We had all sorts of queer experiences. One day I was demanded by Mr. Jerome Wheelock to tell him _why_ the engine exhibited by him was not a _perfect_ engine. I glanced over the long slender bed, a copy of the Corliss bed without its rigidity, and declined to answer his question. Mr. Emery was more compliant; on receiving the same demand, he kindly pointed out to Mr. Wheelock one respect in which his engine could hardly be considered perfect; the steam was exhausted into a large chamber embracing the lower half of the cylinder from end to end. This comparatively cold bath produced the condensation of a large quantity of the entering steam. From the middle of this chamber a pipe took away the exhaust from the opposite ends of the cylinder alternately. Mr. Wheelock admitted the defect, and said in future he would avoid it, so, as I learned, having two exhaust pipes instead of one, he gave to each pipe one half the area of the single one. I had the pleasure of renewing my acquaintance with Professor Sweet, who was superintending the exhibit of the mechanical work of his boys at Cornell; this was very creditable and included quite a show of surface plates. The Corliss engine in this exhibition was far the most imposing, and to the multitude the most attractive single exhibit ever shown anywhere. It consisted of two distinct engines, each having a cylinder 40 inches in diameter, with 10 feet stroke of piston, the motion of which was transmitted through cast-iron walking beams to cranks set at right angles with each other on the opposite ends of a common shaft. This shaft made 36 revolutions per minute and carried a gear-wheel 30 feet in diameter; this wheel engaged with a pinion 10 feet in diameter on the line of shaft under the floor, giving to this shaft a speed of 108 revolutions per minute. One day I said to Professor Sweet: “Do you know, Professor, that an engine with a single cylinder of the same bore as these and 5 feet stroke directly connected with a line shaft and making 150 revolutions per minute, with a fly-wheel 10 or 12 feet in diameter, would exert more power than is afforded by this monster and would run with far greater economy, because the internal surfaces to be heated by the condensation of the entering steam would be one piston instead of two, two heads instead of four, and 5 feet length of exposed cylinder instead of 20 feet?” He replied: “That is all very true, but how would you get the steam in and out of the cylinder properly with a piston travel of 1500 feet per minute?” I was not prepared to answer that question on the instant, but I afterwards found no difficulty about it.