I was much amused by the pat way in which my mother questioned me, and became more interested as I continued my explanation.
“You must know,” I said, “that many powders are violently explosive, and some more so than others. This violence of explosion is called detonation, by which is meant the almost instantaneous conversion of the ultimate molecules of an explosive compound (i.e. the whole concern) into gas.”
“I see; you mean that it goes off quickly,” said my mother, in a simple way that was eminently characteristic.
“Well, yes; but much more quickly than gunpowder does. It were better to say that a powder detonates when it all explodes at the same instant. Gunpowder appears to do so, but in reality it does not. One of the best detonators is fulminate of mercury. Detonating caps are therefore made of this, and one such cap put into the middle of that cartridge of dynamite and set fire to, by any means, would convert the cartridge itself into a detonator, and explode it with a shattering effect.
“A human being,” I continued, “sometimes illustrates this principle figuratively—I mean the violent explosion of a large cartridge by means of a small detonator. Take, for example, a schoolmaster, and suppose him to be a dynamite cartridge. His heart is a detonating cap. The schoolroom and boys form a galvanic battery. His brain may be likened to a conducting-wire. He enters the schoolroom; the chemical elements are seething in riot, books are being torn and thrown, ink spilt, etcetera. Before opening the door, the good man is a quiet piece of plastic dynamite, but the instant his eye is touched, the electric circuit is, as it were, completed; the mysterious current flashes through the brain, and fires his detonating heart. Instantly the gleaming flame shoots with lightning-speed to temples and toes. The entire man becomes a detonator, and he explodes in a violent hurricane of kicks, cuffs, and invective! Now, without a detonator—a heart—the man might have burned with moderate wrath, but he could not have exploded.”
“Don’t try illustration, Jeff,” said my plain-spoken mother, gently patting my arm; “it is not one of your strong points.”
“Perhaps not; but do you understand me?”
“I think I do, in a hazy sort of way.”
Dear mother! she always professes to comprehend things hazily, and indeed I sometimes fear that her conceptions on the rather abstruse matters which I bring before her are not always correct; but it is delightful to watch the profound interest with which she listens, and the patient efforts she makes to understand. I must in justice add that she sometimes, though not often, displays gleams of clear intelligence, and powers of close incisive reasoning, that quite surprise me.
“But now, to return to what we were speaking of—my future plans,” said I; “it seems to me that it would be a good thing if I were to travel for a year or so and see the world.”