32 



A TREATISE ON DREDGES AND DREDGING 



This was proven at New York, where at times hundreds of pounds 

 of dynamite were blasted under the platform without injuring it. 

 In blasting rock at the Iron Gates on the River Danube a different 

 device was used, shown in Fig. 6. This consists of a floating 

 rectangular platform provided with four spuds of large dimensions 

 which can be raised and lowered by means of chains, each com- 

 manded by a windlass. In this way the platform can be either mado 

 to float so as to be easily transported from one point to another, or 

 firmly fixed to the bottom. A very long pit provided with tracks 

 on the edge of the longitudinal sides is located in the center of the 



FIG. 6. Drilling Platform used on the Danube River. 



platform. A platform with boiler and engines and carrying four 

 drills of the rotary type is mounted on a truck running along the 

 tracks. The drills are mounted 5 ft. apart and by moving the truck 

 from one end to another of the long pit, many rows of drill holes r:m 

 be bored. After all the holes have been charged the spuds are mi sod 

 and the float moved 50 or 60 yds. away, to return and resume work 

 after blasting all the holes, by means of wires attached to an 

 electric machine located on board the float. 



For blasting subaqueous rocks there are other drilling machines 

 in which the drills instead of working through pits in the middle of 

 the float, are located at the edges of the boat. These machines may 



