fects in little bubbles that are extremely sensitive

and will go off at the least provocation,

“I remember once,” continued Mr. Douglas, “when I was only a lad, my brother and I were anxious to try our hand at ‘shooting’ Father was a contractor, and was doing a job out in Oregon, and we boys worked there, with the men. Well, as 1 was saying, one day when the men were off at lunch, we went to the dynamite house and got out a case of dynamite.
“HOLED THROUGH,” THE JUNCTION OF TWO TUNNEL HEADINGS. The heading was all ready for the powder, and we thought we could shoot it just as well as any one else. I carried the case of dynamite over to the shaft while my brother was getting the fuses. When I got to the shaft, the bucket was up at the top, near enough, as I thought, for me to reach over and put the case of dynamite on it, even though it did weigh fifty pounds. However, as I leaned over the edge of the shaft, I kicked against a pick or a shovel that lay in my way, and this hit the bucket and pushed it out of my reach; but I had leaned so far that it was impossible for me to regain my equilibrium, and I had the alternative of dropping the fifty pounds of dynamite, or falling down the shaft with it. It did n’t take me a second to make my choice, and then, as the case shot down the shaft, I ran. Yes, I did some real running. My brother saw me coming, took one glance at my face, and then he also ran some. So did the engineer of the hoisting-engine. The shaft was n’t more than one hundred and eighty feet deep, but we ran long enough for that dynamite to haye dropped ten times as far. Then we stopped ta collect our wits. Well, sir, that powder never went off! When my father heard about it the next day, he made it the text of a sermon. All the men were lined up to hear his speech, and it certainly made an impression upon me. ‘I want you to understand,’ says he, ‘that dynamite is dangerous stuff to handle, even though a case of it did fall one hundred and eighty feet with- out exploding. It is dangerous stuff, I tell you, and should always be treated with respect. After that incident of yesterday, you may get the notion that all this talk about the danger of dynamite is mere nonsense, but, let me tell you, that dynamite was perfectly fresh. Two or three months from now that very same powder will be so touchy that you cannot drop a pebble on it without setting it off. The only way to handle dynamite safely is to treat it with due respect always, because you never can tell in just what condition it is,

“Well, as I was saying, if this powder here should happen to go off,” resumed Mr, Douglas, with exasperating deliberation, “the explosion wave would smash into that pocket at the other end of the chamber, where it would come up against a wall of solid rock; then it would have to go off at right angles down the passage, where it would find itself in another pocket: again it would have to dart at right angles, only to dash into the third pocket, and by the time it found its way out to the door, it would have lost much of its energy, and then it would hit the door with a gentle shove of something like five hundred and forty tons, or about one million pounds. It sounds like a long story, but it would all happen like that,” and he snapped his fingers, “The door would slam shut, and the poisonous fumes would be trapped inside without any way of escape. You can get some idea of the energy of dynamite when I tell you that the gases will exert a steady pressure of one hundred and fifty pounds per inch on every square inch of the chamber in the passage until they cool down. In other words, the powder which in the solid state occupied less than fifteen cubic feet, will be turned into a compressed gas occupying twenty thousand cubic