. Bulletin - United States National Museum. Science. then to give it the appearance of having been turned, for, as finished by the die they were forced through, they would be left as near perfection as possible. He asked me to explain what I meant by drawing cylinders, of the magnitude of his drying cylinder, or even supposing such a thing possible? I replied that I did not see any difficulty, that it was only a question of size and power of the machine to do the work; that at the time of the partnership of my father and Jacob Perkins in building fire engines, copper cylinders from 3 to 8 inch
. Bulletin - United States National Museum. Science. then to give it the appearance of having been turned, for, as finished by the die they were forced through, they would be left as near perfection as possible. He asked me to explain what I meant by drawing cylinders, of the magnitude of his drying cylinder, or even supposing such a thing possible? I replied that I did not see any difficulty, that it was only a question of size and power of the machine to do the work; that at the time of the partnership of my father and Jacob Perkins in building fire engines, copper cylinders from 3 to 8 inches diameter were perfectly finished by forcing through well-turned and polished dies; that on one occasion an air vessel of 16 inches diameter had been finished in the same manner. He thought I had said drawing, and now I said forcing through dies; would I explain any difference between drawing and forcing? None other than if drawn horizontally through a die, the great weight of the cast-iron drying cylinder acting as a central mandrel would seriously affect the uniform thickness of the copper and smoothness of the work; that this would be avoided lay a vertical position and forcing upwards through the die. He asked how I would proceed to do the job in that way. I replied that after bending the sheet copper to the size to fit tightly on the cast-iron cylinder and brazing its union, taking care that it had been thoroughly annealed, I would close the upper end sufficiently over the end of the cylinder to insure its entering the die and holding it fast to the inner cylinder, then place it on the platform of a Bramah hydrostatic press with length of plunger or lift greater than the length of cylinder to be covered; the columns of the press would be the guides for the platform, and by having heavy screws and nuts on them they would at the same time hold the great die. The next question was, Did I ever see or hear of anything of the kind? No other than the old toggle-joint press that
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