I was then ignorant of his state of mind on that subject, or of what had produced it. I learned these afterwards, and will state them here. In one of our interviews, in reply to my question as to what had led him to make this invention, he told me it was his experience when he was engineer of the propeller “Curlew,” a freight-boat running on Long Island Sound, between New York and Providence, which had a Corliss engine. He became impressed with what he thought to be a serious defect in the liberating system. The governor did not control the point of cut-off, but the point of release; this point being at the beginning of the closing movement of the valve, while the cut-off took place near the end of that movement. When the engine was worked up to nearly its capacity, as was the case in a ship, the port was opened wide, and quite an appreciable time elapsed between the release and the cut-off. During this interval the piston advanced considerably, and if the engine ran fast enough it might get to the very end of the stroke before the cut-off took place. He said that in smooth water they had no trouble, but in the open ocean, going around Point Judith, it was always rough, and sometimes in stormy weather the screw would be thrown quite out of the water, and the engine, having no fly-wheel, would race most furiously. The faster it ran the further the steam would follow, and was pumped out of the boiler very rapidly. Springs were employed to accelerate the closing movement of the valves, but in these cases they seemed to be of little use, and were continually breaking. He saw that this difficulty could be avoided only by a positive motion gear which would enable the governor to control the point of cut-off itself; and, accordingly, he set himself to work to devise such a system. We know now that this judgment, formed from observations made under very exceptional conditions, was not well founded. The difficulty in question does not practically exist in engines having fly-wheels and the present improved liberating gear, and running at moderate speeds; but the experience naturally made a deep impression upon Mr. Allen’s mind, and led to the invention of the positive motion system.