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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:37:05 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:37:05 -0700 |
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diff --git a/11498-h/11498-h.htm b/11498-h/11498-h.htm new file mode 100644 index 0000000..e18b2ee --- /dev/null +++ b/11498-h/11498-h.htm @@ -0,0 +1,4752 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta name="generator" content="HTML Tidy, see www.w3.org"> +<meta http-equiv="Content-Type" content= +"text/html; charset=ISO-8859-1"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, July 9, 1887</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +--> +</style> +</head> +<body> + + +<pre> + +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: ISO-8859-1 + +*** 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 + + + + + + +</pre> + +<p class="ctr"><a href="./illustrations/1a.png"><img src= +"./illustrations/1a_th.jpg" alt=""></a></p> + +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 601</h1> + +<h2>NEW YORK, JULY 9, 1887</h2> + +<h4>Scientific American Supplement. Vol. XXIV, No. 601.</h4> + +<h4>Scientific American established 1845</h4> + +<h4>Scientific American Supplement, $5 a year.</h4> + +<h4>Scientific American and Supplement, $7 a year.</h4> + +<hr> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> + +<tr> +<td valign="top">I.</td> +<td><a href="#1">ASTRONOMY.--A Star Finder.--A simple apparatus +that can be constructed by any mechanic.--1 illustration.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#2">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.</a></td> +</tr> + +<tr> +<td valign="top">II.</td> +<td><a href="#3">BIOLOGY.--Sponges.--The growth and life history of +sponges.--Report of a recent lecture at the London Royal +Institution by Dr. R. VON LEDENFELD.</a></td> +</tr> + +<tr> +<td valign="top">III.</td> +<td><a href="#4">ELECTRICITY.--Phenomena of Alternating +Currents.--By Prof. ELIHU THOMSON.--16 illustrations.</a></td> +</tr> + +<tr> +<td valign="top">IV.</td> +<td><a href="#5">ENGINEERING.--An English Car +Coupling.--Description of an English automatic coupling.--2 +illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#6">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.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#7">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.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#8">Link Belting.--By CHARLES A. SCHIEREN.--An +interesting and practical paper on leather belting made of links. +--9 illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#9">Recent Progress in Gas Engineering.--A lecture by +Mr. A. MACPHERSON, of Kirkcaldy, reviewing the last improvements in +this branch.</a></td> +</tr> + +<tr> +<td valign="top">V.</td> +<td><a href="#10">MISCELLANEOUS.--Herbet's Tepid Douche.--Apparatus +in use for bathing soldiers in the French barracks.--1 +illustration.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#11">Kent's Torsion Balance.--A new type of balance, +involving torsional suspension instead of knife edges.--5 +illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#12">Preservative Liquid.--Note on preservation of +organic substances.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#13">The Falls of Gairsoppa.--The great Indian falls, +higher than Niagara.--2 illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#14">The New British Coinage and Jubilee +Medal.--Illustrations and descriptions of the new pieces.--8 +illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#15">The Winner of the Derby.--Portrait and +description of Merry Hampton.</a></td> +</tr> + +<tr> +<td valign="top">VI.</td> +<td><a href="#16">NAVAL ENGINEERING.--The Falke Type Torpedo +Boat.--The fastest type of British torpedo boat, constructed by +Messrs. Yarrow & Co.--1 illustration.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#17">The German Navy.--The New Gunboat Eber.--A +description of a late accession to the German navy.--1 +illustration.</a></td> +</tr> + +<tr> +<td valign="top">VII.</td> +<td><a href="#18">ORDNANCE AND GUNNERY.--Magazine +Rifles.--Continuation of this important article, including the +Chaffee-Reece, Kropatschek, and other magazine guns.--3 +illustrations.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#19">New British Torpedo Experiments.--Experiments +with torpedoes against a ship.--The efficiency or torpedo +nets.--The effects of Whitehead torpedoes.</a></td> +</tr> +</table> + +<hr> +<p><a name="16"></a></p> + +<h2>THE FALKE TYPE TORPEDO BOAT.</h2> + +<p>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 26½ 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.--<i>Illustrated London News</i>.</p> + +<p class="ctr"><a href="./illustrations/1b.png"><img src= +"./illustrations/1b_th.jpg" alt= +"THE 'FALKE' TYPE TORPEDO BOAT, AND SECTION SHOWING GENERAL ARRANGEMENT."> +</a></p> + +<p class="ctr">THE "FALKE" TYPE TORPEDO BOAT, AND SECTION SHOWING +GENERAL ARRANGEMENT.</p> + +<hr> +<p><a name="17"></a></p> + +<h2>THE GERMAN NAVY--THE NEW GUNBOAT EBER.</h2> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><a href="./illustrations/1c.png"><img src= +"./illustrations/1c_th.jpg" alt="THE NEW GERMAN GUNBOAT EBER."> +</a></p> + +<p class="ctr">THE NEW GERMAN GUNBOAT EBER.</p> + +<p>The Eber is provided with a two-cylinder, compound engine, which +can generate 650 horse power, giving the vessel a speed of +11½ 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.</p> + +<p>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.--<i>Illustrirte +Zeitung</i>.</p> + +<hr> +<p><a name="19"></a></p> + +<h2>NEW BRITISH TORPEDO EXPERIMENTS.</h2> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The height of the double bottom between the outer and inner skin +plating is 2½ 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 +1½ 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.</p> + +<p>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 <i>coup de grace</i> was not given by means of a +service Whitehead in actual contact until various lessons had been +derived.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The question was sufficiently important to demand an +experimental solution; hence the <i>raison d'etre</i> of the +present demonstration. The double bottom, which is about 2½ +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.</p> + +<p>A complete knowledge of the disaster which has overtaken her +(says the correspondent of the London <i>Times</i>, 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.</p> + +<hr> +<p><a name="5"></a></p> + +<h2>AN ENGLISH CAR COUPLING.</h2> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><a href="./illustrations/3a.png"><img src= +"./illustrations/3a_th.jpg" alt="AN ENGLISH CAR COUPLING."></a></p> + +<p class="ctr">AN ENGLISH CAR COUPLING.</p> + +<p>The trial couplings were applied to old and worn-out coal +wagons, varying in relative heights and widths of buffers, and the +tests were:</p> + +<p>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.</p> + +<p>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.</p> + +<p>The coupling is strong as well as elastic in its parts, and +adjusts itself to the various conditions of +traction.--<i>Engineering</i>.</p> + +<hr> +<p>[Continued from SUPPLEMENT, No. 597, page 9539.]</p> + +<p><a name="18"></a></p> + +<h2>MAGAZINE RIFLES.</h2> + +<p><i>Chaffee-Reece Magazine Rifle</i>.--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.</p> + +<p class="ctr"><img src="./illustrations/3b.png" alt= +"FIG. 9.--KROPATSCHEK MAGAZINE GUN"></p> + +<p class="ctr">FIG. 9.--KROPATSCHEK MAGAZINE GUN</p> + +<p>By means of a cut-off the ratchet bars can be prevented from +acting, and the piece used as a single loader.</p> + +<p><i>Kropatschek Magazine Rifle</i>.--This rifle, which is the +small arm of the French navy, has a bolt-action rifle resembling +the Gras (see Fig. 9).</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/3c.png" alt= +"FIG. 10.--LEE MAGAZINE GUN"></p> + +<p class="ctr">FIG. 10.--LEE MAGAZINE GUN</p> + +<p>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.</p> + +<p><i>Lee Magazine Rifle</i>.--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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p><i>Improved Lee</i>.--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.</p> + +<p><i>Lee-Burton</i>.--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.</p> + +<p class="ctr"><img src="./illustrations/4a.png" alt= +"FIG. 11."></p> + +<p class="ctr">FIG. 11.</p> + +<p>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.</p> + +<p>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.--<i>Engineering</i>.</p> + +<p>(<i>To be continued</i>.)</p> + +<hr> +<p><a name="12"></a></p> + +<h2>PRESERVATIVE LIQUID.</h2> + +<p>For a few weeks' preservation of organic objects in their +original form, dimensions, and color, Prof. Grawitz recommends a +mixture composed of 2½ ounces of chloride of sodium, +2¾ drachms of saltpeter, and 1 pint of water, to which is to +be added 3 per cent. of boric acid.--<i>Annales des Travaux +Publics</i>.</p> + +<hr> +<p><a name="11"></a></p> + +<h2>KENT'S TORSION BALANCE.</h2> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/4b.png" alt= +"KENT'S TORSION BALANCE. Fig 1."></p> + +<p class="ctr">KENT'S TORSION BALANCE. Fig 1.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/4c.png" alt= +"KENT'S TORSION BALANCE. Fig 2."></p> + +<p class="ctr">KENT'S TORSION BALANCE. Fig 2.</p> + +<p>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:</p> + +<p>"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 <i>raison +d'etre."</i></p> + +<p class="ctr"><img src="./illustrations/4d.png" alt= +"KENT'S TORSION BALANCE. Fig 3."></p> + +<p class="ctr">KENT'S TORSION BALANCE. Fig 3.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><a href="./illustrations/4e.png"><img src= +"./illustrations/4e_th.jpg" alt="KENT'S TORSION BALANCE. Fig 4."> +</a></p> + +<p class="ctr">KENT'S TORSION BALANCE. Fig 4.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/4f.png" alt= +"KENT'S TORSION BALANCE. Fig 5."></p> + +<p class="ctr">KENT'S TORSION BALANCE. Fig 5.</p> + +<p>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 (10½ in. +by 4¼ in. by 3¾ in.), we have a balance capable of +weighing 3 lb. avoirdupois by thirty-seconds of an ounce.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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; <i>t</i> is another truss with +stretched wire, F F¹. 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, <i>t</i>. 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, <i>t</i>, 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.--<i>Engineering</i>.</p> + +<hr> +<p><a name="8"></a></p> + +<h2>LINK BELTING.</h2> + +<p>[Footnote: From a paper read before the "Technischen Verein" of +New York, May 28, 1887.]</p> + +<h3>By CHAS. A. SCHIEREN.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>For more than twenty years after Mr. Roullier's visit, nothing +was done with leather link belting in this country.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>How have we attained such success? First: We found that Roullier +made a mistake in using leather offal, as, in the links of an +<i>iron chain</i>, 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.</p> + +<p class="ctr"><img src="./illustrations/5a.png" alt="FIG 1."></p> + +<p class="ctr">FIG 1.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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).</p> + +<p>By close inspection you will observe that it is absolutely +necessary to use half length bolts for the width of wide leather +link belts.</p> + +<p>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.</p> + +<p>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.</p> + +<p>We have not stopped at <i>flat</i> 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.</p> + +<p>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.</p> + +<p>Question.--Can these link belts be used on dynamos for electric +lights?</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/5b.png" alt="Fig. 2."></p> + +<p class="ctr">Fig. 2.</p> + +<p>Quest.--Would you advise link belts for high rate of speed?</p> + +<p>Ans.--No; they give better results on slow running +machinery.</p> + +<p>Quest.--Have these belts any special advantage over flat leather +belting?</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/5c.png" alt="Fig. 3."></p> + +<p class="ctr">Fig. 3.</p> + +<p>Quest.--Why do they give better results when run slow?</p> + +<p>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.</p> + +<p>Quest.--Are they more expensive than ordinary flat belting?</p> + +<p>Ans.--Not when compared to the work they can accomplish.</p> + +<p class="ctr"><img src="./illustrations/5d.png" alt=""></p> + +<p>Quest.--Can they be run in wet places, such as mines, etc.?</p> + +<p>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.</p> + +<p>Quest.--Can they be run on ordinary flat pulleys?</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/5e.png" alt= +"ENGLISH HINGE JOINT:"></p> + +<p class="ctr">ENGLISH HINGE JOINT:</p> + +<p>Quest.--How are they made endless?</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/6a.png" alt= +"Fig. 4 is a complete round link belt."></p> + +<p class="ctr">Fig. 4 is a complete round link belt.</p> + +<p>Quest.--What is the relative strength of a link belt compared to +flat belting?</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/6b.png" alt= +"Fig. 5 is a side view."></p> + +<p class="ctr">Fig. 5 is a side view.</p> + +<p>Quest.--Explain the advantage of your American joint over the +English hinge.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/6c.png" alt= +"Fig. 6 is an end view."></p> + +<p class="ctr">Fig. 6 is an end view.</p> + +<p>Quest.--Have you a table or schedule of their weight per square +foot?</p> + +<p>Ans.--Yes. The following is as near as we can estimate the +weight of leather link belting per square foot:</p> + +<pre> + 1 inch thick, about 5 lb. per sq. ft. + 7/8 " " " 4½ " " " + 3/4 " " " 4 " " " + 5/8 " " " 3½ " " " +</pre> + +<p>Upon motion a vote of thanks was passed, and the paper read +ordered to be printed.</p> + +<p class="ctr"><img src="./illustrations/6d.png" alt= +"Fig. 7 is a single link."></p> + +<p class="ctr">Fig. 7 is a single link.</p> + +<hr> +<p><a name="6"></a></p> + +<h2>A NEW PROCESS OF CASTING IRON AND OTHER METALS UPON LACE, +EMBROIDERIES, FERN LEAVES, AND OTHER COMBUSTIBLE MATERIALS.</h2> + +<p>[Footnote: Abstract of a paper read before the Franklin +Institute, April, 1887.--<i>J.F.I.</i>]</p> + +<h3>By A.E. OUTERBRIDGE, JR.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 <i>upon the face of the casting there was found a +sharp and accurate reproduction of the design, thus forming a +die</i>. 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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?</p> + +<p>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.</p> + +<p>Of course, the method employed to carbonize the materials is +suspectible of variation, but the scientific principles involved +are unchangeable, viz.:</p> + +<p>(1) Partial exclusion of air and substitution therefor of a +carbon atmosphere.</p> + +<p>(2) Slow heating to drive off moisture and volatile +elements.</p> + +<p>(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.</p> + +<p class="ctr"><a href="./illustrations/6e.png"><img src= +"./illustrations/6e_th.jpg" alt=""></a></p> + +<p>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.</p> + +<hr> +<p><a name="9"></a></p> + +<h2>RECENT PROGRESS IN GAS ENGINEERING.</h2> + +<p>At the recent meeting of Scottish gas managers Mr. A. +Macpherson, of Kirkcaldy, the chairman, said:</p> + +<h3>THE REGENERATIVE SYSTEM OF RETORT FIRINGS.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 <img src= +"./illustrations/semicircle.png" alt="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.</p> + +<p>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.</p> + +<p>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.</p> + +<h3>IMPROVEMENTS IN GAS PURIFICATION.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<h3>BURNERS AND REGENERATIVE LAMPS.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<h3>THE WELSBACH GAS LIGHT.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<h3>PARAFFIN AS A RIVAL OF COAL GAS.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<h3>OIL IN GAS MAKING.</h3> + +<p>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.</p> + +<p>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.</p> + +<h3>PRICES OF RESIDUAL PRODUCTS.</h3> + +<p>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:</p> + +<pre> + +--------------------------------------------------------------------+ + | | Highest | Price on | Price on | + | | Price | March 30, | March 30, | + | | | 1886 | 1887 | + | |--------------+---------------+---------------+ + | | per gal. | per gal. | per gal. | + | |----+----+----+---+-----------+---------------+ + | | £ | s. | d. | £ | s. | d. | £ | s. | d. | + | |----+----+----+----+----+-----+----+----+-----+ + |Crude naphtha | 0 | 4 | 0 | 0 | 0 | 4½ | 0 | 0 | 8½ | + |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 | 10½ | 0 | 0 | 10 | + |Creosote oil | 0 | 0 | 3 | 0 | 0 | 0¾ | 0 | 0 | 1 | + | | | | | + | | per ton. | per ton. | per ton. | + | |----+----+----+----+----+-----+----+----+-----+ + | | £ | s. | d. | £ | s. | d. | £ | s. | d. | + | |----+----+----+----+----+-----+----+----+-----+ + |Pitch | 1 | 14 | 0 | 0 | 15 | 0 | 0 | 12 | 6 | + |Sulphate of ammonia | 21 | 5 | 0 | 13 | 10 | 0 | 11 | 10 | 0 | + +--------------------------------------------------------------------+ +</pre> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 <i>the</i> burner, +in short.</p> + +<p>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.</p> + +<p>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.</p> + +<hr> +<p>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.</p> + +<hr> +<p><a name="14"></a></p> + +<h2>THE NEW BRITISH COINAGE AND JUBILEE MEDAL.</h2> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.'"</p> + +<p>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.--<i>Illustrated London News</i>.</p> + +<p class="ctr"><a href="./illustrations/8a.png"><img src= +"./illustrations/8a_th.jpg" alt=""></a></p> + +<p class="ctr">THE NEW BRITISH COINAGE AND JUBILEE MEDAL.<br> +<br> +1. Half Crown. 2 and 3. Double Florin, reverse and obverse. 4. +Double Sovereign. 5. Shilling. 6. Sixpence. 7 and 8. Jubilee +Medal.</p> + +<hr> +<p><a name="7"></a></p> + +<h2>BRICKS AND BRICKWORK.</h2> + +<p>[Footnote: A recent lecture delivered at Carpenters' Hall, +London Wall, E.C.--<i>Building News</i>.]</p> + +<h3>By Professor T. ROGER SMITH, F.R.I.B.A.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 ½ 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>A good brick is uniform in size; standard, 9 by 4½ by +2½ 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>Many of the failures of brickwork in London houses arise from +the external walls, where they are 1½ 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.</p> + +<p>French cross bond, otherwise diagonal bond <i>(liaison en +croix)</i>, 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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:</p> + +<pre> + 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 +</pre> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 ¾ in.--and +the space is filled with a bituminous material.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 £2,000 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, £2,000 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.</p> + +<hr> +<p>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.</p> + +<hr> +<p><a name="4"></a></p> + +<h2>PHENOMENA OF ALTERNATING CURRENTS.</h2> + +<p>[Footnote: From a paper read before the recent meeting of the +American Institute of Electrical Engineers, New York, and reported +in the <i>Electrical World</i>.]</p> + +<h3>By Prof. ELIHU THOMSON.</h3> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/11a.png" alt="FIG. 1"></p> + +<p class="ctr">FIG. 1</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/11b.png" alt= +"FIG. 2."></p> + +<p class="ctr">FIG. 2.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/11c.png" alt="Fig. 3"></p> + +<p class="ctr">Fig. 3</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/11d.png" alt="Fig. 4"></p> + +<p class="ctr">Fig. 4</p> + +<p>Now let us imagine the current in the magnet coils to be not +only cut off, but reversed back and forth.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12a.png" alt="FIG. 5"></p> + +<p class="ctr">FIG. 5</p> + +<p>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:</p> + +<p><i>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.</i></p> + +<p><i>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</i>.</p> + +<p>For want of a better name, I shall call this excess of repulsive +effect the "electro-inductive repulsion" of the coils or +circuits.</p> + +<p class="ctr"><img src="./illustrations/12b.png" alt= +"FIG. 6."></p> + +<p class="ctr">FIG. 6.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12c.png" alt= +"FIG. 7."></p> + +<p class="ctr">FIG. 7.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12d.png" alt= +"FIG. 8."></p> + +<p class="ctr">FIG. 8.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12e.png" alt= +"FIG. 9."></p> + +<p class="ctr">FIG. 9.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12f.png" alt= +"FIG. 10."></p> + +<p class="ctr">FIG. 10.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12g.png" alt= +"FIG. 11."></p> + +<p class="ctr">FIG. 11.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12h.png" alt= +"FIG. 12."></p> + +<p class="ctr">FIG. 12.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12i.png" alt= +"FIG. 13"></p> + +<p class="ctr">FIG. 13</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12j.png" alt= +"FIG. 14."></p> + +<p class="ctr">FIG. 14.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/12k.png" alt= +"FIG. 15"></p> + +<p class="ctr">FIG. 15</p> + +<p>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 m¹, 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 m¹, 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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/13a.png" alt= +"Fig. 16."></p> + +<p class="ctr">Fig. 16.</p> + +<p>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 <i>repulsion</i> +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 <i>attraction</i> exists is from the zero of the +induced current to the zero of inducing current.</p> + +<p>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 <i>repulsion due to the summative effects +of strong opposite currents</i> for a <i>lengthened period</i>, +against an <i>attraction</i> due to the summative effects of +<i>weak currents</i> of the <i>same direction</i> during a +<i>shortened period</i>, the resultant effect being a greatly +<i>preponderating</i> repulsion.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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, B², B³, 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.</p> + +<p>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.</p> + +<hr> +<p><a name="2"></a></p> + +<h2>PHOTOGRAPHIC STUDY OF STELLAR SPECTRA, HARVARD COLLEGE +OBSERVATORY.</h2> + +<h3>HENRY DRAPER MEMORIAL.</h3> + +<h3><i>First Annual Report</i>.</h3> + +<p>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.</p> + +<p>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.</p> + +<p>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° 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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° 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>[A description of an accompanying plate here follows, which is +omitted, as the plate cannot be easily reproduced for ordinary +press printing.]</p> + +<p>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 <i>a Cygni</i>, 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 <i>o Ceti</i> shows that the lines G and <i>h</i> 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 <i>χ' Orionis</i>, discovered by Gore, +in December, 1885, gives a similar spectrum, which affords +additional evidence that it is a variable of the same class as <i>o +Ceti</i>. Spectra of <i>Sirius</i> show a large number of faint +lines besides the well-known broad lines.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The progress of the various investigations which are to form a +part of this work is given below:</p> + +<p>1. <i>Catalogue of Spectra of Bright Stars</i>.--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° 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.</p> + +<p>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° 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>2. <i>Catalogue of Spectra of Faint Stars</i>.--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.</p> + +<p>3. <i>Detailed Study of the Spectra of the Brighter +Stars</i>.--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.</p> + +<p>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.</p> + +<p>4. <i>Faint Stellar Spectra</i>.--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.</p> + +<p>5. <i>Absorption Spectra</i>.--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.</p> + +<p>6. <i>Wave Lengths</i>.--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.</p> + +<p>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.</p> + +<p>EDWARD C. PICKERING,</p> + +<p><i>Director of Harvard College Observatory</i>.</p> + +<p>Cambridge, Mass., U.S.A., March 1, 1887.</p> + +<hr> +<p><a name="15"></a></p> + +<h2>THE WINNER OF THE DERBY.</h2> + +<p>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.--<i>Ill. London +News</i>.</p> + +<p class="ctr"><a href="./illustrations/14a.png"><img src= +"./illustrations/14a_th.jpg" alt= +"MERRY HAMPTON. THE WINNER OF THE DERBY, 1887."></a></p> + +<p class="ctr">MERRY HAMPTON. THE WINNER OF THE DERBY, 1887.</p> + +<hr> +<p><a name="13"></a></p> + +<h2>THE FALLS OF GAIRSOPPA.</h2> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><a href="./illustrations/15a.png"><img src= +"./illustrations/15a_th.jpg" alt=""></a></p> + +<p class="ctr">THE FALLS OF GAIRSOPPA, BETWEEN KANARA AND MYSORE, +BOMBAY PRESIDENCY, INDIA<br> +<br> +The Falls From Below. The Falls From Above.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The best route to them is from Bombay to Honaurre by sea, +<i>via</i> 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.</p> + +<p>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.--<i>London Graphic</i>.</p> + +<hr> +<p><a name="3"></a></p> + +<h2>SPONGES.</h2> + +<p>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 <i>resume</i> 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.</p> + +<p>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 +<i>(Euspongia officinalis)</i> 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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."</p> + +<p>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 <i>Euspongia canalicula</i>, the +lecturer said he had observed muscles approaching very nearly in +character those of the human frame.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<hr> +<p><a name="10"></a></p> + +<h2>HERBET'S TEPID DOUCHE.</h2> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p class="ctr"><img src="./illustrations/16a.png" alt= +"TEPID WATER DOUCHE"></p> + +<p class="ctr">TEPID WATER DOUCHE</p> + +<p>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.</p> + +<p>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.</p> + +<p>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°. When the first ring is unscrewed, the +water will make its exit at a temperature of 38°. 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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>Twenty-two pounds of coal and 260 gallons of water are consumed +per hour, and the boiler produces 130 lb. of steam.--<i>Le Genie +Civil</i>.</p> + +<hr> +<p><a name="1"></a></p> + +<h2>HOW TO MAKE A STAR FINDER.</h2> + +<p>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, <i>x</i>, 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, +5½ in. diameter, made of ¼ 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.--<i>T.R. Clapham in English +Mechanic</i>.</p> + +<p class="ctr"><img src="./illustrations/16b.png" alt= +"A STAR FINDER."></p> + +<p class="ctr">A STAR FINDER.</p> + +<hr> +<p>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.</p> + +<hr> +<h2>THE SCIENTIFIC AMERICAN SUPPLEMENT.</h2> + +<h3>PUBLISHED WEEKLY.</h3> + +<p><b>Terms of Subscription, $5 a Year.</b></p> + +<p>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.</p> + +<p>All the back numbers of THE SUPPLEMENT, from the commencement, +January 1, 1876, can be had. Price, 10 cents each.</p> + +<p>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.</p> + +<p>COMBINED RATES--One copy of SCIENTIFIC AMERICAN and one copy of +SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00.</p> + +<p>A liberal discount to booksellers, news agents, and +canvassers.</p> + +<p><b>MUNN & CO., Publishers,</b></p> + +<p><b>361 Broadway, New York, N.Y.</b></p> + +<hr> +<h2><b>PATENTS.</b></h2> + +<p>In connection with the <b>Scientific American</b>, 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.</p> + +<p>A special notice is made in the <b>Scientific American</b> 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.</p> + +<p>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.</p> + +<p>We also send free our Hand Book about the Patent Laws, Patents, +Caveats, Trade Marks, their costs, and how procured. Address</p> + +<p><b>MUNN & CO., 361 Broadway, New York.</b></p> + +<p>Branch Office, 622 and 624 F St., Washington, D.C.</p> + +<h3>THE SCIENTIFIC AMERICAN</h3> + +<p>Architects and Builders Edition.</p> + +<p>$2.50 a Year. Single Copies, 25 Cents.</p> + +<p>This is a Special Edition of THE SCIENTIFIC AMERICAN, issued +monthly--on the first day of the month. Each number contains about +forty large quarto pages, equal to about two hundred ordinary book +pages, forming, practically, a large and splendid <b>Magazine of +Architecture,</b> richly adorned with <i>elegant plates in +colors</i> and with fine engravings; illustrating the most +interesting examples of modern Architectural Construction and +allied subjects.</p> + +<p>A special feature is the presentation in each number of a +variety of the latest and best plans for private residences, city +and country, including those of very moderate cost as well as the +more expensive. Drawings in perspective and in color are given, +together with full Plans, Specifications, Costs, Bills of Estimate, +and Sheets of Details.</p> + +<p>No other building paper contains so many plans, details, and +specifications regularly presented as the SCIENTIFIC AMERICAN. +Hundreds of dwellings have already been erected on the various +plans we have issued during the past year, and many others are in +process of construction.</p> + +<p>Architects, Builders, and Owners will find this work valuable in +furnishing fresh and useful suggestions. All who contemplate +building or improving homes, or erecting structures of any kind, +have before them in this work an almost <i>endless series of the +latest and best examples</i> from which to make selections, thus +saving time and money.</p> + +<p>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.</p> + +<p>The fullness, richness, cheapness, and convenience of this work +have won for it the <b>Largest Circulation of</b> any Architectural +publication in the world.</p> + +<p>MUNN & CO., Publishers, 361 Broadway, New York.</p> + +<p>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.</p> + +<hr> +<p>BUILDING PLANS and SPECIFICATIONS.</p> + +<p>In connection with the publication of the BUILDING EDITION of +the SCIENTIFIC AMERICAN, Messrs. Munn & Co, furnish plans and +specifications for buildings of every kind, including Churches, +Schools, Stores, Dwellings, Carriage Houses, Barns, etc.</p> + +<p>In this work they are assisted by able and experienced +architects. Full plans, details, and specifications for the various +buildings illustrated in this paper can be supplied.</p> + +<p>Those who contemplate building, or who wish to alter, improve, +extend, or add to existing buildings, whether wings, porches, bay +windows, or attic rooms, are invited to communicate with the +undersigned. Our work extends to all parts of the country. +Estimates, plans, and drawings, promptly prepared. Terms moderate. +Address</p> + +<p>MUNN & CO., 361 Broadway, New York.</p> + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of Scientific American Supplement, No. +601, July 9, 1887, by Various + +*** END OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN, SUPP. 601 *** + +***** This file should be named 11498-h.htm or 11498-h.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/1/1/4/9/11498/ + +Produced by by Jon Niehof, Don Kretz, Juliet Sutherland, Charles Franks +and the DP Team + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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