Engineering reminiscences contributed to "Power" and "American machinist"

by Charles T. Porter

The following is a story with a moral. The moral is, working to gauges is an excellent plan, providing the gauges are mixed with brains. No manufacturing system is perfect that is not fool-proof. If a mistake is possible it is generally made.

A company of English capitalists were spending a good deal of money on the west coast of South America in building railroads into and over the Andes. One of these roads was intended to reach a famous silver mine, from which the Spaniards, two or three hundred years before, had taken large quantities of the precious metal, but which had long ago been drowned out and abandoned. The railroad was to take up pumping machinery by which the mine could be cleared of water and to bring down the ore in car-load lots. For some purpose or other they wanted a stationary engine in those high altitudes, and their agent in this country ordered one from me. I was having my fly-wheels and belt drums cast by Mr. Ferguson, whose foundry was on 13th Street, west of Ninth Avenue, some seven miles distant from my shop in Harlem. He had a wheel-lathe in which I could have them turned and bored, and they were bored to gauges and shipped direct to their destinations. This time I had two wheels to be finished, so I sent the gauges with a tag attached to each describing the wheel it was for, but neglected to go and make a personal inspection of the work. Some months after I received a bitter letter from South America, complaining that they found the wheel had been bored half an inch smaller than the shaft, and that they had to chip off a quarter of an inch all around the hole where the barometer stood at 17 inches, and physical exertion was something to be avoided. The case was somewhat relieved by the fact that I always cored out a larger chamber in the middle of the hub for the purpose of getting rid of a mass of metal which would cause the hub to cool too slowly, finishing only a length of two inches at each end of the hub, which was 10 or 12 inches long. As the engine had been paid for on shipment and ran well when put together, there was no great harm done, but I was sorry for the poor fellows who had to do the work. Except the one already mentioned in my first governor pulley, ten or twelve years before, this was the only misfit I can recall in my whole experience.

Mr. Ferguson told me the best piece-work story I ever heard. He said he had a contract for making a large number of the bases for the columns of the elevated railroad; these castings were quite large and complicated. He gave the job to his best molder, but the man could turn out only one a day. He thought it was slow work and spoke to him about it, but he protested that was all he could make. Mr. Ferguson found he could never complete his contract at that rate, and as he was paying the man three dollars a day, he told him he would pay him three dollars for each perfect casting and asked him to do his best and see how many he could turn out. The man employed a boy to help him, and by systematizing his work he turned out six perfect castings every day and drew his eighteen dollars with supreme indifference. This is a big story to swallow, but the incident was then recent. I had the story from Mr. Ferguson himself, and he was a sterling, reliable man, so that there could be no doubt as to its absolute truth.

CHAPTER XVII

Mr. Allen’s Invention of his Boiler. Exhibition at the Fair of the American Institute in 1870.

At that time the “Field boiler tubes” were attracting considerable attention in London. These were designed to prevent the water from being lifted from the closed bottom of vertical tubes over the fire, which would cause them to be burned out. The Field tubes were smaller internal tubes, provided at the upper end with three wings which centered them in the middle of the external tubes, in which they reached nearly to the bottom. They were made slightly bell-mouthed at the top. The circulation was down the internal tube and upwards, through the annular space. The bell mouth prevented these currents from interfering with each other. One morning Mr. Allen said to me that he had an idea that by inclining the tubes at a small angle from the vertical a better circulation would be got than in the Field tubes. He thought the steam as fast as formed would all go to the upper side of the inclined tubes, and would rush up along that surface without driving the water before it, and so the water would always be at the bottom of the tube, no matter how hard the boiler was fired. I was struck with the idea and determined to test it. I got the largest test-tube I could find, 1¹⁄₄ inches in diameter and 15 inches long, and set it in an adjustable support, and applied the flame of four Bunsen burners, bunched together, at the bottom. In a vertical position the water was instantly thrown clean out of the tube. At about the angle of 20 degrees Mr. Allen’s idea was completely realized. The bubbles of steam united in a continuous stream on the upper side and rushed up with no water before them. With the most rapid generation of steam the water remained solid at the bottom of the tube. The sight was a very interesting one. I reasoned that if this satisfactory result was got under a short column of water, and only the pressure of the atmosphere and in a small tube, it could certainly be relied upon under a column of water several times longer, under a pressure of several atmospheres and in a much larger tube. The greater the pressure the smaller the bubbles of steam would be. Those formed under one atmosphere were about as large as kidney beans.

Mr. Smith was anxious to have us exhibit the engine at the Fair of the American Institute in New York in the fall of 1870. This Institute was then at the height of its usefulness, and its annual fairs were crowded with exhibits and attracted wide attention. Mr. Allen and I consulted about it, and on account of the liability of getting more hot water than steam from the queer boilers that might be exhibited, we agreed that, as the engine would have to be tested for economy, it would not be safe to exhibit unless we could make a boiler according to Mr. Allen’s plan to supply the steam. With this boiler we could certainly get dry steam, and felt confident of getting it superheated.

Our recommendation to that effect was adopted, and we prepared to exhibit two engines, one of them 16 inches diameter of cylinder by 30 inches stroke to make 150 revolutions per minute, and the other 6 inches in diameter by 12 inches stroke to make 300 revolutions per minute, and a boiler. We also made to drive our own shop, to take the place of the portable engine and boiler, an engine of the smaller size above named, except that the cylinder was, by thickening its walls, made 5 inches in diameter only. This was because this size would be ample for the power we required, and I would be able to show the effect of inertia of the heavy reciprocating parts in producing smooth and silent running, much better than with a 6-inch cylinder, which would have about 50 per cent. larger area with no greater weight in the reciprocating parts, except only in the piston. This exhibition, as we shall see, became of great importance. We made also an Allen boiler for ourselves, of four sections; really, as it proved, three or four times as large as we needed, but we could not well make it smaller.

This exhibition at the American Institute was in every respect a great success, not a drawback of any kind about it. The little engine was used by Merrill & Sons to drive their exhibit of forging machinery, hammers and drops. The large engine gave motion to a miscellaneous exhibit of machinery in motion. The exhibition of machinery in motion closed each day for an hour from 12 to 1, and again from 6 to 7, but I ran these engines continuously from 9 A.M. to 10 P.M., to show that high speed asked no favors. There were five boilers, including our own, from the start. The other four were smaller than ours. Another boiler, the largest of all except ours, was started later, as will be told. Ours had a brick flue and chimney, but only 30 feet high. Those of the others were iron. There were a number of other engines and pumps and pulsometers, all steam eaters.