134 Sir Frederick Bramicell [May 19, 



filHng it up where tlie trial heading is to pass through, say a fissure 

 4 or 5 feet wide, and I will take it that we are so fai- below the sur- 

 face of the sea that the pressure amounts to 150 lbs. per square inch, 

 or a little under 10 tons to the square foot. The 7-foot heading 

 contains 38 superficial feet area, so that the pressure of the water 

 endways ao^ainst it would be about 380 tons. A single hydraulic 

 press has been made to give 1000 tons pressure ; 380 tons therefore 

 is an every-day load for a single hydraulic press. One •20-iueh ram 

 would deal with it at only a ton to the circular inch. 



I will now ask you to look at the diagram showing the apparatus 

 bv which such a fissure could be passed. You will see, fixed into the 

 walls of the excavation, a ring containing a stuffing-box, or it may be 

 a cup-leather such as that used for an hydraulic 2)re5s ; through this 

 stuffing-box would slide, water-tight, a horizontal iron vessel, or 

 tube, of nearly the full diameter of the bare of the trial heading 

 of 50, 70, or 100 feet long, as might be needed, and provided 

 with cutting tools in front set to the full diameter of that bore. 

 This vessel or tube would be open-ended towards the fissure, but 

 would be close-ended towards the trial heading. It would be ma<ie 

 capable of slow revolution, and capable of being pushed forward 

 by hydraulic presses having a large margin of power. Water would 

 then' be forced in by a pipe led from the stuffing-box to the space 

 between the outside of the vessel and the inside of the heading, and 

 this water would be pumped at a pressure somewhat greater than 

 that produced by the sea, say if the sea give 150 lbs., then this water 

 should bo. pumped in at 160 lbs. The result of this arrangement 

 would be that before the fissure was reached, and before the sea 

 pressure came upon the tube, the parts would be subjected to a 

 pressure greater than that of the sea, and therefore all the working 

 parts, instead of being exposed to any shock when the sea pressure 

 came on, would absolutely be thereby relieved to a slight extent. 

 The vessel would be slowly revolved, and by its cutting tools would 

 cut its wav forward, the material being w-ashed into the interior of 

 the vessel bv the water pumped into the annular space on its outside ; 

 and until communication with the fissure was made, the material would 

 be allowed to flow out in a regulated manner just enough to preserve 

 a current. It -.vill be seen that this is nothing more than a horizontal 

 borincr crown, such as is commonly used by the Diamond Boring 

 Company, with a current of water at the working-face for continuously 

 washincr' away the debris. Under these circumstances the operation 

 would oro on* until the vessel had advanced, not only to the fissure, 

 but through the fissure and to the opposite side, and had cut into that 

 opposite side a sufficient distance. 



It may be said that when all this was accomplished there would 

 still be left a leakage space round about the end of the vessel as it lay 

 in the cavity itself had made on the opposite side of the fissure, this 

 space being equal to the projection of the cutters from the vessel, but I 

 will show vou this could be closed in the readiest manner possible. 



