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1900.] MARINE REVIEW. 17 fittings which may be varied to suit the desires of the owner, amounts to 6,500 tons. " ; The second dock is one that the author's firm has designed for the navy department of the United States, and which is now fast approaching completion at the Maryland Steel Co.'s works, Sparrow's Point, Md. Its length is 525 ft. over 'blocks, its entrance 100 ft. broad, and it has a lift- ing power up to pontoon deck level of 18,000 tons. In this case no pro- vision hase been made for utilizing the pound of the dock, but the same could be added, at an extremely small cost, at any future time, should it be required to increase the lifting power to not above 20,000 tons. In general shape this dock closely resembles the one for the British govern- ment and is to be moored in the Mississippi at Algiers, La. The dock itself is attached to strong steel columns, sunk in the foreshore, by means of steel lattice booms articulated in all directions. The dock is, there- fore, free to rise and fall with the river, which is subject to very severe freshets, frequently rising some 20 ft. above gulf level, and at the same time can be swung in-shore out of the worst of the current, which here occasionally attains a speed as high as four miles an hour. The booms at the same time form gangways, by which approach may be had to the dock and material conveyed thereon. It may also be noted that this form of attachment to the shore allows all the moorings to be made fast to dolphins driven into the river bank, and leaves the sea side of the dock quite open for maneuvering or anchoring other vessels that may be at the station. This dock will also be completed at the builders' yard and towed to its destination. Its hull weight is 5,850 tons. The end elevations (Figs. 2 and 3) of these two docks are placed together because they show so well the different methods adopted by the governments of the two countries for the shoring or berthing of the ships of the dock. The English custom and also that of Italy and Japan is to support the armor belt on more or less vertical shores inserted under an angle iron firmly attached to the same. These shores are put in. posi- tion as the ship is rising and as the water recedes more and more shores are inserted. It will be noticed that the Bermuda dock has large and powerful altars constructed for this purpose. The 'American custom, on the contrary, is to strengthen the bilges of their ironclads with strong bilge or docking keels, forming, with the keel proper, a level bottom. No shores are required beyond those necessary to roughly center the vessel, and no great care is required in adjusting the berth, and one set of bilge blocks does for all sizes of vessels. If the author's long experience in the study of docking vessels will warrant him giving an opinion on the two meth- ods he would like most strongly to express his very great preference for the American plan. It affords a great saving in weight and quantity of shores, a complete set of which has practically either to be kept in store to suit each type of ironclad or specially cut for such vessels, and, what is more important, it effects great saving in time, not only in the prepara- tion of the berth and centering of the ship, but also in the actual lifting of the same. With the American plan it would be perfectly feasible to dock a vessel completely in the time required to center and adjust her with shores according to English practice. A combination dock would be peculiarly suitable to a large ship building yard undertaking the construction of vessels of all types. This dock consists of three parts, a central one of a length of 386 ft. and a lifting power of 15,000 tons, especially strengthened for the shoring up of ironclads, and two smaller docks each of 3,000 tons, which can be either attached one at each end of the central portion, thus bringing its. length up to 700 ft. over blocks, or 760 ft. over all, and its lifting power to 21,000 tons; or which are capable of acting either separately or to- gether, in the latter case forming a dock of a length of 370 ft. and a lift- ing power of 6,000 tons suitable for dealing with ordinary merchant ves- sels. The total hull weights of these docks amount to 8,550 tons which represents about 36.5 tons of steel for each 100 tons of vessel lifted. It may be remarked that this form really gives a double dock, each half of which can be worked quite independently, being therefore much supe- rior to the graving dock divided in its center with an additional gate, where the innermost vessel may be blocked indefinitely by any accident to the outermost one. It is also worthy of note for future requirements, that the dock would provide sufficient bearing surface for a vessel 900 ft. over all, if built on the same lines as the Oceanic. 'Many other examples of docks might be shown suitable for certain cases. The steel dock is essentially elastic, and easily adapts itself to the peculiarities of the work it has to do. It is not, however, the wish of the author that the present memoir should develop into a catalogue of docks, but rather to call attention to the great facilities afforded by the floating dock, and more especially those which render it so suitable to the uses of a modern navy. That the author should have faith in the future of 'the floating dock is only what is to be expected, but he may perhaps put forward, as independent justification of his belief, the fact that, although the present type of dock was only introduced in 1896, his firm have already been commissioned to design five of these structures of an aggre- gate lifting power of 61,000 tons, two of which are among the largest docks extant, and three of which are for the requirements of various gov- ernments. Indeed, the ordinary law of evolution should tend to show that the floating dock is to be the engine of the future. We are now in the full flood of the constructive age of steel. This metal has already replaced the timber of our roofs and the masonry of our bridges, and in the United States it now forms the strength portion of all large modern dwellings. There should surely be no great venture in prophesying that in the near future the same material must replace the more unwieldy and cumbersome masses of masonry that represent at present the ordinary form of naval graving docks. Mr. H. F. J. Porter of the Bethlehem Steel Co. has been invited to deliver an address on the subject "Evolution of the Engine Shaft' at the convention of the National Kailway Master Blacksmith's Association at the Cadillac hotel, Detroit, Sept. 19. Anyone interested in the subject is welcome at the meeting. The bureau of naval ordnance held a test at the Indian Head prov- ing ground last Saturday of Carnegie plate intended for the side armor on the monitor Arkansas, now building at Newport News, Va. Two shots were fired from a 6-in. gun at velocities of 1,968-foot seconds each. The plate passed the test successfully. DIAMOND SHOAL LIGHT-SHIP. Light-ship No. 72, to be anchored on 'Diamond shoals, off Cape Hat- teras, was launched this week at the yard of the Fore River Engine Co., Weymouth, 'Mass. This vessel is the staunchest and most thoroughly equipped vessel of her class in the world. She must needs be to with- stand the tidal race off the cape. Neither light-ship nor light-house has yet weathered the race of this sea. __ Twenty years ago the contract was let to a New York firm for the sinking of a huge caisson into the sandy bed of the shore, upon which to carry the proposed structure. The caisson, however, was wrecked and the failure discouraged any further effort. A light-ship was then placed on the shoals, but in the big storm' of two years ago she was torn from her moorings and blown out to sea. It became evident that a ship of special design was needed for this terrible station, and the vessel just launched is the product of the best engineering skill that the government had at its command. This light-ship will be steam propelled and electric lighted. © She is 112 ft. between perpendiculars, with a molded beam of 28 ft. 6 in., and a depth of 14 ft. 10% in. measured from the main deck beams to the top of the keel amidships. The vessel has three decks, the main and spar decks running the full length of the ship, while the lower deck is broken by the forward coal bunker and the after bulkhead of the engine room. The hull is divided by watertight steel bulkheads into five com- partments, and the quarters and storerooms are so arranged as to meet all requirements of safety and comfort. The dynamos and engines for the electric light plant will be located on the main deck, and within the engine and boiler casing. The accom- rhodations for the crew are forward on the main deck. There will be two. hollow steel masts, through which the wiring for the masthead flash- lights is to run. These lights, three in number on each mast, are to be adapted for electricity or for oil lamps. The cluster masthead lights will be 59 ft. above the water line, the measurements being taken from the 12-ft. water line to the focus of the lamps. The electric plant will be driven by two noncondensing, double-cylinder engines, running under a steam pressure of 80 Ibs. to the square inch. The vessel will be lighted by eighty 16-candle power 100-volt lamps, which will be placed where nec- essary throughout the ship. The masthead cluster will consist of six 100- candle power 100-volt lamps and these lights will be controlled by an automatic flashing device. It will be driven by means of a belt from the dynamo shaft and a worm and worm wheel, which serve to give the proper rotary speed to a circuit breaker. The light-ship will be propelled by an inverted, surface condensing. single cylinder engine of 250 I.H.P., with a cylinder 23 in. in diameter, 22-in. stroke, driving a cast iron pro- peller 7 ft. 3 in. in diameter. Steam will be supplied by two straight, cylin- drical, tubular boilers, 9 ft. by 16 ft. 7% in., with a working pressure of 100 lbs. to the square inch. When No, 72 is on her station, her mooring tackle will consist of a heavy mushroom anchor, shackled to a chain which will lead through the main hawser hole in the stem of the ship to a steam windlass. In addition to this mooring tackle the vessel will have a 2,000-lb. harbor anchor, a kedge weighing 340 lbs. and 120 fathoms of 1 1-8-in. stud link chain, with a breaking strength of 79,100 lbs. Amidships, on either beam, will be swung two whale boats of about 26 ft. length and 6 ft. beam. The spar deck is protected by a gradually rising steel waist, which starts flush a little forward of abreast the foremast, flaring somewhat at the knight- heads until at the stem propeller it has a depth of five feet. In addition to a powerful steam whistle; the light-ship will be provided with a steam siren for use in thick and foggy weather. None of the ship's machinery was installed when she went overboard, but the work of placing it in position will be carried on uninterruptedly, and it is hoped the vessel will be able to take up guard duty on her perilous station before the win- ter season sets in. During the-past week the coast and geodetic survey vessel Blake has been surveying Diamond shoals for an anchorage for the new light-ship. DEAN OF MAINE SHIP BUILDERS. Amos L. Allen, the dean of Maine ship builders, celebrated his eighty-ninth birthday at his home at Bath on Saturday: last. Mr. Allen was born in Freeport Sept. 8, 1811. He learned the joiners' trade, and when. seventeen years old walked to the town of Damariscotta, thirty- five miles away, to secure employment: A few years later he settled at Bath, and in 1843, with Stephen Larrabee, he went into the ship business. Their first. product: was the ship Sarah Louisa, a craft of 600 tons, which in those-days. was one of the largest ever built. In 1850 Mr, Allen went to Portsmouth, Va., where he-still continued in the ship building busi- ness, remaining there about seven years and, building seventeen vessels, seven of which were-sailing cutters for the United States government. On account of the bitter feeling which was growing stronger day by day between the north and south, business became dull, and Mr. Allen re- turned to Bath, and in 1861 built the gunboats Katahdin and Josco. The former, a craft of 600 tons, was the 'first vessel to ascend the Mississippi river to New Orleans. During the process of construction the govern- ment ordered several costly changes in the hulls of these two vessels and promised to reimburse Mr. Allen for them, but so far has never done so. For several years past he has had a bill before congress amounting to $10,000, and last spring the senate reported in favor of paying the amount. The navy department has disapproved the application of Naval Con- structor R. P. Hobson for the privilege of returning to this country from Japan by way of Siberia and Europe. He suggested the trip that he might make observations of fortifications and dock yards. The depart- ment advised him that he should return at once by the most direct route from Yokohama, reporting at the naval hospital at Brooklyn on arrival here. He will be assigned to duty in the construction department at one of the navy yards when his health will permit it. Mr. Gilbert N. McMillan, formerly secretary and treasurer of the Detroit Dry Dock Co. and Dry Dock Engine Works, Detroit, Mich., and who associated himself recently with the Eastern Ship Building Co. of New London, Conn., has been appointed secretary and purchasing agent, located at New London, Conn. This is the ship building com- pany that is engaged in building the big Hill steamers for Pacific trade.