The cap is a tricky thing that may go off at any jar or scratch or at a spark from pipe or cigarette.
You can, if you are sufficiently careless of possible results, light the twisted paper end of a stick of dynamite and watch the dynamite burn like wax in your fingers; it MAY go off and set your friends to work retrieving portions of your body.

More likely, it will do nothing but burn harmlessly.
Well, then, a piece of fuse is inserted in the open end of the cap, and the metal pressed tight against the fuse to hold it in place.

Pressed down by the miner's teeth, sometimes, if he has been long in the business and has grown careless about his head; otherwise he crimps the cap on with a small pair of pliers or the back of his knife blade--and feels a bit easier when it is done without losing a hand.
You would think, unless you are accustomed to the stuff, that when five holes are loaded with, probably, ten or twelve sticks of dynamite to the lot, each hole containing a six-X exploding cap as well, that the first shot would likewise be the last shot and that the whole tunnel would cave in and the mountain behind it would shake.

Nothing like that occurs.

If there are five loaded holes in the tunnel face, and you do not hear, one after the other, five muffled BOOMS, you will know that one hole failed to go off--and that the miner is worried.