458 MEMOIR OF DANIEL TKEADWELL. 



then was most satisfactory. A Mr. Smith, of New York, has taken a French patent for a slight 

 improvement (?) on us. He makes his rings with a shoulder slightly dovetailed. When one is 

 put over the other hot, it gives a little longitudinal strength. I used this plan for my wonderful 

 nine-pounder, but tliink it unnecessary. I did think of having slight projections on the cylin- 

 drical part of the gun to fit with corresponding hollows in the rings, but I think now that the 

 accuracy to be obtained by forcing the rings by hydrostatic pressure over a very slightly conical 

 surface makes the best way. 



I trust you will revisit Europe, and tliat I may have then tiie pleasure of seeing you. 

 Meanwhile I hope to hear from you. 



I am, dear sir, yours very truly, 



T. A. Blakely. 



To Captain Blakely. 



Cambridge, January 20, 18.W. 



Dear Sir, — I am much obliged to you for your note of December 22, which I should have 

 answered sooner but for a slight illness of myself and a more severe one of Mrs. Treadwell. 



I am much jilcased with your hopeful tone, and trust your account of triumphant experi- 

 ments will not be lost upon the ignorant officials and the yet inore ignorant public. 



Your statement as to what passed between us at our first interview, when you did me the 

 favor to call upon me in Margaret Street [London], early in May, 1855, is very nearly correct ; 

 only you do not take so mucii credit as I believe belongs to you as compared with Professor 

 Peter Barlow. 



To put the whole matter right according to my recollection and belief, I will give you a 

 short history, but not to be published without my consent. 



Before the year 184:3 I perceived the unequal extension of a hollow cylinder when exposed 

 to the strain of an internal fluid ; and in that year I constructed a hydrostatic press of fourteen 

 inches' plunge, having walls of cast iron of four inches in thickness, hooped with rings three and 

 a half inches thick shrunk on. This press was used for making my wrought-iron guns, its force 

 being one thousand tons ; and I was then fully aware that a cannon hooped in this way would have 

 all the advantages I have since claimed for it. I did not then .suppose that the ratio, supposing 

 the cylinder made up of a series of concentric rings, would be a diminution of strength exactly 

 as the inverse square of the diameter of each ring, but simply as the inverse ratio of the diame- 

 ter plus a quantity, whatever it might be, arising from the diminution of the thickness of walls 

 produced by the distention. Soon after this, I saw Barlow's demonstration or paper upon the 

 subject. I did not attend to it so particularly as to take a deep impression from it. 



Not seeing my way clear to go on with the manufacture of guns, either of wrought iron or 

 cast iron hooped with wrought iron, and the subject lay with me in abeyance until the winter of 

 1854-55, when, being in Italy and the war in the Crimea raging, I determined to make an effort 

 in France or England, or both, to supply guns of great calibre of cast iron hooped with wrought 

 iron, rather than of steel and wrought iron, like my first guns. I therefore went back to France, 

 and, arrived in Paris, I addressed a proposal upon the subject to Marshal VaiUant, Minister of 

 War, on the 20th of March, 1851. Not receiving the encouragement that I desired, 1 went over 

 to London very early in May. I had in March or Aj)ril forwarded a request, through Baring 

 Brothers & Co., to be heard upon the subject at the War Office, and it was there early in May 

 that I opened my plans to Captain Lefroy, to whom I had been officially referred. Prom him I 

 learned that his friend. Captain Blakely, — whom, however, he did not then name to me, — was 



