But perhaps this further story is a better indication of developed humor and shrewdness: "A man by the name of Epstein had been in the habit of buying brass chips and trimmings from the lathes, and in some way Bergmann found out that he had been cheated. This hurt his pride, and he determined to get even. One day Epstein appeared and said: `Good-morning, Mr. Bergmann, have you any chips to-day?' `No,' said Bergmann, `I have none.' `That's strange, Mr. Bergmann; won't you look?' No, he wouldn't look; he knew he had none. Finally Epstein was so persistent that Bergmann called an assistant and told him to go and see if he had any chips. He returned and said they had the largest and finest lot they ever had. Epstein went up to several boxes piled full of chips, and so heavy that he could not lift even one end of a box. `Now, Mr. Bergmann,' said Epstein, `how much for the lot?' `Epstein,' said Bergmann, `you have cheated me, and I will no longer sell by the lot, but will sell only by the pound.' No amount of argument would apparently change Bergmann's determination to sell by the pound, but finally Epstein got up to $250 for the lot, and Bergmann, appearing as if disgusted, accepted and made him count out the money. Then he said: `Well, Epstein, good-bye, I've got to go down to Wall Street.' Epstein and his assistant then attempted to lift the boxes to carry them out, but couldn't; and then discovered that cal- culations as to quantity had been thrown out because the boxes had all been screwed down to the floor and mostly filled with boards with a veneer of brass chips. He made such a scene that he had to be removed by the police. I met him several days afterward and he said he had forgiven Mr. Bergmann, as he was such a smart business man, and the scheme was so ingenious.

"One day as a joke I filled three or four sheets of foolscap paper with a jumble of figures and told Bergmann they were calculations showing the great loss of power from blowing the factory whistle. Bergmann thought it real, and never after that would he permit the whistle to blow."

Another glimpse of the "social side" is afforded in the following little series of pen-pictures of the same place and time: "I had my laboratory at the top of the Bergmann works, after moving from Menlo Park. The building was six stories high. My father came there when he was eighty years of age. The old man had powerful lungs. In fact, when I was examined by the Mutual Life Insurance Company, in 1873, my lung expansion was taken by the doctor, and the old gentleman was there at the time. He said to the doctor: `I wish you would take my lung expansion, too.' The doctor took it, and his surprise was very great, as it was one of the largest on record. I think it was five and one-half inches. There were only three or four could beat it. Little Bergmann hadn't much lung power. The old man said to him, one day: `Let's run up-stairs.' Bergmann agreed and ran up. When they got there Bergmann was all done up, but my father never showed a sign of it. There was an elevator there, and each day while it was travelling up I held the stem of my Waterbury watch up against the column in the elevator shaft and it finished the winding by the time I got up the six stories." This original method of reducing the amount of physical labor involved in watch-winding brings to mind another instance of shrewdness mentioned by Edison, with regard to his newsboy days. Being asked whether he did not get imposed upon with bad bank-bills, he replied that he subscribed to a bank-note detector and consulted it closely whenever a note of any size fell into his hands. He was then less than fourteen years old.

The conversations with Edison that elicited these stories brought out some details as to peril that attends experimentation. He has confronted many a serious physical risk, and counts himself lucky to have come through without a scratch or scar. Four instances of personal danger may be noted in his own language: "When I started at Menlo, I had an electric furnace for welding rare metals that I did not know about very clearly. I was in the dark-room, where I had a lot of chloride of sulphur, a very corrosive liquid. I did not know that it would decompose by water. I poured in a beakerful of water, and the whole thing exploded and threw a lot of it into my eyes. I ran to the hydrant, leaned over backward, opened my eyes, and ran the hydrant water right into them. But it was two weeks before I could see.

"The next time we just saved ourselves. I was making some stuff to squirt into filaments for the incandescent lamp. I made about a pound of it. I had used ammonia and bromine. I did not know it at the time, but I had made bromide of nitrogen. I put the large bulk of it in three filters, and after it had been washed and all the water had come through the filter, I opened the three filters and laid them on a hot steam plate to dry with the stuff. While I and Mr. Sadler, one of my assistants, were working near it, there was a sudden flash of light, and a very smart explosion. I said to Sadler: `What is that?' `I don't know,' he said, and we paid no attention. In about half a minute there was a sharp concussion, and Sadler said: `See, it is that stuff on the steam plate.' I grabbed the whole thing and threw it in the sink, and poured water on it. I saved a little of it and found it was a terrific explosive. The reason why those little preliminary explosions took place was that a little had spattered out on the edge of the filter paper, and had dried first and exploded. Had the main body exploded there would have been nothing left of the laboratory I was working in.

"At another time, I had a briquetting machine for briquetting iron ore. I had a lever held down by a powerful spring, and a rod one inch in diameter and four feet long. While I was experimenting with it, and standing beside it, a washer broke, and that spring threw the rod right up to the ceiling with a blast; and it came down again just within an inch of my nose, and went clear through a two-inch plank. That was `within an inch of your life,' as they say.

"In my experimental plant for concentrating iron ore in the northern part of New Jersey, we had a verti- cal drier, a column about nine feet square and eighty feet high. At the bottom there was a space where two men could go through a hole; and then all the rest of the column was filled with baffle plates. One day this drier got blocked, and the ore would not run down. So I and the vice-president of the company, Mr. Mallory, crowded through the manhole to see why the ore would not come down. After we got in, the ore did come down and there were fourteen tons of it above us. The men outside knew we were in there, and they had a great time digging us out and getting air to us."

Such incidents brought out in narration the fact that many of the men working with him had been less fortunate, particularly those who had experimented with the Roentgen X-ray, whose ravages, like those of leprosy, were responsible for the mutilation and death of at least one expert assistant. In the early days of work on the incandescent lamp, also, there was considerable trouble with mercury. "I had a series of vacuum-pumps worked by mercury and used for exhausting experimental incandescent lamps. The main pipe, which was full of mercury, was about seven and one-half feet from the floor. Along the length of the pipe were outlets to which thick rubber tubing was connected, each tube to a pump. One day, while experimenting with the mercury pump, my assistant, an awkward country lad from a farm on Staten Island, who had adenoids in his nose and breathed through his mouth, which was always wide open, was looking up at this pipe, at a small leak of mercury, when the rubber tube came off and probably two pounds of mercury went into his mouth and down his throat, and got through his system somehow. In a short time he became salivated, and his teeth got loose. He went home, and shortly his mother appeared at the laboratory with a horsewhip, which she proposed to use on the proprietor. I was fortunately absent, and she was mollified somehow by my other assistants. I had given the boy considerable iodide of potassium to prevent salivation, but it did no good in this case.