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diff --git a/11498.txt b/11498.txt new file mode 100644 index 0000000..763cb67 --- /dev/null +++ b/11498.txt @@ -0,0 +1,4340 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 601, +July 9, 1887, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 601, July 9, 1887 + +Author: Various + +Release Date: March 7, 2004 [EBook #11498] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN, SUPP. 601 *** + + + + +Produced by by Jon Niehof, Don Kretz, Juliet Sutherland, Charles Franks +and the DP Team + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 601 + + + + +NEW YORK, JULY 9, 1887 + +Scientific American Supplement. Vol. XXIV, No. 601. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + +TABLE OF CONTENTS. + +I. ASTRONOMY.--A Star Finder.--A simple apparatus that can be + constructed by any mechanic.--1 illustration. + + Photographic Study of Stellar Spectra, Harvard College Observatory. + --First annual report of the Henry Draper memorial observations. + --Review of the work by Prof. EDWARD C. PICKERING. + +II. BIOLOGY.--Sponges.--The growth and life history of sponges.--Report + of a recent lecture at the London Royal Institution by Dr. + R. VON LEDENFELD. + +III. ELECTRICITY.--Phenomena of Alternating Currents.--By Prof. + ELIHU THOMSON.--16 illustrations. + +IV. ENGINEERING.--An English Car Coupling.--Description of an + English automatic coupling.--2 illustrations. + + A New Process of Casting Iron and other Metals upon Lace, + Embroideries, Fern Leaves, and other Combustible Materials. + --By A.E. OUTERBRIDGE, JR.--A new and eminently practical + process of producing ornamental castings.--4 illustrations. + + Bricks and Brick Work.--By Prof. T. ROGER SMITH, F.R.I.B.A. + --The history and technical review of this subject.--A most + remarkable contribution to the engineering of architecture. + + Link Belting.--By CHARLES A. SCHIEREN.--An interesting and + practical paper on leather belting made of links. + --9 illustrations. + + Recent Progress in Gas Engineering.--A lecture by Mr. A. + MACPHERSON, of Kirkcaldy, reviewing the last improvements + in this branch. + +V. MISCELLANEOUS.--Herbet's Tepid Douche.--Apparatus in use + for bathing soldiers in the French barracks.--1 illustration. + + Kent's Torsion Balance.--A new type of balance, involving + torsional suspension instead of knife edges.--5 illustrations. + + Preservative Liquid.--Note on preservation of organic + substances. + + The Falls of Gairsoppa.--The great Indian falls, higher than + Niagara.--2 illustrations. + + The New British Coinage and Jubilee Medal.--Illustrations and + descriptions of the new pieces.--8 illustrations. + + The Winner of the Derby.--Portrait and description of Merry + Hampton. + +VI. NAVAL ENGINEERING.--The Falke Type Torpedo Boat.--The fastest + type of British torpedo boat, constructed by Messrs. Yarrow + & Co.--1 illustration. + + The German Navy.--The New Gunboat Eber.--A description of + a late accession to the German navy.--1 illustration. + +VII. ORDNANCE AND GUNNERY.--Magazine Rifles.--Continuation of + this important article, including the Chaffee-Reece, + Kropatschek, and other magazine guns.--3 illustrations. + + New British Torpedo Experiments.--Experiments with torpedoes + against a ship.--The efficiency or torpedo nets.--The effects of + Whitehead torpedoes. + + * * * * * + + + + +THE FALKE TYPE TORPEDO BOAT. + + +Among the different classes of vessels designed for special services, +constructed by Messrs. Yarrow & Co., at Poplar, for the British +government, is one which is stated to be the fastest torpedo boat in her +majesty's navy. This boat has been put through its official trials; with +a load of 15 tons, running continuously for two hours without stopping, +a speed of 23 knots, which is equal to 261/2 statute miles, an hour was +obtained. The boat is 135 ft. long by 14 ft. beam. Its design is known +as the Falke type, being in many respects similar, but very superior, to +a torpedo boat of that name which was built two years ago by the same +firm for the Austrian government. The form of the hull is of such a +character as to give exceptional steering capabilities; at the time of +trial it was found to be able to steer round in a circle of a diameter +of 100 yards, averaging 62 seconds. The forward part of the boat is +completely covered over by a large turtle back, which is the customary +form of the boats built by Messrs. Yarrow & Co. It was first introduced +in the Batoum, which they constructed eight years ago for the Russian +government. This turtle back increases the seaworthiness of the craft by +throwing the water that comes upon it freely away. It forms, also, good +and roomy accommodation for the crew, and incloses a large portion of +the torpedo apparatus. The forward torpedo gear consists of one torpedo +gun, adapted for ejecting the Whitehead torpedo by means of gunpowder, +now preferred on account of its simplicity. The boiler, one of Messrs. +Yarrow & Co.'s special construction, of a type which has undergone many +years of constant trial, is capable of developing 1,660 horse power. In +the engine room there are six engines--one for driving the boat, two for +compressing the air for the torpedoes, an engine for working the dynamo +for producing the electric light, an engine for forcing air into the +stoke-hole, and an engine working in conjunction with the distilling +apparatus for supplying drinking water for the crew and the waste +incidental to the boiler. Aft of the engine room come the officers' +quarters. The stern of the boat is fitted up as a pantry and for the +stowage of ammunition and stores. On the deck are mounted three machine +guns, and near the stern an additional conning tower for use in case of +need, around which revolve two torpedo guns for firing the torpedoes off +either side. These torpedo guns can be trained to any angle it may be +desired to fire them at. On both conning towers are machine +guns.--_Illustrated London News_. + +[Illustration: THE "FALKE" TYPE TORPEDO BOAT, AND SECTION SHOWING +GENERAL ARRANGEMENT.] + + * * * * * + + + + +THE GERMAN NAVY--THE NEW GUNBOAT EBER. + + +The gunboat Eber is an improved vessel of the Wolf type, but differs +from other vessels of its class in that it has not a complete iron hull, +only the frame and deck beams being of iron, while the planking is of +wood and yellow metal. No copper is used on the bottom. The "composite +system" of building is looked upon with favor for ships of this kind, +because iron vessels which are kept permanently at stations in the +tropics soon become overgrown in spite of good care, and thus suffer a +great loss of speed. In a wooden vessel the crew's quarters are better +and more healthful than in iron vessels, for they are not as much +affected by the temperature outside of the ship. + +The greatest length of the Eber is about 245 ft.; its breadth, 26 ft.; +its depth, 14 ft.; and it has a displacement of about 500 tons. The +armament will consist of three long 5 in. guns in center pivot +carriages, and a small number of revolvers. One of the former will be +placed at the stern on the quarter deck, and the two others on the +forecastle. Some of the revolvers will be on the quarter deck and some +on the forecastle, care being taken to arrange the guns so as to obtain +the widest possible range, thus enabling the ship to protect itself +perfectly. + +[Illustration: THE NEW GERMAN GUNBOAT EBER.] + +The Eber is provided with a two-cylinder, compound engine, which can +generate 650 horse power, giving the vessel a speed of 111/2 knots. The +coal bunkers are so large that the ship can travel 3,000 miles at a +speed slightly less than that just mentioned without requiring a fresh +supply of coal. The rigging is the same as in iron vessels of the Wolf +class, and the sails are sufficiently large to allow the vessel to +proceed without steam. The ship will carry about 90 men, including +officers, crew, engineers, and firemen. + +A sum of $145,000 was appropriated for the construction and equipment of +the Eber, which was begun at Kiel in the latter part of 1885, and was +launched February 15, 1887.--_Illustrirte Zeitung_. + + * * * * * + + + + +NEW BRITISH TORPEDO EXPERIMENTS. + + +The torpedo experiments against the Resistance, which have been +suspended since November last, were resumed on June 9 at Portsmouth by +the officers of the Vernon. The injuries received by the ironclad in the +previous experiments having been repaired, so as to make the vessel +watertight, the old ship was towed up the harbor, and moored in Fareham +Creek. Our readers are aware that the Resistance is an obsolete ironclad +which has finished her career as a battle ship, and that nothing could +have converted her into a modern armorclad. + +Although it was intended to render the experiments final and conclusive +as a practical demonstration under service conditions of the destructive +effects of the Whitehead torpedo when directed against a modern vessel +of war, the results still leave behind them much uncertainty. The +Resistance was built of iron, whereas battle ships are now exclusively +constructed of steel, and it would be perhaps hazardous to state that +the behavior of the two metals under a sudden and violent shock would be +exactly the same. The construction of the double bottom of the old ship +is also different. Since the last experiments were carried out against +her, however, measures have been taken to make her as far as possible +the counterpart, so far as under water arrangements and coal protection +are concerned, of a modern ship of war. + +At the last attack, the Whitehead was directed against the after part of +the hull on the port side in wake of the boilers. During the present +series of experiments the old ship was assailed on the same side, but +directly amidships, in the neighborhood of the engine room. As no steam +was got up in the boilers, the effect of the jar upon the steam pipes, +glands, and feed connections remains a matter of speculation. So far as +the consequences of the burst upon the structure of the hull itself is +concerned, every care was taken to make the ordeal as complete and +instructive as possible. The wing passage, which has a maximum diameter +of 3 ft. diminishing to a point, was left empty, although at the former +experiments the lower portions were filled with coal. But behind this, +and at a distance of 8 ft. from the bulkhead, a longitudinal or fore and +aft steel bulkhead 3/8 in. thick had been worked to a length of 61 ft., +and, with the coal with which the intervening compartment was packed, +formed (as in recent armorclads) a solid rampart, 20 ft. high, for the +defense of the engine room. + +The height of the double bottom between the outer and inner skin plating +is 21/2 ft. The watertight compartments were divided into stations by +means of vertical lightening plates pierced by three holes, and in order +to make them, as far as was practicable, resemble the bracket frames of +a modern armorclad, the center of the plates was cut away so as to leave +a single oval hole instead of the three circular holes. In view of the +differences of opinion which exist on the part of experts on the subject +of under water protection, the officers of the Vernon had determined to +submit the problem to the test of experiment. For this purpose steel +armor 11/2 in. thick had been worked along the outside of the upper skin +of the double bottom throughout one of the compartments, in addition to +the other protection mentioned. The Resistance had been brought down by +iron ballast to a trim of 25 feet 9 in. aft and 19 ft. 7 in. forward, +giving a mean draught of 22 feet 8 inches. She was consequently rather +further down by the stern than before, but was in other respects the +same. + +When in commission, the Resistance had a mean draught of 26 feet 10 +inches. The present series of experiments was of even greater importance +than the first series. The attack was gradually developed by means of +fixed and outrigger charges of increasing power, and the _coup de grace_ +was not given by means of a service Whitehead in actual contact until +various lessons had been derived. + +The opening experiment on June 9 consisted of an attack directed against +a new system of torpedo defenses which are to be carried by ships in +action, or when in expectation of an attack, rather than an assault upon +the ship herself. The previous experiments had clearly demonstrated that +a Whitehead, when projected against a vessel at close range, and +consequently with a maximum of motive force, could not get through the +ordinary wire netting before expending its explosive energy in the air, +and that the spars by which the nets are boomed out from the ship's side +could be reduced to 25 ft. in length without danger to the hull. The +ordinary wooden booms employed on board ship, however, are heavy and +unwieldy, weighing, as they do, more than half a ton each. In ordinary +circumstances, the spars cannot be lowered into place and the nets made +taut in less than a couple of hours, and the work of stowing them is +equally slow and laborious. + +Mr. Bullivant, who manufactures the torpedo netting and hawsers for the +navy, has devised a method of getting rid of the difficulties complained +of by substituting steel booms for the wooden booms and an arrangement +of pulleys and runners, whereby the protection can be run out and in, +topped and brailed up out of the way, with great facility. The system +was tried at Portsmouth last year with considerable success upon the +Dido, but as it was thought that some of the fittings were somewhat +frail and might collapse beneath the shock of a live torpedo, it was +resolved to submit them to a practical test under service conditions +upon the Resistance. The ship was consequently fitted with three of the +steel booms on the port side. They were 32 ft. long and spaced 45 ft. +apart, and connected by a jackstay to which the nets were attached. Each +steel boom weighed 5 cwt., or less than half the weight of the ordinary +boom, and whereas the latter is fixed to the ship's side by a hook which +is liable to be disconnected or broken by the jerk of an exploding +torpedo, Mr. Bullivant's boom works in a universal or socket joint, +which cannot get out of gear except by fracture, and which permits the +boom to be moved in any direction, whether vertically or fore and aft, +close in against the sides. Below each boom is a flange, which serves as +a line along which a traveler moves, the latter being actuated by means +of a topping line running over a pulley at the head and another near the +heel. + +Upon the booms being topped to a perpendicular position, the nets are +attached to the runners at the bottom of the booms close inboard +(instead of, under the existing system, to the tops of the booms from +boats alongside or otherwise), and when this is done, the mere +depression of the booms into position will cause the nets to run out of +their own accord. In like manner, when the occasion for their use has +passed, the raising of the boom will cause the nets to come alongside, +when they can either be brailed up through the grummets or disconnected +for future use. + +The action of the gear is so simple and rapid that the torpedo +protection can be always ready without arresting the way of the ship. As +a length of net 30 ft. by 20 ft. deep weighs about 3 cwt., it will also +be seen that the reduction of strains by working the crinolines from the +heel instead of the head of the booms is considerable. The attack by the +Whitehead upon the booms and nettings was made shortly before 2 p.m., at +the time of high tide. + +The whole affair occupied a very few minutes. As soon as the red pennant +was struck on board to show that Mr. Bullivant was satisfied with the +arrangements, and that the target was ready, the torpedo vessel Vesuvius +got under way, and after circling round the doomed hulk discharged a +Whitehead against the netting from her under-water bow torpedo tube at +an approximate range of 50 yards. As on former occasions, the missile +was one of the old 16 inch pattern, but it was understood that the +charge of gun cotton had been reduced to 87 lb., so that the net +protection should not bear a greater strain than would be the case in +actual hostilities. The torpedo, which was set to a depth of about 10 +feet, struck the net in the middle and threw up an immense spout of +water, but without getting to the ship, which was apparently uninjured. +Although it hit the net immediately below the center boom, no fracture +occurred, and the points remained intact. Although at the short range +the torpedo would spin through the water at from 30 to 40 horse power, +and would deliver a formidable blow upon the net, the thrust was +effectually resisted, though as a matter of course the net was much torn +by the explosion of the baffled projectile. + +Although at the second torpedo attack made on the Resistance, the +following day, the offensive power that was brought to bear was quite +exceptional, the victory remained with the ship. The charge exploded was +an exceptionally heavy one. It consisted of 220 lb. of gun cotton. It +was consequently more destructive than any which is ever likely to be +launched against an armorclad much better prepared to resist it than the +obsolete and time-worn Resistance. An idea, however, had got abroad that +the Russians either have or intend to have a locomotive torpedo capable +of carrying the same weight of explosive in its head, and the object of +the experiment was to ascertain what would be the effect of the +detonation of such an enormous charge upon the submerged portions of a +ship of war. + +But, while this was no doubt the primary purpose in view, the experiment +also served the secondary purpose of determining the result of the +explosion upon the net defenses of a ship. Mr. Bullivant's booms and +runners, which were found to be scarcely anything the worse from the +ordeal of the previous day, were again used. The damaged net was taken +away and one of the old service grummet nets slung in its place, the +cylinders containing the gun cotton being attached to the jackstay +immediately in front of the battered sides, and 30 feet from the hulk, +and sunk to a distance of 20 feet below the water line, which would +bring it about opposite the bend of the bilge. By 3 p.m. everything was +ready for the explosion of the charge--everybody had cleared out of the +ship while the surrounding small craft drew off to a distance of 300 +feet. The charge was electrically fired from a pinnace. The burst was +terrific and the reverberation was heard and the shock distinctly felt +in the dockyard. But the remarkable thing was that the hulk did not +appear to jump in the least, though there was not more than six feet of +water under her keel. That she would not be seriously crippled by the +discharge seems to have been accepted as a foregone conclusion by +Captain Long and the other torpedoists, as the day for the third +experiment had been fixed in advance; but that the steel booms with +their double flange running ways, stays, travelers, and hinges should +have resisted the tremendous jar and upheaval was a genuine surprise for +all concerned, and goes far to prove that except a vessel be taken +unawares, it will be impossible for a torpedo to come into actual +contact with it. At the experiments last year the wooden booms were +unhinged and splintered under a much less violent shock. But the steel +booms employed, though somewhat bent, remained unbroken and in position, +and the joints were quite uninjured. All that is necessary for perfect +defense is that the booms should be made a little heavier. + +The torpedo experiments against the Resistance were resumed on June 13, +when the old ironclad suffered some rough treatment. As the experiment +was understood to be the last of the second series, and was fully +expected to have a sensational termination, a considerable number of +interested spectators were attracted to the scene in Fareham Creek. The +torpedoists resorted to severe measures, but with a distinctly useful +purpose in view, having bound the ship hand and foot, so to speak, in +such a way that her name became a solecism. They exploded 95 lb. of gun +cotton 20 ft. below the water, and in contact with her double bottom. +This amount of explosive represents the full charge of the old pattern +16 in. Whiteheads; but as the hulk was, for prudential reasons, moored +close to a mud bank, and as the water was consequently much too shallow +to allow of a locomotive torpedo being set to run at the required depth, +a fixed charge was lashed fore and aft against the bottom plating of the +ship and electrically exploded from No. 95 torpedo boat. + +In previous experiments this year the ironclad was attacked on the port +side, which had been specially strengthened for the occasion, and the +result was a victory for the defense. On June 13 the starboard side was +selected for attack, in order that a comparison might be instituted with +the effects produced under different conditions by a similar experiment. + +Last year in the latter case the double bottom was filled with coal; and +after the charge, which was lashed against the ship in the same way, had +been exploded, it was found that the bilge keel had been shivered for a +length of 20 ft., while the lower plating had been much bulged above the +bilge keel. Four strakes of the skin plating extending up to the armor +shelf had also been forced inward and fractured where they crossed the +longitudinal frames. They had parted in the middle for a distance of 8 +ft., while some of the butts had been opened so that gashes 2 in. or 3 +in. wide appeared between them. The coal had been pulverized and +scattered in all directions, and other internal damage inflicted. +Nevertheless, the watertight bulkheads remained intact, and by confining +the influx of water to a single compartment so much buoyancy was +preserved that, though the ship heeled over to starboard and was maimed, +she remained afloat, and might have continued to fight her guns, +provided always that no injury had been sustained by her machinery, a +point which these experiments do not touch. Crippled, however, as she +was, it was thought at the time (and the probability was strengthened by +subsequent examination of the ship in dock) that the coal, instead of +being a protection to the double bottom, had in reality proved a source +of weakness by receiving the energy of the explosion from the outer +plating and communicating it to the inner plating, and so distributing +it throughout the submerged portions of the hulk. + +The question was sufficiently important to demand an experimental +solution; hence the _raison d'etre_ of the present demonstration. The +double bottom, which is about 21/2 ft. deep, was consequently kept empty, +and the torpedo placed in immediate contact with it in such a manner +that, being overhung by the contour of the hull, the ship would feel the +full force of the upward as well as the lateral energy of the charge. On +other accounts the importance of the experiment was obvious, for, +although it had been ascertained that torpedo nets were capable of +protecting a battle ship from the bursts of the heaviest locomotive and +outrigger charges, it might happen, of course, that the nets would be +rent or displaced by shell fire or swept away by a grazing ram or even +attacked by a double torpedo, the second passing through the gashes made +by the explosion of the first in any case. It was, therefore, of urgent +necessity that the effect of a torpedo bursting in immediate contact +with a ship's bottom should be practically and clearly determined. The +charge on June 13 was fired just before 5 p.m. in the wake of the +boilers, and it was soon perceived that something of a fatal character +had taken place from the appearance of coal dust sweeping up through the +hold. The report had not the dull boom to which the spectators had +become accustomed. Instead of this, the gun cotton exploded with a +sharp, angry, whistling noise, while the manner in which the mud was +churned up showed that the force of the rebound was terrific. The ship +lifted bodily near the stern, after which it was seen to leisurely heel +over to starboard some eight or ten degrees, and finally repose, though +not until the tide fell, upon the mud. The old hulk had been mortally +wounded at last. + +A complete knowledge of the disaster which has overtaken her (says the +correspondent of the London _Times_, to which we are indebted for the +above particulars) will not be obtained until a careful investigation +has been made of the hull in dock. But, from a hasty exploration which +was conducted on board, it was evident that the shot had not only +dislocated the inner plating of the double bottom, but had penetrated +the bunker compartment, stored as it was with coal, that the watertight +doors and compartments had ceased to operate, and that water was flowing +into the hull through a hundred crevices. To such an extent was this the +case that, though a strong working party was at hand ready for any +emergency, it was deemed useless to attempt to free the ship of water +until her gashes had been temporarily closed from outside. When this has +been done, she will be pumped out and brought into dock for careful +examination. From what has been said, it will be seen that while the +explosion of 95 lb. of gun cotton in actual contact last November simply +crippled the Resistance, the explosion of a like charge at the same +spot, and under approximately the same conditions, has in this instance +not simply disabled, but really sunk the ship. + + * * * * * + + + + +AN ENGLISH CAR COUPLING. + + +The new automatic railway coupling illustrated below is the invention of +Mr. Richard Hill, and has been practically developed by Mr. B.H. +Thwaite, of Liverpool. It will be seen that the system is somewhat +similar to the parallel motion when in action. + +The catch and peculiarly shaped hooks slide over the cross and catch +bars. These latter turn horizontally on a central pivot attached to the +jaw end of the drawbar. The cross catch bars adjust themselves to the +direction of the line of pull in the drawbar. The cranking of the +drawbar allows for the deflection of the buffer springs. + +The arrangement of uncoupling, or throwing hooks out of gear, is +extremely simple and effective. The cranked part of the rod passing +across the end of the wagon, and with handles at each end workable from +the 6 ft. way, is attached to the catch hooks by means of a light chain. +On throwing the handle over, and against the end of the wagon, the crank +moves over and below the center, lifting up the catch into a position +out of range of action, and from this position it cannot fall except it +is released by the shunter. A shackle and links hang from the end of the +drawbar for attachment to ordinary wagons. + +After a long and costly series of experiments the form of coupling shown +in illustration was adopted. Part of the experimental couplings used +were made by the Hadfield Steel Foundry Company, but the couplings used +at a recent trial at Gloucester were forged by the Gloucester Wagon +Company. + +[Illustration: AN ENGLISH CAR COUPLING.] + +The trial couplings were applied to old and worn-out coal wagons, +varying in relative heights and widths of buffers, and the tests were: + +1. Coupling and uncoupling, and passing coupled round curves of less +than two chains radius. 2. Coupling under rapid transit movement and +violent shock. 3. Coupling under slow movement, the wagons being shunted +together by two shunters. 4. Wagons brought violently together while the +coupling hooks were lifted out of action, to test the rigidity of the +hooks in this position. 5. Tested in competition with the ordinary +coupling stock. + +The trial was a success. The new automatic coupling satisfactorily +underwent the various conditions, and it was proved that: 1. It can be +lifted out of action with one hand and quite easily. 2. It can be +coupled and uncoupled six times as fast as with the pole hook in the +daytime. At night this advantage would be considerably increased. + +The coupling is strong as well as elastic in its parts, and adjusts +itself to the various conditions of traction.--_Engineering_. + + * * * * * + +[Continued from SUPPLEMENT, No. 597, page 9539.] + + + + +MAGAZINE RIFLES. + + +_Chaffee-Reece Magazine Rifle_.--We do not insert a drawing of this +arm--one of the three selected by the American board--as it belongs to +the same class and is similar in general construction to the Hotchkiss. +There is, however, an important difference in the magazine, which has no +spiral spring, but is furnished instead with an ingenious system of +ratchet bars. One of these carries forward the cartridge a distance +equal to its own length at each reciprocal motion of the bolt, while a +second bar has no longitudinal motion, but prevents the cartridges from +moving to the rear in the magazine tube after they have been moved +forward by the other bar. The magazine is loaded through an aperture in +the butt plate, the opening of the spring cover of which causes the two +ratchet bars to be depressed, so that the magazine can be filled by +passing the cartridges along a smooth middle bar. The act of closing the +spring cover again brings the two ratchet bars into play. + +[Illustration: FIG. 9.--KROPATSCHEK MAGAZINE GUN] + +By means of a cut-off the ratchet bars can be prevented from acting, and +the piece used as a single loader. + +_Kropatschek Magazine Rifle_.--This rifle, which is the small arm of the +French navy, has a bolt-action rifle resembling the Gras (see Fig. 9). + +The magazine is a brass tube underneath the barrel, as in the +Winchester, Vetterli, Mauser, and other rifles of class 1. It contains +six cartridges, while a seventh can be placed in the trough or carrier, +T. + +When the breech is opened by pulling back the bolt, a projection on the +latter strikes the carrier at N, causing its front extremity to raise +the cartridge into the position shown in the section. This movement is +accelerated by the spring, A, acting against a knife-edge projection on +the trough, T; in the upper position of the trough, the spring acts upon +one face of the angle, and upon the other face when in the lower +position. + +On closing the breech, the bolt pushes the cartridge into the chamber, +and when the handle is locked down to the right, a part of the bolt +presses against a stud, and thus depresses the trough to be ready to +receive another cartridge from the magazine. + +The magazine can be cut off and the rifle used as a single loader by +pushing forward a thumb-piece on the right side of the shoe. The effect +of this is that, on turning down the handle to lock the bolt, the latter +does not act on the stud to depress the carrier, so that no fresh +cartridges are fed up from the magazine. + +[Illustration: FIG. 10.--LEE MAGAZINE GUN] + +There is a projection, Z, on the fore part of the carrier, which keeps +the next cartridge from leaving the magazine while the trough is in the +upper or loading position. A supplementary cartridge stop, R, pivoted at +P and having a spring, L, underneath it, acts in conjunction with Z in +retaining the cartridges in the magazine, and especially in preventing +more than one at a time from passing out into the carrier when the +latter is depressed; it also retains the cartridges in the magazine tube +while the latter is being filled. + +_Lee Magazine Rifle_.--This arm (see Fig. 10), which occupied the place +of honor in the report of the American "Board on Magazine Guns," +embodied two new principles of considerable importance, viz., the +central position of the magazine, and having it detachable with ease, so +that two or more magazines can be carried by the soldier. + +The breech action of the Lee does not materially differ in design from +other bolt rifles, except that the bolt is in two pieces only--the body, +or bolt proper, and the hammer or cocking-piece. The firing pin, or +striker, is screwed into the hammer; the spiral main spring, which +surrounds the striker, is contained in a hollow in the body. The handle +is placed at the rear end of the bolt, and bent down toward the stock, +so as to allow the trigger to be reached without wholly quitting hold of +the bolt. The extractor is so connected with the bolt head as not to +share the rotation of the latter when the handle is turned down into the +locking position. When the handle is turned up to unlock the bolt, the +hammer is cammed slightly to the rear, by means of oblique bearings on +the bolt and hammer, so as to withdraw the point of the striker within +the face of the bolt. This oblique cam action also gives great power to +the extractor at first starting the empty cartridge case out of the +chamber. + +The magazine, M, is simply a sheet iron or steel box of a size to hold +five cartridges, but there seems no reason why it should not be of +larger dimensions. It is detachable from the rifle, and is inserted from +underneath into a slot or mortise in the stock and in the shoe, in front +of the trigger guard. A magazine catch, C, just above the trigger guard, +engages in a notch, N, in the rear of the magazine, the projection, L, +first entering a recess prepared for it in the shoe. There is a magazine +spring, D, at the bottom of the magazine box which pushes the cartridges +up into the shoe. The point of the top cartridge is pushed into the +projection, L, and this keeps the lower cartridges in their places in +the box while the latter is detached; when the magazine is inserted in +the rifle, the withdrawal of the bolt causes the top cartridge to be +slightly drawn back, so that it is now free to be fed up into the shoe +by the magazine spring, D. + +There is a later pattern of magazine, which has its front face quite +plain, with no projection, L, as the magazine catch was found sufficient +to hold the box in its place. To prevent the cartridges being pressed +out of the magazine before the latter is inserted in the rifle, there is +a strong spring placed vertically in one side of this box, the curved +upper end of which bears upon the top cartridge; when the magazine is in +its place in the shoe, this side spring is so acted upon that it ceases +to hold down the cartridges in the box. + +To use the rifle as a single loader, formerly the magazine had to be +detached, when a spring plate in the shoe, which is pushed aside by the +insertion of the magazine, starts back into its place and nearly fills +the magazine slot, so as to prevent cartridges falling through to the +ground when fed into the chamber by hand. The later pattern, however, +has two notches on the magazine for the catch, C, to engage in. When the +magazine is inserted in the slot only as far as the upper notch, the +rifle can be used only as a single loader, but on pressing the box home +to the second notch, the magazine immediately comes into play. + +The magazine can be released from the slot by an upward pressure on the +lower projecting end of the magazine catch, C, which is covered by the +trigger guard. + +_Improved Lee_.--This rifle is precisely similar in principle to the +Lee, the chief difference being that the magazine is permanently fixed +in its slot underneath the shoe, and in front of the trigger guard. The +cartridges are inserted from above. There is a stop by means of which +the cartridges can be prevented rising up into the shoe, and which forms +a sort of false bottom to the slot in the latter, so that the arm can be +used as a single loader. + +_Lee-Burton_.--The bolt action is the same as the Lee, but the box +magazine is attached to the right side of the shoe, instead of being +underneath, as in that rifle. When the magazine is raised to its higher +position, the cartridges pass successively into the shoe by the action +of gravity alone, and are thus pressed home into the chamber by the +closing of the bolt. + +[Illustration: FIG. 11.] + +A number of the Lee-Burton and improved Lee rifles are now being +manufactured for issue to the troops, in order to undergo experimental +trials on an extended scale. + +Several other magazine rifles have the box central magazine, but placed +in different positions as regards the shoe and the axis of the bore. In +the original pattern of the Jarman (Sweden and Norway), the magazine is +affixed to the upper part of the shoe, inclined at a considerable angle +to the right hand (see vertical cross section, Fig. 11). Here the +operation of gravity obviates the necessity of a magazine spring, but +the magazine was found to be very much in the way and liable to be +injured. It has therefore been replaced by a magazine underneath the +barrel, as in the Kropatschek and other rifles.--_Engineering_. + +(_To be continued_.) + + * * * * * + + + + +PRESERVATIVE LIQUID. + + +For a few weeks' preservation of organic objects in their original form, +dimensions, and color, Prof. Grawitz recommends a mixture composed of 21/2 +ounces of chloride of sodium, 23/4 drachms of saltpeter, and 1 pint of +water, to which is to be added 3 per cent. of boric acid.--_Annales des +Travaux Publics_. + + * * * * * + + + + +KENT'S TORSION BALANCE. + + +The United States Torsion Balance Company, of New York, has recently +brought before the public a new form of balance which presents so many +ingenious and excellent features that we illustrate it below, on the +present page. The instrument in its simplest form is shown in Fig. 1. It +consists of a beam, A, which is firmly attached to a wire or band, B, at +right angles to it, and which wire is tightly stretched by any +convenient means. Then, since the wire and beam are both horizontal in +their normal position, and since the center of gravity of the beam is +immediately above or below the middle line of the wire, the torsional +resistance of the latter tends to keep the beam horizontal and to limit +its sensitiveness. When the beam is deflected out of its horizontal +position and the wire thereby twisted, the resistance to twisting +increases with the arc of rotation. To counteract this resistance and to +render the beam sensitive to a very slight excess of load at either end, +a poise, D, is attached to the beam by a standard, C, which poise +carries the center of gravity of the structure above the axis of +rotation. This high center of gravity tends to make the beam "top +heavy," or in unstable equilibrium. By properly proportioning the poise +and its distance above the wire to the resistance of the wire, the +top-heaviness may be made to exactly neutralize the torsional +resistance, and when this is done the beam is infinitely sensitive. + +[Illustration: KENT'S TORSION BALANCE. Fig 1.] + +The moment of the weight or its tendency to fall increases directly as +the sine of the arc of rotation, while the torsional resistance +increases as the arc, and for small angles the sine and the arc are +practically equal. + +When arranged as in Fig. 1, the scale is balanced only when the center +of gravity of the structure is vertically above the middle line of the +wire, and the support of the scale must be leveled in the direction of +the beam, so as to cause the center of gravity to take this normal +position. After the scale is thus leveled, if from any cause whatever, +such as shifting the scale on a table, or shifting the table itself, the +scale support is thrown out of level, the center of gravity of the poise +and beam is shifted from the vertical line above the support, and its +moment immediately becomes greater than the torsional resistance, and +the beam tips out of balance, and cannot be used as a correct scale +until the support is again leveled. + +[Illustration: KENT'S TORSION BALANCE. Fig 2.] + +In spite of all the foregoing facts, it was reserved for the +"Encyclopedia Britannica," in its ninth edition, to use the following as +the result of its condensed wisdom: + +"In the torsion balance proper, the wire is stretched out horizontally, +and supports a beam so fixed that the wire passes through the center of +gravity. Hence the elasticity of the wire plays the same part as the +weight of the beam does in the common balance. An instrument of this +sort was invented by Ritchie, for the measurement of very small weights, +and for this purpose it may offer certain advantages; but clearly if it +were ever to be used for measuring larger weights, the beam would have +to be supported by knife edges and bearing, and in regard to such +applications therefore (as in serious gravimetric work), it has no +_raison d'etre."_ + +[Illustration: KENT'S TORSION BALANCE. Fig 3.] + +This would seem to settle the whole case, for if the encyclopedia says +it has no reason to be, then, like the edict of the Mikado, it is as +good as dead, and if that is the case, "Why not say so?" On the +contrary, the torsion balance seems very much alive. But as it is not +very generally known, perhaps the early history of this form of balance, +briefly sketched, may prove of interest. + +One of the first forms of the torsion balance which met the disapproval +of the "Encyclopedia Britannica" was attended with the difficulty that +the pivoted wires were attached directly to the bifurcated ends of the +beam, and could not be tensioned without bending these ends unless the +beam was made so heavy as to interfere with its employment in delicate +weighing. + +[Illustration: KENT'S TORSION BALANCE. Fig 4.] + +The next step was the substitution of light forms stiffened by the wires +being tensioned over them. This was the invention of Professor Roeder, +recently deceased. The next step was the common counter scale, and then +that form of letter scale in which one of the bands acts as a fulcrum +and the other as a pivot. + +After Professor Roeder's death, Dr. Alfred Springer, of Cincinnati, +continued perfecting this invention, and with marked success--scales not +intended for anything but the weighing of the ordinary articles of a +grocery store working so accurately that up to 50 lb. two grains would +turn the balance. + +As will be noted, this balance dispenses entirely with knife edges, and +this statement carries with it the gist of its entire merit. There is no +friction, and the elegance of the work and the nice adjustments of the +parts struck the writer at once. + +[Illustration: KENT'S TORSION BALANCE. Fig 5.] + +The prescription scale and the proportional scale (see Fig. 4) are +particularly interesting. The former is sensitive to 1/64 of a grain, +and the latter, invented by Mr. Kent, is a most ingenious method for +weighing, by which, in a small compass (101/2 in. by 41/4 in. by 33/4 in.), we +have a balance capable of weighing 3 lb. avoirdupois by thirty-seconds +of an ounce. + +For ordinary balances on the torsion system, in which extreme +sensitiveness is not needed, the trouble caused by change of level of +the scale is insignificant; but it becomes a matter of importance in +more sensitive scales, such as fine analytical balances in places where +it is impossible to keep the table or support of the scale level, for +instance on shipboard. + +To counteract this effect of the change of level, Dr. Alfred Springer +devised the system which is shown in its most elementary form in Fig. 2. +An additional beam, E, with wire, F, and poise, H, on support, C, were +added to the balance, and connected to it by a jointed connecting piece, +J. The moment of the structure, E C H, about its center of rotation was +made equal to the moment of A C D about the center. The wires, B and F, +are attached at their ends to supports which are both rigidly connected +to the same base or foundation. If this base, the normal position of +which is horizontal, is tipped slightly, the weights, C and H, will both +tend to fall in the same direction. But suppose the right hand end of +the base is raised, causing both of the weights to tip to the left of +the vertical, D, tending to fall over, the left tends to raise the right +hand end of the beam, and the connecting piece, J H, also tending to +fall to the left, tends to lower the left hand end of E and the piece, +J. The moments of the structure, E C H, and A B D being equal, and one +tending to raise J and the other to lower it, the effect will be zero, +and J will remain in its normal position. + +It is not at all necessary, however, to have the weights and dimensions +of the structure, E C H, equal to those of A B D. All that is necessary +is that the components of the weight of each part of the structure which +act vertically on J shall be equal and opposite. For, if the left end of +the beam, E, is made shorter than the right end of the beam, A, a given +angle of rotation of the beam, A, will cause a greater-angle of rotation +of E, consequently will tip the weight, H, further from the vertical +than the weight, D, is tipped, and in that case the weight, D, must be +made smaller than H, to produce an equal and opposite effect upon J. In +practice it is convenient to make the beam, E, only one-fifth to +one-twentieth as long as A, and to correspondingly reduce the weight, H, +relatively to D. In this case, on account of the angle of rotation of +the beam, E, being greater than the angle of rotation of A, the beam, E, +becomes a multiplier of the indications of the primary beam, A. + +Mr. Kent has devised a modification of Dr. Springer's system, which is +shown in Fig. 3. It is applied in those varieties of the torsion balance +in which there are two parallel beams, connected by either four or six +wires. The wire, F, carrying the secondary beam, E, and poise, H, +instead of being carried on an independent support, rigidly attached to +the base, as above described, is attached directly to a moving part of +the balance itself, and preferably to the two beams. In Fig. 3, T T T +are trusses over which are tightly stretched the wires, B B B. A A' are +two beams rigidly clamped to the wires; _t_ is another truss with +stretched wire, F F. The upper wire, F', is attached by means of a +flexible spring and standard, S, to the upper beam, and the lower wire +is attached either directly or through a standard to the lower beam. The +secondary poise, H, is rigidly attached to the truss, _t_. The secondary +beam, E, is also rigidly attached to the truss, and acts as a +multiplying beam. The secondary structure thus completely fills two +functions: First, that of multiplying the angle of rotation and thereby +increasing the apparent sensitiveness of the scale, and, second, that of +overcoming the effect of change of level. The secondary beam may be +dispensed with if a multiplier is not needed, and the secondary truss, +_t_, with its standard and counterpoise, H, used alone to counteract the +effect of change of level. Fig. 5 shows a modification of this extremely +ingenious arrangement.--_Engineering_. + + * * * * * + + + + +LINK BELTING. + +[Footnote: From a paper read before the "Technischen Verein" of New +York, May 28, 1887.] + +By CHAS. A. SCHIEREN. + + +The old saying that "there is nothing new under the sun" may well be +applied to leather link belting. It is generally believed that these +belts are of recent invention, but that is an error. They are over +thirty years old. + +Mr. C.M. Roullier, of Paris, experimented that long ago with small +leather links one and one-half inches long by three-quarters of an inch +wide. These links had two small holes at equal distances apart, and were +joined with iron bolts, which were riveted at the ends, thus making a +perfectly flat surface, and in that way forming a belt entirely of +leather links. + +Mr. Roullier's idea was to economize; he therefore utilized the material +left over from the manufacture of flat belting. He perfected his belt +and came to this country in 1862, when he patented the article here and +tried to introduce it. At first it produced quite a sensation, and many +tests were made, but it was soon found that Roullier's belts were not +suited to running our swift motion machinery, and they were therefore +abandoned as impracticable. + +Mr. Roullier then introduced his invention into England, where he met +with some success, as his belt was better suited to English slow motion +machinery. + +These belts are now largely used in England, many good improvements have +been made in them, and almost every belt maker in Great Britain +manufactures them. + +Mr. Jabez Oldfield, of Glasgow, has the reputation of making the best +and most reliable link belt in Great Britain. He has also the reputation +of being the originator of these belts. This is, however, an error, the +credit of the invention belonging, as we have said, to Mr. Roullier. + +Mr. Oldfield, nevertheless, has invented many useful machines for +cutting and assorting the links. He has also introduced improved methods +for putting the links together. + +For more than twenty years after Mr. Roullier's visit, nothing was done +with leather link belting in this country. + +In 1882, however, Mr. N.W. Hall, of Newark, N.J., patented a link belt, +composed of leather and steel links. His method was to place a steel +link after every third or fourth leather one, in order to strengthen the +belt. In practical use this belt was found to be very defective, because +the leather links soon stretched, and thus all the work had to be done +by the steel links. The whole strain coming thus upon the steel links, +they in course of time cut through the bolts and thus broke the belt to +pieces. So this invention proved worthless. + +In 1884 a Chicago belt company obtained a patent on another style of +link belt. In this belt all the little holes in the links were lined +with metal, similar to the holes in laced shoes. This produced an effect +similar to that produced by Hall's patent. The metal lining of the holes +cut the bolts into pieces by friction and thus ruined the belt. +Therefore this patent proved a failure also. + +After all these failures it fell to our lot to improve these belts so +that they may now be worked successfully on our American fast running +machinery. During the past two years we have made and sold over five +hundred leather link belts, which are all in actual use and doing +excellent service, as is proved by many testimonials which we have +received. + +Our success with these belts has been so surprising that we think we +have found, at last, the long looked for "missing link," not in +"Darwinism," however, but in the belting line. We prophesy a great +future for these belts in this country. + +How have we attained such success? First: We found that Roullier made a +mistake in using leather offal, as, in the links of an _iron chain_, if +one link is weak or defective, the whole chain is worthless, so in link +belts, if one or two links are weak or made of poor material, the whole +belt is affected by them. It is therefore of vital importance that only +the best and most solid leather be used in making the links; second, the +leather must be made very pliable, but at the same time its toughness +and tenacity must not be injured, or it will stretch and break. + +[Illustration: FIG 1.] + +These things are of great importance, and are the principal reasons for +the failures of all former efforts. The leather which Roullier used was +stiff, hard, and husky. He believed that the harder the link the greater +its tensile strength, but upon actual test this was found to be a fatal +error. + +Our leather links are saturated with a mixture of tallow, neatsfoot oil, +etc. This makes them very pliable and increases their toughness, so that +they will stand a strain three times as great as a piece of hard rolled +sole leather. + +In manufacturing this belt, the joining together is important. The links +must be accurately assorted as to thickness, and the outer links +countersunk, to admit the bolt. Then the most valuable improvement of +all is our "American joint" (see Fig. 1). + +By close inspection you will observe that it is absolutely necessary to +use half length bolts for the width of wide leather link belts. + +Examine Figs. 2 and 3. In the latter you will notice one length of bolt +placed on a round faced pulley. That belt must either bend or break, and +in any case it will not give satisfaction; but, on the other hand, +examine Fig. 2; here two half length bolts are used, and ingeniously +joined in the center. It gives just pliability enough to lay the belt +flat upon the pulley. We experimented for some time before perfecting +this important improvement. + +We also took out four patents for different methods of joining, but +abandoned them all and adopted the "American joint" system (Fig. 1) as +the most efficient, simple, and reliable. It gives the belt an unbroken +flat surface and is far superior to anything so far introduced for that +purpose. + +We have not stopped at _flat_ link belting, but have turned our +attention to manufacturing round solid leather link belting, and believe +that we have almost attained perfection in that line. As the +illustrations clearly show, there is quite a demand for inch and upward +solid round belting, and the difficulty always has been to join such a +belt together. All steel hooks, etc., do not seem to satisfy. This, our +new invention, is so simple that it hardly needs explanation. A belt of +this kind can be taken apart in a short time, and shortened or +lengthened at pleasure. + +Now, Mr. President and gentlemen, I shall be glad to answer any +questions in reference to these link belts, or give any further +explanation you may desire. + +Question.--Can these link belts be used on dynamos for electric lights? + +Answer.--Yes. In England they are used almost exclusively on dynamos. +However, they run only 700 revolutions per minute there, whereas our +slowest dynamo runs 1,100. + +[Illustration: Fig. 2.] + +Quest.--Would you advise link belts for high rate of speed? + +Ans.--No; they give better results on slow running machinery. + +Quest.--Have these belts any special advantage over flat leather +belting? + +Ans.--Yes, decidedly. When belts are run half crossed, or what is termed +quarter turn, it is very hard to make flat belts lie perfectly even on +the pulleys. These link belts, however, cover the entire face of the +pulley (see illustration), and therefore are superior for that purpose. + +[Illustration: Fig. 3.] + +Quest.--Why do they give better results when run slow? + +Ans.--Partly because of their great weight over ordinary belting, also +their grip power is stronger when run slow. No belt is superior to them +for slow, hard working machinery. + +Quest.--Are they more expensive than ordinary flat belting? + +Ans.--Not when compared to the work they can accomplish. + +[Illustration] + +Quest.--Can they be run in wet places, such as mines, etc.? + +Ans.--Yes; by waterproofing the leather, no cement being used as in flat +belts. The links can be made positively waterproof. We have furnished +paper mills, tanneries and bleacheries, and other exposed places with +waterproof link belts, and all have been entirely satisfactory so far. + +Quest.--Can they be run on ordinary flat pulleys? + +Ans.--Yes; our "American joint" link belt can be run on any straight or +rounded pulley, whether made of iron, paper, or wood, and being all +endless they run much smoother than other belting. + +[Illustration: ENGLISH HINGE JOINT:] + +Quest.--How are they made endless? + +Ans.--By a very simple process (see illustration), and takes almost less +time than lacing a flat belt. All that is necessary is to take both ends +and interlock the links, then pass the bolt through and rivet it, and +when you wish to shorten the belt proceed likewise: File off the end of +the bolt and take out, or add rows of links at pleasure and rejoin it +again. + +[Illustration: Fig. 4 is a complete round link belt.] + +Quest.--What is the relative strength of a link belt compared to flat +belting? + +Ans.--Nothing definite has yet been ascertained. We are preparing a +table showing results, and so far we can report that they can stand +about twice the strain of double flat belts. A four inch link belt one +inch thick is able to do the work of an eight inch flat double belt. + +[Illustration: Fig. 5 is a side view.] + +Quest.--Explain the advantage of your American joint over the English +hinge. + +Ans.--The American joint gives a perfect unbroken surface of entire +width of belt, whereas the English hinge joint makes two half widths, +and whenever a sudden change of power occurs and the belt runs half way +off the pulley, it will catch at the edge and tear everything to pieces. + +[Illustration: Fig. 6 is an end view.] + +Quest.--Have you a table or schedule of their weight per square foot? + +Ans.--Yes. The following is as near as we can estimate the weight of +leather link belting per square foot: + + 1 inch thick, about 5 lb. per sq. ft. + 7/8 " " " 41/2 " " " + 3/4 " " " 4 " " " + 5/8 " " " 31/2 " " " + +Upon motion a vote of thanks was passed, and the paper read ordered to +be printed. + +[Illustration: Fig. 7 is a single link.] + + * * * * * + + + + +A NEW PROCESS OF CASTING IRON AND OTHER METALS UPON LACE, EMBROIDERIES, +FERN LEAVES, AND OTHER COMBUSTIBLE MATERIALS. + +[Footnote: Abstract of a paper read before the Franklin Institute, +April, 1887.--_J.F.I._] + +By A.E. OUTERBRIDGE, JR. + + +The art of making charcoal--if, indeed, so crude a process is worthy of +being dignified by the name of an art--dates back to a remote antiquity, +and has been practiced with but little change for hundreds of years. It +is true that some improvements have been recently made, but these relate +to the recovery of certain volatile by-products which were formerly +lost. + +Every one is familiar with the appearance and characteristics of +ordinary charcoal, yet I hope to show you this evening that we still +have something new to learn about its qualities and the unexpected +practical uses to which it may be applied. + +We commonly regard charcoal as a brittle, readily combustible substance, +but we have before us specimens in which these qualities are +conspicuously absent. Here is a piece of carbonized cotton sheeting, +which may be rolled or folded over without breaking, and, as you see, +when placed in the flame of a Bunsen burner, the fibers may be heated +white hot in the air, and when removed from the flame, the material +shows no tendency to consume. Here, again, we have a piece of very fine +lace, which has been similarly carbonized, and displays the same +qualities of ductility and incombustibility. + +These carbonized fabrics may be subjected to much more severe tests with +impunity; and when I tell you that they have been exposed to a bath of +molten iron without injury, you will readily admit that they possess +some qualities not ordinarily associated with charcoal. When removed +from the mould in which they were placed after the iron casting had +cooled, not a single fiber was consumed, but _upon the face of the +casting there was found a sharp and accurate reproduction of the design, +thus forming a die_. This die may be used for a variety of purposes, +such as embossing leather, stamping paper, sheet metal, etc., or for +producing ornamental surfaces upon such castings. + +Some of the carbonized fabrics displayed upon the table are almost as +delicate as cobwebs, and one would naturally suppose that when a great +body of molten metal is poured into a mould in which they are placed, +they would be torn to fragments and float to the surface even though +they were unconsumed, yet such is not the case. I have found in practice +that the most delicate fabrics may be subjected to this treatment +without danger of destruction, and that no special care is needed either +in preparing the mould or in pouring the metal. + +By the aid of the megascope, the enlarged images of some of these +castings, showing the delicate tracery of the patterns, will now be +projected upon the screen, and you can all see how perfectly the design +is reproduced. + +In these experiments, the mould was made in "green sand" in the ordinary +manner, and the fabric laid smoothly upon one face, being cut slightly +larger than the mould, in order that it might project over the edge, so +that when the moulding flask was closed, the fabric was held in its +proper position. As the molten metal flowed into the mould, it forced +the fabric firmly against the sand wall, and when the casting was +removed, the carbonized fabric was stripped off from its face without +injury. In this way several castings have been made from one carbonized +material. + +These castings are as sharp as electrotypes, whether made of soft fluid +iron or of hard, quick-setting metal. This peculiarity is owing to the +affinity between molten iron or steel and carbon. The molten metal tends +to absorb the carbon as it flows over it, thus causing the fabric to hug +the metal closely. It is somewhat analogous to the effect of pouring +mercury over zinc. You know that when mercury is poured upon a board, it +runs in a globular form, it does not "wet" the board, so to speak; but +when poured upon a plate of clean zinc, it flows like water and wets +every portion of the zinc, or, as we say, it amalgamates with the zinc. +So when molten iron is poured into an ordinary sand mould, which has +been faced with this refractorily carbonized fabric, it wets every +portion of it, tending to absorb the carbon, and doubtless would do so +if it remained fluid long enough, but as the metal cools almost +immediately, there is no appreciable destruction of the fibers. + +The casting which I shall now exhibit represents a very interesting and +novel experiment. In this case, the piece of lace, having open meshes a +little larger than a pin's head, instead of being laid upon one face of +the mould, was suspended in it in such a way as to divide it into two +equal parts. Two gates or runners were provided, leading from the +"sinking head" to the bottom of the mould, one on each side of the lace +partition. The molten iron was poured into the sinking head, and flowing +equally through both runners, filled the mould to a common level. The +lace, which was held in position by having its edges embedded in the +walls of the mould, remained intact. When the casting was cold, it was +thrown upon the floor of the foundry and separated into two parts, while +the lace fell out uninjured, and the pattern was found to be reproduced +upon each face of the casting. + +The question naturally arises, Why did not the iron run through the +holes and join together? The answer may be found in the fact that the +thin film of oxide of iron, or "skin," as it is popularly called, which +always forms on the surface of molten iron, was caught in these fine +meshes, and thus prevented the molten metal from joining through the +holes. I have repeated the experiment a number of times, and find that +the meshes must be quite small (not over one fiftieth of an inch), +otherwise the metal will reunite. + +I think that this observation explains the cause of many obscure flaws +found in castings, sometimes causing them to break when subjected to +quite moderate strains. We frequently find little "cold shot," or +metallic globules, embedded in cast iron or steel, impairing the +strength of the metal, and it has long been asked, "What is the cause of +this defect?" The pellicles have been carefully analyzed, under the +supposition that they might be alloys of iron and nickel, or some other +refractory metal, but the analysis has failed to substantiate this +theory. Is it not probable that in the process of casting, little drops +of molten metal are sometimes splashed out of the stream, which +immediately solidify and become coated with a skin of oxide, then +falling back into the stream of rapidly cooling metal, they do not +remelt, neither do they weld or amalgamate with the mass, owing to this +protective coating, thus forming dangerous flaws in the casting? + +The process of carbonizing the delicate fabrics, leaves, grasses, etc., +is as follows: The objects are placed in a cast iron box, the bottom of +which is covered with a layer of powdered charcoal or other form of +carbon, then another layer of carbon dust is sprinkled over them, and +the box is covered with a close fitting lid. The box is next heated +gradually in an oven, to drive off moisture, and the temperature slowly +raised until the escape of blue smoke from under the lid ceases. The +heat is then increased until the box becomes white hot. It is kept in +this glowing condition for at least two hours. It is then removed from +the fire, allowed to cool, and the contents are tested in a gas flame. +If they have been thoroughly carbonized, they will not glow when removed +from the flame, and the fibers may even be heated white hot before +consuming. + +Of course, the method employed to carbonize the materials is suspectible +of variation, but the scientific principles involved are unchangeable, +viz.: + +(1) Partial exclusion of air and substitution therefor of a carbon +atmosphere. + +(2) Slow heating to drive off moisture and volatile elements. + +(3) Intense and prolonged heating of the partly charred objects to +eliminate remaining foreign elements, and to change the carbon from the +combustible form of ordinary charcoal to a highly refractory condition. + +[Illustration] + +NOTE.--Fig. 1 is photographed from a white iron casting made upon +carbonized coarse lace; the lower portion of the plate shows the lace +embedded in the iron. Fig. 2 is a casting in gray iron upon lace laid on +an iron plate. Fig. 3 is a casting in hard iron upon lace laid on dand. +Fig. 4 is a casting in gray iron upon a piece of thin summer dress goods +with machine embroidery. + + * * * * * + + + + +RECENT PROGRESS IN GAS ENGINEERING. + + +At the recent meeting of Scottish gas managers Mr. A. Macpherson, of +Kirkcaldy, the chairman, said: + + +THE REGENERATIVE SYSTEM OF RETORT FIRINGS. + +For me to attempt, with the time at my disposal, to do full justice to +many important points which have cropped up since our last meeting, and +which will, no doubt, have been engaging your individual attention, +would be impossible. But I think there can be no doubt that, although at +our last meeting we had a very full and interesting discussion on the +different systems of regenerative retort settings, still we might very +profitably spend a little time to-day in hearing the experience of those +who have had some of the systems introduced into their works since then, +or who may have gained further experience with the system they were then +working, or have introduced improvements or modifications thereon. + +For the purpose of inducing a discussion on this subject, I will give +you the result of the working of the bench of retorts which I erected +three years ago on the Siemens system. As I stated last year, my +experience up to that time had not been altogether a happy one, but one +of sunshine and cloud alternately. I am glad to be able to say, however, +that since then I have had nothing but the utmost satisfaction in the +working of the regenerative settings. The chief difficulties I have +before experienced were of a mixed nature--choked ascension pipes, +entailing considerable loss of gas; the choking of the orifices from +which the secondary heated air issued to join the producer gas; and the +eating away, in a "scooped-out" sort of fashion, of the brick lining of +the producers at the points where the primary air entered. These, I am +pleased to be able to say, I am now completely clear of; and this has +had the effect of converting what was before a considerable source of +annoyance and anxiety into as perfect a working bench of retorts as any +one could desire. + +The results I have obtained have caused me much surprise, being far in +excess of anything I ever anticipated; and the saving effected will +materially assist in compensating for the greatly reduced value of +residuals. I may state that I have used 30 per cent. of fuel on an +average, saved from 25 to 30 per cent. on stokers' wages, and increased +my production of gas per ton of coal; while the regularity of the heats +was a pleasure to look upon. + +As showing what I have been able to accomplish, I will give you a few +details. I was able regularly to produce 10,000 cubic feet of gas per +mouthpiece in 24 hours--the size of my retorts being 18 by 13 inches by +9 feet long, inside measure; and on a sudden dullness coming on, with an +increase of first class cannel I produced from 33 retorts 357,000 cubic +feet, or at the rate of 11,500 feet per mouthpiece in 24 hours. With 32 +retorts I made as much gas as would have required 42 retorts to produce +on the old system. But I know that even this can be excelled; and I am +aware that there are works where, by the introduction of retorts +measuring 21 by 15 inches, instead of 18 by 13 inches--and which, I may +say, can be put quite easily into the same arch--a production of 12,000 +cubic feet per mouthpiece can be obtained. This will, of course, still +further reduce the cost of production. + +With such an experience, gentlemen, I think it is almost needless for me +to add that I am a strong advocate of the regenerative system. I have +often heard it asked, "But can the system be profitably adapted to small +works?" In answer to this, I will say I have proved that it can. During +last summer the manager of a small gas works in my neighborhood called +on me regarding the working of this system, and expressed a desire, if +it was at all possible to adapt it to his present settings without much +expense, to try it. I must say I admired his progressive spirit and +pluck; and, after a somewhat lengthy conversation with him, during which +I gathered the full details of his working and his requirements, I +determined to encourage him in his desire to prove if it could be +successfully applied to a works of the size mentioned. The present +setting consisted of three [semicircle] retorts in one arch; and one of +his stipulations to me was: "You must so contrive the setting that if it +should prove a failure I can reconvert it into the old system in a few +hours." I at once saw that the stipulation was reasonable, or he might +be caught in a fix in midwinter. But, with true "Scotch caution" and +forethought, he was, while anxious to experiment, determined not to be +"caught napping." After some consideration, I prepared a sketch for him +of how I thought it could be done, and at the same time comply with his +stipulation; and having received full explanations, he set about it, and +has had it working now for something like six months. His experience has +been somewhat similar to that of most of those who have gone in for the +new system. It did not answer very well at first. But after a little +manipulation and experience in the proper working and management, it is +now acting in first rate style, and is saving fuel, with better and more +regular heats; and this although it is not constructed in such a way as +to yield the best possible results, owing to the before mentioned +stipulation having to be considered and allowed for in construction. + +In answer to an inquiry I made the other day, the gentleman referred to +informed me that he has now had this setting in operation for six +months. He has three retorts, 14 by 16 inches, and 8 feet long, in an +oven carbonizing 2 cwt. of coal every four hours; the heats are higher +and more regular; and the retorts easier kept clear of carbon. The coke +drawn from the top retort is sufficient for fuel. My oven would hold +four retorts; and the same fuel would heat this number just as well as +the three. I used only the coke from Cowdenheath parrot coal for this +setting; but had to mix it with Burghlee coke for the old system of +setting. + +No doubt most of you will have noticed the satisfactory results obtained +by Mr. Hack, of the Saltley Gas Works, Birmingham, and by Mr. McMinn, of +Kensal Green, with the furnaces employed by them for gaseous firing +without recuperation, whereby they are enabled to save fuel and +carbonize more coal per mouthpiece than with the old system. Still they +admit that the saving by this setting is only in fuel, with increased +production, but without any economy of labor--one of the points in favor +of regenerative setting being a saving of at least 25 per cent. in the +latter respect. Even where regenerative settings cannot be had, I think +the system of using gaseous fuel is well worthy the attention of +managers; the expense of altering the existing settings to this method +being very small. + + +IMPROVEMENTS IN GAS PURIFICATION. + +I must now, however, pass on to some other topics. After the proper +production of the gas, we have still the processes of purification to +consider, and how this operation can best be effected at the smallest +cost, combined with efficiency and the least possible annoyance to +residents in the immediate vicinity of gas works. I think all gas +engineers are agreed that in ammoniacal liquor we have a useful and +powerful purifying agent, although each one may have his own particular +idea of how this can be most efficiently applied--some advocating +scrubbers, others washers. But these are things which each one must +determine for himself. But in whatever way it is applied, we know that +it can be profitably used for this purpose; and I am not without hope +that it may soon be found possible to remove nearly all the impurities +by this means. + +At present, however, this is not so. And consequently we have a variety +of other methods employed for the complete removal of the impurities. +But, by whatever means it is effected, it is unquestionably the duty of +the gas engineer to send out to the public an article from which the +whole of the impurities have been removed. + +In Scotland, no doubt, our chief purifying material is lime, although I +know that several of our friends have for some time been using oxide of +iron, and perhaps they will favor us with their experience and a +statement of the relative cost of lime and oxide. I am not aware that +either the Hawkins method or the Cooper coal liming process has yet +received a trial from any Scotch gas engineer. + + +BURNERS AND REGENERATIVE LAMPS. + +But even after we have been able to produce and send out gas of the +greatest purity, our troubles are frequently only beginning, as, very +often, consumers do not use, but simply waste and destroy the gas by bad +burners and fittings. Nothing, however, will convince them that they are +in any way to blame for the light being poor. I am certainly of opinion +that gas companies would do the public a service in supplying them with +suitable burners for the quality of gas that is being sent out for +consumption. I have myself for some years adopted this policy, and +almost invariably find that complaints cease and consumers are pleased +with the results. + +We have now also so large a number of really good regenerative lamps +which give excellent results, and can be made in a great variety of very +neat and ornamental designs, that we ought to endeavor to the utmost of +our power to introduce them to the public, and, if possible, induce them +to use them not only in halls and similar places, but in their dwelling +houses, as with these lamps a most thorough and efficient system of +ventilation can be carried out, by which the heat that is so much +complained of in gas-lighted apartments is reduced to a minimum, and the +atmosphere of such apartments is rendered healthy and agreeable. + +With such improved lamps at our command, I think we have nothing to fear +from the competition of the electric light, which during the past year +has not made any very startling advance--generally attributed by +electricians to the restrictive legislation under which they have been +placed. Let us hope this is now about to be removed. I am sure we all +rejoice that such is the case, as all we want is a "fair field and no +favor." We can with confidence await the result. + + +THE WELSBACH GAS LIGHT. + +In the mean time, however, while electricity for lighting purposes has, +to say the least, not made any startling advances, we have, besides the +regenerative lamps before mentioned, the new Welsbach light, which is +exhibited before you to-day, by the kindness of Dr. Wallace; and if the +results said to be obtained by it are at all what they are represented +to be, we certainly have a new departure in gas lighting of no mean +order. Dr. Wallace--a gentleman who is well known to us as one well +qualified to test its merits--has found that the Welsbach burner +produces a light equal to more than 9 candles per cubic foot of gas of +25 candle power, thus nearly doubling the amount of light compared with +gas consumed in the ordinary way. + +The construction and manufacture of the burner I have seen described in +these terms: Chemists have been diligently working for many years on the +problem of how to convert into light the highly condensed heat of the +Bunsen burner; and a Vienna chemist now claims to have solved it. + +The first condition of the problem was to find a medium on which the +heat could be perfectly concentrated and raised to illuminating power. +Many experiments have been made with platinum in a Bunsen flame, and a +brilliant enough light has been produced, but at a cost altogether +outside commercial use. The Vienna chemist, Dr. Welsbach, has discovered +a composition which is as good a non-conductor--that is to say +concentrator--of heat as platinum, is much more durable, and a great +deal cheaper. The base of it is a peculiar clay, found in Ceylon, which +combines the indestructibility of asbestos with the non-conducting +property of platinum; and having found the incandescent medium, he has +next adapted it to the Bunsen burner. + +In this arrangement there is the simplicity of genius. He gets a fine +cotton fabric woven into the shape of a cylinder, with a tapering point. +In its first stage it is about 2 inches in diameter; and after being +coated with the composition, it is subjected to a strong heat. This has +two effects--first, the cotton fiber is completely burned out, while the +composition retains the shape of the woven surface on which it was +moulded. Then the cylinder contracts and solidifies until it becomes +about the size of the forefinger of a glove. Dr. Welsbach calls this his +"mantle;" and by a simple arrangement he fits it on a Bunsen burner, and +places an ordinary lamp chimney over it. When the flame is applied, the +"mantle" becomes incandescent, and gives out a brilliant yellow light, +which, it may be said without exaggeration, will compare favorably with +any electric light yet put on the market. + +For decorative effect a pretty frosted globe is used; and by varying the +globe a pure white or a pure yellow may be obtained. It is also added +that there is no act of Parliament required for it, nor even a +provisional order of the Board of Trade. No streets have to be broken up +in order to lay down pipes; and no wires have to be hung across the +roofs of protesting householders. + +The whole apparatus can be got ready to fit on an ordinary gas bracket; +and two or three spare frames with "mantles" can be kept in the house in +case of accident. Whoever sees the Welsbach incandescent light in +operation will readily admit that it is the "coming light." It has +beauty, brilliancy, purity, and economy all on its side. + +Let us hope (added the chairman) this description is not overdrawn; but +of this you will later on have an opportunity of judging for yourselves. +No doubt the general or even partial adoption of this light would have a +tendency to reduce the consumption of gas, as a smaller quantity would +be required to produce the same amount of illumination. Nevertheless, +gas engineers will hail it with approval if it in any way tends to +popularize the use of gas, and helps to increase the comfort and improve +the sanitation of our houses, churches, halls, etc. Moreover, gas is +continually being adopted for fresh purposes; and we can confidently +look forward to an almost unlimited field in the rapid and ever +increasing use of gas as a fuel and for cooking purposes, as well as for +motive power. The new and really excellent gas engines now being brought +into the market will, no doubt, create a healthy rivalry, and tend to +cheapen these useful machines, and so bring them within the reach of +many persons who have hitherto been prevented from employing them by +their considerable first cost. + + +PARAFFIN AS A RIVAL OF COAL GAS. + +But while the day has gone by when any one of us fears the electric +light as a possible rival, we are not insensible to the fact that +paraffin oil, from its present low-price, is a rival which we cannot +afford to despise. And more especially is this the case in many of the +smaller towns and villages, where the charge for gas is of necessity +higher than in the larger towns. + +Doubtless, with oil there is not the same cleanliness as with gas; while +there is also more trouble, attention, and considerable danger attending +its use. Still, in these "hard times," most people are inclined to adopt +the cheapest article, even at the cost of these drawbacks, so as to make +their money go as far as possible. + +But not only as an illuminant is it being brought into direct +competition with gas, but also as a fuel and for cooking purposes, as +well as for motive power. And I am inclined to think that the sooner we +set about trying to solve the problem of how to meet this new +competitor, the better. + + +OIL IN GAS MAKING. + +A new departure has also recently taken place in the adoption of oil for +gas making purposes. This, of course, is more fraught with danger to the +coal master than to gas companies, inasmuch as, should this prove to be +a more economical raw material from which to produce illuminating gas +than coal, our present coal gas works could be easily remodeled and +turned into oil gas works. This process has recently been introduced +into a village in Fifeshire. And I have made it a point to visit and +inspect the works, which have been converted into an oil gas works, so +that I might be able to lay a few particulars before you. The process, +however, has not been in operation long enough to enable me to give you +much information on the subject, especially in the way of details of +cost, working expenses, or permanency of the gas under varying and low +temperatures. The patentees claim that they can produce 100 cubic feet +of 60 candle gas from a gallon of oil, or at a cost of 3s. 11d. per +1,000 cubic feet for oil, fuel, and labor; no more expense being +incurred, as the gas does not require purification. + +At Colinsburgh (the village alluded to), I was informed that the man +sent by the patentees could produce 100 cubic feet of gas per gallon of +oil; but they had no means of testing the illuminating power. The gas +company's own servant, however, only produced 80 cubic feet per gallon, +which they attributed to his want of experience in knowing the proper +heat at which to work the retorts. Whether or not this was so I cannot +tell; but of this I am certain, that the statement made that the gas +does not require purification will not bear investigation. When I tested +it for sulphureted hydrogen and for ammonia, both were indicated in such +an unmistakable manner as none of us would care to see in our coal gas +as sent out to the consumer. + + +PRICES OF RESIDUAL PRODUCTS. + +What is of far more real consequence to us than the possible change from +coal gas to oil gas, however, as long as we remain manufacturers of the +former, is the value of our residual products, which has suffered so +great and sudden a decline in value, for which various remedies have +been proposed, though none of them, I regret to say, have as yet +restored anything like the former value. A statement of the highest +prices realized for coal tar products, and a comparison with those +obtained on the 30th of March last year and at the same time this year, +may not be uninteresting: + + +--------------------------------------------------------------------+ + | | Highest | Price on | Price on | + | | Price | March 30, | March 30, | + | | | 1886 | 1887 | + | |--------------+---------------+---------------+ + | | per gal. | per gal. | per gal. | + | |----+----+----+---+-----------+---------------+ + | | L | s. | d. | L | s. | d. | L | s. | d. | + | |----+----+----+----+----+-----+----+----+-----+ + |Crude naphtha | 0 | 4 | 0 | 0 | 0 | 41/2 | 0 | 0 | 81/2 | + |Benzol (90 per cent.)| 0 | 15 | 0 | 0 | 1 | 4 | 0 | 2 | 6 | + |Solvent naphtha | 0 | 2 | 6 | 0 | 1 | 0 | 0 | 1 | 2 | + |Burning naphtha | 0 | 1 | 7 | 0 | 0 | 101/2 | 0 | 0 | 10 | + |Creosote oil | 0 | 0 | 3 | 0 | 0 | 03/4 | 0 | 0 | 1 | + | | | | | + | | per ton. | per ton. | per ton. | + | |----+----+----+----+----+-----+----+----+-----+ + | | L | s. | d. | L | s. | d. | L | s. | d. | + | |----+----+----+----+----+-----+----+----+-----+ + |Pitch | 1 | 14 | 0 | 0 | 15 | 0 | 0 | 12 | 6 | + |Sulphate of ammonia | 21 | 5 | 0 | 13 | 10 | 0 | 11 | 10 | 0 | + +--------------------------------------------------------------------+ + +This shows a great fall in value from highest to lowest, which seems to +have been touched last year, except in the case of pitch and sulphate of +ammonia, both of which have marked a considerable decline, even since +last year, but it is pleasing to note that the others have shown at +least some slight improvement--crude naphtha and benzol having during +the year risen nearly one hundred per cent. in value. Let us hope that +this is the precursor of a general rise in value from which we shall all +profit. For the purpose of bringing about this much desired end, I +understand that some of the gentlemen present to-day have been burning +their tar in the retort furnaces, and as it will be interesting to know +what success they have attained, I hope some of them will favor us with +their experience on this subject. + +In conclusion, let me express the hope that the time is not far distant +when the general trade of the country will attain to its wonted +prosperity, by which every branch of industry will benefit--ours among +the number; and that the hard times we have experienced, now for a +considerable number of years, may not again return. + +Discussion next took place regarding the Welsbach incandescence gas +light, which was opened by Mr. McGrilchrist, who remarked on the very +fragile and tender nature of the "mantle," and expressed a hope that in +this direction improvement might be looked for. It was certainly a +beautiful light, and as to its consumption, he stated that the lamp then +shown to the meeting was only burning two cubic feet of gas per hour. [A +voice: Two and two-tenths.] He felt satisfied that it would enable the +manufacturers of gas to compete with paraffin oil, so that with Glasgow +gas they could have such a light as they saw at the rate of 4d. for +about fifty hours. + +Mr. W. Key (Tradeston Gas Works) made a statement giving the results of +inquiries he had made at St. Enoch Station Hotel, where the light has +for some time been on exhibition. From the answers given to his +inquiries he spoke rather disparagingly of the lamp, but chiefly on +account of the expense involved in renewing the "mantles" and the glass +chimneys. He admitted, however, that the lamps which he had seen were +placed very unfavorably, being exposed to the action of somewhat violent +draughts, and he subsequently remarked that the lamp was of such a +nature as to effect the complete combustion of the carbon contained in +the gas. The burner must, therefore, be regarded as a great boon--as +_the_ burner, in short. + +Mr. D.M. Nelson (Glasgow) gave his experience gained in connection with +the light, remarking that one of the great drawbacks to it was the very +great rarity of the mineral from which the zirconium was obtained. So +scarce was it that it would become dearer than platinum and more +valuable than gold if the lamp came into general use. The light which +the lamp gave out, though it possessed intensity, was deficient in +diffusibility as compared with that given out from ordinary flat flame +gas burners, and this was another objection to it. He argued at some +length against the financial aspects of the scheme which was being +promoted to buy up the Welsbach patents, and to introduce the lamp into +this country. His advice to his friends was not to have anything to do +with the Welsbach company, and, as investors, to be very careful in +accepting all the statements made about the light, which he predicted +would not be a financial success. + +Mr. McCrae was strongly opposed to any discussion being raised in regard +to the question being considered in its financial aspects. They, as gas +engineers, did not require to trouble themselves with the doings of +investors. He regarded the Welsbach burner as an improved appliance for +consuming gas. It was an invention which was quite new to him, and as he +was not in possession of any facts which would enable him to condemn it, +he thought they ought, at least, to give it a fair trial. Referring to +the fragile nature of the "mantle," he remarked that there were minds at +work aiming at giving a purer and more brilliant light from gas, and so +far he was of opinion that the light before them was a success. His +opinion as to the diffusibility of the light emitted from the burner +differed from that of Mr. Nelson, as he considered the light possessed +that quality in a high degree. He had no doubt that the minds already at +work on the incandescent light would seek out means for improving the +burner. + + * * * * * + +To varnish chromos, take equal quantities of linseed oil and oil of +turpentine; thicken by exposure to the sun and air until it becomes +resinous and half evaporated; then add a portion of melted beeswax. +Varnishing pictures should always be performed in fair weather, and out +of any current of cold or damp air. + + * * * * * + + + + +THE NEW BRITISH COINAGE AND JUBILEE MEDAL. + + +An important addition will be made to the coins now in circulation by +the issue of the double florin, the design of which is shown in one of +our engravings. The reverse is composed of crowned shields, bearing the +arms of the United Kingdom arranged in the form of a cross between +scepters, a device which was first adopted for coins of Charles II. It +was designed by Thomas Simon, the greatest of all English engravers, and +it remains to be seen whether this handsome coin will be generally +popular. The reverse of the florin will for the future bear the same +design. + +During the past year her majesty was pleased to signify her pleasure +that a portrait medallion, by Mr. J.E. Boehm, R.A., modeled from life, +should be substituted for the effigy which the coins have hitherto +borne. In the new effigy, her majesty appears crowned and veiled, with +the ribbon and star of the garter and the Victoria and Albert order. The +legend "Victoria Dei Gratia Britanniarum Regina, Fidei Defensor" is +variously arranged on the different coins, according to the exigencies +of the design. + +The opportunity has at the same time been taken, with her majesty's +approval, for making certain alterations in the designs for the reverses +of some of the coins by abandoning those which did not appear to possess +sufficient artistic merit to warrant their retention. The reverse of the +sovereign will still bear the design of St. George and the Dragon, by +Pistrucci, first adopted for the sovereigns of George IV., and the +reverses of the half-sovereign and threepence remain unchanged, except +that the crown has been assimilated to that used for the new effigy. The +St. George and the Dragon design will be resumed for the five-pound +piece, the double sovereign, and the crown, this design having been +adopted for these pieces when originally struck. The half-crown will +bear the same reverse as that coin bore when first issued, a design of +considerable merit, by Merlin. During the last half century public taste +appears to have been satisfied, both in this country and abroad, with +some such insignificant design as a wreath surrounding words or figures +indicating the value of the coin; and the shilling and sixpence have, +during the present reign, been examples of this treatment. They will in +future, like the half-crown, bear the royal arms, crowned, and +surrounded by the garter. + +The queen was further pleased to command that the fiftieth anniversary +of her majesty's accession should be commemorated by the issue of a +medal. The effigy for this medal, which is also from a medallion by Mr. +Boehm, has a somewhat more ornate veil than that on the coin; and on the +bust, in addition to the Victoria and Albert order, is shown the badge +of the imperial order of the crown of India. The reverse is a beautiful +work by Sir Frederic Leighton, President of the Royal Academy, of which +the following is a description: "In the center a figure representing the +British empire sits enthroned, resting one hand on the sword of justice, +and holding in the other the symbol of victorious rule. A lion is seen +on each side of the throne. At the feet of the seated figure lies +Mercury, the God of Commerce, the mainstay of our imperial strength, +holding up in one hand a cup heaped with gold. Opposite to him sits the +Genius of Electricity and Steam. Below, again, five shields, banded +together, bear the names of the five parts of the globe, Europe, Asia, +Africa, America, and Australasia, over which the empire extends. On each +side of the figure of Empire stand the personified elements of its +greatness--on the right (of the spectator), Industry and Agriculture; on +the left, Science, Letters, and Art. Above, the occasion of the +celebration commemorated is expressed by two winged figures representing +the year 1887 (the advancing figure) and the year 1837 (with averted +head), holding each a wreath. Where these wreaths interlock, the letters +V.R.I. appear, and, over all, the words 'In Commemoration.'" + +The issue of both the new coins and the medal began on June 21, the day +appointed for the celebration of her majesty's jubilee.--_Illustrated +London News_. + +[Illustration: THE NEW BRITISH COINAGE AND JUBILEE MEDAL. + +1. Half Crown. 2 and 3. Double Florin, reverse and obverse. 4. Double +Sovereign. 5. Shilling. 6. Sixpence. 7 and 8. Jubilee Medal.] + + * * * * * + + + + +BRICKS AND BRICKWORK. + +[Footnote: A recent lecture delivered at Carpenters' Hall, London Wall, +E.C.--_Building News_.] + +By Professor T. ROGER SMITH, F.R.I.B.A. + + +Timber, stone, earth, are the three materials most used by the builder +in all parts of the world. Where timber is very plentiful, as in Norway +or Switzerland, it is freely used, even though other materials are +obtainable, and seems to be preferred, notwithstanding the risk of fire +which attends its use. Where timber is scarce, and stone can be had, +houses are built of stone. Where there is no timber and no stone, they +are built of earth--sometimes in its natural state, sometimes made into +bricks and sun-dried, but more often made into bricks and burned. + +London is one of the places that occupies a spot which has long ceased +to yield timber, and yields no stone, so we fall back on earth--burnt +into the form of bricks. Brick was employed in remote antiquity. The +Egyptians, who were great and skillful builders, used it sometimes; and +as we know from the book of Exodus, they employed the forced labor of +the captives or tributaries whom they had in their power in the hard +task of brick making; and some of their brick-built granaries and stores +have been recently discovered near the site of the battle of +Tel-el-Kebir. + +The Assyrians and Babylonians made almost exclusive use of brickwork in +erecting the vast piles of buildings the shapeless ruins of which mark +the site of ancient Nineveh and of the cities of the valley of the +Euphrates. Their bricks, it is believed, were entirely sun-dried, not +burnt to fuse or vitrify them as ours are, and they have consequently +crumbled into mere mounds. The Assyrians also used fine clay tablets, +baked in the fire--in fact, a kind of terra cotta--for the purpose of +records, covering these tablets with beautifully executed inscriptions, +made with a pointed instrument while the clay was soft, and rendered +permanent by burning. We don't know much about Greek brickwork; but it +is probable that very little brick, if any, was made or used in any part +of Greece, as stone, marble, and timber abound there; but the Romans +made bricks everywhere, and used them constantly. They were fond of +mixing two or more materials together, as for example building walls in +concrete and inserting brickwork at intervals in horizontal layers to +act as courses of bond. They also erected buildings of which the walls +were wholly of brick. They turned arches of wide span in brickwork; and +they frequently laid in their walls at regular distances apart courses +of brick on edge and courses of sloping bricks, to which antiquaries +have given the name of herring-bone work. + +The Roman bricks are interesting as records, for it was customary to +employ the soldiers on brick making, and to stamp the bricks with names +and dates; and thus the Roman bricks found in this country give us some +information as to the military commanders and legions occupying +different parts of England at different periods. Flue bricks, for the +passage of smoke under floors and in other situations, are sometimes +found. The Roman brick was often flat and large--in fact, more like our +common paving tiles, known as foot tiles, only of larger size than like +the bricks that we use. They vary, however, in size, shape, and +thickness. Not a few of them are triangular in shape, and these are +mostly employed as a sort of facing to concrete work, the point of the +triangle being embedded in the concrete and the broad base appearing +outside. After the Roman time, brick making seems to have almost ceased +in England for many centuries. + +It is true we find remains of a certain number of massive brick +buildings erected not long after the Norman conquest; but on examination +it turns out that these were put up at places where there had been a +Roman town, and were built of Roman bricks obtained by pulling down +previous buildings. The oldest parts of St. Albans Abbey and portions of +the old Norman buildings at Colchester are examples of this sort. +Apparently, timber was used in this country almost exclusively for +humble buildings down to the 16th century. This is not surprising, +considering how well wooded England was; but stone served during the +same period for important buildings almost to the exclusion of brick. +This is more remarkable, as we find stone churches and the ruins of +stone castles in not a few spots remote from stone quarries, and to +which the stone must have been laboriously conveyed at a time when roads +were very bad and wheel carts were scarce. + +About the time of the Tudors, say the reign of Queen Elizabeth, the +making of bricks was resumed in England, and many dwelling houses and +some few churches were built of good brickwork in that and succeeding +reigns. We find in such buildings as Hampton Court Palace, St. James' +Palace, and Chelsea Hospital examples of the use of brickwork in +important buildings near London at later dates. The fire of London, in +1666, gave a sudden check to the use of timber in house building in the +metropolis. Previous to that date the majority of houses had been of a +sort the most ornamental examples of which were copied in "Old London" +at the Colonial Exhibition. The rebuilding after the fire was largely in +brick; and in the suburbs, in the latter part of the 17th and the 18th +centuries, many dignified square brick mansions, with bold, overhanging +eaves and high roofs and carved ornaments, entered through a pair of +florid wrought iron high gates, were built, some few of which still +linger in Hampstead and other suburbs. The war time at the beginning of +this century was a trying time for builders, with its high prices and +heavy taxes, and some of the good-looking brick buildings of that day +turn out to have been very badly built when they are pulled about for +alterations. With the rapid, wonderful increase in population and wealth +in this metropolis during the last 50 years a vast consumption of bricks +has taken place, and a year or two back it was reported by the +commissioners of police that the extensions of London equaled in a year +70 miles of new house property, practically all of brick. Brick were +heavily taxed in the war time which I have referred to, and the tax was +levied before burning. + +There was a maximum size for the raw brick, which it was supposed served +to keep bricks uniform, and the expectation was entertained that when +the duty came off, many fancy sizes of bricks would be used. This has +not, however, turned out to be the case. The duty has been taken off for +years; but the differences in the size of bricks in England are little +more than what is due to the different rate of shrinkage of brick earth +under burning. It must not, however, be supposed that they have always, +and in all countries, been of about the same dimensions. + +The size and proportions of bricks have varied extremely in different +countries and in the same country at different periods. Some bricks of +unusual shapes have also been employed from time to time. Other +countries besides England possess districts which from various +circumstances have been more or less densely built on, but do not yield +much stone or timber; and, accordingly, brickwork is to be met with in +many localities. Holland and Belgium, for example, are countries of this +sort; and the old connection between Holland and England led to the +introduction among us, in the reign of William III., of the Dutch style +of building, which has been in our own day revived under the rather +incorrect title of Queen Anne architecture. Another great brick district +exists on the plains of Lombardy and the northern part of Italy +generally, and beautiful brickwork, often with enrichments in marble, is +to be found in such cities as Milan, Pavia, Cremona, and Bologna. + +Many cities and towns in Northern Germany are also brick built, and +furnish good examples of the successful treatment of the material. In +some of these German buildings, indeed, very difficult pieces of +construction, such as we are in the habit of thinking can only be +executed in stone, are successfully attempted in brick. For example, +they execute large tracery windows in this material. Great brick gables, +often with the stepped outline known as crows' feet, are an excellent +architectural feature of these German brick-built towns. In parts of +France, also, ornamental brickwork was from time to time made use of, +but not extensively. It is not necessary to go very minutely into the +manufacture of bricks; but perhaps I ought to say a word or two on the +subject. Good brick earth is not simple clay, but a compound substance; +and what is essential is that it should burn hard or, in other words, +partly vitrify under the action of heat. The brick earth is usually dug +up in the autumn, left for the frosts of winter to break it up, and +worked up in the early spring. + +The moulding is to a very large extent done by hand, sometimes in a wet +mould, sometimes in a dry sanded mould, and the bricks are first +air-dried, often under some slight shelter, as the rain or frost damages +them when fresh made; and then, when this process has made them solid +enough to handle, they are burned, and sorted into qualities. The +ordinary or stock brick of London and the neighborhood presents a +peculiarity the origin of which is not known, and which is not met with, +so far as I know, in other parts. Very fine coal or cinders is mixed +with the brick earth, and when the bricks are fired these minute +particles of fuel scattered through the material all of them burn, and +serve to bake the heart of the brick. Stock bricks are burnt in a clamp +made of the raw bricks themselves with layers of fuel, and erected on +earth slightly scooped out near the middle, so that as the bricks shrink +they drop together, and do not fall over sideways. + +Most other varieties of bricks are kiln burnt. A very large number of +inventions for making bricks by machinery have been patented. If you +have occasion to look through the specifications of these patents, you +will find four or five main ideas appearing and reappearing, and only +here and there an invention which is to some extent different from the +others. A great majority of these inventions include machinery for +preparing the clay or brick earth, so that it may be dug up and filled +into a receptacle and worked up, screened from pebbles, and made fit for +use in a short time, so as not to have to wait a whole winter. This is +done in some sort of pug mill. A pug mill is a machine consisting of a +large cylinder with a central shaft passing through it from top to +bottom. Knives or blades are arranged spirally on the shaft, and other +blades project into the interior of the cylinder from the walls of it. +The material, after being screened, is fed into this at the top, and +properly moistened. The shaft is caused to rotate, and the blades divide +and subdivide the material, forcing it always downward, so that it at +last escapes at the bottom of the pug mill in a continuous stream of +moist, well worked up clay, issuing with some force. In one type of +machine this clay stream is forced through a square orifice, from which +it comes out of the section of a brick, and by a knife or wire or some +other means it is cut into lengths. + +In another type of machine there is a large revolving drum working on a +horizontal axis, with open moulds all round its edge. The clay enters +these moulds, and there is an arrangement of plungers by which it is +first compressed within the mould and then forced out on to an endless +band or some other contrivance that receives it. A third type of machine +has the moulds in the flat top of a revolving table, which, as it turns, +carries each mould in succession first to a part where it is filled from +the pug mill, next to where its contents are compressed, and lastly to +where they are pushed out for removal. However made, the brick, when +moulded, dried, and burnt, and ready for market, belongs to some one +sort, and is distinguished from other sorts by its size, color, quality, +and peculiarities. + +The sorts of brick that are to be met with in the London market are very +varied. To enumerate them all would make a tedious list; to describe +them all would be equally tedious. I will endeavor, however, to give +some idea of the most conspicuous of them. We will begin with that +family of bricks of which the London stock brick is the type. It has +been said these are clamp burnt, and almost all the internal +brickwork--and not a little of the external--of the metropolis is of +stock brickwork. A good London stock brick is an excellent brick for +general purposes, but cannot be called beautiful. + +Considering the vast quantity of brickwork done in the metropolis, it is +a matter for congratulation that such sound materials as good stock +bricks, stone lime, and Thames sand are so easily procurable, and can be +had at a price that puts them within the reach of all respectable +builders. When a clamp has been burnt its contents are found to have +been unequally fired, and are part of them underburnt, part well burnt, +part overburnt. They are sorted accordingly into shuffs, grizzles, +stocks of two or three qualities, shippers, and burrs. Several sorts of +malm stocks, which are superior in color and texture, are made, and are +used for facing bricks and for cutting; and what are called paviors, +which are dark and strong bricks, are also made. The London stock is +erroneously, but usually, described as gray. It is really of a pie crust +yellow of various tones. Sometimes it is the same color when cut, but +the hardest stocks are of a dark, dirty purple or brown, or sometimes +nearly black inside. A stock brick is rarely quite square or quite true; +its surface is often disfigured by black specks and small pits, and a +stack of them often looks uninviting; yet a skillful bricklayer, by +throwing out the worst, by placing those of bad colors or much out of +shape in the heart of the wall, and by bringing to the front the best +end or side of those bricks which form part of the face, can always make +the bricks in his work look far better than in the stack. Another +important group is the group of Suffolk and Norfolk bricks, red and +white. These are very largely employed as facing bricks and for arches +and cut mouldings. + +Moulded bricks are also to a large extent made of the same material. +These bricks are brought to London in large quantities. They have a +sanded face, are mostly square, true, and of uniform color, but they are +usually porous, soft, and absorbent. Still, they are in great demand as +facing bricks, and the moulded bricks enable the architect to produce +many architectural effects at a moderate outlay. These fields furnish +many sorts of bricks, which are called rubbers, and which are employed +(as malm stocks also are) for arches of the more elaborate sort, where +each brick is cut to its shape and rubbed true, and for mouldings, and +even sometimes for carving. + +Mouldings that are formed by cutting the bricks can be got more +perfectly true than when moulded bricks are used; but the expense is +greater, and when it is done the material is less durable, for the +softer sorts of brick are naturally used for cutting, and the moulded +face is less sound than the original burnt face of any brick. Red bricks +are to some extent made in fields within easy reach of London; but the +best come from some distance. Red Suffolk bricks have been alluded to. +There is a considerable importation of red Fareham bricks, brought all +the way from the vicinity of Portsmouth; these are good both in quality +and color. Good red bricks are also now made at Ascot, and are being +used to a considerable extent in the metropolis. A strawberry-colored +brick from Luton has been extensively used at Hampstead. It is hard, and +of a color which contrasts well with stone, but not very pleasing used +alone. Glazed bricks of all colors are obtainable. They are usually very +hard and square, and the use of them where an impervious glazed face is +required, as, for example, in a good stable, is better than the +employment of glazed tiles, in the employment of which there is always a +possibility of part of the lining becoming loose or falling off. There +is a difficulty in obtaining a large quantity (of some colors, at least) +exactly uniform in tint. Bricks with a very hard face, but not glazed, +are obtainable. What is called a washing brick is now made in various +colors, adapted for the lining of interiors, and there are hard bricks +of a very pale straw color, known as Beart's patent bricks, made, I +believe, of gault clay, which were some years ago bought up by the Great +Northern Railway in large numbers. These bricks have the peculiarity of +being pierced with holes about 1/2 in. in diameter, passing quite through +the brick, and they are extremely hard, partly because these holes +permit the hot air and smoke in the kiln to approach very near to the +interior of the brick. I am of opinion that the glazed or dull qualities +of hard bricks might with great advantage be often introduced into +London streets. What we want is something that will wash. The rough +surface of stocks or Suffolk facing bricks catches the black in the +London atmosphere and gradually gets dark and dull. A perfectly hard +face is washed clean by every shower. A good many years ago I built a +warehouse with stock bricks, and formed the arches, strings, etc., of +bricks with a very hard face, and, as I expected, the effect of time has +been to make these features stand out far better than when they were +fresh; in fact, the only question is whether they have not now become +too conspicuous. To return to the bricks in the London market: we have +firebricks made of fireclay, and almost vitrified and capable of +standing intense heat. These are used for lining furnaces, ovens, flues, +etc. + +Then we have almost, if not quite, as refractory a material in +Staffordshire blue bricks, used--in various forms--for paving channels, +jambs of archways, etc. There are also small bricks called clinkers, +chiefly used for stable paving. Dutch clinkers, formerly imported +largely from Holland, were small, rough bricks, laid on edge, and +affording a good foothold for the horse. Adamantine clinkers, made of +gault clay, are much used; they must have chamfered edges, otherwise +they make too smooth a floor for a stable. Many other varieties are +obtainable in London, and are more or less used, but these are the most +prominent. In many parts of England special varieties of brick are to be +found, and every here and there one falls upon a good brickmaker who is +able to produce good moulded or embossed or ornamental bricks, such as +those which have been supplied to me years ago by Mr. Gunton, and more +recently by Mr. Brown, both of Norwich, or by Mr. Cooper, of Maidenhead. + +It is of importance to those whose business it is to look after or +engage in building operations, that they should early learn what to look +out for in each material. Of course, a man only becomes a judge of +bricks, or timber, or stone by experience; but he is far better able to +take the benefit of experience when it comes to him if he knows from the +first to what points to direct attention. Wherefore I make no apology +for trying to put before you the points of a good brick, and in doing so +I shall partly quote from a memorandum published now a good many years +ago by the Manchester Society of Architects. + +A good brick is uniform in size; standard, 9 by 41/2 by 21/2 in.; weight +about 7 lb. each = 110 lb. per foot cube; is rectangular, true faced, +but only one end and one side need be smooth; has no print sinking on +either face, but a hollow on one or both beds. When saturated with +water, a brick should not absorb more than 20 per cent, of its own +weight of water, should absorb it reluctantly, and part with it freely +at ordinary temperatures. It should be uniformly burnt, should be sound, +free from cracks, flaws, stones, lumps of any kind, but especially lumps +of lime, should be of a good color for its sort (whether red, yellow, or +white), should have a metallic clang when two bricks are struck +together; when broken should be sound right through, should be tough and +pasty in texture, not granular, and should require repeated blows to +break it, rather than one hard blow (such bricks will withstand cartage +and handling best). So much for bricks. To make brickwork, however, +another ingredient is required--namely, mortar or cement. + +All mortars and, in fact, all the cementing materials used (except +bituminous ones) in bricklaying have lime as their base, and depend upon +the setting quality of quicklime, which has to be mixed with sand or +some suitable substitute for it, to make mortars. Limes and cements are +far too wide a subject to be dealt with as part of an evening's lecture +on another topic, and no doubt they will hereafter form the subject of a +lecture or lectures. To-night I propose only to remind you that there +are such substances as these, and that they possess certain qualities +and are obtainable and available for the bricklayer's purposes, without +attempting an investigation into the chemistry of cements, or their +manufacture, etc. Ordinarily, brickwork may be divided into brickwork in +mortar and in cement; but there are many qualities of mortar and several +sorts of cement. Mortar made with what are called fat or rich +limes--that is to say, nearly pure lime, such as is got by calcining +marble or pure chalk--sets slowly, with difficulty, and is rarely +tenacious. Burnt clay or brick reduced to powder improves the setting of +such lime, especially if the two materials be calcined together; so will +an admixture of cement. Mortar made with what is known as slightly +hydraulic lime, that is to say, lime containing a small proportion of +clay, such as the gray stone lime of Dorking, Merstham, and that +neighborhood, sets well, and is tenacious and strong. Mortar made with +hydraulic lime, that is to say, lime with a considerable admixture of +clay, such as the lias lime, sets under water or in contact with wet +earth. It is best to use this lime ground to powder, and not to mix so +much sand with it as is used with stone lime. A sort of mortar called +selenitic mortar, the invention of the late General Scott, has been made +use of in many of the buildings of the School Board for London, and was +first employed on a large scale in the erection of the Albert Hall. The +peculiarity consists in the addition of a small dose of plaster of Paris +(sulphate of lime) very carefully introduced and intimately mixed. The +result is that the mortar so made sets rapidly, and is very hard. + +It is claimed that a larger proportion of sand can be used with +selenitic lime than with ordinary, thus counterbalancing the extra +expense occasioned by royalty under the patent and special care in +mixing. When a limestone contains 20 to 40 per cent, of clay, it becomes +what is called a cement, and its behavior is different from that of +limestones with less clay. Ordinary limestones are, as you know, +calcined in a kiln. The material which comes from the kiln is called +quicklime, and, on being dosed with water, it slakes, and crumbles to +powder, and in the state of slaked lime is mixed up with mortar. Cement +stones are also calcined; but the resulting material will not fall to +pieces or slake under water. It must be ground very fine, and when +moistened sets rapidly, and as well under water as in air, and becomes +very hard and is very tenacious. Brickwork in mortar will always settle +and compress to some extent. Not so brickwork in cement, which +occasionally expands, but is never to be compressed. This quality and +the rapid setting, tenacity, and strength of brickwork in cement make it +a most valuable material to use in those buildings or parts of a +building where great steadiness and strength are wanted, and in sewage +and dock work, where there is water to contend with. A good many cements +made from natural stones used to be employed, such as Medina, Harwich, +Atkinson's, or Roman cement. The last named is the only one which is now +much employed, except locally. It has the quality of setting with +exceptional rapidity, and is on that account sometimes the best material +to employ; but for almost every purpose the artificial compound known as +Portland cement is preferable. + +Portland cement is made largely near Rochester. Its materials are simple +and cheap. They may, without much departure from the truth, be said to +be Thames mud and chalk; but the process of manufacture requires care +and thoroughness. The article supplied, when of the best quality, has +great strength, and is quick setting, and is far better than what was +manufactured from stones in which the ingredients existed in a state of +nature. In England we slake our lime and make use of it while it is +fresh; but it may interest you to know that the custom in Italy and +parts of France is different. There it is customary to slake the lime +long before it is wanted, and to deposit it in a pit and cover it up +with earth. In this condition it is left for months--I believe in Italy +for a year--and when taken out it is stiff, but still a pasty substance. +It is beaten, and more water added, and it is then made into mortar with +sand. It is claimed for mortar made in this way that is exceptionally +strong. + +Now that we have considered bricks and partly considered mortar, it +remains to pay some attention to brickwork. The simplest and most +familiar work for a bricklayer to do is to build a wall. In doing this +his object should be to make it as stout as possible for the thickness, +and this stoutness can only be obtained by interlacing the bricks. If +they were simply laid on the top of each other, the wall would be no +more than a row of disconnected piles of bricks liable to tumble down. +When the whole is so adjusted that throughout the entire wall the joints +in one course shall rest on solid bricks and shall be covered by solid +bricks again--in short, when the whole shall break joint--then this wall +is said to be properly bonded, and has as much stability given to it as +it can possibly possess. There are two systems of bonding in use in +London, know as English bond and Flemish bond. English bond is the +method which we find followed in ancient brickwork in this country. + +In this system a course of bricks is laid across the wall, showing their +heads at the surface, hence called "headers," and next above comes a +course of bricks stretching lengthways at the wall, called stretchers, +and so on alternately. With the Dutch fashions came in Flemish bond, in +which, in each course, a header and a stretcher alternate. In either +case, at the corners, a quarter-brick called a closer has to be used in +each alternate course to complete the breaking joint. There is not much +to choose between these methods where the walls are only one brick +thick. But where they are thicker the English has a decided advantage, +for in walls built in Flemish bond of one and a half brick thickness or +more there must be a few broken bricks, or bats, and there is a strong +temptation to make use of many. If this takes place, the wall is +unsound. + +Many of the failures of brickwork in London houses arise from the +external walls, where they are 11/2 bricks thick, being virtually in two +skins; the inner 9 in. does the whole of the work of supporting floors +and roof, and when it begins to fail, the outer face bulges off like a +large blister. I have known cases where this had occurred, and where +there was no header brick for yards, so that one could pass a 5 ft. rod +into the space between the two skins and turn it about. This is rather +less easy to accomplish with English bond, and there are other +advantages in the use of that bond which make it decidedly preferable, +and it is now coming back into very general use. There are some odd +varieties of bond, such as garden bond and chimney bond. But of these I +only wish to draw your attention to what is called cross bond. The name +is not quite a happy one. Diagonal bond is hardly better. The thing +itself is to be often met with on the Continent, and it is almost +unknown here. But it would be worth introducing, as the effect of it is +very good. + +French cross bond, otherwise diagonal bond _(liaison en croix)_, is +English bond, but with the peculiarity that in every fourth course one +header is made use of in the stretcher course at the quoin. The result +is that the stretchers break joint with each other, and all the joints +range themselves in diagonal lines, and if in any part of the work +headers of a different brick are introduced, the appearance of a cross +is at once brought out; and even without this the diagonal arrangement +of joints is very perceptible and pleasing. + +Besides wall building, the bricklayer has many other works to perform. +He has to form fireplaces, flues, chimneys, and the flat trimmer arches +which support the hearth, and has to set the stove, kitchen range, +copper, etc., in a proper manner. He has to form various ornamental +features and much else, some of which we shall have an opportunity of +noticing rather later. The strangest business, however, which is +intrusted to the bricklayer is building downward--by the method known as +underpinning--so that if a foundation has failed, a sounder one at a +greater depth may be reached; or if a basement is required under an +existing building which has none, the space may be excavated and the new +walls built so as to maintain the old. + +This work has to be done with great caution, and bit by bit, and is +usually left to experienced hands. The mode in which the mortar joints +of a brick wall are finished where they show on the external or internal +face is a matter worth a moment's attention. It is important that the +joints of the work shall be so finished as to keep out wet and to be as +durable as possible, and it is desirable that they should improve, or at +any rate not disfigure, the appearance of the work. + +The method which architects strongly advocate is that the joints shall +be struck as the work proceeds--that is, that very shortly after a brick +is laid, and while the mortar is yet soft, the bricklayer shall draw his +trowel, or a tool made for the purpose, across it, to give it a smooth +and a sloping surface. This is best when the joint is what is called a +weather joint--i.e., one in which the joint slopes outward. Sloping it +inward is not good, as it lets in wet; finishing it with a hollow on the +face is often practiced, and is not bad. Bricklayers, however, most of +them prefer that the mortar joints should be raked out and pointed--that +is to say, an inch or an inch and a half of the mortar next the outer +face be scratched out and replaced with fresh mortar, and finished to a +line. + +In cases where the brickwork is exposed to frost, this proceeding cannot +be avoided, because the frost damages the external mortar of the joints. +But the bricklayers prefer it at all seasons of the year, partly because +brickwork is more quickly done if joints are not struck at the time; +partly because they can, if they like, wash the whole surface of the +work with ocher, or other color, to improve the tint; and partly +because, whether the washing is done or not, it smartens up the +appearance of the work. The misfortune is that this pointing, instead of +being the edge of the same mortar that goes right through, is only the +edge of a narrow strip, and does not hold on to the old undisturbed +mortar, and so is far less sound, and far more liable to decay. There is +a system of improving the appearance of old, decayed work by raking out +and filling up the joint, and then making a narrow mortar joint in the +middle of this filling in, and projecting from the face. This is called +tuck pointing. It is very specious, but it is not sound work. + +Brick arches are constantly being turned, and of many sorts. An arch +consists of a series of wedge shaped blocks, known as voussoirs, +arranged in a curve, and so locking one another together that unless the +abutments from which the arch springs give way, it will not only carry +itself, but sustain a heavy load. It is a constant practice to cut +bricks to this shape and build them into an arch, and these are +sometimes cut and rubbed; sometimes, when the work is rougher, they are +axed. But in order to save the labor of cutting, arches are sometimes +turned with the bricks left square, and the joints wedge shaped. In this +case the rings should be only half a brick each, so that the wedge need +not be so very much wider at back than at face, and they are set in +cement, as that material adheres so closely and sets so hard. Arches of +two or more half-brick rings in cement are good construction, and are +also used for culvert work. + +A less satisfactory sort of arch is what is called the flat arch. Here, +instead of being cambered as it ought to be, the soffit is straight; but +the brickwork being deep, there is room enough for a true arch that does +the work, and for useless material to hang from it. These arches are +generally rubbed or axed, and are very common at the openings of +ordinary windows. But no one who has studied construction can look at +them without a kind of wish for at least a slight rise, were it only two +inches. Sometimes when these straight arches are to be plastered over +they are constructed in a very clumsy manner, which is anything but +sound, and from time to time they give way. The weight of brickwork, of +course, varies with the weight of the individual bricks. But stock +brickwork in mortar weighs just about one hundred weight per cubic foot, +or 20 cubic feet to the ton. In cement it is heavier, about 120 lb. to +the cubic foot. + +The strength of brickwork depends of course on the strength of the +weakest material--i.e., the mortar--though when it is in cement the +strength of brickwork to withstand a weight probably approaches that of +the individual bricks. Some experiments quoted in Rivington's Notes give +the following as the crushing weight per foot--that is to say, weight at +which crushing began--of piers having a height of less than twelve times +their diameter: + + Tons per + foot. + Best stocks, set in Portland cement and + sand 1 to 1, and three months old. 40 + Ordinary good stocks, three months old. 30 + Hard stocks, Roman cement and sand 1 to 1, + three months old. 28 + Hard stocks, lias lime, and sand 1 to 2, + and six months old. 24 + Hard stocks, gray chalk lime, and sand, + six months old. 12 + +The rule given in popular handbook, that brickwork in mortar should not +have to carry more than three tons per superficial foot, and in cement +more than five tons, is probably sound, as in no building ought the load +to approach the crushing point, and, indeed, there are many sorts of +foundations on which such a load as five tons per foot would be too +great to be advisable. + +It is a rather interesting inquiry, whenever we are dealing with a +building material, if we ask what can we best do with it, and for what +is it ill fitted. The purposes for which brick can be best used depend, +of course, upon its qualities. Speaking generally, such purposes are +very numerous and very various, especially the utilitarian purposes, +though rich and varied ornamental work can also be executed in +brickwork. + +Perhaps the most remarkable quality of brickwork is that it can be +thrown into almost any shape. It is in this respect almost like a +plastic material, and this peculiarity it owes chiefly to the very small +size of each brick as compared with the large masses of the brickwork of +most buildings. Stone is far less easily dealt with than brick in this +respect. Think for a moment of the great variety of walls, footings, +piers, pilasters, openings, recesses, flues, chimney breasts, chimney +shafts, vaults, arches, domes, fireproof floors, corbels, strings, +cappings, panels, cornices, plinths, and other features met with in +constant use, and all formed by the bricklayer with little trouble out +of the one material--brickwork! A little consideration will convince you +that if the same material furnishes all these, it must be very plastic. +As a limitation we ought to note that this almost plastic material +cannot be suddenly and violently dealt with--that is to say, with the +exception of some sorts of arches, you cannot form any abrupt or +startling feature in brickwork, and you are especially limited as to +projections. + +If you wish to throw out any bold projection, you may support it on a +long and sloping corbel of brickwork. But if there is not room for that, +you must call in some other material, and form the actual support in +stone, or terra cotta, or iron, and when you have gained your +projection, you may then go on in brickwork if you like. + +Brick cornices should be steep, but cannot be bold, and so with other +ornamental and structural features. A noteworthy property of brickwork, +and one of immense value, is that it is thoroughly fireproof; in fact, +almost the only perfectly fireproof material. There is an interesting +account of the great fire of London by one of the eye witnesses, and +among the striking phenomena of that awful time he notes that the few +brick buildings which existed were the only ones able to withstand the +raging fire when it reached them. + +In our own day a striking proof of the same thing was given in the great +fire in Tooley street, when Braidwood lost his life. I witnessed that +conflagration for a time from London Bridge, and its fury was something +not to be described. There were vaults under some of the warehouses +stored with inflammable materials, the contents of which caught fire and +burnt for a fortnight, defying all attempts to put them out. Yet these +very vaults, though they were blazing furnaces for all that time, were +not materially injured. When the warehouses came to be reinstated, it +was only found necessary to repair and repoint them a little, and they +were retained in use. The fact is that the bricks have been calcined +already, so has the lime in the mortar, and the sand is not affected by +heat, so there is nothing in brickwork to burn. Against each of these +good qualities, however, we may set a corresponding defect. + +If brickwork is easily thrown into any shape, it is also easily thrown +out of shape. It has little coherence or stability, less than masonry +and very considerably less than timber. If any unequal settlement in the +foundation of a brick building occurs, those long zigzag cracks with +which we in London are only too familiar set themselves up at once; and +if any undue load, or any variation in load, exists, the brickwork +begins to bulge. Any serious shock may cause a building of ordinary +brickwork to collapse altogether, and from time to time a formidable +accident occurs owing to this cause. The fact is, the bricks are each so +small compared to the mass of the work, and the tenacity or hold upon +them of even fairly good lime mortar is so comparatively slight, that +there is really but little grip of one put upon another. + +Persons who have to design and construct brick buildings should never +forget that they have to be handled with caution, and are really very +ticklish and unstable. One or two of the methods of overcoming this to +some extent may be mentioned. The first is the introduction of what is +called bond. At the end of the last century it was usual to build in, at +every few feet in height, bond timbers, which were embedded in the heart +of the walls. If these had always remained indestructible, they would no +doubt have served their purpose to some extent. Unfortunately, timber +both rots and burns, and this bond timber has brought down many a wall +owing to its being destroyed by fire, and has in other cases decayed +away, and caused cracks, settlements, and failures. + +The more modern method of introducing a strong horizontal tie is to +build into the wall a group of bands of thin iron, such as some sorts of +barrels are hooped with--hence called hoop iron. The courses of bricks +where this occurs must be laid in cement, because iron in contact with +cement does not perish as it does in contact with mortar. + +If in every story of a building four or five courses are thus laid and +fortified, a great deal of strength is given to the structure. Another +method, which has rather fallen into disuse, is grouting. This is +pouring liquid mortar, about the consistency of gruel, upon the work at +about every fourth course. The result is to fill up all interstices and +cavities, and to delay the drying of the mortar, and brickwork so +treated sets extremely hard. I have seen a wall that had been so treated +cut into, and it was quite as easy to cut the bricks (sound ones though +they were) as the mortar joints. + +Grouting is objected to because it interferes with the good look of the +work, as it is very difficult to prevent streaks of it from running down +the face, and it is apt to delay the work. But it is a valuable means of +obtaining strong brickwork. Another and a more popular method is to +build the work in cement, now usually Portland cement. This, of course, +makes very strong, sound work, and does not involve any delay or dirt +like grouting, or the introduction of any fresh material like hoop iron. +But it, of course, adds to the expense of the work considerably, as +cement is much more costly than lime. I ought to add that the advocates +of Scott's selenitic mortar claim that it not only sets quickly and +hard, but that it is extremely tenacious, and consequently makes a much +more robust wall than ordinary mortar. I dare say this is true; but I +have not happened to see such a wall cut into, and this is the best test +of solidity. + +The second deficiency in brickwork which I am bound to notice is that, +though it is very fireproof, it is far from being waterproof. In an +exposed situation rain will drive completely through a tolerably stout +brick wall. If water be allowed to drop or fall against it, the wall +will become saturated like a sponge. If the foot of a wall becomes wet, +or if the earth resting against the lower parts of it be moist, water +will, if not checked, rise to a great height in it, and if the upper +part of the wall be wet, the water will sink downward. With most sorts +of brick the outer face absorbs moisture whenever the weather is moist; +and in time the action of the rain, and the subsequent action of frost +upon the moisture so taken up, destroys the mortar in the joints, which +are to be seen perfectly open, as if they had been raked out, in old +brickwork, and in some cases (happily not in many) the action of weather +destroys the bricks themselves, the face decaying away, and the brick +becoming soft. + +Against this serious defect in our staple building material a series of +precautions have been devised. Damp rising from the foot of the wall, or +from earth lying round its base, is combated by a damp course--a bed of +some impervious material going through the wall. Damp earth may be kept +off by surrounding the walls with an open area or a closed one--usually +termed a dry area. Damp against the face of the walls may be partly +combated by a careful selection of a non-absorbent brick with a hard +face and by struck joints. But it is most effectually kept at bay by the +expedient of building the wall hollow; that is to say, making the +external wall of the house to consist of two perfectly distinct walls, +standing about 2 in. apart, and held together by ties of earthenware or +iron. The result is that the moisture blowing through the outer skin +does not pass the cavity, but trickles down on the inner face of the +outer wall, while the inner wall remains dry. The ties are constructed +of shapes to prevent their conducting water themselves from without to +the inner wall. In addition to this, a series of slates forming an +intermediate protection is sometimes introduced, and forms an additional +and most valuable screen against weather. Sometimes, the two skins of +the wall are closer together--say 3/4 in.--and the space is filled with a +bituminous material. + +A substance of a bituminous nature, called hygeian rock, has been of +late years introduced, and is being extensively used for this purpose; +it is melted and poured into the open space hot, and quickly hardens. +The use of such a material is open to the objection that no air can pass +through it. The rooms of our houses are receiving air constantly through +the walls, and much of the constant current up our chimneys is supplied, +to our great advantage, in this very imperceptible manner. The house +breathes, so to speak, through the pores of its brickwork. When this is +rendered impossible, it seems clear that fiercer draughts will enter +through the chinks and crevices, and that there will be a greater demand +upon flues not in use, occasioning down draught in the chimneys. + +Another mode of keeping out weather is to cement the face of the +brickwork. But this hides up the work, and so tends to promote bad work, +besides being often very unsightly. + +Among other peculiarities of brickwork are the facilities for +introducing different colors and different textures of surface which it +presents, the ease with which openings and arches can be formed in it, +the possibility of executing ornament and even carving, and the ease +with which brickwork will combine with other building materials. It +cannot be well made use of for columns, though it may readily enough be +turned into piers or pilasters. It cannot, generally speaking, with +advantage be made use of for any large domes, though the inner dome of +St. Paul's and the intermediate cone are of brick, and stand well. But +it is an excellent material for vaulting arcades and all purposes +involving the turning of arches. + +Brickwork must be said to be durable, but it requires care. If not of +the best, brickwork within the reach of the constant vibration caused by +the traffic on a railway seems to be in danger of being shaken to +pieces, judging from one or two instances that have come under my own +observation. The mortar, and even in some cases the bricks themselves, +will rapidly deteriorate if moisture be allowed to get into the heart of +a brick wall, and in exposed situations this is very apt to happen. Care +should always be taken to keep the pointing of external brickwork in +good order, and to maintain all copings and other projections intended +to bar the access of water coming down from above, and to stop the +overflowing of gutters and stack pipes, which soon soaks the wall +through and through. + +Of course, if there is a failure of foundations, brickwork, as was +pointed out earlier, becomes affected at once. But if these be good, and +the materials used be sound ones, and if the other precautions just +recommended be taken, it will last strong and sturdy for an immense +length of time. In some cases, as for example in the Roman ruins, it has +stood for 1,500 years under every possible exposure and neglect, and +still shows something of a sturdy existence after all, though sadly +mutilated. If we now return to the question, What can be well done in +brickwork? no better answer can be given than to point to what has been +and is being done, especially in London and within our own reach and +observation. + +Great engineering works, such as railway viaducts, the lining of railway +tunnels, the piers and even the arches of bridges, sewage works, dock +and wharf walls, furnace chimneys, and other works of this sort are +chiefly done in brickwork. And notwithstanding that iron is far more +used by the engineer for some purposes and concrete for others now than +formerly, still there is a great field for brickwork. The late Mr. +Brunel, who was fond of pushing size to extremes, tried how wide a span +he could arch over with brickwork. And I believe the bridge which +carries the G.W.R. over the Thames at Maidenhead has the widest arch he +or any other engineer has successfully erected in brick. This arch has, +it is stated, a span of 128 ft. It is segmental, the radius being 169 +ft., and the rise from springing to crown 24 ft., and the depth of the +arch 5 ft. 3 in. Nowadays, of course, no one would dream of anything but +an iron girder bridge in such a position. Mr. Brunel's father, when he +constructed the Thames Tunnel, lined it with brickwork foot by foot as +he went on, and that lining sustained the heavy weight of the bed of the +river and the river itself. + +If you leave London by either of the southern lines, all of which are at +a high level, you go for miles on viaducts consisting of brick arches +carried on brick walls. If you leave by the northern lines, you plunge +into tunnel after tunnel lined with brickwork, and kept secure by such +lining. Mile after mile of London streets, and those in the suburbs, +present to the eye little but brick buildings; dwelling houses, shops, +warehouses, succeed one another, all in brickwork, and even when the eye +seems to catch a change, it is more apparent than real. + +The white mansions of Tyburnia, Belgravia, South Kensington, and the +neat villas of the suburbs are only brickwork, with a thin coat of +stucco, which serves the purpose of concealing the real structure--often +only too much in need of concealment--with a material supposed to be a +little more sightly, and certainly capable of keeping the weather out +rather more effectually than common brickwork would. + +More than this, such fine structures, apparently built entirely of +stone, as are being put up for commercial purposes in the streets of the +city, and for public purposes throughout London, are all of them nothing +more than brick fabrics with a facing of masonry. Examine one of them in +progress, and you will find the foundations and vaults of brickwork, and +not only the interior walls, but the main part of the front wall, +executed in brickwork, and the stone only skin deep. There are, however, +two or three ways of making use of brickwork without covering it up, and +of gaining good architectural effects thereby, and to these I beg now to +direct your attention. + +The architect who desires to make an effective brick building, which +shall honestly proclaim to all the world that it is of brick, may do +this, and, if he will, may do it successfully, by employing brickwork +and no other material, but making the best use of the opportunities +which it affords, or he may erect his building of brickwork and stone +combined, or of brickwork and terra cotta. Mr. Robson, till lately the +architect to the School Board for London, has the merit of having put +down in every part of the metropolis a series of well contrived and well +designed buildings, the exterior of which almost without exception +consists of brickwork only. + +If you examine one of his school-houses, you will see that the walls are +of ordinary stock brickwork, but usually brightened up by a little red +brick at each angle, and surmounted by well contrasted gables and with +lofty, well designed chimneys, rising from the tiled roof. The window +openings and doorways are marked by brickwork, usually also red, and +sometimes moulded, and though I personally must differ from the taste +which selected some of the forms employed (they are those in use in this +country in the 17th and the last centuries), I cordially recognize that +with very simple and inexpensive means exceedingly good, appropriate, +and effective buildings have been designed. + +Among examples of architecture wholly, or almost wholly, executed in red +brick, I cannot pass over a building built many years ago, little known +on account of its obscure situation, but a gem in its way. I allude to +the schools designed by Mr. Wilde, and built in Castle street, Endell +street. + +Of buildings where a small amount of stone is introduced into brickwork +we have a good many fine specimens in London. One of the best--probably +the best--is the library in Lincoln's Inn Fields. This is a large and +picturesque pile, built under Mr. Hardwick, as architect, in red brick, +with patterns in the blank parts of the walls done in black brick. It +has splendid moulded brick chimneys, and the mullions of the windows, +the copings, the entrances, and some other architectural features done +in stone. The building is a good reproduction of the style of building +in Tudor times, when, as has been already mentioned, brickwork was taken +into favor. + +Another building of the same class, but not so good, is the older part +of the Consumption Hospital, at Brompton. Brickwork, with a little +stone, has been very successfully employed as the material for churches, +and in many such cases the interior is of unplastered brickwork. Such +churches often attain, when designed by skillful hands, great dignity +and breadth of effect. St. Albans, Holborn; the great church designed by +Mr. Butterfield, in Margaret street; Mr. Street's church near Vincent +square, Westminster; and several churches of Mr. Brooks', such as he was +kind enough to enable me to illustrate tonight, may be mentioned as +examples of the sort. Mr. Waterhouse has built an elaborate +Congregational church at Hampstead, which shows the use with which such +effects of color may be obtained in interiors, and has kindly lent some +drawings. Mr. Pearson's church at Kilburn may also be referred to as a +fine example of brick vaulting. Brick and terra cotta seem to have a +natural affinity for one another. Terra cotta is no more than a refined +brick, made of the same sort of material, only in every respect more +carefully, and kiln baked. Its similarity to brick is such that there is +no sense of incongruity if moulded or carved brickwork and terra cotta +are both employed in the same building, and this can hardly be said to +be the case if the attempt is made to combine ornamental brickwork and +stone ornaments. + +At South Kensington, a whole group of examples of brickwork with terra +cotta meet us. The Natural History Museum, the finest of them all, is +hardly fit for our present purpose, as it is as completely encased in +terra cotta as the fronts of the buildings in this avenue are in stone. +But here are the Albert Hall, a fine specimen of mass and effect; the +City and Guilds Institute; the College of Music, and some private houses +and blocks of flats, all in red brick with terra cotta, and all showing +the happy manner in which the two materials can be blended. In most of +them there is a contrast of color; but Mr. Waterhouse, in the Technical +Institute, has employed red terra cotta with red bricks, as he also has +done in his fine St. Paul's School at Hammersmith, and Mr. Norman Shaw +has, in his fine pile of buildings in St. James' street. This +combination--namely, brick and terra cotta--I look upon as the best for +withstanding the London climate, and for making full use of the +capabilities of brickwork that can be employed, and I have no doubt that +in the future it will be frequently resorted to. Some of those examples +also show the introduction of cast ornaments, and others the employment +of carving as means of enriching the surface of brick walls with +excellent effect. Here we must leave the subject; but in closing, I +cannot forbear pointing to the art of the bricklayer as a fine example +of what may be accomplished by steady perseverance. Every brick in the +miles of viaducts or tunnels, houses, or public buildings, to which we +have made allusion, was laid separately, and it is only steady +perseverance, brick after brick, on the part of the bricklayer, which +could have raised these great masses of work. Let me add that no one +brick out of the many laid is of no importance. Some time ago a great +fire occurred in a public asylum, and about L2,000 of damage was done, +and the lives of many of the inmates endangered. When the origin of this +fire came to be traced out, it was found that it was due to one brick +being left out in a flue. A penny would be a high estimate of the cost +of that brick and of the expense of laying it, yet through the neglect +of that pennyworth, L2,000 damage was done, and risk of human life was +run. I think there is a moral in this story which each of us can make +out if he will. + + * * * * * + +A fireproof whitewash can be readily made by adding one part silicate of +soda (or potash) to every five parts of whitewash. The addition of a +solution of alum to whitewash is recommended as a means to prevent the +rubbing off of the wash. A coating of a good glue size made by +dissolving half a pound of glue in a gallon of water is employed when +the wall is to be papered. + + * * * * * + + + + +PHENOMENA OF ALTERNATING CURRENTS. + +[Footnote: From a paper read before the recent meeting of the American +Institute of Electrical Engineers, New York, and reported in the +_Electrical World_.] + +By Prof. ELIHU THOMSON. + + +The actions produced and producible by the agency of alternating +currents of considerable energy are assuming greater importance in the +electric arts. I mean, of course, by the term alternating currents, +currents of electricity reversed at frequent intervals, so that a +positive flow is succeeded by a negative flow, and that again by a +positive flow, such reversals occurring many times in a second, so that +the curve of current of electromotive force will, if plotted, be a wave +line, the amplitude of which is the arithmetical sum of the positive and +negative maxima of current or electromotive force, as the case may be, +while a horizontal middle line joins the zero points of current or +electromotive force. + +[Illustration: FIG. 1] + +It is well known that such a current passing in a coil or conductor laid +parallel with or in inductive relation to a second coil or conductor, +will induce in the second conductor, if on open circuit, alternating +electromotive forces, and that if its terminals be closed or joined, +alternating currents of the same rhythm, period, or pitch, will +circulate in the second conductor. This is the action occurring in any +induction coil whose primary wire is traversed by alternating currents, +and whose secondary wire is closed either upon itself directly or +through a resistance. What I desire to draw attention to in the present +paper are the mechanical actions of attraction and repulsion which will +be exhibited between the two conductors, and the novel results which may +be obtained by modifications in the relative dispositions of the two +conductors. + +[Illustration: FIG. 2.] + +In 1884, while preparing for the International Electrical Exhibition at +Philadelphia, we had occasion to construct a large electro-magnet, the +cores of which were about six inches in diameter and about twenty inches +long. They were made of bundles of iron rod of about 5/16 inch diameter. +When complete, the magnet was energized by the current of a dynamo +giving continuous currents, and it exhibited the usual powerful magnetic +effects. It was found also that a disk of sheet copper, of about 1/16 +inch thickness and 10 inches in diameter, if dropped flat against a pole +of the magnet, would settle down softly upon it, being retarded by the +development of currents in the disk due to its movement in a strong +magnetic field, and which currents were of opposite direction to those +in the coils of the magnet. In fact, it was impossible to strike the +magnet pole a sharp blow with the disk, even when the attempt was made +by holding one edge of the disk in the hand and bringing it down +forcibly toward the magnet. In attempting to raise the disk quickly off +the pole, a similar but opposite action of resistance to movement took +place, showing the development of currents in the same direction to +those in the coils of the magnet, and which currents, of course, would +cause attraction as a result. + +[Illustration: Fig. 3] + +The experiment was, however, varied, as in Fig. 1. The disk, D, was held +over the magnet pole, as shown, and the current in the magnet coils cut +off by shunting them. There was felt an attraction of the disk or a dip +toward the pole. The current was then put on by opening the shunting +switch, and a repulsive action or lift of the disk was felt. The actions +just described are what would be expected in such a case, for when +attraction took place, currents had been induced in the disk, D, in the +same direction as those in the magnet coils beneath it, and when +repulsion took place the induced current in the disk was of opposite +character or direction to that in the coils. + +[Illustration: Fig. 4] + +Now let us imagine the current in the magnet coils to be not only cut +off, but reversed back and forth. + +For the reasons just given, we will find that the disk, D, is attracted +and repelled alternately; for, whenever the currents induced in it are +of the same direction with those in the inducing or magnet coil, +attraction will ensue, and when they are opposite in direction, +repulsion will be produced. Moreover, the repulsion will be produced +when the current in the magnet coil is rising to a maximum in either +direction, and attraction will be the result when the current of either +direction is falling to zero, since in the former case opposite currents +are induced in the disk, D, in accordance with well known laws, and in +the latter case currents of the same direction will exist in the disk, +D, and the magnet coil. The disk might, of course, be replaced by a ring +of copper or other good conductor, or by a closed coil of bare or +insulated wire, or by a series of disks, rings or coils superposed, and +the results would be the same. Thus far, indeed, we have nothing of a +particularly novel character, and, doubtless, other experimenters have +made very similar experiments and noted similar results to those +described. + +[Illustration: FIG. 5] + +The account just given of the effects produced by alternating currents, +while true, is not the whole truth, and just here we may supplement it +by the following statements: + +_An alternating current circuit or coil repels and attracts a closed +circuit or coil placed in direct or magnetic inductive relation +therewith; but the repulsive effect is in excess of the attractive +effect. + +When the closed circuit or coil is so placed, and is of such low +resistance metal that a comparatively large current can circulate as an +induced current, so as to be subject to a large self-induction, the +repulsive far exceeds the attractive effort_. + +For want of a better name, I shall call this excess of repulsive effect +the "electro-inductive repulsion" of the coils or circuits. + +[Illustration: FIG. 6.] + +This preponderating repulsive effect may be utilized or may show its +presence by producing movement or pressure in a given direction, by +producing angular deflection as of a pivoted body, or by producing +continuous rotation with a properly organized structure. Some of the +simple devices realizing the conditions I will now describe. + +[Illustration: FIG. 7.] + +In Fig. 2, C is a coil traversed by alternating currents. B is a copper +case or tube surrounding it, but not exactly over its center. The copper +tube, B, is fairly massive and is the seat of heavy induced currents. +There is a preponderance of repulsive action, tending to force the two +conductors apart in an axial line. The part, B, may be replaced by +concentric tubes slid one in the other, or by a pile of flat rings, or +by a closed coil of coarse or fine wire insulated, or not. If the coil, +C, or primary coil, is provided with an iron core such as a bundle of +fine iron wires, the effects are greatly increased in intensity, and the +repulsion with a strong primary current may become quite vigorous, many +pounds of thrust being producible by apparatus of quite moderate size. + +The forms and relations of the two parts, C and B, may be greatly +modified, with the general result of a preponderance of repulsive action +when the alternating currents circulate. + +Fig. 3 shows the part, B, of an internally tapered or coned form, and C +of an externally coned form, wound on an iron wire bundle, I. The action +in Fig. 2 may be said to be analogous to that of a plain solenoid with +its core, except that repulsion, and not attraction, is produced, while +that of Fig. 3 is more like the action of tapered or conically wound +solenoids and taper cores. Of course, it is unnecessary that both be +tapered. The effect of such shaping is simply to modify the range of +action and the amount of repulsive effort existing at different parts of +the range. + +[Illustration: FIG. 8.] + +In Fig. 4 the arrangement is modified so that the coil, C, is outside, +and the closed band or circuit, B, inside and around the core, I. +Electro-inductive repulsion is produced as before. + +It will be evident that the repulsive actions will not be mechanically +manifested by axial movement or effort when the electrical middles of +the coils or circuits are coincident. In cylindrical coils in which the +current is uniformly distributed through all the parts of the conductor +section, what I here term the electrical middle, or the center of +gravity of the ampere turns of the coils, will be the plane at right +angles to its axis at its middle, that of B and C, in Fig. 4, being +indicated by a dotted line. To repeat, then, when the centers or center +planes of the conductors, Fig. 4, coincide, no indication of +electro-inductive repulsion is given, because it is mutually balanced in +all directions; but when the coils are displaced, a repulsion is +manifested, which reaches a maximum at a position depending on the +peculiarities of proportion and distribution of current at any time in +the two circuits or conductors. + +[Illustration: FIG. 9.] + +It is not my purpose now to discuss the ways of determining the +distribution of currents and mechanical effects, as that would extend +the present paper much beyond its intended limit. The forms and relative +arrangement of the two conductors may be greatly varied. In Fig. 5 the +parts are of equal diameter, one, B, being a closed ring, and the other, +C, being an annular coil placed parallel thereto; and an iron core or +wire bundle placed in the common axis of the two coils increases the +repulsive action. B may be simply a disk or plate of any form, without +greatly affecting the nature of the action produced. It may also be +composed of a pile of copper washers or a coil of wire, as before +indicated. + +[Illustration: FIG. 10.] + +An arrangement of parts somewhat analogous to that of a horseshoe +electro magnet and armature is shown in Fig. 6. The alternating current +coils, C C', are wound upon an iron wire bundle bent into U form, and +opposite its poles is placed a pair of thick copper disks, B B', which +are attracted and repelled, but with an excess of repulsion depending on +their form, thickness, etc. + +[Illustration: FIG. 11.] + +If the iron core takes the form of that shown by I I, Fig. 7, such as a +cut ring with the coil, C, wound thereon, the insertion of a heavy +copper plate, B, into the slot or divided portion of the ring will be +opposed by a repulsive effort when alternating currents pass in C. This +was the first form of device in which I noticed the phenomenon of +repulsive preponderance in question. The tendency is to thrust the +plate, B, out of the slot in the ring excepting only when its center is +coincident with the magnetic axis joining the poles of the ring between +which B is placed. + +If the axes of the conductors, Fig. 5, are not coincident, but +displaced, as in Fig. 8, then, besides a simple repulsion apart, there +is a lateral component or tendency, as indicated by the arrows. Akin to +this is the experiment illustrated in Fig. 9. Here the closed conductor, +B, is placed with its plane at right angles to that of C, wound on a +wire bundle. The part, B, tends to move toward the center of the coil, +C, so that its axis will be in the middle plane of C, transverse to the +core, as indicated by the dotted line. This leads us at once to another +class of actions, i.e., deflective actions. + +[Illustration: FIG. 12.] + +When one of the conductors, as B, Fig. 10, composed of a disk, or, +better, of a pile of thin copper disks, or of a closed coil of wire, is +mounted on an axis, X, transverse to the axis of coil, C, through which +coil the alternating current passes, a deflection of B to the position +indicated by dotted lines will take place, unless the plane of B is at +the start exactly coincident with that of C. If slightly inclined at the +start, deflection will be caused as stated. It matters not whether the +coil, C, incloses the part, B, or be inclosed by it, or whether the +coil, C, be pivoted and B fixed, or both be pivoted. In Fig. 11 the +coil, C, surrounds an iron wire core, and B is pivoted above it, as +shown. It is deflected, as before, to the position indicated in dotted +lines. + +[Illustration: FIG. 13] + +It is important to remark here that in cases where deflection is to be +obtained, as in Figs. 10 and 11, B had best be made of a pile of thin +washers or a closed coil of insulated wire instead of a solid ring. This +avoids the lessening of effect which would come from the induction of +currents in the ring, B, in other directions than parallel to its +circumference. + +[Illustration: FIG. 14.] + +We will now turn our attention to the explanation of the actions +exhibited, and afterward refer to their possible applications. It may be +stated as certainly true that were the induced currents in the closed +conductor unaffected by any self-induction, the only phenomena exhibited +would be alternate equal attractions and repulsions, because currents +would be induced in opposite directions to that of the primary current +when the latter current was changing from zero to maximum positive or +negative current, so producing repulsion; and would be induced in the +same direction when changing from maximum positive or negative value to +zero, so producing attraction. + +This condition can be illustrated by a diagram, Fig. 12. Here the lines +of zero current are the horizontal straight lines. The wavy lines +represent the variations of current strength in each conductor, the +current in one direction being indicated by that portion of the curve +above the zero line, and in the other direction by that portion below +it. The vertical dotted lines simply mark off corresponding portions of +phase or succession of times. + +[Illustration: FIG. 15] + +Here it will be seen that in the positive primary current descending +from m, its maximum, to the zero line, the secondary current has risen +from its zero to m, its maximum. Attraction will therefore ensue, for +the currents are in the same direction in the two conductors. When the +primary current increases from zero to its negative maximum, n, the +positive current in the secondary closed circuit will be decreasing from +m, its positive maximum, to zero; but, as the currents are in opposite +directions, repulsion will occur. These actions of attraction and +repulsion will be reproduced continually, there being a repulsion, then +an attraction, then a repulsion, and again an attraction, during one +complete wave of the primary current. The letters, r, a, at the foot of +the diagram, Fig. 12, indicate this succession. + +In reality, however, the effects of self-induction in causing a lag, +shift, or retardation of phase in the secondary current will +considerably modify the results, and especially so when the secondary +conductor is constructed so as to give to such self-induction a large +value. In other words, the maxima of the primary or inducing current +will no longer be found coincident with the zero points of the secondary +currents. The effect will be the same as if the line representing the +wave of the secondary current in Fig. 12 had been shifted forward to a +greater or less extent. This is indicated in diagram, Fig. 13. It gives +doubtless an exaggerated view of the action, though from the effects of +repulsion which I have produced, I should say it is by no means an +unrealizable condition. + +[Illustration: Fig. 16.] + +It will be noticed that the period during which the currents are +opposite, and during which repulsion can take place, is lengthened at +the expense of the period during which the currents are in the same +direction for attractive action. These differing periods are marked r, +a, etc., or the period during which _repulsion_ exists is from the zero +of the primary or inducing current to the succeeding zero of the +secondary or induced current; and the period during which _attraction_ +exists is from the zero of the induced current to the zero of inducing +current. + +But far more important still in giving prominence to the repulsive +effect than this difference of effective period is the fact that during +the period of repulsion both the inducing and induced currents have +their greatest values, while during the period of attraction the +currents are of small amounts comparatively. This condition may be +otherwise expressed by saying that the period during which repulsion +occurs includes all the maxima of current, while the period of +attraction includes no maxima. There is then a _repulsion due to the +summative effects of strong opposite currents_ for a _lengthened +period_, against an _attraction_ due to the summative effects of _weak +currents_ of the _same direction_ during a _shortened period_, the +resultant effect being a greatly _preponderating_ repulsion. + +It is now not difficult to understand all the actions before described +as obtained with the varied relations of coils, magnetic fields, and +closed circuits. It will be easily understood, also, that an alternating +magnetic field is in all respects the same as an alternating current +coil in producing repulsion on the closed conductor, because the +repulsions between the two conductors are the result of magnetic +repulsions arising from opposing fields produced by the coils when the +currents are of opposite directions in them. + +Thus far I have applied the repulsive action described in the +construction of alternating current indicators, alternating current arc +lamps, regulating devices for alternating currents, and to rotary motors +for such currents. For current indicators, a pivoted or suspended copper +band or ring composed of thin washers piled together and insulated from +one another, and made to carry a pointer or index has been placed in the +axis of a coil conveying alternating currents whose amount or potential +is to be indicated. Gravity or a spring is used to bring the index to +the zero of a divided scale, at which time the plane of the copper ring +or band makes an angle of, say, 15 degrees to 20 degrees with the plane +of the coil. This angle is increased by deflection more or less great, +according to the current traversing the coil. The instrument can be +calibrated for set conditions of use. Time would not permit of a full +description of these arrangements as made up to the present. + +In arc lamps the magnet for forming the arc can be composed of a closed +conductor, a coil for the passage of current, and an iron wire core. The +repulsive action upon the closed conductor lifts and regulates the +carbons in much the same manner that electro magnets do when continuous +currents are used. The electro-inductive repulsive action has also been +applied to regulating devices for alternating currents, with the details +of which I cannot now deal. + +For the construction of an alternating current motor which can be +started from a state of rest the principle has also been applied, and it +may here be remarked that a number of designs of such motors is +practicable. + +One of the simplest is as follows: The coils, C, Fig. 14, are traversed +by an alternating current and are placed over a coil, B, mounted upon a +horizontal axis, transverse to the axis of the coil, C. The terminals of +the coil, B, which is wound with insulated wire, are carried to a +commutator, the brushes being connected by a wire, as indicated. The +commutator is so constructed as to keep the coil, B, on short circuit +from the position of coincidence with the plane of C to the position +where the plane of B is at right angles to that of C; and to keep the +coil, B, open-circuited from the right-angled position, or thereabouts, +to the position of parallel or coincident planes. The deflective +repulsion exhibited by B will, when its circuit is completed by the +commutator and brushes, as described, act to place its plane at right +angles to that of C; but being then open-circuited, its momentum carries +it to the position just past parallelism, at which moment it is again +short-circuited, and so on. It is capable of very rapid rotation, but +its energy is small. I have, however, extended the principle to the +construction of more complete apparatus. One form has its revolving +portion or armature composed of a number of sheet iron disks wound as +usual with three coils crossing near the shaft. The commutator is +arranged to short-circuit each of these coils in succession, and twice +in a revolution, and for a period of 90-degrees of rotation each. The +field coils surround the armature, and there is a laminated iron field +structure completing the magnetic circuit. I may say here that +surrounding the armature of a dynamo by the field coils, though very +recently put forth as a new departure, was described in various +Thomson-Houston patents, and to a certain extent all Thomson-Houston +machines embody this feature. + +Figs. 15 and 16 will give an idea of the construction of the motor +referred to. CC' are the field coils or inducing coils, which alone are +put into the alternating current circuit. II is a mass of laminated +iron, in the interior of which the armature revolves, with its three +coils, B, B squared, B cubed, wound on a core of sheet iron disks. The commutator +short-circuits the armature coils in succession in the proper positions +to utilize the repulsive effect set up by the currents which are induced +in them by the alternations in the field coils. The motor has no dead +point, and will start from a state of rest and give out considerable +power, but with what economy is not yet known. + +A curious property of the machine is that at a certain speed, depending +on the rapidity of the alternations in the coil, C, a continuous current +passes from one commutator brush to the other, and it will energize +electro magnets and perform other actions of direct currents. Here we +have, then, a means of inducing direct currents from alternating +currents. To control the speed and keep it at that required for the +purpose, we have only to properly gear the motor to another of the +ordinary type for alternating currents, namely, an alternating-current +dynamo used as a motor. The charging of storage batteries would not be +difficult with such a machine, even from an alternating-current line, +though the losses might be considerable. + + * * * * * + + + + +PHOTOGRAPHIC STUDY OF STELLAR SPECTRA, HARVARD COLLEGE OBSERVATORY. + +HENRY DRAPER MEMORIAL. + +_First Annual Report_. + + +Dr. Henry Draper, in 1872, was the first to photograph the lines of a +stellar spectrum. His investigation, pursued for many years with great +skill and ingenuity, was most unfortunately interrupted in 1882 by his +death. + +The recent advances in dry-plate photography have vastly increased our +powers of dealing with this subject. Early in 1886, accordingly, Mrs. +Draper made a liberal provision for carrying on this investigation at +the Harvard College Observatory, as a memorial to her husband. The +results attained are described below, and show that an opportunity is +open for a very important and extensive investigation in this branch of +astronomical physics. Mrs. Draper has accordingly decided greatly to +extend the original plan of work, and to have it conducted on a scale +suited to its importance. The attempt will be made to include all +portions of the subject, so that the final results shall form a complete +discussion of the constitution and conditions of the stars, as revealed +by their spectra, so far as present scientific methods permit. It is +hoped that a greater advance will thus be made than if the subject was +divided among several institutions, or than if a broader range of +astronomical study was attempted. + +It is expected that a station to be established in the southern +hemisphere will permit the work to be extended so that a similar method +of study may be applied to stars in all parts of the sky. The +investigations already undertaken, and described below more in detail, +include a catalogue of the spectra of all stars north of--24 deg. of the +sixth magnitude and brighter, a more extensive catalogue of spectra of +stars brighter than the eighth magnitude, and a detailed study of the +spectra of the bright stars. + +This last will include a classification of the spectra, a determination +of the wave lengths of the lines, a comparison with terrestrial spectra, +and an application of the results to the measurement of the approach and +recession of the stars. A special photographic investigation will also +be undertaken of the spectra of the banded stars, and of the ends of the +spectra of the bright stars. + +The instruments employed are an eight inch Voigtlander photographic +lens, reground by Alvan Clark & Sons, and Dr. Draper's 11 inch +photographic lens, for which Mrs. Draper has provided a new mounting and +observatory. The 15 inch refractor belonging to the Harvard College +Observatory has also been employed in various experiments with a slit +spectroscope, and is again being used as described below. Mrs. Draper +has decided to send to Cambridge a 28 inch reflector and its mountings, +and a 15 inch mirror, which is one of the most perfect reflectors +constructed by Dr. Draper, and with which his photograph of the moon was +taken. The first two instruments mentioned above have been kept at work +during the first part of every clear night for several months. It is now +intended that at least three telescopes shall be used during the whole +night, until the work is interrupted by daylight. + +The spectra have been produced by placing in front of the telescope a +large prism, thus returning to the method originally employed by +Fraunhofer in the first study of stellar spectra. Four 15 deg. prisms have +been constructed, the three largest having clear apertures of nearly +eleven inches, and the fourth being somewhat smaller. The entire weight +of these prisms exceeds a hundred pounds, and they fill a brass cubical +box a foot on each side. The spectrum of a star formed by this apparatus +is extremely narrow when the telescope is driven by clockwork in the +usual way. A motion is accordingly given to the telescope slightly +differing from that of the earth by means of a secondary clock +controlling it electrically. The spectrum is thus spread into a band, +having a width proportional to the time of exposure and to the rate of +the controlling clock. + +This band is generally not uniformly dense. It exhibits lines +perpendicular to the refracting edge of the prism, such as are produced +in the field of an ordinary spectroscope by particles of dust upon the +slit. In the present case, these lines may be due to variations in the +transparency of the air during the time of exposure, or to instrumental +causes, such as irregular running of the driving clock, or slight +changes in the motion of the telescope, resulting from the manner in +which its polar axis is supported. + +These instrumental defects may be too small to be detected in ordinary +micrometric or photographic observations, and still sufficient to affect +the photographs just described. + +A method of enlargement has been tried which gives very satisfactory +results, and removes the lines above mentioned as defects in the +negatives. A cylindrical lens is placed close to the enlarging lens, +with its axis parallel to the length of the spectrum. In the apparatus +actually employed, the length of the spectrum, and with it the +dispersion, is increased five times, while the breadth is made in all +cases about four inches. The advantage of this arrangement is that it +greatly reduces the difficulty arising from the feeble light of the +star. Until very lately, the spectra in the original negatives were made +very narrow, since otherwise the intensity of the starlight would have +been insufficient to produce the proper decomposition of the silver +particles. The enlargement being made by daylight, the vast amount of +energy then available is controlled by the original negative, the action +of which may be compared to that of a telegraphic relay. The copies +therefore represent many hundred times the original energy received from +the stars. If care is not taken, the dust and irregularities of the film +will give trouble, each foreign particle appearing as a fine spectral +line. + +Our methods of enlargement have been considered, and some of them tried, +with the object of removing the irregularities of the original spectra +without introducing new defects. For instance, the sensitive plate may +be moved during the enlargement in the direction of the spectral lines; +a slit parallel to the lines may be used as the source of light, and the +original negative separated by a small interval from the plate used for +the copy; or two cylindrical lenses may be used, with their axes +perpendicular to each other. In some of these ways the lines due to dust +might either be avoided or so much reduced in length as not to resemble +the true lines of the spectrum. + +The 15 inch refractor is now being used with a modification of the +apparatus employed by Dr. Draper in his first experiments--a slit +spectroscope from which the slit has been removed. A concave lens has +been substituted for the collimator and slit, and besides other +advantages, a great saving in length is secured by this change. It is +proposed to apply this method to the 28 inch reflector, thus utilizing +its great power of gathering light. + +[A description of an accompanying plate here follows, which is omitted, +as the plate cannot be easily reproduced for ordinary press printing.] + +The results to be derived from the large number of photographs already +obtained can only be stated after a long series of measurements and a +careful reduction and discussion of them. An inspection of the plates, +however, shows some points of interest. A photograph of _a Cygni_, taken +November, 26, 1886, shows that the H line is double, its two components +having a difference in wave length of about one ten-millionth of a +millimeter. A photograph of _o Ceti_ shows that the lines G and _h_ are +bright, as are also four of the ultra-violet lines characteristic of +spectra of the first type. The H and K lines in this spectrum are dark, +showing that they probably do not belong to that series of lines. The +star near _[chi]' Orionis_, discovered by Gore, in December, 1885, gives +a similar spectrum, which affords additional evidence that it is a +variable of the same class as _o Ceti_. Spectra of _Sirius_ show a large +number of faint lines besides the well-known broad lines. + +The dispersion employed in any normal map of the spectrum may be +expressed by its scale, that is, by the ratio of the wave length as +represented to the actual wave length. It will be more convenient to +divide these ratios by one million, to avoid the large numbers otherwise +involved. If one millionth of a millimeter is taken as the unit of wave +length, the length of this unit on the map in millimeters will give the +same measure of the dispersion as that just described. When the map is +not normal, the dispersion of course varies in different parts. It +increases rapidly toward the violet end when the spectrum is formed by a +prism. Accordingly, in this case the dispersion given will be that of +the point whose wave length is 400. + +This point lies near the middle of the photographic spectrum when a +prism is used, and is not far from the H line. The dispersion may +accordingly be found with sufficient accuracy by measuring the interval +between the H and K lines, and dividing the result in millimeters by +3.4, since the difference in their wave lengths equals this quantity. +The following examples serve to illustrate the dispersion expressed in +this way: Angstrom, Cornu, 10; Draper, photographer of normal solar +spectrum, 3.1 and 5.2; Rowland, 23, 33, and 46; Draper, stellar spectra, +0.16; Huggins, 0.1. + +The most rapid plates are needed in this work, other considerations +being generally of less importance. Accordingly, the Allen and Rowell +extra quick plates have been used until recently. It was found, however, +that they were surpassed by the Seed plates No. 21, which were +accordingly substituted for them early in December. Recognizing the +importance of supplying this demand for the most sensitive plates +possible, the Seed Company have recently succeeded in making still more +sensitive plates, which we are now using. The limit does not seem to be +reached even yet. Plates could easily be handled if the sensitiveness +were increased tenfold. A vast increase in the results may be +anticipated with each improvement of the plates in this respect. +Apparatus for testing plates, which is believed to be much more accurate +than that ordinarily employed, is in course of preparation. It is +expected that a very precise determination will be made of the rapidity +of the plates employed. Makers of very rapid plates are invited to send +specimens for trial. + +The photographic work has been done by Mr. W.P. Gerrish, who has also +rendered important assistance in other parts of the investigation. He +has shown great skill in various experiments which have been tried, and +in the use of various novel and delicate instruments. Many of the +experimental difficulties could not have been overcome but for the +untiring skill and perseverance of Mr. George B. Clark, of the firm of +Alvan Clark & Sons, by whom all the large instruments have been +constructed. + +The progress of the various investigations which are to form a part of +this work is given below: + +1. _Catalogue of Spectra of Bright Stars_.--This is a continuation of +the work undertaken with the aid of an appropriation from the Bache +fund, and described in the Memoirs of the American Academy, vol. xi., p. +210. The 8 inch telescope is used, each photograph covering a region of +10 deg. square. The exposures for equatorial stars last for five minutes, +and the rate of the clock is such that the spectra have a width of about +0.1 cm. The length of the spectra is about 1.2 cm. for the brighter, and +0.6 cm. for the fainter stars. The dispersion of the scale proposed +above is 0.1. + +The spectra of all stars of the sixth magnitude and brighter will +generally be found upon these plates, except in the case of red stars. +Many fainter blue stars also appear. Three or four exposures are made +upon a single plate. The entire sky north of -24 deg. would be covered +twice, according to this plan, with 180 plates and 690 exposures. It is +found preferable in some cases to make only two exposures; and when the +plate appears to be a poor one, the work is repeated. The number of +plates is therefore increased. Last summer the plates appeared to be +giving poor results. Dust on the prisms seemed to be the explanation of +this difficulty. Many regions were reobserved on this account. The first +cycle, covering the entire sky from zero to twenty-four hours of right +ascension, has been completed. + +The work will be finished during the coming year by a second cycle of +observations, which has already been begun. The first cycle contains 257 +plates, all of which have been measured, and a large part of the +reduction completed. 8,313 spectra have been measured on them, nearly +all of which have been identified, and the places of a greater portion +of the stars brought forward to the year 1900, and entered in catalogue +form. In the second cycle, 64 plates have been taken, and about as many +more will be required. 51 plates have been measured and identified, +including 2,974 spectra. A study of the photographic brightness and +distribution of the light in the spectra will also be made. + +The results will be published in the form of a catalogue resembling the +Photometric Catalogue given in volume xiv. of the Annals of Harvard +College Observatory. It will contain the approximate place of each star +for 1900, its designation, the character of the spectrum as derived from +each of the plates in which it was photographed, the references to these +plates, and the photographic brightness of the star. + +2. _Catalogue of Spectra of Faint Stars_.--This work resembles the +preceding, but is much more extensive. The same instrument is used, but +each region has an exposure of an hour, the rate of the clock being such +that the width of the spectrum will be as before 0.1 cm. Many stars of +the ninth magnitude will thus be included, and nearly all brighter than +the eighth. In one case, over three hundred spectra are shown on a +single plate. This work has been carried on only in the intervals when +the telescope was not needed for other purposes. 99 plates have, +however, been obtained, and on these 4,442 spectra have been measured. +It is proposed to complete the equatorial zones first, gradually +extending the work northward. In all, 15,729 spectra of bright and faint +stars have been measured. + +3. _Detailed Study of the Spectra of the Brighter Stars_.--This work has +been carried on with the 11 inch photographic telescope used by Dr. +Draper in his later researches. A wooden observatory was constructed +about 20 feet square. This was surmounted by a dome having a clear +diameter of 18 feet on the inside. The dome had a wooden frame, sheathed +and covered with canvas. It rested on eight cast iron wheels, and was +easily moved by hand, the power being directly applied. Work was begun +upon it in June, and the first observations were made with the telescope +in October. + +Two prisms were formed by splitting a thick plate of glass diagonally. +These gave such good results that two others were made in the same way, +and the entire battery of four prisms is ordinarily used. The safety and +convenience of handling the prisms is greatly increased by placing them +in square brass boxes, each of which slides into place like a drawer. +Any combination of the prisms may thus be employed. As is usual in such +an investigation, a great variety of difficulties have been encountered, +and the most important of them have now been overcome. + +4. _Faint Stellar Spectra_.--The 28 inch reflector will be used for the +study of the spectra of the faint stars, and also for the fainter +portions near the ends of the spectra of the brighter stars. The form of +spectroscope mentioned above, in which the collimator and slit are +replaced by a concave lens, will be tried. The objects to be examined +are, first, the stars known to be variable, with the expectation that +some evidence may be afforded of the cause of the variation. The stars +whose spectrum is known to be banded, to contain bright lines, or to be +peculiar in other respects, will also be examined systematically. +Experiments will also be tried with orthochromatic plates and the use of +a colored absorbing medium, in order to photograph the red portions of +the spectra of the bright stars. Quartz will also be tried to extend the +images toward the ultra-violet. + +5. _Absorption Spectra_.--The ordinary form of comparison spectrum +cannot be employed on account of the absence of a slit. The most +promising method of determining the wave lengths of the stellar spectra +is to interpose some absorbent medium. Experiments are in progress with +hyponitric fumes and other substances. A tank containing one of these +materials is interposed and the spectra photographed through it. The +stellar spectra will then be traversed by lines resulting from the +absorption of the media thus interposed, and, after their wave lengths +are once determined, they serve as a precise standard to which the +stellar lines may be referred. The absorption lines of the terrestrial +atmosphere would form the best standard for this purpose if those which +are sufficiently fine can be photographed. + +6. _Wave Lengths_.--The determination of the wave lengths of the lines +in the stellar spectra will form an important part of the work which has +not yet been begun. The approximate wave lengths can readily be found +from a comparison with the solar spectrum, a sufficient number of solar +lines being present in most stellar spectra. If, then, satisfactory +results are obtained in the preceding investigation, the motion of the +stars can probably be determined with a high degree of precision. The +identification of the lines with those of terrestrial substances will of +course form a part of the work, but the details will be considered +subsequently. + +From the above statement it will be seen that photographic apparatus has +been furnished on a scale unequaled elsewhere. But what is more +important, Mrs. Draper has not only provided the means for keeping these +instruments actively employed, several of them during the whole of every +clear night, but also of reducing the results by a considerable force of +computers, and of publishing them in a suitable form. A field of work of +great extent and promise is open, and there seems to be an opportunity +to erect to the name of Dr. Henry Draper a memorial such as heretofore +no astronomer has received. One cannot but hope that such an example may +be imitated in other departments of astronomy, and that hereafter other +names may be commemorated, not by a needless duplication of unsupported +observatories, but by the more lasting monuments of useful work +accomplished. + +EDWARD C. PICKERING, + +_Director of Harvard College Observatory_. + +Cambridge, Mass., U.S.A., March 1, 1887. + + * * * * * + + + + +THE WINNER OF THE DERBY. + + +The dark bay colt Merry Hampton had never run in public before winning +the Derby on the 25th of May last. This colt, by Hampton out of Doll +Tear-sheet, was one of Mr. Crowther Harrison's draught of yearlings sent +up to the Doncaster sales in 1885, and fell to the bid of Mr. T. Spence, +acting for Mr. Abingdon, for 3,100 guineas. The Oaks, on May 27, was won +by a daughter of the same sire. Merry Hampton is to compete for the +Grand Prize of Paris and for the St. Leger. He has also liabilities in +the Thirty-ninth Triennial and Grand Duke Michael stakes at Newmarket, +First October; Newmarket Derby at the Second October; Ascot Derby and +Twenty-fifth New Biennial; Drawing-room stakes at Goodwood; Great +International Breeders' Foal stakes at Kempton Park, August; North Derby +at Newcastle, Summer; St. George stakes at Liverpool, July; Bickerstaffe +stakes and St. Leger at Liverpool, August; Midland Derby stakes at +Leicester, July; and Ebor St. Leger at York, August; in addition to the +following races in 1888: Champion stakes at Newmarket, Second October; +Rous Memorial and Hardwicke stakes at Ascot, and Eclipse stakes at +Sandown Park, Second Summer. Merry Hampton's name also appears in the +Kempton Park Royal stakes of 10,000 sovereigns at the Spring Meeting of +1889.--_Ill. London News_. + +[Illustration: MERRY HAMPTON. THE WINNER OF THE DERBY, 1887.] + + * * * * * + + + + +THE FALLS OF GAIRSOPPA. + + +At the extreme south of the presidency of Bombay, separating the +district of Kanara from the territory of Mysore, are the too little +known Falls of Gairsoppa. + +Far higher than Niagara, four distinct divisions of the river Shiravatti +(traditionally created by a cleft made by the arrow of the great god +Rama) fall over a precipice of gneiss rock into an abyss eight hundred +feet below. Each of these cataracts differs in type of flow. + +The "Rajah," eight hundred and thirty feet, and at a breadth of +fifty-six, shoots silent and sheer over an uplifted lip of rock in the +bed of the stream, casting a dark shadow behind him when faced by the +sun; the "Roarer" makes noise enough in its headlong rush to vibrate the +strong, stone-built travelers' bungalow on the heights above; the +"Rocket" is straight in descent, and, as a commentator has already +remarked, as much like a rocket as anything else; and "La Dame Blanche," +a triptych of rhythmical flow, spreads a dainty, silky, sheen of white, +whispering, glistening, softly falling water over a slightly shelving +width of rock, touched here and there with prismatic color and strong +light. + +[Illustration: THE FALLS OF GAIRSOPPA, BETWEEN KANARA AND MYSORE, BOMBAY +PRESIDENCY, INDIA + +The Falls From Below. The Falls From Above.] + +At the bottom of the chasm, seven hundred feet across, and stretching +over a muddy, turbulent, seething cauldron of spray, a brilliantly +distinct rainbow in the full light of day may be seen with its scarcely +less glorious reflection, dazzlingly beautiful. + +In these regions 210 inches of rain is an average downpour for the +monsoon between May and October, the heaviest fall being generally in +July. The cataracts then become frequently confluent, though not more +picturesque. They are then too difficult of access, and the whole +district is very malarious. December and January are the best months for +travelers, before the dry season fairly sets in again, during which +there is but little water, even insufficient to form four distinct +falls. + +The best route to them is from Bombay to Honaurre by sea, _via_ Kawai, +and on to Old Gairsoppa by river boat and palanquin to the "Jog," as the +special points of interest (the "Falls") are called by the Kanarese. + +To the enthusiastic shikari, however, the way from Hubli (on the +Southern Mahratta Railway, easily reached by G.I.P. line from Bombay), +taking him, as it does, through the very happiest hunting grounds of the +presidency, where all game, small and large, abounds, will have +attraction enough; and at Giddapur, the last stage, within twelve miles +of the Falls, there is a courteous English-speaking native magistrate, +willing and able to help the traveler on his way. Our engravings are +from drawings by Mr. J.E. Page, C.E.--_London Graphic_. + + * * * * * + + + + +SPONGES. + + +As the last of a course of lectures upon "Recent Scientific Researches +in Australasia," Dr. R. Von Ledenfeld lately delivered a lecture at the +Royal Institution, upon "Recent Additions to our Knowledge of Sponges." +The lecturer did not confine himself to the sponges of Australia alone, +but gave a _resume_ of the results of recent investigations on sponges, +together with several new interesting details observed more especially +in studying the growth of Australian sponges. With a passing reference +to some peculiarities of the lower marine animals of the Australian +coast, Dr. Ledenfeld remarked upon the preponderance of sponges over +other forms of marine life in that part of the world. It has long been a +point of discussion as to whether sponges belong to the vegetable or +animal kingdom, but naturalists are now generally agreed in regarding +them as animals, a conclusion, the lecturer remarked, that Aristotle had +also arrived at. + +Sponges grow in a variety of more or less irregular shapes, but it has +been observed that the most regular structures occur in the calcareous +species. As to color, Dr. Ledenfeld remarked that some of the Australian +sponges are of exceptionally brilliant hues, while others range from the +black of the common sponge _(Euspongia officinalis)_ to a pure white. +Also, it may be remarked, the sponges growing in deep water are of less +decided color and more elastic in character than those living in shallow +water, and from the last named quality are more valuable in commerce. +The irregular honeycombed appearance of the sponge is due to a most +complicated canal system, consisting of a series of chambers through +which the water is drawn by the animal in always the same direction. + +The inhalent pores are very minute, and open into small subdermal +cavities which communicate by means of interradial tubes with the +ciliated chambers, the latter being very small ramifications of the +interradial channels, and in them the movement causing the current of +water is maintained. From hence all faecal and other matter is +discharged through the oscula, the larger openings observed on the +surface of the sponge. Dr. Ledenfeld showed the different parts of +sponges by means of microscopic slides thrown on to a screen, and also +the shape and arrangement of the chambers in different species. The +ciliated chambers especially attracted attention. They are very small +and circular, and the interior is clothed with cells very similar to the +cilia cells in higher animal life. + +These cells are arranged around the ciliated chambers in the form of a +collar, and from each cell flagella protrude, which are in continual +motion. These flagella, like bats' wings, are capable of being bent in +only one direction, so that, in the course of their pendulum-like +motion, in the movement one way the flagella are bent, while in the +return movement they remain stiff, thus causing a current of water +always flowing in one and the same direction. These ciliated chambers +are easily detected in the sponge by means of a microscope, as they +appear more highly colored. After the lecturer had thus given a general +outline of the structure of the sponge, he drew attention to the +character of its food and its method of digestion. It is not known +exactly what the sponge lives upon, but if upon other animals they must +be necessarily very small, owing to the size of its inhalent pores. + +The sponge, like the tape-worm, has no stomach, but must absorb its food +through the outer skin from matter in a soluble state, similarly to the +roots of trees. This process of absorption is probably accomplished in +the interradial or ciliated chambers, more probably in the former, as +the latter are generally considered excretory in function. Lime or +silica must also be absorbed from the water by most sponges in order to +make up the skeleton. The skeleton of calcareous sponges consists of a +number of spicules composed of carbonate of lime. These spicules are of +very varied though regular shape, but ordinarily assume a rod-like +needle shape or else a stellate form. In silicious sponges the spicules +are composed of silica, and are generally deposited around axial rods in +concentric layers. The spicules are joined together and cemented by a +body that has been named "spongin," which has much the same chemical +composition as silk, and, like silk, is very elastic. In some varieties +of sponges, especially in the kinds which come into the market, the +skeleton is almost entirely composed of fibers of pure "spongin." These +fibers are so close together as to draw up water by capillary action, +and, indeed, a great deal in the value of a sponge depends upon the +fineness and tenuity of these fibers. + +Dr. Ledenfeld again illustrated this stage of his lecture by means of a +number of microscopic slides in which the variety of shape and size of +these spicules and "spongin" fibers were shown. The spicules are some +crutch-like, others spined or echinated, while the deep-sea sponges +appear to grow long thick spicules, which attach the sponge to the +ground by means of grapnel-like ends. In some cases the skeleton seems +to be more or less replaced by sand, the small grains of which are +cemented together by the "spongin." + +Dr. Ledenfeld then drew attention to the presence of more highly +developed organs in the sponge. Muscles pervade the whole tissue of the +sponge, but are found more particularly in the superficial parts. One +set of muscles affect the size of the inhalent pores, causing them to +contract or expand, while another set are able to close the pores +altogether, thus acting as a protection from the attack of an enemy. All +these muscles are composed of spindle shaped cells, which are capable of +spasmodic motion, but recently in an Australian sponge, the _Euspongia +canalicula_, the lecturer said he had observed muscles approaching very +nearly in character those of the human frame. + +That sponges have nerves is a discovery of recent date by a member of +the Royal Microscopical Society. Dr. Ledenfeld also about the same time +found indications of the presence of a nervous system, but the form in +which he observed the nerves at first apparently differed from those +observed simultaneously. This difference, however, he afterward found to +be due to the manner in which the section had been prepared for +observation. The nerves consist of two cells at the base of a cone-like +projection on the epidermis, and from each cell a fiber runs to the +point of the cone, besides several others connecting them with the +interior of the sponge. + +It is remarkable that here again Aristotle has predicted that sponges +have a nervous system, basing his statement on the fact that ancient +Greek mariners foretold storms by the alleged contraction of the sponge. +The reproductive organs of sponges are also very highly developed, and +both ova and spermatozoa are found throughout the sponge, though more +concentrated in the interior. The ova consist of spherical cells, while +the spermatozoa resemble an arrow-head in shape. It has not yet been +ascertained whether two sexes exist in sponges, or whether the ova and +spermatozoa are produced at different periods by the same sponge. When +the embryo has become partly developed, it detaches itself from the +parent sponge, and, issuing from the oscula, propels itself through the +water by means of a number of flagella. + +Silicious spicules next appear in its structure, and it then attaches +itself to a rock and assumes its mature form. Sponges are most numerous +in the waters of the temperate and sub-tropical zones, and the +salt-water varieties are by far more numerous than the fresh water. +Thus, while there are not more than ten fresh-water species known, Dr. +Ledenfeld remarked that about one thousand species of salt-water sponges +had been recognized. Each species of the salt-water sponge is, however, +generally found only in limited areas, and very few, all of which +inhabit deep water, are cosmopolitan. This is the more remarkable as Dr. +Ledenfeld asserts that all the sponges inhabiting the rivers of +Australia are identical with the fresh-water sponges of Europe, and in +order to explain this fact he put forward a rather interesting theory. +He assumes that sponge life in rivers has been originally generated by +the introduction of a single, or at most two or three germs by means of +aquatic birds. The inbreeding consequent upon this paucity of sponge +life has produced a certain fixity of character in fresh-water sponges, +and is in direct opposition to the effects of hybridization in the +salt-water sponges, by which they have acquired the capacity of adapting +themselves to local circumstances. + + * * * * * + + + + +HERBET'S TEPID DOUCHE. + + +Keeping the body clean is indispensable for the preservation of good +health, through obtaining an operation of the skin and expelling matter +whose presence aids in the development of diseases. It is unfortunately +necessary to say that, considering the population as a whole, the +proportion of those who take baths is very small. This is due to the +fact that the habit of cleanliness, which should become a necessity, has +not been early inculcated in every individual; and the reason that this +complement to education is not realized is because the means of +satisfying its exigencies are usually wanting. + +We shall not speak of the improved processes that are used solely by the +rich or well-to-do, as these become impracticable where it is a question +of the working classes or of large masses of individuals. It is, in +fact, the last named category that interests us, and we are convinced +that if we get young soldiers and children to hold dirtiness in horror, +we shall be sure that they will later on take care of their bodies +themselves. + +The most tempting solution of this question of washing seems to be found +in the use of large pools of running tepid water; but such a process is +too costly for general use, and the most economical one, without doubt, +consists in giving tepid douches. + +[Illustration: TEPID WATER DOUCHE] + +To our knowledge, the only apparatus in this line that has been devised +was exhibited last year at the exhibition of hygiene in the Loban +barracks. It has been used daily for six years in several garrisons, and +therefore has the sanction of practice. + +This apparatus, which is due to Mr. Herbet, consists of a steam boiler +and of an ejector fixed to a reservoir of water and provided with a +rubber tube to which a nozzle is attached. The steam generated in the +boiler passes into the ejector, sucks up the water and forces it out in +a tepid state. + +The apparatus thus established did not sufficiently fulfill the purpose +for which it was designed. It was necessary to have a means of varying +the temperature of the water projected, according to the season and +temperature of the air, to have an instantaneous and simple method of +regulating the apparatus, that could be understood by any operator, and +to have the apparatus under the control of the person holding the +nozzle. These difficulties have been solved very simply by causing the +orifice of the nozzle to vary. This nozzle, from whence the jet escapes, +is formed of rings that screw together. When the nozzle is entire, the +jet escapes at a temperature of say 40 deg.. When the first ring is +unscrewed, the water will make its exit at a temperature of 38 deg.. In +order to lower the temperature still further, it is only necessary to +unscrew the other rings in succession, until the desired temperature has +been obtained. + +As it is, the apparatus is rendering great services where it has been +introduced; for example, at Besancon and Belfort. It serves, in fact, +for an entire garrison, while that before, the washing was done in each +regiment, thus requiring the use of much space and causing much loss of +time. + +Eight men are washed at once for five minutes, say 96 men per hour. +Every minute the men turn right about face, and when they are in file +each rubs the other's back. + +Twenty-two pounds of coal and 260 gallons of water are consumed per +hour, and the boiler produces 130 lb. of steam.--_Le Genie Civil_. + + * * * * * + + + + +HOW TO MAKE A STAR FINDER. + + +Being all of wood, it is easily made by any one who can use a few tools, +the only bit of lathe work necessary being the turned shoulder, K, of +polar axis. A is the baseboard, 9 in. by 5 in., near each corner of +which is inserted an ordinary wood screw, S S, for the purpose of +leveling the base, to which two side pieces are nailed, having the +angle, _x_, equal to the co-latitude of the place. On to these side +pieces is fastened another board, on which is marked the hour circle, F. +Through this board passes the lower end of the polar axis, having a +shoulder turned up on it at K, and is secured by a wooden collar and pin +underneath. On to the upper part of the polar axis is fastened the +declination circle, C, 51/2 in. diameter, made of 1/4 in. baywood, having +the outer rim of a thin compass card divided into degrees pasted on to +it. The hour circle, F, is half of a similar card, with the hours +painted underneath, and divided to 20 minutes. G is the hour index. D is +a straight wooden pointer, 12 in. long, having a piece of brass tube, E, +attached, and a small opening at J, into which is fixed the point of a +common pin by which to set the pointer in declination. H is a nut to +clamp pointer in position. By this simple toy affair I have often picked +up the planet Venus at midday when visible to the naked eye.--_T.R. +Clapham in English Mechanic_. + +[Illustration: A STAR FINDER.] + + * * * * * + +The best mode of finding or tracing trichinae in pork by means of a +microscope is the following: Cut a very thin longitudinal slice of the +muscle by means of a very sharp knife or razor. Press it between two +glass slips, and examine by transmitted light, The coiled trichinae may +be readily distinguished from the muscle fiber. + + * * * * * + + + + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + +PUBLISHED WEEKLY. + +TERMS OF SUBSCRIPTION, $5 A YEAR. + + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of THE SUPPLEMENT, from the commencement, January +1, 1876, can be had. Price, 10 cents each. + +All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. Price of each volume, $2.50, stitched in +paper, or $3.50, bound in stiff covers. + +COMBINED RATES--One copy of SCIENTIFIC AMERICAN and one copy of +SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00. + +A liberal discount to booksellers, news agents, and canvassers. + +MUNN & CO., PUBLISHERS, + +361 BROADWAY, NEW YORK, N.Y. + + * * * * * + + + + +PATENTS. + + +In connection with the SCIENTIFIC AMERICAN, Messrs. MUNN & Co. are +Solicitors of American and Foreign Patents, have had 42 years' +experience, and now have the largest establishment in the world. Patents +are obtained on the best terms. + +A special notice is made in the SCIENTIFIC AMERICAN of all Inventions +patented through this Agency, with the name and residence of the +Patentee. By the immense circulation thus given, public attention is +directed to the merits of the new patent, and sales or introduction +often easily effected. + +Any person who has made a new discovery or invention can ascertain, free +of charge, whether a patent can probably be obtained, by writing to MUNN +& Co. + +We also send free our Hand Book about the Patent Laws, Patents, Caveats, +Trade Marks, their costs, and how procured. Address + +MUNN & CO., 361 BROADWAY, NEW YORK. + +Branch Office, 622 and 624 F St., Washington, D.C. + + +THE SCIENTIFIC AMERICAN + +Architects and Builders Edition. + +$2.50 a Year. Single Copies, 25 Cents. + +This is a Special Edition of THE SCIENTIFIC AMERICAN, issued monthly--on +the first day of the month. 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All who contemplate building or +improving homes, or erecting structures of any kind, have before them in +this work an almost _endless series of the latest and best examples_ +from which to make selections, thus saving time and money. + +Many other subjects, including Sewerage, Piping, Lighting, Warming, +Ventilating, Decorating, Laying out of Grounds, etc., are illustrated. +An extensive Compendium of Manufacturers Announcements is also given, in +which the most reliable and approved Building Materials, Goods, +Machines, Tools, and Appliances are described and illustrated, with +addresses of the makers, etc. + +The fullness, richness, cheapness, and convenience of this work have won +for it the LARGEST CIRCULATION OF any Architectural publication in the +world. + +MUNN & CO., Publishers, 361 Broadway, New York. + +A Catalogue of valuable books on Architecture, Building, Carpentry, +Masonry, Heating, Warming, Lighting, Ventilation, and all branches of +industry pertaining to the art of Building, is supplied free of charge, +sent to any address. + + * * * * * + +BUILDING PLANS and SPECIFICATIONS. + +In connection with the publication of the BUILDING EDITION of the +SCIENTIFIC AMERICAN, Messrs. 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