Page:Walker (1888) The Severn Tunnel.djvu/160

Rh in the workings, and was not strong enough for the hard rock.

The fumes of dynamite were so deleterious, and even dangerous, that we abandoned the use of it altogether.

Gelatine produced the best results in the hard rock, but we only used it for some months, when the makers were required by the Board of Trade to suspend the sale of it, and return all the material to store.

Nearly all the work was done with tonite made by the Cotton Powder Company. This is a carefully prepared explosive, made up into handy packages which the miners know as ‘pills,’ with a detonator attached to some of the cartridges, which were then known as ‘primers.’ The fuse was attached to a primer, and then, according to the depth of the hole and the strength of the material to be blasted, a primer and one, two, three, or four pills were placed in the hole.

Very little tamping was required; but in very hard rock the tonite would leave what the miners call a ‘socket;’ that is, a short length of the hole at the bottom where the explosive had not been strong enough to dislodge the rock. When using gelatine we found no sockets left, showing the extra strength of that explosive.

The tonite was not injured by water, nor did it seem to be affected by cold, as dynamite is; and the fumes were so slight that it was quite possible to