132 Chronicles of Science, [Jan. 



The battery with which the experiment was tried consisted of 

 six heads, all working in one coffer, contained in a strong cast-iron 

 framing ; the crank-axle running in two plummer-blocks, carried on 

 top of side frames, which are 62 inches apart ; and the height from 

 ground to centre of axle, 110 inches; the total weight, including 

 everything, 8^ tons. The difficulty to overcome was to give a long 

 and variable stroke of head, with a short and constant throw of 

 crank; this, however, has been accomplished, as with forging 

 hammers, in the following manner : — The upper end of the cylinder 

 is bored, to receive the piston, to a depth of 14 inches ; the piston- 

 rod plays air-tight through the cylinder cover, which is screwed 

 metal to metal on the cylinder. The working barrel of cylinder is 

 pierced with two sets ol small holes, for the ingress and egress of 

 air, discharging the air behind the piston after it has been once used 

 as an elastic cushion. Suppose the head to be set in motion with 

 the crank in a horizontal position, the piston being in the middle, 

 vertically of the working barrel of cylinder, and midway between the 

 two sets of air-holes referred to. As the crank and attached piston 

 rise, the air is compressed between the piston and cylinder cover, 

 and the cylinder, with stamp-head attached, is forced upwards. 

 When in rapid motion, the elasticity of the compressed air between 

 the piston and cover flings the cylinder, with head, some inches 

 above the range, due to the motion of the crank; on the descent of 

 the piston below the bottom set of holes in the cylinder, the air is 

 compressed in a similar manner, and the cylinder is forced down by 

 the compressed air between the piston and cylinder bottom, until 

 the stamp-head strikes the ore in a coffer-trough ; thus, whether the 

 quantity of ore be large or small, the blow is always effective. 



At the last meeting of the Midland Institute of Mining En- 

 gineers, a discussion took place on the paper read by Mr. A. Lupton, 

 in August last, " On the Use of Hydraulic Machines for Breaking 

 down Coal : " — 



On first introducing the subject, Mr. Lupton, with the aid of a 

 number of diagrams, gave the results of several experiments which 

 he made for the purpose of testing the value of the hydraulic ma- 

 chines, including those of Mr. Grafton Jones, Mr. Bidder, and Mr. 

 Chubb. The machine of Mr. Grafton Jones, the principle of which 

 consists in driving a wedge by means of a hydraulic press between 

 two blocks of steel which are rendered incapable of any but lateral 

 movement, by tension-bars connecting them with the press, was 

 tested at the Shipley Colliery, in Derbyshire, where the bed of coal 

 is worked on the long wall system in banks from 80 to 100 yards 

 in length, the coal being 4 ft. 7 in. thick. As much work could be 

 done by it and two men, Mr. Lupton said, in from two to three 

 hours, and as much coal got, as would take two men by the ordinary 

 method from one-and-a-half to two days. 



