684 Boring Operations in Fort William. [No. 103. 



again, the original cylindrical case was found to have been compressed 

 by the water, into the shape of an octagon, acute ridges, about \ of an 

 inch in height, alternating with the flattened sides (sketch No. V.) 

 The pressure had ruptured the tin at the edge of the top of the case, 

 and the sand was saturated with the water. A double case was then 

 constructed, having interior cross pieces to strengthen it, but a similar 

 result to the preceding followed the lowering of this, and for it also the 

 pressure (upwards of 5,000 lbs.) was found too great. A cylinder of 

 wrought iron was then prepared, and on sending it down the bore it 

 was found so far capable of resisting the pressure of the water as to 

 retain its shape, but the sand was still damped. Since however the 

 water had only partially wetted the sand, it seemed probable that ad- 

 ditional care in soldering and in applying the water-proof covering 

 might exclude it altogether, and accordingly it was determined to make 

 the first attempt with this wrought iron case. 



The depth of water being about 465 feet, the galvanic battery 

 was of course the only igniting agent which could be employed ; 

 and the following are the details of the arrangements adopted. A 

 wooden plug was turned somewhat larger at one extremity than 

 the collar of the cylinder into which it was subsequently to be driven. 

 On opposite sides of this plug, grooves were prepared for the re- 

 ception of the interior conducting wires. Considerable difficulty was 

 experienced in making the grooves perfectly impervious to water 

 under great pressure, in consequence of the wires being twisted, but 

 ultimately the following means were employed with entire success. 

 The grooves were first filled with fine Europe sealing wax, and the 

 wires being previously made very hot, were forced into and completely 

 imbedded themselves in it. Subsequently a red-hot iron was held 

 near the wax of each groove, till it boiled freely, and a strip of wood 

 was then forced in over the wire so as effectually to close every 

 aperture. The interior extremities of the wires were as usual 

 connected by a short piece of thin platinum, in contact with which 

 a cartridge of dry fine powder was placed. The main conducting 

 wires were one-sixth of an inch in diameter, and their entire length was 

 nearly 1003 feet. As the bore was lined to the bottom with iron 

 tubing, it appeared essential to insulate the conductors as perfectly 

 as possible, and each wire was accordingly first cased in hempen 



