3-021-619 - The Print Collector/Heritage Images

The new overland route to India and the railway tunnel of the Alps: boring-machine in the tunnel, 1869. 'The Sardinian Government then appointed M. Maus, a Belgian engineer, and M. Sismonda, a geologist, to devise the best line of tunnel and the best mode of construction...If a quantity of air be compressed into one sixth of its ordinary space, it acquires an elastic force equal to six times the common pressure of the atmosphere - namely, 84 lb. to the square inch...The width and height of the intended excavation, including the space to be filled with masonry at the roof and sides, are so considerable that it has to be carried forward in three drifts or galleries, at different elevations.... The boring tool, drill, or needle...is simply an iron bar, with a point 2 in. wide, shaped like that of a chisel or adze, and very frequently sharpened, hundreds and thousands of these tools being soon worn out...Whenever the requisite number of holes, which varies with the situation of the working and with the nature of the rock, have been bored for one blasting, the engine travels back out of the gallery; the men charge the holes with mining-powder, lay a train or light a slow match, and retire behind the closed doors till the rock is blown up'. From "Illustrated London News", 1869.