There was no one in the cellar but a boy firing the boilers. I asked him if he knew who put that pipe there. He knew nothing about it, but supposed our men put it there when they set up the engine. I hunted up the engineer and asked him the same question, and got the same answer. I went to the people who did the engineering work for the Post Office and who had put in the pipes; they knew nothing about it. I could find out nothing, but had to content myself with telling the engineer that I had closed the valve and relied upon him to keep it closed. I asked him what he thought caused the thump in the engine; he said he had not the slightest idea, but he would try to cure it. I contented myself with writing to the Postmaster that I had removed the cause of the waste of steam and hoped he would now find the engine satisfactory. Soon after Mr. Merrick was in New York for two or three days. When he came home he said: “I have cured the thump in that Post Office engine.” “How did you do it?” I asked. He replied: “I gave the engineer a twenty-dollar gold piece, and when I went to see it the next morning the thump was gone.” I should add that when the old engine was taken down I had the back cylinder head removed, which was done without difficulty, and found the diameter fourteen inches. “For ways that are dark and tricks that are vain” this engineer was “peculiar” in my experience.
I had brought with me from Newark an order from the Willimantic Linen Company, who were manufacturers of cotton thread, for two engines for quite an interesting application. They were building a new mill entirely unique in its design, which has never been repeated, being an ignorant freak. It was a one-story mill 800 feet long and 250 or 300 feet wide, intended to contain five lines of shafting. Each line was independent and drove the machinery for all the successive operations from opening the cotton bales to packing the spools of thread. These lines of shafting 800 feet long were to be in the basement and to drive these machines by belts through the floor, the engine to be in the middle of each line. For this purpose I supplied a pair of condensing engines, 11 inches diameter of cylinder and 16 inches stroke, making 350 revolutions per minute, with their cranks set at right angles with each other in the line of shafting. These required no fly-wheel and would start from any position. I had a great deal of trouble with this order on account of the delay in its execution, so much so that before the first engine was finished the order for the second one was countermanded, and this order was placed with the Hartford Engineering Company, a new concern which was foolish enough to undertake the same speed. However, after my first engine was started they found themselves face to face with an impossibility and had to throw up their contract, whereupon the president of the company became very civil and asked me to be kind enough to make the second engine for them, which I was quite happy to do, as I had on hand the peculiar bed for these engines, which I did not break up after the order was countermanded, but had it set up against the wall of the shop in readiness for what might happen. These two engines were both in successful operation when my own operations ceased; the remaining three engines were to be added as their business required.
The engineer of that company was an original investigator. He had a battery of return-tubular boilers, each one crammed full of tubes according to the usual methods of boiler-makers. He provided himself with pieces of lath one inch wide, one eighth of an inch thick, and four inches long, and laid one in the front end of each tube in one of his boilers and left them there for twenty-four hours. He had made a diagram of his boiler on which he numbered every tube and put a corresponding number on every piece of lath. In taking them out they presented an astonishing revelation, which he showed me. Some of the pieces were burned almost to a coal and some were scarcely discolored, while the great body of them presented various effects of heat between these extremes. These showed distinctly the enormous differences in the temperature of the gases passing through the different tubes, and that fully one half of the tubes did little or no work in evaporating the water. They taught a lesson which boiler-makers, who count every additional tube they can get into a boiler as so much added heating surface and rate their boilers accordingly, have no anxiety to learn, but which I afterwards turned to good account, as will be seen.
About the last and the most interesting engine that I built while in Philadelphia was one for the firm of Cheney Brothers, silk-manufacturers, of South Manchester, Conn. This was a cross-compound, the first and the last compound engine that I ever built, and it is the only engine in this country to which I applied my condenser. The cylinders were 12 and 21 inches in diameter, the stroke 24 inches, and the shaft made 180 revolutions per minute. The condenser presented a new design in one respect; the air-pump was double-acting and made only 45 double strokes per minute, being driven by a belt from the engine shaft and the motion reduced by gears 1 to 4. This engine ran perfectly from the start, and I looked forward with confidence to a demand for many more of the same type. The [diagrams] made by it are here reproduced.
Scale, 1″ = 32 Lbs.
Atmosphere
Scale, 1″ = 16 Lbs.
Atmosphere
Diagrams from my First and Only Compound Engine.