130 Sir Frederick BrannceU [May 19, 



weight of this 150 tons. The height through which this will have 

 to be lifted is some 60 yards, a distance so slight that there is no 

 reason on the score of expense why there should not be two or three 

 independent shafts, or, better still, one large shaft with two or three 

 separate lifts in it, so that each lift would bring up about 50 tons 

 an hour, or 500 tons in the 10 hours. There are coal-pits where as 

 much as 770 tons in the ten hours are raised, not from a dej)th of 

 60 yards, but from a depth of 600 yards, or ten times 60 yards. This 

 su22ested difficulty, therefore, it will be seen, has no foundation. 



But although, I trust, I have made it abundantly clear that there 

 is no practical difficulty whatever in getting the excavated materials, 

 by the use of ordinary waggons drawn by compressed air engines, 

 to the base of the shaft, nor in raising by winding engines, there 

 is another mode of getting rid of that material, and another system 

 of working, which has been suggested by Mr. Crampton, a mode 

 that well deserves consideration. His proposition is to employ 

 hydraulic power (water under pressure) as the motive agent, to 

 drive either the sj)ecial cutting machine which he suggests, or any 

 other cutting machine, at the face of the heading or tunnel, and also 

 to drive the pumps necessary to send this water back along the 

 tunnel to a sump at the foot of the shaft, from which it can be 

 pumped up. or to send it by one pumping direct to the surface. He 

 shows that the water, after having worked the engines requisite to 

 drive the cutting machine and the pumps, would, in any given time, 

 be in bulk equal to from five to six times that of the chalk whicli 

 would be cut in that time. He proposes that the fine shavings of 

 chalk, as they are cut, should be delivered into a mixing machine 

 (of a description similar to that which he has employed for very many 

 years for brick-making piu-poses), where the waste water from the 

 engines would be united with the shavings of chalk, resulting in the 

 production of a creara containing one part of chalk to six parts of 

 water in volume ; the ordinary cream of a brick-field being one 

 volume of chalk and one volume of water. He then shows, that by 

 this process the whole of the material might be continuously delivered 

 through pipes to the surface, without needing any train accommodation 

 at all, or any winding apparatus. This would leave the rails in the 

 tunnel perfectly free for the trains bringing the material for the lining 

 of the tunnel. I stated at the British Association meeting at York 

 last year that at the pressure ordinarily used by Sir William Arm- 

 strong, viz. 700 lbs. on the square inch, 300 horse-power can be con- 

 veyed through a 10-inch pipe, with a loss in friction of only 2 per 

 cent, for each mile in length, so that in mid-channel there would be 

 no greater loss than 20 per cent. This plan, having regard to the 

 extreme simplicity of the mode wliich it affords of getting rid of 

 the excavated material, is, I think, well worthy of consideration, 

 but it must be borne in mind that air pipes would still have to 

 be laid down, and blowing machinery (although not compressing 

 machinery) would have to be erected for the purpose of ventilation, 



