130 A TREATISE ON DREDGES AND DREDGING 



hull will make a cut about equal to the width of the hull, while the 

 latter is anchored by its two spuds. When it is desired to make 

 a wide cut the suction pipe is secured in its mid-position and the 

 swinging lines are carried out on each side to a shore anchorage, and 

 the entire dredge swings on its stern spud, thus making a cut from 

 150 to 175 ft. wide at one time. The spuds are oscillating so as to 

 permit the dredge to move up without drifting out of position, 

 and when the move is made, they are lifted and dropped again in 

 vertical position and the work proceeds. The moving up is accom- 

 plished by giving a turn or two to the stern wheel by the propelling 

 engines. 



The auxiliary engines are on the forward deck. These are for the 

 purpose of working the swinging lines and also hoisting the forward 

 spud. The operator of the dredge controls all the movements of 

 feeding and moving up through the medium of these engines and 

 by bell signals to the engineer. The entire dredge is therefore under 

 the control of one man. 



The boilers, as shown on the plan, are of the Heine water-tube 

 type. This type of boiler is not, strictly speaking, a marine boiler, 

 although it has answered very well for this class of work. They 

 are of the usual land type, cased in steel, lined with firebrick. The 

 boilers are designed for a working pressure of 200 Ibs. per sq.in., 

 and have an excess of capacity to provide steam for all machinery, 

 and in case of necessity the dredge can work at fair capacity, wit h 

 only one boiler in commission, while the other is under repairs. 



In the engine room the usual auxiliaries are found, such as surface 

 condenser, air pump, centrifugal circulating pump and independent 

 feed and fire pumps. These are all of ample size and conveniently 

 arranged for ease of access and repairs. 



The propelling engines are of the stern-wheel type, so often seen 

 on the western rivers. They are of the direct-acting long-stroke 

 horizontal type and have cylinders 16 in. diameter by 6 ft. stroke. 

 They are mounted on a steel frame and have answered the purpose 

 very well. 



It will be seen that the whole of the main deck is occupied with 

 machinery and the whole of the upper deck is given up to quarters 

 for the officers and crew. 



The performance of the dredge has been quite satisfactory, 

 although no very large or continuous outputs hnvr bmi inado, 

 owing to the fact that the work to be done has UM-H principally 



