I had an order from John W. Hyatt of Newark for a 6×12-inch engine to make 450 revolutions per minute, to drive an attrition mill running at 900 revolutions per minute, in which he pulverized bones to dust for manufacturing artificial ivory. This was the highest number of revolutions per minute that I had ever employed, and perhaps it was the most absolutely silent running engine that I ever made. Not long after its completion I had a call from a young gentleman who introduced himself to me as Harris Tabor. He told me he had invented a steam-engine indicator which he thought would be superior to the Richards indicator, as the pencil movement was very much lighter and would draw a straight vertical line. He said he called in the hope that I might give him an opportunity to test his indicator on a very high-speed engine. I told him I thought I could do just what he wanted. I took him down to Mr. Hyatt’s place where the engine was running with the indicator rig on it which I had been using; he was, of course, greatly pleased with this remarkable opportunity. He took a number of diagrams with his indicator, and they proved to be quite free from the vibrations which were produced by the Richards indicator at the same speed. I gave him a certificate that these diagrams had been taken by his indicator from a Porter-Allen engine at a speed of 450 revolutions per minute. With these he started for Boston to see Mr. Ashcroft. With the result of that interview the engineering world is familiar. To my great regret not one of the diagrams taken at that time has been preserved either by Mr. Tabor, Mr. Ashcroft or myself, an omission that none of us can account for. The Hyatt plant was afterwards, I understood, removed to Albany, N. Y.