SKETCH OF GENERAL JOHN NEWTON. 839 



sufficient to remove all the rock from above. The same project was 

 to be applied also to the Gridiron Reef. This method of excavation 

 was not new, as it had been proposed by General Alexander, of the 

 United States Engineers, for the removal of Blossom Rock, San 

 Francisco Harbor, and afterward carried out by Van Schmidt, a civil 

 engineer ; but that reef was a very small one in comparison with those 

 to be removed at Hell-Gate. The general also, in the same report, 

 proposed a plan for a scow to remove the isolated reefs. This scow 

 was constructed in 1870. It consisted of an iron dome thirty feet in 

 diameter, supported centrally in a well, in a scow one hundred and 

 twenty feet long by forty- eight feet beam ; this dome could be raised 

 or lowered by derricks on the scow. When resting on the rock, the 

 space inclosed was virtually cut off from all currents, the drills could 

 be worked steadily, and the space was accessible to divers. Above 

 the dome were steam-drills, the drills passing through tubes in the 

 dome. This dome-scow proved a practical success, and was not only 

 used at Hell-Gate but also on other reefs, as at Coenties and Diamond 

 Reefs. 



The progress was so satisfactory at Hallet's Point that shafts were 

 sunk at Flood Rock in 1876. General Newton had been at the same 

 time making extensive experiments on all the known explosives, to 

 test their applicability to the breaking up masses of stone, while exten- 

 sive experiments were also made with batteries, wires, and fuses, with a 

 view to their use in the final blast. The excavation being completed, 

 and the mines charged and wired, the explosion at Hallet's Point took 

 place September 24, 1876. 



It was a success. The work at Flood Rock was prosecuted more 

 energetically, but with varying appropriations ; essentially in its gen- 

 eral features it was like the work at Hallet's Point, but with such 

 modifications as had been developed by experience. In one essential 

 feature both differed from what had been originally designed by Gen- 

 eral Newton. In his first report he had proposed to make the cavi- 

 ties of the galleries sufficient to receive the superincumbent stone. As 

 he proceeded, he did not consider this necessary ; a great deal of stone 

 since the blast at Hallet's Point had been removed by grapples, which 

 was practically found to be cheaper than by mining. In its applica- 

 tion to the work at Flood Rock, the spaces were smaller compared 

 with the solid rock than at Hallet's Point ; galleries were considered 

 only necessary to give access, so as thoroughly to shatter the rock. 

 Flood Rock was fired on the 10th of October, 1885, and a full descrip- 

 tion of the work was furnished by General Newton for the February 

 number of this journal. 



All the problems which were involved in the several steps leading 

 up to the consummation of that stupendous work were completely and 

 conscientiously studied out ; and the accuracy of the studies was fully 

 exemplified in the exact correspondence of results with what was aimed 



