Among the orders which I brought from Newark was one from the firm of B. F. Avery & Sons, plow-manufacturers, of Louisville, Ky., the head of which had first established the manufacture of plows in the Southern States. Mr. George Avery, one of the sons, had come to me and asked for a list of the engines I had running, and took the pains to visit a number of them, also those of other prominent builders, and as a result of this extended comparison he brought me his order for an 18×30-inch engine, with strong expressions of the manifest superiority of the high-speed engine. This engine was about the first one I finished in the Southwark Foundry. By great carelessness it was permitted to go out without the crank-pin being hardened and ground, which was contrary to my invariable practice. The man who erected the engine left the crank-pin boxes too loose, and young Mr. Avery, who was quite an amateur mechanic, undertook to tighten them up; he succeeded in heating the pin and causing it to be badly torn. He made the best job of it that he could with a file, and the engine ran in that crippled condition. Soon after I left Philadelphia, they concluded they ought to have a hardened crank-pin and wrote to the Southwark Foundry respecting it. They received a reply that it would be necessary to take the shaft out and send it to Philadelphia, and their works would need to be interrupted about three weeks. The firm then wrote to me in New York asking me to come to Louisville and examine the engine and advise them what to do, which invitation I accepted. The letter to the Southwark Foundry had been written by their manager, and in it he stated that the engine pounded so badly that it could be heard two blocks away, it was so wasteful it was almost impossible to keep up steam for it, and that they lived in such dread of its breaking down that their hair was all turning white. I felt that this letter, after making full allowance for its obvious exaggerations, reflected pretty badly, not only on the engine, but also on the boilers. These were two return-tubular boilers which I had designed myself. I had reflected a good deal on the observation shown to me by the engineer at Willimantic, and had felt that tubular boilers needed a better vertical circulation. This was limited by the small space left for the descending currents, the sides being filled with tubes almost touching the shell. So I allowed a space five inches wide between the shell of the boiler on the sides and bottom and the nearest tubes, as it was evident to me that the water, filled with bubbles of steam, would rush up among the tubes fast enough if the comparatively solid water at the sides could only get down. I also left off the upper row of tubes to allow more space above them for the steam, and from this arrangement I anticipated very superior results.