The holes are made by means of a bar or drill. A great deal depends, of course, upon the hardness of the soil. Sometimes a steel bar has to be driven in by a sledge-hammer. At others a pointed bar can be pushed down by hand. In some cases it will be found that the best tool to employ is a "dirt-auger," a tool like a carpenter's auger, which on being turned round and round bores its way into the earth. However it may be done, one or more cartridges of dynamite are lowered into the finished hole, one of them being fitted with the necessary detonator and fuse. Then a little loose earth or sand is dropped into the hole until it is filled to a depth of six inches or so above the uppermost cartridge. Above that it is quite safe to fill the hole with earth, ramming it in with a wooden rammer. This is called "tamping," and it is necessary in order to prevent the force of the explosion being wasted in simply blowing up the hole. What is wanted is that the explosion shall take place within an enclosed chamber so that its effect may be felt equally in all directions. The holes are generally about an inch and a half or an inch and three-quarters in diameter. There are two ways of firing the charges. One is by means of fuses. The detonator is fastened to one cartridge and a length of fuse is attached to the detonator, which passing up the hole terminates above the ground. The fuse is a tube of cotton filled with gunpowder, and it burns at the rate of about two feet a minute. Thus if three feet of fuse be used the man who lights it has a minute and a half in which to find a place of safety from falling stones. The other way is by electricity. In this case an electric fuse is attached to the cartridge and two wires are led up the hole. These are connected to an electrical machine, which causes a current to pass down into the fuse, where, by heating a fine platinum wire, it fires the detonating material with which it is packed. This detonating material in turn fires the dynamite. The advantage of the electrical method is that twenty or thirty holes being simultaneously connected to the same machine can all be fired at once.