DOCK. 342 DOCK. tant foreign and Ainerican dry docks: London- Jilackwall, 47IX«JX:i."J fffl"; Tilbury. 840 X 70X35 feet (can be divided) ; Liverpool, Xew laiiada Graving Dock, 'J:i5 X U4 feet, ami olio X 70 X 22.4 feet, and 708 X 00 X 22.10 feet; Birk- enhead. 750 X 85 X 20.7 feet; Belfast, 800 X 80X25.8 feet: tJlasgow. 880X83X20.0 feet; Simtlianipton. 000 X HI X 32.0 feet; PIvmoutli, 404 X 80 X 22 feet; Hull, 550 X 05 X 21.0 feet; Loilli, 410 X 70 X 21 feet: Barrow. .500 X 00 X 22 feet ; Newcastle, 550 X 80 X 20.8 feet ; Car- diff, 018 X 62 X 27 feet; Newport, 520 X 65 X Hall cro6»-8ection. .K-h, tbrough dock. CROSS-SECTION- MASONBY DRY DOCK, BOSTO.N SAVY-YARD. 32 feet ; Barry, two docks. 747 X 60 X 28 feet (divided), and 610 X 05 X 29 feet, in construc- tion: Antwerp, 459X81X23 feet; Bordeaux, 540X72X27 feet; Dunkirk, 022X08X26 feet ; Genoa, 622 X 08 X 26 feet ; Brenierhavcn, 700 X 80 X 31 feet ; Svdnev, 040 X 00 X 20 feet, and 608 X 84 X 32 feet : Buenos Avres, 587 X 05 X 26 feet; Chile. 017 X 87 X 30 feet : Ports- mouth. N. H.. 3.50 X 00 X 25 feet: Boston. Mass., 307% X 60 X 25.8 feet: New York. N. Y., 459.8 X 85 X 25 'A feet, and 338 V4 X 66 X 25 »4 feet, and 620% X lOSU X 29 feet: l.eafnie Isl- and, Pa.. 459.8 X 85 X 25V„ feet : Norfolk, Va., 302% X 60 X 25 feet, and 495% X 85 X 25M; feet: Port Roval. S. C, 459X97X26 feet; -Mare Island, " Cal., 459 X 8011. X 27>4 feet; Pupet Sound. Wash.. 0181^ X 92.6 X 30 feet. Of the eleven American docks last named, three only are built of masonry. In 1898-99 Congress authorized the construc- tion of four new dfK'ks. two of masonry and two of timber, at the Government Navy Yards at Boston, Mass., Portsmouth. N. H.. Txague Island, Philadelphia, Pa., and Mare Island. San Francisco, Cal. The following are the dimen- sions adopted for these docks: States Naval Station at Algiers, La. The Algiers Dock lias a lifting capacity of 15,000 tons (a battle-ship of this size is siiown in the sectional drawing) and consists of live separate pontoons or water-tight boxes. Thrw of these pontoons compose the bottom of the dock, while two form the side walls. These |>onloons are divided by means of interior partitions into forty watertight compartments, and each of these compartments has an inlet lor the admis- sion of sea-water and an outlet connected by piping with steam-pumps for expelling the water. The ■ X operation of raising a ves- sel with the dock is sub- .stantially as follows; When a 1 1 compart- ments of the dock are enip- ty it floats at a draught of four feet. To sink it, the valves are opened, ad- mitting water to the various <■ o m 1) a )■ t - ments. It may such a depth that it will take of 30 feet draught. The vessel and carefulh' centred over the I 1 «, Hall cross-Bectlon, C— D, through dock. be sunk to in a vessel is floated in keel-blocks, and the pumps are then set to work to remove the water from the compartments. In pumping out the water the chief care is to see that the dock keeps level. This is accom- Lengt'h on rnping •• floor i 726 Width on coping In liod.v [ ISO nt alintinent 101 Width on floor In body 80 •• atenttance 101 Depth, coping to floor { 39 Timber docks Ft. /D«. 750 .. Masonry docks Ft. Ins. 750 725 144 6 101 » 80 .. 100 39 :i Fi-OATixn Dry Docks have been built in con- sidcral>le numbers in both Kurope an<l America, the nuijority of them l)cing for vess<-ls of from 2000 to 4000 tons. One of the largest and most recent of tlic^e do<'ks is that for the Unitc-d 'SSV:^;";:;::.r:vJ.....J SECTIO.V OF THE ALGIERS FLOATING 1)RV noCR. plished by altering the speed of ]mmpiiig from the dilTcrent compartments to suit the condi- tions. .s the dock raises the vessel out of the water, shores are inserted between the vessel's hull and the side walls, and the pumping is conliiiiied until the floor of the do<'k is raised above the water-level. The keel-blocks are high enough to raise the bottom of the vessel some four feet above the floor of the dock at the point next the keel, giving space enough to work underneath the vessel. Only a few books on dock construction arc now available. Colson, yioles on Duck f'onslruciion (London, 1894). and Stevenson. Th.'iiqn rind Cnnxti iirliini of llinhnrx (London. 1880). are standanl treatises, but both are wanting in the discus.sion of recent work. A recent book in French is Cardmoy. Lrs ports nuidtnim (Paris, 1900). By far the most fruit-
