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."