DIPPER DREDGES 163 



gypsy winches on the main deck. The two stern gypsy winches are 

 operated by a separate 6- X 9-in. double-cylinder engine, the power 

 being transmitted through bevel gears as for the forward winches. 

 All the speed drums and their gearings are interchangeable. This 

 includes four drums, their shafts, frictions and other details, the 

 bevel gear wheels and pinions operating the capstans and the capstans 

 themselves. This reduces to a minimum the possibility of delays 

 and cost in making repairs in case of breakdowns, making it 

 possible to be ready for repairs by carrying in stock only one 

 spare piece of each of the parts subject to the greatest risk of breakage. 

 For instance, the level pinions are intentionally selected as the break- 

 ing pieces for the capstan gear. There are four of these, yet only 

 one carried in stock allows quick repairs to be made. 



The boiler is of the Scotch marine type, 11 ft. in diameter, 12 

 ft. long and has two 42-in. corrugated furnaces. There are three 

 4000-gal. steel water tanks in the hold, one on each side and one 

 near the stern. The last is always kept full as a reserve supply and 

 for ballast. There are two double-cylinder Blake steam pumps, 

 one for the boiler feed and the other to pump from the bilge, from 

 a water boat, or from the tanks. 



The boom is built of angles, cover plates and lattice bars in the 

 usual manner, and is 53 ft. 2 in. long over all. The head sheaves are 

 attached by a specially designed compact universal joint which 

 gives the wheel freedom of motion in every direction and prevents 

 the breakage of the flanges, which sometimes occurs when a less 

 flexible connection is used. The leads from the tip of the boom to 

 the top of the A frame are attached to the latter by a ball-and-socket 

 joint. This joint is in effect as if the two leads met at one point. 

 Torsional strains in the boom are thus avoided when the boom swings 

 to one side or the weight on the lifting chains is unequal. The 

 four guy cables are l|-in. plow steel. The dipper is of the usual 

 type and the 58 ft. handle is made of a 16X16 in. Oregon fir stick, 

 and four 6X6Xi~in. angles. The handle is built under the Howard 

 patent. The four angles of the timber are reinforced by 6X6 X-J- 

 in. angle irons riveted through and through. 



The turntable is carried by eight conical wheels attached to the 

 movable or upper plate and rolling on a fixed circular track. The 

 horizontal thrust is taken by twelve vertical cylindrical rollers, 

 equally spaced about the circumference of the moving plate and 

 attached to it. These rollers bear against the outside of the same 



