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to the regular load, can be sent over these feeders, and if this current can be stored in some way in a location within but near to the economical limit, so that it can be used at the period of heavy load, this storage substation will in turn become a point of distribution from which current can be sent out as far again as the economical limit. Here is where the storage battery filled the want. In 1894 we find storage-battery substations installed in Boston and New York, and soon thereafter companies in other cities adopted them. In Boston a number of battery substations were installed in the nearer outlying districts, all of them being connected with one another and with the steam station. The batteries are charged during the hours of light load by means of boosters, which form part of the substation equipment. Their usefulness, however, is not by any means limited to outlying districts. As an auxiliary to a generating station, it is considered good practice from the standpoint of economy to install a storage battery if the peak of the load does not exceed two and one-half hours. As a safeguard against interruption of service, and as a help in maintaining a uniform pressure on the system, they have been found almost invaluable.

(To be Concluded)

Mechanical Appliances in Modern
Shipbuilding

Modern Devices that are Working a Revolution in the Shipbuilding Industry

By WALDON FAWCETT

IN THE COURSE of his testimony

I

at the recent Congressional hearing relative to the condition of Ameri

can shipping and shipbuilding, Mr. Cramp, probably the best known shipbuilder in the United States, made the statement that in this industry the advantage conferred by the superiority of the American workman is a thing of the

past. His explanation of this surprising statement was, that in this age speed and economy in shipbuilding are secured largely by the employment of the wonderful time-saving and labor-saving machinery introduced during the past few years, and that these products of Yankee ingenuity are being installed in foreign shipyards just as rapidly as the manu

facturers can turn them out. Since these highly perfected automatic machines can be operated by any workman of average intelligence-by the poorly paid labor of Europe quite as well as by the highpriced American artisan-it is claimed that vessel construction all over the world will ere long be on one basis.

Steam and Electric Cranes

Of all the classes of mechanical appliances which are serving as factors in inducing the new status of steel shipbuilding, unquestionably the most important

the shipyard, is placed a high trestle upon a track, on top of which is mounted one of the cranes. The horizontal boom of the crane is high enough above the shipways to pass over the highest point of the ships being built, while the arms of the cantilever project over the full width of the ship on each side of the trestle. The cantilever of the crane is equipped with a trolley and hoist block, whereby the load can be hoisted from the ground and traversed from one end of the cantilever to the other. Thus, inasmuch as the crane travels up and down the trestle, the en

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MONSTER CANTILEVER CRANE AT ORAMP SHIPYARD, PHILADELPHIA, PA.

is that made up of the various kinds of cranes. Chief among these are the steam and electrically operated balanced cantilever cranes-one of the American inventions which has of late been most extensively adopted in the shipyards of the Old World. These giant burdenThese giant burdenbearers, unquestionably the most perfect machines yet devised for handling material about ships in course of construction, embody new features in crane construction which allow the long spans and high speeds for which they are designed and equipped.

All the cranes of this type in use either in the United States or abroad are the invention of Mr. Alexander Brown, the well-known engineer, and all have the same plan of operation. Between each pair of shipways or building berths in

tire length and width of the two ships are covered, and materials may be handled and delivered to any part of the ships under construction. The trolley will attain any speed desired on the tramway, while the crane is capable of traveling along the track at a speed of 750 feet per minute.

One pair of engines, or an electric motor controlled by a single operator; drives all functions of one of these large cranes. The engines or motor and the machinery are located in the pier, and there is no dead weight carried either on the bridge or on the trolley. This allows the lightest form of bridge construction and very quick movement of trolley, and, especially, allows the trolley to be started, run at full speed, or stopped instantly. The cantilever cranes are equipped with

an automatic counterweight running on a track located on the bridge, above the hoisting-trolley tracks, and connected by ropes to the trolley so that whatever position the hoisting-trolley may occupy on one arm of the crane, the counterweight

GREAT FLOATING DERRICK "ATLAS," AT THE CRAMP SHIPYARD, PHILADELPHIA, PA.

at, all times automatically keeps a similar position on the opposite arm.

Probably the best exemplification of the possibilities of these adjuncts of twentieth century shipbuilding is afforded at the Cramp plant at Philadelphia, where there are several of these cranes, all driven by electricity. Each crane is mounted on a steel trestle of special design and construction, about 600 feet long, and of sufficient height to bring the under side of the crane-girder 105 feet above the ground. One of these cranes, which may be considered as representative of its class, is 102 feet long from end to end of girders, with 190 feet effective travel of trolley. It will lift 30,000 pounds at 60 feet either side of the center, and 9,000 pounds at either end of bridge. A single electric motor operates all functions of the crane at the following speeds:

Hoisting a full load of 30,000 pounds-125 feet per minute.

Trolley across cantilever-400 to 800 feet per minute.

Entire crane along trestle, on track of 20foot gauge-400 to 700 feet per minute, depending on load and wind-pressure. The minimum of 400 feet is with full load and against a wind pressure of 30 miles per hour.

Recently this crane placed in position on shipboard, a battleship sternpost weighing eighteen tons, and, with the assistance of but a few men, conveyed it from the cars at the opposite end of the yard, an operation never accomplished under the old plan in less than two or three days nor without a large force of workmen engaged.

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Derricks

Ranking with the cantilever cranes for marvelous achievement are the monster derricks to be found at several American shipyards. The best example is afforded by the "Atlas" at the Cramp yard-the largest and most powerful floating derrick in the world. The pontoon of the structure is 73 feet in length, 62 feet in width, and 13 feet deep. When carrying the maximum load of 125 tons at the boom end, and with water ballast aft sufficient to bring her to an even keel, the "Atlas" has a freeboard of 16 inches and a displacement of 1,563 tons. The cone has a diameter of 40 feet at the base; the length of boom from the axis is 581⁄2 feet; and the boom swings 36 feet clear of the pontoon. The height from deck to masthead is 116 feet; and from deck to boom, 65 feet. The maximum hoisting height is 50 feet. The pontoon is of iron, while the boom, mast,

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hole punching machine, which is accounted the heaviest in the United States, and which, with a pressure of 1,500 pounds, punches a manhole 18 by 27 inches in size from plates 3/4 inch thick; 32-foot bending rolls, which are the largest in the world; some of the heaviest cutting shears ever made, with maximum dimension of cut of four inches; 36-, 60-, and 84-inch planers; a wall planer measuring 22 feet plane by 22 feet slot, which has no parallel in the world; and a 125-inch shafting lathe, which will take

of power riveting which surpasses anything previously attained anywhere in the world. At first an attempt was made to use pneumatic compression riveters similar to those in use in many bridge shops; but it was soon demonstrated that their great weight for the large gaps necessary in shipbuilding made it impracticable to handle them with either facility or economy in the case of ships on the stocks.

The shipbuilders, however, knew from experience, of the value for chipping and

calking of the pneumatic hammer, consisting of a piston rapidly reciprocating inside of a cylinder, and striking the end of a chisel; and this apparatus was gradually adapted to the driving of rivets.

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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PNEUMATIC STEEL CUTTER IN OPERATION.

Shipbuilders in this country who have. made a careful computation, figure out that machine riveting, adding the cost of air, repairs, etc., effects a saving of from one to two cents per rivet over piecework prices for hand riveting, the degree of economy depending upon the location in the ship, and averaging fully 14 cents. In the shipyards on the Great

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