
+were, and note the appearance of the stars there, or the rising or
+setting moon, we will see that the atmosphere there gives a redness
+to the rising body, which it does not have when it has ascended to
+mid-heaven. On a clear night, which is caused by the presence of the
+area of high barometer, the moon when in mid-heaven is of a clear,
+silver-white, and it is the same moon that at the horizon was a deep
+red. The color of the moon has not changed; it is simply the medium
+through which it is seen that produces the difference in color.
+
+Occasionally, on a clear, bright ("high") night, when the moon is full,
+prior to rising, when just below the horizon, it will so illuminate this
+lower strata of atmosphere as to appear like a great fire; the moon
+rises red, but its deep color gradually fades as it rises, and when well
+up in the heavens we perceive that this deep coloring was an illusion
+and merely the influence of its surroundings. I never, though, knew of
+any one to attempt to account for this by "meteoric dust;" and yet it is
+an embodiment of the same principle. Place the sun where the moon is,
+and from its far superior abundance of light we have a much grander
+display.
+
+Under no other conditions or relations of the sun and earth is it
+possible to have this phenomenon of the delicate red sky but when a
+positive area of high barometer is passing and extends over us. In
+order to produce this effect we must have the clear atmosphere of high
+barometer, when there is a minimum of moisture present. The action of
+the sun's rays upon this extensive area of slightly moist rarefied
+air is unconfined by clouds, and reaches far and wide, and produces
+a delicacy of color which from no other source or condition can be
+realized.
+
+ISAAC P. NOYES.
+
+Washington, D. C., 1884.
+
+       *       *       *       *       *
+
+
+
+
+A THEORY OF COMETARY PHENOMENA.
+
+
+_To the, Editor of the Scientific American_:
+
+The following subject, substantially, was written more than a year ago
+with a view to its publication. It was not, however, until January of
+the present year that I sent a brief communication to the _Brooklyn
+Eagle_, which was published Feb. 3, giving my views in relation to
+cometary phenomena. With this I might remain satisfied, were it not
+that the interesting paper by G. D. Hiscox, published in the SCIENTIFIC
+AMERICAN SUPPLEMENT, Feb. 16, impressed me with the idea that the theory
+I advanced might assist in explaining others, if brought to the notice
+of those interested through the columns of your valuable journal.
+
+The theory that I advance to account for the several phenomena relating
+to comets' tails is, that comets are non-luminous, transparent bodies;
+that they transmit the light of the sun; that the transmitted light
+reflected by the particles of matter in space constitutes the tails of
+comets. "Like causes produce like effects." By contraries, then, like
+effects must be produced by similar causes; for, if an effect produced
+by a cause which is known is similar to an effect produced by a cause
+which is not known, the cause which is known must be similar to the
+cause which is not known. This is true or not.
+
+I submit the following experiments to substantiate the theory advanced.
+
+Partially fill a vial or a tumbler with water, hold it by the rim,
+and move it around a lighted candle placed upon a table. A shadow
+surrounding the transmitted light will be cast upon the table. As the
+tumbler approaches the light, the shadow follows the tumbler, and when
+receding the tumbler follows the shadow; and as the tumbler is moved
+around the light, the shadow will swing round from one side to the
+other. If the tumbler be held so that a puff of smoke can be blown
+into the transmitted rays, the particles of smoke will reflect the
+transmitted light, and will illustrate my idea of what constitutes a
+comet's tail. A dark band may be observed in this stream of light, as
+also in the light cast upon the table.
+
+In these experiments, we see the effects produced by a cause which is
+known; the effects are similar to those observed in the tails of comets,
+the cause of which we do not know; but is it not reasonable to assume
+that the cause is similar?
+
+Assuming now that comets are transparent, can any other phenomena
+peculiar to comets be accounted for upon this hypothesis? Next to
+the tail itself, the curve is the most noticeable feature, and if we
+consider the extraordinary length of these appendages, the astounding
+velocity at which comets move in their orbits, and the time that would
+elapse before a ray of light, emitted from the nucleus, would reach the
+end of the tail, perhaps the curve--which, if I am not deceived in my
+observations, always dips toward its orbit--can be accounted for. If a
+comet moved in a direct line toward the center of the sun, there would
+be no curve to the tail. But taking Donati's comet of 1858 as an
+example, the tail of which was said to be about 200,000,000 miles long,
+a ray of light traveling at the rate of 192,000 miles per second would
+be about twenty minutes in going from the nucleus to the end of the
+tail.
+
+But during that time the comet would move in its orbit, say, 50,000
+miles, and as light moves in a straight line, and other rays are
+constantly emerging from the nucleus as it moves along in its course,
+the result is that the tail has a curved appearance.
+
+I have no data at hand regarding this comet, but what I have said will
+serve to illustrate my ideas. Again, referring to this comet, I remember
+to have read the statement of an astronomer that, after passing round
+the sun, a new tail was formed opposite the original one. Now, it seems
+to me that that is just what would happen, for in moving round the sun
+the comet would travel say 3,000,000 miles; the greater portion of the
+tail then, would extend millions of miles upon one side of the sun,
+while from the nucleus upon the opposite side of the sun a new tail
+would appear to be formed.
+
+Upon this hypothesis, the extraordinary length of their tails and the
+fact that stars are visible through the densest portion of them is
+explained; as also the fact that they so rapidly disappear from view
+when moving from the sun, the light received by them from the sun
+being in proportion to their distance from it, and but little of that
+reflected.
+
+JOHN M. HUGHES.
+
+Brooklyn, N. Y.
+
+       *       *       *       *       *
+
+[FOR THE SCIENTIFIC AMERICAN.]
+
+
+
+
+ON COMETS.
+
+
+When we see a comet approaching the sun with its tail following in the
+orbit of the nucleus, we have no great difficulty in believing the
+common theory that a comet consists of nucleus attracted toward the sun,
+while the tail is repelled; and that we see the whole of it. But as it
+approaches the sun, difficulties arise that make us doubt whether the
+theory be true.
+
+Let us suppose a comet with a tail 50,000,000 miles in length, and that
+it will require two days to pass round the sun. Now the tail, being
+always in a line drawn through the center of the sun and center of the
+nucleus, will, when it reaches the long axis of the elliptical orbit,
+stand perpendicularly to the orbit of the nucleus. That is, the
+extremity of the tail farthest from the sun, in addition to its onward
+motion, has acquired a lateral motion that has lifted it 50,000,000
+miles in the first day of its perihelion. The velocity of the extremity
+has been vastly accelerated over that of the nucleus, and it has
+moreover a sheer lift above the orbit of the nucleus. Now this lift is
+in opposition to gravity; neither is it in consequence of any previous
+momentum, for its velocity is accelerated and its previous momentum
+would be a hindrance; nor is the lift in consequence of any repelling
+force from the sun, for such force would be diminished in proportion to
+the square of the distance, and the far end would be acted on less than
+the nucleus end of the tail, whereas the velocity of the former is
+increased a hundred fold over that of the latter. A polar force in the
+comet would merely draw the comet into the sun. We therefore find no
+force adequate for such a lift, but on the contrary all the forces are
+opposed to it.
+
+But if the first day of the perihelion overwhelms us with difficulty,
+the second day will prove disastrous to the common theory. For the
+extremity of the tail farthest from the sun will be required to pass
+with lateral motion from its perpendicular 100,000,000 miles, so that it
+may be in advance of the nucleus and again rest on its orbit. This orbit
+is an impassable line, and therefore instantly arrests the prodigious
+lateral velocity of the tail. That impassable orbital line is to it
+as solid and inflexible as a wall of adamant. The motion so instantly
+arrested would be disastrous to any tail, whether composed of gas,
+meteorites, or electricity, whatever that may be.
+
+Having shown that the common theory of comets is filled with insuperable
+difficulties, I will again call attention to a theory proposed about
+eighteen months ago in the SCIENTIFIC AMERICAN.
+
+According to this theory, a comet consists of a nucleus and an
+atmosphere, for the most part invisible, surrounding it on all sides to
+an extent at least equal to the length of the tail. The rays of the sun
+in passing through or near the nucleus are so modified as to become
+visible in their further progress through the cometic atmosphere, while
+all the rest remain invisible. What we call the tail is merely a radius
+of the cometic atmosphere made visible, and as the comet moves through
+space, only different portions of the atmosphere come in sight, in
+obedience to the ordinary laws of light. There is no difficulty in
+accounting for the rise and fall of the tail at perihelion, nor for the
+tail preceding the nucleus afterward.
+
+The spherical theory accounts easily for the different forms of tail
+seen in different comets. The sword shaped tails, at variance with the
+common theory, can be accounted for by supposing a slight difference in
+density or material in the cometic atmosphere, which will deflect the
+light as seen. The comet of 1823, which cannot be explained on the
+common theory, is very easily explained on the spherical. That comet
+showed two tails, apparently of equal length, which moved opposite to
+each other, and perpendicularly to the orbit of the nucleus, and showing
+no signs of repulsive force from the sun. On the spherical theory it is
+only necessary to suppose such an arrangement of the nucleus as would
+reflect the rays of the sun laterally; a slight modification of the
+nucleus would give not only two but any number of tails pointing in
+different directions.
+
+It may be objected to the spherical theory that a tail 50,000,000 miles
+long would call for a sphere 100,000,000 miles in diameter, and that
+would be too vast for our solar system. But it is claimed for this
+sphere that it consists of the same material as the so-called tail, and
+that it has the same capability of moving among planets without manifest
+disturbance to either.
+
+The sphere at the perihelion would envelop the sun, and as a noticeable
+reduction is sometimes found in its so-called tail, the cometic
+atmosphere may impart to the sun at that time whatever is necessary to
+its use.
+
+That there is something in common between the sun's corona and cometary
+matter was shown by the last solar eclipse observed in South Pacific
+Ocean, where the spectrum of sun's corona was found to be the same as
+that of a comet's tail. Are we to attribute in any degree the different
+appearances of the sun's corona to the presence or absence of a comet
+at its perihelion? At the eclipse of the sun seen in Upper Egypt two or
+three years ago, a comet was seen close to the sun, but I have seen no
+account of the appearance of the corona at that time.
+
+FURMAN LEAMING, M.D.
+
+Romney, Tippecanoe Co. Indiana.
+
+       *       *       *       *       *
+
+
+
+
+FORMS OF IVY.
+
+
+It is scarcely possible for us to bee too emphatic in our praises of the
+most distinct forms of ivy, since but few other hardy climbing plants
+ever give to us a tithe of their freshness and variety. A good long
+stretch of wall covered with a selection of the best green-leaved kind
+is always interesting, and never more so than during the winter months,
+especially if at intervals the golden Japanese jasmine is planted among
+them or a few plants of pyracantha or of Simmon's cotoneaster for the
+sake of their coral fruitage. The large-leaved golden ivy is also very
+effective here and there along a sunny wall, especially if contrasted
+with the small-leaved kind--atropurpurea--which has dark purple or
+bronzy foliage at this season. Of the large-leaved kinds, one of the
+most distinct is canariensis, or large-leaved Irish ivy, and Raegner's
+variety, with leathery, heart-shaped foliage, is also handsome. The
+birdsfoot ivy (pedata) is curious, as it clings to the stones like
+delicate leaf embroidery, and for shining green leafage but few equal
+to the one called lucida. The two other kinds sketched are hastata and
+digitata, both free growing and distinct sorts.
+
+[Illustration: VARIOUS FORMS OF IVY. Heart-leaved Ivy (Hedera
+Raegenerana). Glossy Ivy (H. lucida). Arrow-leaved Ivy (H. hastata).]
+
+_Ivy Leaves_.--Common ivy is tolerably plentiful nearly everywhere, but
+it is not common to find a good distinct series of its many varieties
+even in the best gardens. Of all the different forms of ivy, I think
+the large-leaved golden one of the best; certainly the best of the
+variegated kinds. Raegner's variety is also very bold, its great glossy,
+heart-shaped leaves most effective. Algeriensis is another fine-leaved
+kind, the form dentata producing foliage even still larger when well
+grown. For making low evergreen edgings on the turf, for carpeting
+banks, the covering of bare walls and the old tree stumps, we have no
+other evergreen shrub so fresh and variable, or so easily cultivated as
+are these forms of the ivy green. Perhaps one reason why the finer kinds
+of ivy are comparatively uncommon is the fact that a strong prejudice
+exists against ivy in many minds. It is an erroneous notion that ivy
+injures buildings against the walls of which it is planted; it never
+injures a good wall, nor a sound house, but on the contrary, hides and
+softens the stony bareness of the one and adds beauty and freshness to
+the other.--_The Garden_.
+
+[Illustration: VARIOUS FORMS OF IVY. Finger-leaved Ivy (H. Itata). Irish
+Ivy (H. canariensis). Rira's foot Ivy (H. pedata).]
+
+       *       *       *       *       *
+
+
+
+
+PROPAGATING ROSES.
+
+
+In an article on this subject an English horticultural journal describes
+the method pursued by a London florist. After stating that out of a case
+containing 310 cuttings only five failed to root, the article proceeds:
+The case or box is made of common rough deal boards. It is five feet
+six inches long and one foot in depth. Within half an inch of the top a
+groove is cut inside the box, into which the glass is slid, after the
+manner of a sliding box lid. In the end of the third week in July the
+box was placed in the kitchen garden under the shadow of a high north
+wall; it was then about half filled with good turfy loam, to which had
+been added a little leaf mould and a good sprinkling of sharp sand. The
+soil was then pressed down very firmly (the box being nearly half full
+when pressed), and then thoroughly well soaked with rain water, and
+allowed to stay uncovered until the next day. The next day good stout
+cuttings were taken of all the roses, both tea and hybrid perpetual,
+which it was desired to add to the stock. They were then inserted
+closely and firmly in the soil, just over the bottom leaf, the glasses
+were slipped on and puttied down; the grooves in which the glass slid,
+and even the joints in the glass, being filled with putty, so as to
+exclude the air. The whole thing completed, nothing more remained to be
+done but to leave the box in its cool, shady nook for five or six weeks,
+when the growing points of the free starting kinds gave notice that the
+glasses might be removed, a bit at a time, with safety. Nothing could be
+more simple, or demand less skill, and the operation may be carried out
+successfully by an amateur at any time during the season, when good firm
+cuttings can be got, and when six weeks' tolerably fine weather may be
+counted on. The success of the whole thing depends on having the glasses
+fixed so that they may not be removed until the cuttings are rooted, and
+in placing the boxes in a shady place. So treated, carnations and many
+of our shrubs and herbaceous perennials may be propagated by unskilled
+persons with certainty, and without much trouble.
+
+       *       *       *       *       *
+
+
+
+
+A FEW OF THE BEST INULAS.
+
+
+Of the fifty-six species of Inula described in scientific works,
+probably not more than thirty are at present in cultivation in
+this country, and those are chiefly confined to botanic gardens,
+notwithstanding the fact that many of them are useful garden plants.
+They are principally distributed throughout Southern Europe, although we
+find them extending to Siberia and the Himalayas; indeed, it is to the
+Himalayas we are indebted for the kinds that are most ornamental. Some
+of the low-growing species are extremely useful for the rockery, such
+as I. montana (the Mountain Inula), a fine dwarf plant with woolly
+lanceolate leaves and dense heads of orange-colored flowers, resembling
+in habit and general appearance some of the creeping Hieraciums. It is a
+handsome and desirable plant for the decoration of old walls and similar
+places, where it can be a little sheltered from rain and drip. Another
+very useful species for this purpose is I. rhizocephaloides, found
+plentifully in the Himalayas. It is one of the prettiest Alpine
+composites we have. It seldom attains more than from one inch to two
+inches in height, forming a dense rosette of short, hairy, oval leaves,
+in the center of which the bright purple involucres, in the form of a
+ball, are extremely interesting. It is easily cultivated, requiring,
+however, a rather snug nook, where it will not be allowed to become too
+dry. It is best propagated from seed. Then there is the woolly Inula (I.
+candida), a pretty plant with small oval leaves, covered with a thick,
+silky down, and much in the way of the white-leaved I. limonifolia, both
+of which are very effective when grown in masses, which should always
+be low down near the front of a rockery, or as an edging for a mixed
+border. The glandular-leaved Inula (I. glandulosa), of which a good
+representation is here given, is a beautiful hardy perennial. It is a
+native of Georgia and the Caucasian Alps, near the Caspian Sea. It is
+a rather robust-growing species, with large, bright, orange-yellow
+flowers, varying from three to five inches in diameter, the narrow and
+very straggly ray florets contrasting nicely with the rather prominent
+disk. The leaves, although quite entire, seem notched, owing to large
+black glands which form on their margins. They are lanceolate, and clasp
+the stem. The plant is very variable, both as regards robustness and
+size of flowers, and this may in a measure account for the confusion
+existing between it and I. Oculus-Christi.
+
+The soil most suitable for the full development of I. glandulosa is a
+strong, clayey, retentive loam; it does not thrive well in the light
+shallow soils in the neighborhood of London, except in shady positions.
+I. Hookeri is a free-flowering perennial, with pointed lanceolate
+leaves, of a delicate texture, bright green, and very finely toothed.
+The flowers, which are sweet-scented, are not so large as those of I.
+glandulosa, and are produced singly, the ray florets being, however,
+much more numerous, rarely numbering less than thirty. It is found in
+abundance in rocky places in Sikkim, where it replaces the nearly allied
+I. grandiflora, a dwarfer species, with much shorter, shining leaves;
+both are very desirable plants either for rockery or flower border work.
+The Elecampane (I. Helenium) is an imposing, robust-growing species,
+having large, broad leaves a foot or more in length. It grows from four
+feet to five feet in height, and its thick, shaggy branches are crowned
+with large yellow flowers. For isolating in woods this plant, is very
+useful, and with the exception of Telekia cordifolia, it would be hard
+to find a rival to it. It is, I believe, pretty extensively used for
+planting in shrubberies, but unless they are thin and open it is seldom
+seen to advantage. It is found wild or naturalized in some parts of
+England. It flowers in June and July, and even into August when the
+season has been favorable.
+
+[Illustration: INULA GLANDULOSA (_flowers deep yellow_.)]
+
+For naturalizing in woods the following will be found useful, _viz_., I.
+salicina, I. Oculus-Christi, I. squarrosa, I. britannica, and many more,
+the true beauty of which can only be realized in this way. With the
+exception of I. rhizocepbaloides, they are all propagated by division
+with the greatest ease, or by seed, which is best sown as soon as it is
+ripe.--_D.K., The Garden_.
+
+       *       *       *       *       *
+
+
+
+
+FRUIT GROWING.
+
+By P.H. FOSTER.
+
+
+In the first place, if you contemplate appropriating a portion of your
+land for the raising of fruits, you should have the orchard so situated
+that no large animals can run at large on the grounds. Prepare your soil
+in the most thorough manner; underdrain, if necessary, to carry off
+surplus water; dig deep, large holes; fill in the bottom with debris;
+in the very bottom put a few leaves, clam and oyster shells, etc., then
+sods; above and below the roots put a good garden or field soil; do not
+give the trees fresh manure at the time of setting, but the following
+fall manure highly with any kind on top of the ground; dig it in the
+following spring; keep the soil frequently worked during the summer,
+and, if convenient, mulch with hay, straw, or leaves.
+
+Now you are on the road to progress, provided you have made no mistake
+in the selection of your trees. The purposes for which you intend your
+fruit is highly important. You should well consider at the outset if
+for family or market use. This is a business which requires a long look
+ahead, for it is said, "He who plants pears looks ahead for his heirs."
+
+Caution should be used in procuring your stock; little should be planted
+that is not fairly tested on the Island, purchased of parties who can be
+fully relied upon to give you what you want. Do not buy your stock of
+parties who carry labels in their pockets to make to order what you want
+out of the same bundle of trees.
+
+Now, having your trees set out in a proper manner, of such varieties
+as you desire, the next important step is to bring the trees into
+usefulness. My plan is to use bone--fine bone--very freely about every
+three years. Another important matter is that of trimming. "Fire
+purifies," and the knife regulates the grand balance or equilibrium
+between roots and tops. In most cases the top outgrows the roots, the
+consequence of which is an ultimate weakness of the tree. It is thrown
+into excessive fruiting, disease, and premature decay. To avoid this
+result, use the knife when required. Thin out the inside branches when
+small, and if the tree does not make a satisfactory growth, cut back
+half way to the ground.
+
+We will suppose that you have got your trees growing nicely, and they
+have begun to bear fruit. There are other important steps to be taken,
+which will be of little cost to you. Provide a wind-break for the
+orchard. Evergreens answer the purpose, being a protection against the
+wind. Having this matter attended to, there are other enemies with which
+we must contend. I refer to the apple and peach tree borers. The former
+will live in the tree for three years, if unmolested; the latter, one
+year only. They are very easily destroyed by looking over the trees and
+taking them out with a knife; or maybe prevented from touching the trees
+by wrapping a piece of felt paper, 8 inches wide, around the tree near
+the ground, the bottom being covered with dirt and the top tied tightly
+above. The pear is not generally disturbed by these insects--only the
+apple, peach, and quince. We have another insect very destructive to the
+plum, peach, cherry, and apple--the _curcutio_, or plum weavel. This
+season for the first time in twenty years we have gathered a small
+crop of that very desirable plum, the Purple Favorite. We simply threw
+air-slaked lime over the trees nearly every morning for from four to six
+weeks, from the time the tree was out of bloom. Peach trees should be
+treated in the same manner. Another method of fighting this insect is to
+spread a sheet under the tree, and with a blow jar off the little Turk
+and secure him on the sheet. But I consider the lime procedure the less
+trouble and more effective. The tent caterpillar, which is easily seen,
+should be destroyed at once. We have yet another insect to contend with
+which infests the apple and pear, commonly called the Coddling Moth,
+and the larva, the apple-worm (_Garpocapsa pomonella_). The loss by the
+ravaaes of this insect alone to the fruit growers of the United States
+fan hardly be estimated, as in many cases the whole crop is rendered
+worthless. Such a vast destruction of two of the most valuable fruits
+the world produces should stimulate scientists in this age of progress
+to discover an effectual remedy against such a gigantic evil.
+
+I have never yet discovered nor tried an effectual remedy against this
+insect. The nearest I have approached his extermination is in the
+following manner: After it has entered the fruit and accomplished its
+damage, the time arrives when it has to leave the fruit and hide itself
+in a quiet, secure position to undergo the transition from the larva to
+the pupa state, which requires, in the early part of the season, eight
+or ten days; after this time the miller is hatched and is again ready to
+besiege the fruit with its sting. The insect, being two-brooded in this
+climate at least, if not disturbed, has an aggregating force to do
+mischief the second time. The progeny for the succeeding year have alone
+to depend on the security of this second generation of larvæ. As they
+may often be found in bark of apple trees during winter, my plan of
+destruction is, about the first of July to take woolen rags long enough
+to wrap around the trees, and say four inches wide. Each week I look
+over the trees, and destroy the worms secreted under the rags and
+wherever I find them until the fruit is off the trees. I have all the
+green fruit, of every kind, carefully picked up as soon as it falls,
+thereby destroying many of the curculio as well as the apple-worms.
+
+One word upon the grape--the insect part of the question. The
+_Phylloxera vastatrix_, or grape-vine louse, is already at work on Long
+Island. It is found very difficult to raise many of our fine, new grapes
+with us in consequence of the depredations of this very minute insect,
+it being almost too small to be seen by the naked eye. There has lately
+been discovered a remedy which is entirely chemical and as yet but
+little disseminated. Very soon, no doubt, a discovery will be made that
+will stay the progress of this destructive enemy.
+
+We should plant aplenty of cherry and small fruit trees to yield feed
+for birds. In return they will assist us in our efforts to preserve a
+bountiful supply of this health producing element.
+
+       *       *       *       *       *
+
+
+
+
+COARSE FOOD FOR PIGS.
+
+
+A recent subscriber wants advice how to feed pigs of 25 to 35 pounds
+weight, that are to be kept over winter and fitted for sale at about six
+months old--whether coarse food will not help them as much in winter as
+in summer. How roots and pumpkins will answer in lieu of grass, and what
+can be fed when this green food is gone? He has had poor success in
+growing young pigs on corn alone. He has a reasonably warm pen for
+winter.
+
+The question of food is constantly recurring, and this is one of the
+best evidences of the advancement of the country in the feeder's
+art. When people are making no inquiry as to improved methods in any
+direction, no progress can be made. There has been more progress made
+in the philosophy of feeding during the last thirty years than in the
+century and a half previous.
+
+In pig feeding in the dairy districts, young pigs generally grow up in
+a very healthy condition, owing to the refuse milk of the dairy, which
+furnishes the principal food of young pigs. Skim-milk contains all the
+elements for growing the muscles and bones of young pigs. This gave them
+a good, rangy frame, and, when desired, could be fed into 400 or 500
+pounds weight. But the fault attending this feeding was, that it was too
+scanty to produce such rapid growth as is desired. It took too long to
+develop them for the best profit. It had not then been discovered by the
+farmer that it costs less to put the first hundred pounds on the pig
+than the second, and less for the second than the third, etc.; that it
+was much cheaper to produce 200 pounds of pork in six months than in
+nine and twelve months. When it became evident that profit required more
+rapid feeding, then they began to ply them continually with the most
+concentrated food--corn meal or clear corn. If this was fed in summer,
+on pasture, no harm was observed, for the grass gave bulk in the
+stomach, and the pigs were were healthy and made good progress. But if
+the young pigs were fed in pen in winter upon corn meal or clear corn,
+the result was quite different; this concentrated food produced feverish
+symptoms, and the pigs would lose their appetite for a few days,
+drinking only water, which, after a while, would relieve the stomach,
+and the pigs would eat vigorously again. Now, had they been fed a few
+quarts of turnips, carrots, beets, or pumpkins, to give bulk to the
+stomach, and separate the concentrated food, no harm would have come.
+This gives the gastric juice a free circulation through the contents of
+the stomach, the food is properly digested and applied to the needs of
+the body instead of causing fever by remaining in the stomach.--_Live
+Stock Journal_.
+
+       *       *       *       *       *
+
+
+
+
+METE KINGI.
+
+
+Our engraving is a portrait of a familiar character in New Zealand,
+chief Mete Kingi, who recently died at the age of one hundred years.
+He was a fine specimen of the Maori race, the native New Zealanders, a
+branch of the Malayo-Polynesian family. The New Zealanders surpassed
+all other people in the art of tattooing, to which their chiefs gave
+especial attention. Mete Kingi, as our picture shows, was no exception.
+Tattooing on the face they termed _moko_. The men tattoo their faces,
+hips, and thighs; the women their upper lips; for this purpose charcoal
+made from kauri gum is chiefly used. It has the blue color when pricked
+into the skin, growing lighter in shade in the course of years. The
+subject of our illustration embraced Christianity, and was much
+respected. Our engraving is from the _Illustrated Australian News_.
+
+[Illustration: THE LATE MAORI CHIEF METE KINGI.]
+
+       *       *       *       *       *
+
+
+
+
+LAKE TAHOE.
+
+
+Some very interesting information by Prof. John Le Conte, is given in
+the _Overland Monthly_, being the result of some physical observations
+made by the author at Lake Tahoe, in 1873. Lake Tahoe, also called Lake
+Bigler, is situated at an altitude of 6,247 feet in the Sierra Nevada
+Mountains, partly in California, partly in Nevada. The lake has a length
+of 22 and a width of 12 miles. As regards its origin, the author regards
+it as a "plication hollow," or a trough produced by the formation of two
+mountain ridges, afterward modified by glacial agency. The depth of the
+lake is remarkable; the observations taken at ten stations along the
+length of the lake gave the following depths in feet: 900, 1,385, 1,495,
+1,500, 1,506, 1,540, 1,504, 1,600, 1,640, 1645. This depth exceeds that
+of the Swiss lakes proper--Lake Geneva, for example, has a maximum depth
+of 1,096 feet--but is considerably less than that of Lakes Maggiore and
+Como, on the Italian side of the Alps. A series of observations of the
+temperature of the water were taken between the 11th and 18th of August.
+The average corrected results are as follows:
+
+   Depth in feet.                               Temp. (C.)
+     0(surface).................................19.4
+    50..........................................17.2
+   100..........................................12.8
+   150..........................................10.0
+   200.......................................... 8.9
+   250.......................................... 8.3
+   300.......................................... 7.8
+   330 (bottom)................................. 7.5
+   400.......................................... 7.2
+   480 (bottom)................................. 6.9
+   500.......................................... 6.7
+   600.......................................... 6.1
+   772 (bottom)................................. 5.0
+  1506 (bottom)..............,.................. 4.0
+
+The temperature, therefore, diminishes with increasing depth to about
+700 or 800 feet, and below this remains sensibly the same down to 1,506
+feet; or in other words, a constant temperature of 4° C. prevails at all
+depths below about. 820 feet. This is in accordance with the theory, the
+temperature named being that of the maximum density of water, and it
+confirms the recent observations of Prof. Forel in Switzerland; he
+found, for example, that a constant temperature of 4° C. was reached in
+Lake Zurich at a depth of nearly 400 feet, the lake being then covered
+with 4 inches of ice. The explanation of the observed fact that Lake
+Tahoe does not entirely freeze over even in severe winters is found in
+the extreme depth; and the fact that the bodies of drowned persons do
+not rise to the surface after the lapse of the usual time is explained
+by the low temperature prevailing near the bottom, which does not allow
+the necessary decomposition to go forward so as to produce the ordinary
+result.
+
+The water of Lake Tahoe is remarkable both for its transparency and
+beauty of color. A series of observations made at the close of August or
+beginning of September showed that a horizontally adjusted dinner plate
+of about 9½ inches diameter was visible at noon at a depth of 108 feet.
+The maximum depth of the limit of visibility as found by Prof. Forel, in
+Lake Geneva, was 56 feet. He showed, moreover, that this limit is much
+greater in. winter than in summer, as explained in part by the greater
+absence of suspended matter and in part by the fact that increase of
+temperature increases the absorbing power of water for light. The
+maximum depth of visibility in the Atlantic Ocean, as found by Count
+de Pourtales, was 162 feet, and Prof. Le Conte states his belief that
+winter observations in Lake Tahoe would place the limit at even a
+greater depth than this. The author gives a detailed and interesting
+discussion in regard to the blue color of lake waters, reviewing in full
+the results of previous writers on the subject, and concludes that while
+pure water unquestionably absorbs a larger part of the red end of the
+spectrum, and hence appears blue by transmitted light, the color seen by
+diffuse reflection is mainly due to the selective reflection from the
+fine particles suspended in it.
+
+The last subject discussed by the author is that of the rhythmical
+variations of level, or "seiches," of deep lakes; he applies the usual
+formula to Lake Tahoe, and calculates from it the length of a complete
+longitudinal and of a transverse "seiche;" these are found to be
+eighteen or nineteen minutes in the first case and thirteen minutes in
+the second.
+
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+End of the Project Gutenberg EBook of Scientific American Supplement,
+No. 433, April 19, 1884, by Various
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