St H.MAK1NK II NM.l.INd 209 



Hi-Is, all of which indicated a n>rk bottom; and the results of 

 these, together with .surface indications, where at both the Long 

 Island and New York shores, as well as on Blackwell's Island, 

 bedrock lay exposed, led all to conclude that nothing but rock 

 was to be encountered. On these investigations a contract was 

 entered into on June 25, 1891, for the construction of a suj>- 

 posedly rock tunnel, which the contractor guaranteed to com- 

 plete by April, 1893. 



Work was begun at the Ravenswood or Long Island side 

 on June 28 by sinking a shaft i> ft. square about 200 ft. back 

 from the river to a depth of about 148 ft. below the surface; 

 while at New York, on .Inly 7, a shaft of the same dimensions 

 was sunk to a depth from the surface of 139 ft. In both these 

 shafts rock was entered after about 8 ft. of soil ; but while the 

 rock at New York was quite dry, at Ravenswood it proved 

 seamy and very wet. 



The tunnel-roof grade had been established at 109 ft. below 

 mean high water at the New York shaft, with a grade for drain- 

 age of $ towards Ravenswood. This gave a minimum cover 

 of 41 ft. at the deepest point in the west or New York channel 

 on the Mast IJiver. where there is 70 ft. of water at mean high 

 tide. The east or Long Island channel is comparatively shallow,, 

 the deepest point being only 35 ft. below mean high water level. 

 The one thing feared was that fissures yielding large volumes- 

 of water might extend to the tunnel roof and largely augment 

 the cost of pumping. The size of the tunnel section was to be 

 8 ft. 6 ins. in height by 10 ft. 6 ins. in width, this giving suffi- 

 cient room for the laying of two 3-ft. gas mains and one 4-ft. 

 main. 



In the shafts, on both sides of the river, the headings were 

 now turned. At Ravenswood the work was delayed by meet- 

 ing considerable quantities of silty water, but at New York the 

 tunnel was practicalh dry until towards the end of December, 

 l^'.fj. when, at a distance of 338 ft. from the shaft, a fissure 

 was struck yielding alnnit a 3-in. stream of salt water. The 



