28 A TREATISE ON DREDGES AND DREDGING 



shaped point, resembling the end of a projectile. At the upper end 

 there is an eye to which a steel cable is attached, leading from a 

 very powerful steam winch of special design, built by the Lobnitz 

 Co., of Renfrew, Scotland. 



The hull is maneuvered by a six-drum steam Mundy hoisting 

 engine, by means of six J-in. wire cables, each 1000 ft. long. One 

 of these leads forward from the bow, one aft from the stern, and 

 one each from the four corners to port and starboard. The anchor 

 cables pass from the drums through the deck sheaves, and run out 

 from the deck level to the anchors, previously placed in position. 

 After the machine has been placed, the steel cylinder is raised by 

 the hoisting winch, and then let fall onto the bed rock. This operation 

 is repeated until the desired result is achieved. The hull is then 

 moved to a new position by taking in the cables on one side and 

 paying them out on the opposite one, after which the rock crusher 

 is raised and let fall, and so on. 



Steam is furnished by a large locomotive boiler. The machine 

 is also supplied with an electric plant and searchlight for night work. 



The contract price for removing the bed of rock on this work 

 is $1.85 per cu.yd. measured in place. 



An American company has lately been organized to manufacture 

 and sell rockcutters of the Lobnitz pattern. 



There is also now being used in this country a rockbreaker or 

 cutter that instead of the hammer falling in a shaft by gravity, it 

 operates in a compressed air cylinder. It is claimed that a more 

 powerful blow is struck in this manner and the blow is controlled. 

 Except for air being used the principle is similar to the Scott & 

 Godsir cutter, 



