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68 for 180 lbs. working steam pressure. Each boiler has three 46-in. corrugated furnaces with . separate combustion chambers, and 313 3-in. tubes. total heating surface of both boilers is 4400 sq. ft. and total grate surface 149.5 sq. ft. For supplying steam to winches and for general harbor use there is a don- The ' THE Marinzc REVIEW key boiler of the Scotch type located on the upper deck level above the main boilers. This boiler is 9 ft. diameter x 10 ft. 514 in, long, has one 52-in. cor- : rugated furnace, 108 3-in. tubes and is built for a working pressure of 90 lbs. The hull and machinery are being built under Lloyds special survey to class *A-I. © ® The Steamer Commonwealth. By Warren T. Berry, Esq., and J. Howland Gardner. MiHE COMMON- | wealth was built for service between New York and Fall River, a run of 180 statute miles, mak- ing one stop of about half an hour at Newport. The maximum designed speed is 22 statute miles per hour, although the establish- ed schedule requires a speed of only 18 statute miles, and with fair tide and wind 16 statute miles are all that are necessary. A speed of 20 ot 22 miles is often required to min- amize delays caused by head_ tides, high winds, delays at terminals and fog detention. Inquiry was made as to visability of installing tte type of turbine, but the economical results appeared to be rather expefi- mental for speeds varying between 16 and 22 miles per hour. Experience with propeller and side- wheel steamers, in this particular ser- vice, demonstrates that very much greater overhang of guard can be fitted to the side-wheel boat. On the Commonwealth 19 ft. S in) over- hang, each side of hull, was necessary to provide for the spacious saloons and staterooms demanded by the traveling public. This extreme breadth of guard is in addition a very effi- cient safeguard against serious dam- age to the hull in case of collision. The compound inclined engine with feathering wheels, as adopted, combines the ability to stop and back very quickly, utilizes only lower hold space, which is of very little value for freight or passenger ac- the ad- Parsons *Paper read at annual meeting Society of Naval Architects and Marine Engineers, New York. commodation, and avoids the exces- sive vibration common to screw pro- pellers in shallow draught vessels. he ¢ontract. for © building -- this steamer was made by the New Eng- land Navigation Co. with the Quint- atd< tron Works Co, on Oct, 12, 1906, the specified time of delivery July 1, 1908. The hull was launched at the yards of The William Cramp & Sons Ship & Engine Building Co., Oct. 9, 1907, and the work of install- ing machinery and joiner work im- mediately commenced. The steamer was finally delivered, ready for ser- vice, with furniture and outfit com- plete, June 23, 1908. General dimensions are as follows: Length over all, 455 ft. 2 in. . Length between perpendiculars, 437 ft. 1) in, Beam of hull molded, 55 ft. Beam over guards, 94 ft. 7 in. Molded depth lowest point of sheer, 22° ft. Table of Weights. Hull, ship carpenter work and_ steel construction, 2,210 gross tons. Joiner work, 835 gross tons. Steam engineering, 1,760 gross tons. Hull engineering, 240 gross tons. Coal, 150 gross tons. Water, 40 gross tons. Equipment, furniture and outfit, 175 gross tons. Total, 5,410 gross tons. Displacement. light: (13 ft. draught salt water) 5,410 gross tons. Displacement loaded (15 ft. draught salt. water) 6,410 "gross tons, The. hull is built on the bracket plate and longitudinal system of the general scantling shown on midship section. Seven water-tight bulkheads extend to the main deck without doors or other openings, dividing the hull into eight water-tight compart- ments above the double bottom. The double bottom extends for a length of 335 ft. and the margin plate is 5 ft. above the base line. This doy- ble bottom is divided into 46 water. tight compartments, To obtain quick handling in the harbors of Newport and New York, a rudder. 14 ft, 8 in. lenge ge 6 in. deep, is installed. This rudder is operated by 26-in. diameter by 16- in. stroke Sickles type steering en- gine, located in the forward hold, connected by wire cables 15% in, di- ameter to a circular steering head, This sfeering head is fastened to rudder stock at center and _nigger- head at aft end of rudder, in order to distribute the stresses on the rudder and do away with the use of aft quarter blocks, he: stock is «utilized as 4 stand. ment and for connecuon to a hand- auxiliary gear of the diamond screw type located on the saloon deck, A mechanical telegraph is fitted for communication from the _ pilot-house with direct reply from the rudder stock, Two stockless anchors of 6,500 Ibs. each, with 180 fathoms of 2-in. stud link chain cable, are handled by a two-cylinder, 14-in. by 14-im. anchor windlass with a capstan attachment on saloon deck. and two capstan heads on main deck. For warping steamer into dock two 12-in. by 14-1n. steam capstans are located on the aft quarters. Propelling Machinery. The propelling machinery, designed for a maximum indicated horsepower of 10,000, is composed of a double compound, inclined, reciprocating en- gine with two high-pressure cylinders 50 in. diameter and two low-pres- sure cylinders 96 in. diameter, with | a common piston stroke of 114 in. connected to two pairs of cranks set at right angles, shrunk on hollow forged steel shafts. The shaft is in three sections: two outboard or wheel shafts and one center shaft, all 27 in. diameter at the main journals and 30 in. diameter at the gunwale bear- ings. . The pins: are 22°. diameter shrunk' in cranks on out- board shafts, but arranged with loose brass the inboard cranks to provide for any change of align- crank chocks in "ment. All cylinders are fitted with double poppet valves, Sickles adjustable cut- off on the high-pressure cylinders, and Stevens fixed cut-off on the low- all operated with Stephenson links controlled by a 20- ine by 244in: 'Two pressure cylinders, engine. condensers of cylin- each containing 8,000 sq: steam reversing surface drical type,