MEMOIR OP DANIEL TREADWELL. 



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each thread one inch,' and < to make the threads of the female screws sensibly finer than those of 

 the male, to draw, by the shrink, the inner rings together endwise.' The advantage this form of 

 construction will appear in this : that by the rapid advance of the hoop to its plaoe, the shrinks* 

 from cooling during its passage over the body will be avoided; while the dividing of the inch spac 

 of the spiral into several parts enables us to give a great bearing surface to very shallow threads. 

 Small splines should be inserted under every hoop to prevent its turning by the n ail 



"I give here a drawing of the threads as I would form them for a six-threaded screw. 



They have an .18 inch pitch, and a depth of .04 in., being .11 in. thick at the root or 1 t- 

 tom, and .07 in. in breadth upon the face. Threads of this shape may be more easily and 

 exactly made than any other, as a large part of the surfaces left by the boring and turning tools 

 requires no change from the screw tool, but remains and forms the flat faces of both the male 

 and female screws. By this means the gauged sizes and requisite diameters of both the body 

 and the hoops are more easily ascertained and preserved, when the screw threads are formed. 



"The depth of the threads given in this figure must be ample; for, as the threads, when once 

 interlocked and in place, are kept in contact by the shrinkage of the hoops and the distension of 

 the gunpow r der, the idea of the outer threads slipping and riding over the inner on -$, like a loose 

 nut upon a screw bolt, is simply preposterous." 



In the summer of 1854 he made a voyage to Europe. Soon aft 

 war beoran to raire in the Crimea, and he thought of brinirimr li 



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the French government ; but as he could not well arrange his engagements so as to stop 

 in Paris, he went to Italy. Reading there the accounts of the bursting of guns in the 

 Crimea, he determined to go back to Paris as soon as possible to propose his invention 

 of hooped guns to the French War Office, and addressed a letter to Murechal Vaillant, 

 Minister of War, stating that in 1845 he had manufactured for the United States guns 

 of wrought iron, and that he at the same time made a 32-pounder and sent it with the 

 aid of the French Consul in Boston as a present to the King of the French, and it was 

 then at the fort of Vincennes. He requested that a learned and intelligent officer 

 might be appointed to whom he could communicate new and improved methods which 

 he had since devised. After waiting in Paris several weeks, and receiving no inti- 

 mation that an officer would call upon him, he went to London, and after three weeks 

 received a letter from a French officer who had been appointed to meet him. 



Professor Treadwell on the receipt of this letter would have gone immediately to 

 Paris and communicated his invention to the French government, but feared that the 

 delay might occasion the loss of his invention in this country, as public attention was 

 then turned both in Europe and America to improvements in cannon. He therefore 

 concluded to take out the patent in America, and to that end sat down in his lodgings 

 in London, and, without the aid of legal advice or books, drew up the specifications of 

 his invention as it appears in the first patent issued. 



