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 was 

 used by Jacob Perkins and my father in drawing fire 

 engine cylinders; that the Bramah press, that was 

 then being extensively introduced in the English paper 

 mills, was the natural sequence of the crude toggle- 

 joint with all its wedges and keys. Suggesting the use 

 of the hydrostatic press was only an application and no 

 great stretch of imagination. 



Probably not, said Mr. Donkin, having had the 

 advantage of seeing a copper cylinder of 16 inches 

 diameter successfully finished in that wav. But 



Figure 54. — John Dickinson (1782- 1869). 

 From The Firm 0] John Dickinson and Co., 

 Ltd. (London, 1896). Library of Congress 

 photograph. 



without this to conceive of and put into practice on 

 so large a scale required no little thought and much 

 boldness in the necessary outlay — machinery that, if 

 not successful, would prove a serious loss. 



I remarked that since seeing the machine in his 

 erecting shop I had learned some facts in relation to 

 drying on iron cylinders without the copper covering. 

 The finest qualities of copper plate paper, used by 

 John Murray, the Ackermanns and Windsor & 

 Newton, for the finest works of the engraver, were 

 from John Dickinson's mills, and entirely free from 

 iron mould or specks. 



But what assurance, asked Mr. Donkin. have you 

 that the paper was not dried on copper cylinders. 



J replied the assurance of Mr. Dickinson himself; 

 that I had dined and spent last evening with him, and 

 the subject of drying paper by steam-heated cylinders 

 had been fully discussed; that for gradual, steadily 

 increasing heat with uniformity Mr. Dickinson gave 

 a decided preference to iron over copper: that he had 

 sketched his arrangement giving the number and size 

 of the drying cylinders that he had found the most 

 effective and reliable for his heavy plate paper; that 



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