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plating so heavy that to draw it up requires rivets too large to be properly driven by hand. From an economical standpoint, the power riveters perform wonders. In deck and tank topwork, for instance, three men and a heater boy will drive from 800 to 1,000 rivets a day. Not only is the whole operation of driving a rivet completed much more quickly than by hand, but it is done so expeditiously that the rivet has not lost its heat ere completion, and consequently there is gained the benefit of the resulting contraction, which, as the rivet cools, draws everything together with firmness.

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Lakes, where pneumatic machinery of this class is used very extensively, the saving on an ordinary lake steamer of 4,000 tons is from $4,000 to $5,000. One machine will not infrequently drive 450 ^-inch rivets in a single day. At the regular hand-work rate, this would involve an outlay of $15.75; whereas, with the machine, the cost is but $5.50, including the wages of operatives and the cost of power.

Another class of pneumatic tools in use in shipyards consists of chipping, calking, and bending hammers, machines which range in weight from 7 to 11 pounds and which have a stroke of from one to four inches at speeds varying from 3,400 to 2,200 strokes per minute according to size. These hammers require 20 feet of free air per minute, and work at a pressure of from 70 to 80 pounds. The heavy chipping hammers weigh fifteen pounds, and attain a speed of 1.200 blows per minute for the 7-inch stroke. Most powerful of all the hammers is what is known as the "9-inch stroke riveting hammer," which has a speed of ooo strokes per minute. A pneumatic holderon is in use in many shipyards, instead of the ordinary bar, for holding up the head of the rivet. It can readily be put

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Pneumatic Drill In Operation.

furnished in most instances by a 2j4inch main; and an air pressure of at least no pounds is carried, supplied by an air compressor capable of delivering, say, 5,000 cubic feet of air per minute.

Machine and Brass Shops

The machine and brass shops and other under-cover portions of modern American shipyards have within the past few years shown vast improvement in equipment and arrangement. An ideal structure of this kind—the newest shop at the Cramp plant—is 335 by 143 feet, and of steel-skeleton framework construction. The floor load in the second story is 400 pounds per square foot, while the third floor is designed for a load of 350 pounds per square foot. The structure has a main central traveling-crane runway, served by two 50-ton electric cranes, with a span of about 57 feet, center to center of supporting girders. On either side of the main central portion are galleries 42 feet wide. The floor space in the lower story of both wings is served by electric cranes of from 10 to 30 tons' capacity.

Some idea of the magnitude of a present-day shipyard of the first class, may be gained from the fact that the Cramp yard at Philadelphia represents an expenditure of more than $7,000,000; and the great shipyard at Newport News, Ya., on Hampton Roads, involved an even greater outlay. In the laying out of all our big shipbuilding plants, heavy expenditure has been made to secure convenience, speed, and economy in the conduct of operations—a continuous, unretarded movement forward of the material from the time it enters the yard in raw state until it is ready to leave as part of a completed ship. To this end, buildings have been grouped—at the Cramp plant, joiner, pattern, machine, and erecting shops are combined within the shelter of one immense structure 1,164 feet m length—and all material is conveyed by short hauls.

Use of Electric Power In conclusion, a word should be said regarding the extent to which electrical energy is displacing steam power in the operations of the more important shipyards. Not only are almost all the cranes, large and small, electrically operated, but almost every one of the big machine tools is impelled by an individual motor, thus insuring a great saving, since the power need be turned on only when actually needed. The electrical outfit which at the Newport News yard furnishes power for running all the machines in the shops and also supplies current for the 2,500 incandescent and 150 arc lights in the plant, consists of three 600-K. W. generators driven by three compound engines; two 125-K. YV. generators driven by one horizontal-compound engine; and two 75-K. W. generators driven by simple engines.

The Machinery of Modern Warfare

No. II. Ingenious Devices that Increase the Efficiency of Peacemakers

By RUTLEDGE RUTHERFORD

THIS IS AN AGE of new machines of war. In the last issue of The Technical World were described several of the new weapons and methods of destruction that were making their appearance in the Japanese-Russian war. But these are not all. The fever to invent devices that will destroy life and property in the quickest and most wholesale manner, is catching; and nations seem to vie with one another in their efforts to produce the most deadly weapons. Indications are that the next decade will witness radical changes in the features and methods of manufacture of all war materials.

The new era of fighting devices through which we are now passing, seems to have had its birth in the recent South African war. That stubborn struggle not only tested the courage and en

durance of the English, but incited the Englishman's wits, awakened his latent mechanical genius, and brought forth new inventions that have surprised the world. In Thibet the British are now testing for the first time several marvelous new contrivances that had their inception in ideas originating in South Africa.

The Hyposcope

The very newest of these contrivances, and one that has a most promising future, is a new rifle-sight that enables a soldier to shoot at the enemy while the marksman hides behind a rock or tree or otherwise completely obscures himself. This is regarded as war's masterpiece of protective mechanism, and is causing a great amount of comment in Europe. The sight is called the "Hyposcope." The pictures of the rifle with the new arrange

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An ingenious arrangement of mirrors is the basis of this new and remarkable invention. The mirrors are contained in a light, strong metallic case, which is easily attached to the rifle and which enables the marksman to take aim from behind an embankment or other obstacle, without exposing himself. When first tested a short time ago in Thibet, the hyposcope fully demonstrated all that was ever claimed for it. The Thibetans, falling before the fire of the unseen foe, ■were completely nonplussed and fled in dismay, declaring that the very rocks and hills rained death on them when they went forth to fight the British. The result has been to create an uncontrollable superstition among the Llama's forces that they are the objects of Divine enmity and that the unseen powers of Providence are fighting against them.

The hyposcope, it is claimed, can be used at any range shown on the back sight of any rifle. Shooting may be as accurately continued without an ordinary back sight as with one—which is equivalent to an additional back sight, should that on the rifle be rendered useless. A trustworthy telescope is thus also added. The elevation of the hyposcope can be accurately and immediately effected by

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Close-range Sighting From Behind Breastwork.

is known as the ''ordnance" hyposcope, and is attached to field pieces or automatic guns.

The Pom-Pom

Another English device that has demonstrated its destructive qualities is the pom-pom. This was also a product of the Boer war. A gun having the power of a cannon, which can be carried about on the backs of horses, up mountain paths, across streams, over narrow bridges, through thickets and marshes, and, in fact, everywhere a horse can go, it has in real action proved itself to be one of the most valuable military additions of a decade. Lieutenant-Colonel Simpson of the British Army, who, in the fighting around Ladysmith, first employed pom-poms, says:

"One of the revelations of the South African war has been the pom-pom. Shortly after the relief of Ladysmith, I was ordered to exchange the guns of one section of No. 4 Battery for four pom-poms, with a view to its conversion into two sections under special pompom officers. They did good work until they were taken up at the end of the war. It struck me at the time how useful a section of jointed pom-poms in pack transport attached to a brigade division of mountain artillery might

be in Indian frontier warfare; and I made certain representations to the authorities, which, I am glad to see, have borne fruit, orders having been given by the Indian Government for the construction of a section of jointed pom-poms for experimental trial in India. These guns will probably be handed over to the infantry, and treated rather as a glorified Maxim* than as a piece of artillery; 1 hope otherwise."

The pom-pom is a gun of the field type, slightly modified to enable the barrel and water-jacket to be detached from the breech casing. The carriage is constructed so as to be readily taken to pieces, and consists of crosshead, elevating bracket, elevating gear, trail, axle, and wheels. The crosshead, which carries the gun, is attached to an elevating bracket by means of holding-down lugs, and can easily be detached from the mounting by turning the same 80 degrees. The elevating bracket is support

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