80 



A TREATISE ON DREDGES AND DREDGING 



operations and especially the continuous movements of tugboats 

 and scows in the service of the dredge would not interfere with 

 traffic through the narrow 7 channel, and also on account of the heavy 

 seas prevailing in the locality, it was decided to build this ladder 

 dredge with a large hopper to receive the debris. The hopper loaded, 

 the steamer would go out to unload its cargo into deep water and 

 return to resume its dredging operations. 





FIG. 17. Dredge "Pas-de-Calais." 

 The principal dimensions of the steamer are : 



Ft. In. 



Length 180 3J 



Width 32 7 



Depth 14 6 



The motive power is provided by two independent compound 

 engines with three cylinders each, developing together 650 H.P. 

 The engines are furnished with a regulator, by means of which it 

 is possible to regulate the speed of the buckets according to the 

 resistance of the soil encountered in dredging. 



Steam is generated by two tubular boilers of marine type and 

 so arranged that they can work either together or separately and 



