50 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. [48] 



comotive slide valve, actuated by a rod and a pin in the end of the shaft. 

 The cranks are cast-iron disks, one of which is scored to receive a round 

 belt for driving the drum which carries the sounding wire. 



The steam cylinder is 5^ inches in diameter and the stroke of piston 

 is 5 inches. The diameter of the driving wheel (or crank) measured to 

 the center line of the round belt is 13 inches, and the diameter of the 

 drum, measured in the same manner, is 24-^ inches. The power ot the 

 engine is ample and its design is simple. It exhausts into the main 

 condenser, and the cylinder cocks have been piped to discharge into 

 the exhaust passage. 



The belt is unshipped when the sounding wire is being paid out, and 

 must be shipped each time it is hove in, which occasions a little delay, 

 but when this is finished and the cylinder clear of water, the engine 

 hauls in the wire at the average rate of about 100 fathoms per minute. 

 The speed of the engine is usually regulated to the tension on the wire 

 as recorded by the dynamometer, the attendant keeping it as nearly as 

 possible at 80 pounds, which is about 40 percent of the maximum strength 

 of the wire. 



THE STEAM WINDLASS. 



This machine, shown in elevation in Plate XIV, is commercially 

 known as the " No. 4, Providence capstan windlass," and was built by 

 the American Ship Windlass Company. It is situated under the fore- 

 castle on the main deck. The windlass portion consists of a horizontal 

 wrought-iron shaft, mounted in journals on cast-iron frames, and car- 

 ries two gypsy heads, a «, two cam-clutch wheels, d d, -a, bevel gear- 

 wheel, and a spiral gear-wheel, which are keyed to the shaft; it also 

 carries a pair of chain-holders, b &, and friction-breaks, c c, which are 

 not keyed to the shaft. The bevel gear communicates motion to or 

 from the capstan, and may be uncoupled by unkeying the pinion; the 

 spiral gear is for communicating the motion of the engine to the wind- 

 lass. By revolving the cam -wheels, d d, a fraction of a revolution they 

 are coupled to the chain-holders, b b, by which means the chain-holders 

 may be made to revolve with the shaft at pleasure, and by this means the 

 chain may be veered to one anchor while the other is hoisted; both may 

 be hoisted or both veered while the engine is in motion. The capstan 

 is on the forecastle deck and is keyed to the shaft or spindle/. This 

 capstan, which is revolved through the bevel gears, is used for catting 

 and fishing the anchors, for hauling upon hawsers, hoisting boats, &c. 



The engines are placed horizontally beneath the forecastle deck. 

 They rotate in the same i)lane, are placed at an angle of 90°, and act 

 upon the same crank-pin. They have locomotive slide valves actuated 

 by " loose " eccentrics, by which means the engines are reversible. The 

 cylinders and their respective cross-head guides are in one casting, 

 while the outer cylinder heads only are movable. The cylinders are 

 sufficiently large to ho-ist both anchors at ordinary depths of water, 



