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

by Charles T. Porter

I have a pleasant memory connected with this engine. The silk-mill is located in a very large park, scattered about which are the residences of different members of the family. About twelve years after the engine was built, in company with my wife, I was visiting relatives in Hartford, from which South Manchester is about twelve miles distant. One day we were driven over there with our friends to make a social call. On our arrival I left the party to make a visit to my old engine. The mill seemed to have been changed very much, and I lost my way. Finally I recognized, as I thought, the old engine-room and went in. My engine was not there, but in its place stood another engine, a pair of tandem compounds of much larger dimensions. These had evidently just been erected, as they stood idle. “Oh, dear,” said I to myself, “my engines have been superseded for some reason or other.” While I was indulging in that reflection the engineer came in. I introduced myself and said to him: “I see that my old engines have been supplanted.” “Oh, no,” said he, “your engines are all right; they are running just where they always have been. They have built a new mill twice as large as the old one, and your engines have been giving such satisfaction they have ordered another pair of compounds from the Southwark Foundry, and these are the engines; they have not been started yet, as the mill is not ready for them and won’t be for a month.”

He directed me to the old engine-room, where I found my engines gliding away as though they had been erected yesterday. At that time I regarded these engines as only a stepping-stone to far higher things. I was engaged on a plan for a great development of the high speed system, but which has not materialized. I still consider it as on the whole superior to the turbine, a superiority, however, which may never be established.

In the spring of 1881, in our anxiety to revive the manufacture of the engine, we were foolish enough to send one to the Atlanta exhibition. We eagerly believed the promises of the agent that we should find all the machinery that we wanted to drive, and sent an engine finished with great care, and a skillful man to erect and run it. We also printed the heading of a lot of diagrams, to be given to visitors. The facts were found to be that we had nothing to drive but an idle line of shafting and one Clark’s spool-winder, while the exhaust main was so small and choked with the exhausts from other engines that we had a back pressure of ten pounds above the atmosphere; so we could take no diagrams; and the fact that we did not take any was used as a conclusive argument against high-speed engines; so the exhibition did us harm instead of good.

I pass over other distressing experiences at the works, and come at once to the final catastrophy in the late fall of 1882.

Another exhibition opened in the fall of 1882, for which I made great preparations, and from which I anticipated important results. This was the exhibition of the New England Manufacturers’ and Mechanics’ Institute, held in Boston. I obtained an important allotment of space with plenty of machinery to drive, and, besides a fine engine, sent a large exhibit of our finished work, in the parts of several sizes of engines, expecting to attract the attention of all New England manufacturers. I prepared for a regular campaign. I rented an office and engaged a young man to represent us in Boston as our agent, and another, Mr. Edwin F. Williams, to travel and solicit orders and take the charge of erecting engines. Our engine arrived without a piston. Mr. Merrick had thought he had found a defect in the piston, and ordered another one to be made. When we came to put the engine together in the exhibition, this piston would not enter the cylinder. On examination it was found to have been turned conical, the bases of the two cones meeting in the middle, so the middle was one eighth of an inch larger in diameter than the faces. We had to get a coarse file and file down the middle of the piston all around until it would enter the cylinder. Then I had a great disappointment—the greatest I ever experienced—the engine thumped badly on both centers. The only way in which we could stop the thumping was by shutting off the steam until the initial pressure was brought down to the height reached by the compression of the exhaust. In this plight we had to run through the exhibition. We could not take a diagram and had to watch the engine constantly, for whenever the pressure rose ever so little too high in the cylinder it would begin to thump. I attributed this to the shocking condition of the surface of the piston. I could not comprehend how this should cause the thump, but it must be that, for I could conceive of nothing else that could produce it. This thump made my exhibition a total failure, and necessitated the abandonment of all my plans.

At the close of the exhibition I went home utterly discouraged. When I went into the shop the first person I met was the foreman of the lower floor, where the engine had been built. I told him of the plight in which I found myself placed and to which I attributed my failure. The fellow gave me the lie direct, saying with a conceited smirk: “It is impossible, Mr. Porter, that any such work as you have described can have gone out of this establishment.” I turned on my heel and left him, and in less than half a minute I saw at a distance of fifty feet a 22-inch piston being finished for an engine we were building for the Tremont and Suffolk Mill. The workman had finished turning the piston and was then cutting the grooves for the rings. The reflection from the surface showed me the same two cones meeting in the middle. I went up to the lathe, the back side of which was toward me, and told the workman to stop his lathe and bring me a straight-edge. This rocked on the edge in the middle of the piston, opening nearly one eighth of an inch on each face alternately. I sent a boy to find the foreman and asked him what he thought of that and left him. I had influence enough to have both the foreman and the workman discharged that night. Think of it; superintendent, general foreman, the foreman of the floor, and workman, altogether, never saw what I detected at a glance from the opposite side of the shop.

I want to stop here to express my disgust with the American system of making the tailstock of a lathe adjustable, which enables either an ignorant, careless or malicious workman to ruin his work after this fashion. To their credit, English tools have no such feature.

The very next day we received a call from Mr. Bishop, the engineer of the works of Russell & Irwin at New Britain, Conn., to tell us that their engine just put in by us had a very bad thump which he was afraid could not be cured as it was evidently caused by the piston projecting over the admission ports when at the end of its stroke. “Impossible,” I exclaimed; “I never made such an engine in my life.” I should here state that in experimenting with the first little engine that I made before I went to England, I at first made the piston project over the port one quarter of an inch, and the engine thumped. I satisfied myself that this was caused by the impact of the entering steam against the projecting surface of the piston, driving it against the opposite side of the cylinder; this was aggravated in high-speed engines. In this case the engine made 160 revolutions per minute and the steam was admitted through four simultaneous openings, so it entered the cylinder with great velocity. I turned a quarter of an inch off from each face of the piston, and the thump disappeared. I then made it a law from which I never varied, that the piston should come to the admission port and not project over it at all, and this feature was shown in every drawing.

Mr. Bishop replied to me: “It does project, Mr. Porter; it projects seven eighths of an inch over the port at each end of its stroke, for I have measured it.” I rushed up to the drawing-office and called for the horizontal sectional drawing of that cylinder, and there I saw the piston not only drawn, but figured—projecting seven eighths of an inch over the port. I felt as though I were sinking through the floor. That was what had ruined my Boston exhibition and sent me home disgraced and broken-hearted and the badly fitting piston, shameful as that was, had nothing to do with it. The first question that occurred to me was: “How came this drawing to exist and I to know nothing about it?” The answer to this question was simple.

When the first pair of Willimantic engines was started I was disappointed in their economy, and made up my mind that the excessive waste room was accountable for it. The proportion of cross-section area to the stroke being fifty per cent. greater than in my table of sizes increased in the same degree the proportion of waste room to the piston displacement. I felt that there was need here for improvement. By far the greatest amount of waste room was in the exhaust ports. I accepted a modification of the exhaust valves by which this item of the waste room was reduced fully one half and made a new pair of cylinders for this engine. The improvement in the economy was so marked that I determined to change the exhaust valves of all the engines. Only the exhaust valves and ports needed to be changed. These were drawn anew in pencil and carefully studied and approved of by me. It was necessary that the entire combined cylinder drawing should be retraced, but this, except only the exhaust ports and valves, was to be copied over the existing tracings. This did not require my attention, and I gave no thought to it. Here was the superintendent’s opportunity. In copying these tracings he had only to move the straight line representing each face of the piston on the longitudinal section of the cylinder seven eighths of an inch, thus adding this amount to the piston at each end, and shorten the cylinder heads to correspond, and the job was done; and there did not exist among the large number of persons in the drawing-office and shop who must have been aware of this change, loyalty enough to let me know anything about it.