I had this work done by Mr. Joseph Banks, whose shop was in a large building at the corner of Second Avenue and Twenty-second Street. Mr. A. S. Cameron, the inventor and manufacturer of the celebrated Cameron steam-pumps, was then an apprentice in that shop. Mr. Banks was an excellent mechanic, and I was greatly indebted to him for the accuracy of the work that I procured. He devised an expanding-drill to cut a groove at the bottom of these sockets, in which the chips from the slotting-tool made in squaring the holes would come off. The finishing slotting-tool I designed myself. I had noticed in all slotting-machines that came under my observation at that time that the tool would spring off a little at the commencement of the cut, so that a full square angle was never obtained. To avoid this defect and to size the slots equally I made a slotting-tool to cut on opposite sides. The cutting edges were each about ¹⁄₈ inch long and the corners rounded. The bar for the tool-holders had to be set three times on account of its length. It was set in contact with the same angle-bar, which was bolted on this table parallel with its transverse feed. This finishing-tool being once set, the upper and lower faces of all the sockets were thus readily finished in perfect line and with square edges. The tool being then turned at right angles to its first position, for which purpose its shank had been planed square, finished the sides of the sockets. These were identical in every respect, and any tool could go anywhere. The springs behind the hammers were prepared with great care. I had large bars of spring steel reduced under a tilt-hammer to a section ³⁄₈ inch square. These were coiled with only ¹⁄₄ inch space between the coils, so that in case a spring broke within the hammer it could not get out of place. These springs were exceptionally durable. We took off the back cross-bar occasionally--perhaps once a month--to examine for broken springs, and sometimes we found one, which was replaced with a new one because we assumed that it was fatigued, but the hammers worked just as well with broken springs as they did with whole ones. The springs, having considerable initial compression, did not become loose. It seems proper to add that, except the help from Mr. Banks, I did not in designing the machine or organizing the work receive assistance or suggestion from anyone. With these details I bid a final good-by to you, my old schoolmaster. I have a warm place in my heart for you. You set me my first lessons in mechanics. Your life was short. You were not ordained to cut much of a figure in the world. But you were faithful. You always did your work and did it well. CHAPTER II The Evolution and Manufacture of the Central Counterpoise Governor. Introduction of Mr. Richards.