90 ANNUAL OF SCIENTIFIC DISCOVERY. 



Island with Croton water to the amount necessary for 5000 inhabi- 

 tants. The island is situated just below Hell Gate, the upper or north- 

 ern end of it reaching the southern limit of that far-famed pass. The 

 water thus divided by the island rushes past it in two deep channels, 

 with a tide little inferior in power to that of the most dangerous parts 

 of " the Gate " itself. For the entire length of the island, the centre- 

 depth of the channel next to the New York shore is from 70 to 75 feet, 

 with a rock bottom. The range of the ledges of rock is in a line with 

 the flow of the tide, while, the rift being nearly perpendicular, the wear- 

 ing away of the rock has caused the bed of the stream to be exceed- 

 ingly irregular ; the transverse soundings showing profiles singularly 

 uneven and abrupt in their rise and fall. It was on such a bottom and 

 in such a tide that the pipe was to be laid. At the point selected the 

 channel is about 900 feet wide, and the depth of water in the line of 

 crossing varies from 55 to 75 feet, the bed of the stream falling off 

 boldly and attaining the former depth within a short distance from either 

 shore. The difficulty and expense attending the laying a leaden pipe in 

 such a location induced the trial of gutta percha pipe. By all that 

 could be yet ascertained in reference to this comparatively new material, 

 the experiment was warranted, and a contract was accordingly made for 

 the manufacture of the pipe. A pipe was accordingly manufactured, 

 of a strength sufficient to sustain a pressure of 180 Ibs. to the square 

 inch. Owing to the great strength of the tide, the operation of laying 

 down the pipe was one of considerable difficulty. It could only be done 

 during the few minutes of comparatively slack water, when a partial 

 cessation of the current ceases from five to twenty minutes. During 

 this time the pipe was to be run across the river from shore to shore ; 

 anchors for sinking and holding it in its bed put on at every joint, 

 lowering lines attached from the several boats, and the pipe lowered 

 to its place by movements so graduated that the whole line of it con- 

 forming to the profile of the bottom should reach its bed at the same 

 moment. This was considered necessary in order to obviate all risk 

 of the high projecting points of rock chafing the pipe by the vibrating 

 action of the tide, in case it should hang suspended between two rocks. 

 The arrangements and mode of operation were as follows : A line of 

 12 large boats was stretched across the river and held by stem and 

 stern anchors. Thirteen other boats were stationed near" the shore, 

 the men ready to pull to their respective posts as soon as the order was 

 given. Each of these 25 boats was provided with an anchor to attach 

 to the pipe, with a strap to hold the pipe during the operation, and a 

 lowering line. The pipe in one continuous length of 1100 feet was 

 ready on the shore, and a coil of rope, one end of which was attached 

 to it, placed in a well-manned and swift boat. As soon as the tide 

 would permit the crossing, this boat started for the opposite shore, 

 across the stems of the anchored boats. As the boat struck the oppo- 

 site shore, the rope she carried was immediately manned by a sufficient 

 number of men stationed there, and, aided by those who manned it on 

 the island, the pipe was rapidly drawn across the river. At the 

 moment the pipe was stretched on the surface, from shore to shore, 

 straps were passed around it from the boats in line, the anchors 



