BUI DOE. 



.129 



:tice. at the top, and tapered to three inches at the bot- 

 v" torn. Tliis was driven down to the rock tin 



the small quantity that the r.uger conlil not clear. 



.'id which was inclosed by the pipe was i'li ,u - 



cd off the rock by a cylindrical iron tube, three inches 



in di I'r.i-teroii theuut^de, and three feet long, which 



li.ul ii valve fixed within two inches of the bottom, 



: -d on a small ring fastened in the irsi.' 



tube for that purpose. On the top of the tube- 

 was a PCIYW, by which it was fastened to a set of 

 boring rods. It was then passed down the inside to 

 the bottom of the square wooden pipe, and, by 

 working it by short and quick stroke?, the before- 

 - nd and small gravel worked above the 



a by the agitation of t!u- water. The tube was 



i taken up and emptied of the sand ; and this ope- 

 ration was repeated, until the rock within the square 

 tube was perfectly clean. It was found absolutely 

 :uvay this sand, as otherwise it en- 

 tirely prevented the jumper from turning on the 



. 



mper was then passed down the square direct- 

 ing- pipe, and worked by a lever on the upper scaf- 

 fold, until a hole two inches and a half in diameter, 

 and t-.vcnty inches deep, was bored into the rock, to 

 receive an iron dowell two inches square. This do- 

 well was fixed in its place, by fastening it into a 

 square socket made in the end of an inch and a half 

 square iron bar by a small cord, to prevent it from 

 falling out of the socket while lowering down the 

 square directing-pipe to the rock. It was driven 

 into the hole in the rock, by striking with a large 

 hammer on the head of the bar. When it had been 

 driven eighteen inches into the hole, the timber was 

 lifted by a sudden jirk, which broke the cord, and 

 left the dowll in its intended situation. The frame 

 and square directing pipe were then lifted out of the 

 cylinder. The pile, previous to being let down, had 

 two hoops put on its lower end, and a hole cut to re- 

 ceive the end of the iron dowell which stood in the 

 rock. And, from the side of this hole to the inside 

 of the lower hoop, four pieces of iron were driven 

 into the end of the pile, to prevent the timber at the 

 sides of the dowell from giving way, when the late- 

 ral pressure came upon the pile. On the four sides, 

 near the lower end of the pile, pieces of timber were 

 nailed, to increase its si/.e to twenty-two inches, this 

 being the inside diameter of the cylinder. By this 

 meai.s the hole was kept in its precise situation, and 

 was formed to pass exactly upon the dowell. It was 

 then set hard to the rock by a stroke of the pile 

 engine. This completed the iixing of one main pile. 

 A strong chain was then fastened to the top of the 

 cylinder, and, after the main pile was wedged down, 

 to prevent it from rising, a strong purchase of ropes 

 and blocks was applied to raise the cylinder out of 

 the sand ; but all the power which could be applied 

 was ineffectual. A beam of fifty feet in length was 

 therefore procured for a lever. The fulcrum of this 

 lever was laid on the top of the main pile. The 

 outer end of it was lifted up by ropes and blocks 

 from the mast of a sloop, that was laid along the 

 outside of the dam for this purpose. The chain 

 from the top of the cylinder was now fixed to the 

 inner end of the lever, and six men got on the outer 



VOL. IV. I'ART II. 



end, and net ii in motion. The cylinder at length '' 



lint, before it moved, it took a pu rebate ot ' 

 fifty ions. After it was worked up a little 

 lnvir, tli :nd blocks were again ap- 



.uid lilted the cylni t!n- top of the 



pile. '.' of tiie pile was now forced against 



the inside of ;he upper leading frame, and a screw- 

 bolt put through both. The whole apparatus waa 

 then shifted to the situation of the next main pile, and 

 similar operations took place, until the whole of the 

 main j; fixed, excepting in some instance i 



where the sand was shallow, and then the cylinder was 

 lifted without employing this enormous lever. 



The main piles having been all properly fixed lit 

 the bottom, and fastened at the heads, temporary 

 leading beams were bolted on the outside of the pile ; 

 formerly described as driven 15 or 20 feet ap 

 round the outside of the main leading frames. The 

 spaces were now filled up with piles set close side by 

 side, and driven down to the rock : then the lower 

 temporary leading frame was taken off, the upper 

 one being left to steady the piles until the puddle 

 was brought up in the cofferdam. The inside braces 

 were now put in ; they rested upon brackets fasten- 

 ed to the main piles, and also upon the tops of these 

 piles which were driven to the rock under the main- 

 stretching brace. The braces were besides prevented 

 from floating, by brackets nailed above them, and by 

 stones laid on temporary scaffolds. The outer row 

 of piles, in front of the cofferdam, was begun by 

 placing a pile engine on a float made of large fir logs 

 from 40 to 50 feet long, and one foot square. These 

 were fastened together by half logs spiked across 

 them. The width of this float was 14> feet, which 

 just filling the space between the rows of piles, was 

 thereby kept steady ; and this was also the means of 

 getting readily into a straight line the rvter row of 

 piles which stood at twenty feet apart. These being 

 driven, a long leading beam was made by fishing, as 

 formerly described, and bolted to the outside of these 

 piles on a level with the inside leading frame. A 

 temporary leading beam was then fixed on the inside 

 of the outer row of piles, one foot lower than the 

 outside beam ; there was then a scaffold erected on 

 the top over the space between the rows of piles, by 

 which means were taken to secure the outer piles 

 from any motion they might otherwise have had 

 with the tide. The piling-engine was next got on 

 this scaffold, and an outside leading beam bo!' 

 the same level with the middle leading frame on the 

 inside. The space betwixt the first-mentioned piles 

 was now filled up by others set close together and 

 driven down to the rock, by the time the outside 

 and two return rows of piles at the angles were all 

 driven : the bank and puddle at each side of the dam- 

 was brought forward to the front of the inner row of 

 piles. 



The connecting bolts were now put in, one through 

 each main pile, opposite the middle leading frame, 

 through which it went, also across the puddle, jnd 

 through the front leading beam on the outside oi the 

 outer row of piles. These connecting bolts were 

 fastened by a strong cotterei through each end, with 

 a strong iron plate under them. There were likewise 

 two of these connecting faults through each main 



