English: "For the driving of tunnels of large section, such as railway tunnels, a special form of carriage support needs to be used such as illustrated in the figure, which was designed by Mr. Richard Schram, M.I.C.E., to carry four of his drilling machines for use in driving 2 1/2 miles of tunnel on the Khwaja-Amran branch of Quetta Railway. The carriage carries two stretcher bars, each of which supports two drilling machines, the arrangement of the carriage and bars being such that trucks for the demoval of debris, etc., can be run right through it, so that it is unnecessary to provide any sidings in which to run the carriage when removal of spoil becomes necessary. This arrangement has the further advantage that the drilling machinery can be brought up to the working face before all the debris has been removed, thereby economising time. In case where timbering is necessary, and the stretcher bars have to be lowered to clean up, arrangement is made whereby these, with their machines can be turned back down on the carriage. The small receiver shown on top of the carriage is for the distribution of air, and it has two inlets and four outlets, corresponding to the number of drills. The tanks shown on each side are the water injectors, injection being effected by admitting air under pressure above the surface of the water. The tunnel for which the machines are designed will be driven not only from each end but by sinking a shaft midway two additional working faces will be provide, making four points of attack.The four sets of tunneling plant required were all supplied by Messrs. Schram, amounting, in toto, to eight locomotive type boilers, four air compressors, with their receivers, four carriages of the type just described, and thirty-two rock-boring machines, with the accessories necessary for opening out the tunnel.

In mining proper, a tunnel of such large dimensions would rarely, if ever, be undertaken; but I illustrate the method adopted in such cases because men accustomed to the use of rock drills are often drafted from their legitimate sphere to conduct works coming under the designation of civil engineering. The drill hole, when the machine is at work, must be kept constantly full of water, not only in order to remove the chippings, but also to keep the point of drill cool, A water tank of iron mounted on a truck, and brought as near the working face as possible, is therefore a necessity.

In the figure this water tank is shown fixed in the carriage support, and surmounted by a funnel. The pressure of the air drives out the water through an indiarubber hose, with a fine brass nozzle into the hole which is being drilled, and so fulfills the above-mentioned duties, and stops the formation of dust, which, with certain minerals, would be very deleterious to the workmen."