MEMOIR OF DAIVIEL TREADWELL. 409 



and boring, this frustum of a cone is formed into the cannon, the breech being closed by a screw 

 plug, and the trunnions fixed upon a band, wliich is liiiewise screwed upon the outside of tlie 

 gun. The trunnion-band and trunnions are formed, like the cannon, by machinery moved by 

 the hydrostatic press." * 



After the machinery was got ready, Professor Treadwell had little doubt that a 

 few months would see the cannon finished. In this he was mistaken; and in the 

 following January he thus writes : — 



To Colonel Talcott. 



Cambridge, January 10, 1843. 

 Dear Sir, — When I left Washington in March last, I determined that I would not trouble 

 you with any correspondence until I could inform you that the six six-pounder cannon, for which 

 I had contracted, were completed, which I then supposed would be in a few months. Accord- 

 ingly, on my I'eturn home I gave myself wholly up to making the machinery for constructing 

 them, and others which should follow them, and from that time to this 1 have been so employed, 

 spending money the while much beyond what I at first thought would be required. Step by step 

 I have found some alteration to make, some error to be corrected, or some improvement to be 

 introduced ; and tlius ten months have passed away. I have now, however, as I believe, brought 

 my preparations very nearly to a close, and confidently expect to carry these six guns tlirough 

 the furnace in a very few weeks. I as confidently expect, moreover, that they will be most per- 

 fect pieces of ordnance, and that you will not find reason to hesitate to adopt them to the exclu- 

 sion of all other kinds of cannon. But I will not anticipate what a few weeks will now bring to 

 a sensible proof. In tlie mean time let me assure you that I have not forgotten, but still hold in 

 high consideration, the open and gentlemanly manner in which you received my propositions at 

 my several interviews with you last spring. 



Daniel Treadwell. 



"After about a year and a half," he says, "of most devoted and exhausting 

 labor and a very large outlay of money, I completed the six six-pounders to my 

 satisfaction." They were delivered to the officer appointed to receive them at the 

 Navy Yard at Charlestown, where they were tested and accepted. They were thence 

 sent to Fort Monroe, where they were proved in the manner now to be described. 



It was suggested by the officers of Government that the most satisfactory result 

 as to endurance and strength might be obtained by firing heavy charges, — say, 

 to begin with, the first proof charge, and increase the resistance by additional shot, 

 and perhaps by a corresponding augmentation of the powder charge, until the gun 

 should be rendered unserviceable. This was considered the cheapest and most prompt 

 mode of determining the strength of the gun. 



For this purpose Captain Huger tested the Treadwell wrought-iron six-pounder 

 No. 4, and reported as follows : " After firing 1,501 rounds, the average increase of 



* See Appendix III. Sir Joseph Whitwortli, in England, has recently used hydrostatic pressure in his heavy 

 forging, with wonderful success. 



