MEMOIR OF DAXIEL TKEADWELL. 485 



At the monthly meeting of the Academy in May, 1863, Mr. Treadwell read a 

 paper on the effect of cannon shot upon iron-clad ships and armor plates generally, 

 being a sequel to the memoir " On the Practicability of constructing Cannon of 

 Great Calibre," published in the sixth volume of the Memoirs. 



In this paper it is proposed to substitute for a globular shot one of a cylin- 

 drical or prismoidal form, with a steel face Avith sharp corners, the length of the 

 cylinder being less than its diameter, its rotation from the rifling being about the 

 shorter axis of the body. "Should any practical difficulty arise to disturb the di- 

 rectness of its flight from the want of length in the cylinder, it may be lengthened 

 by giving greater length to the sides for the rifle grooves or projections, and a most 

 effectual disposition to the metal for driving the corners through the plate, while 

 the weight is collected more in the head, as it is in its prototype, the shuttlecock. 

 Or it may be made with cavities, which may be left full of the core sand, or filled 

 with powder for exploding within the ship." It was proposed to make these shot 

 28 inches in diameter. The gun from which this missile is to be thrown is that 

 described in the sixth volume of the Memoirs, " in which the strength should 

 follow the ratio of the thickness in contradistinction to the common cast iron 

 gun, to which no thickness can ever be given by which it can be made to sustain 

 a charge beyond a very narrow amount." 



" Under the conclusions that I have exhibited, I can see no limit to the in- 

 crease in the size of cannon ; but as a gun of this kind of 28 inches calibre must be 

 made to weigh about 90,000 pounds, it will of course be out of the question to 

 carry such on shipboard, while they may well be borne by the solid earth. This 

 will give to the fort, and consequently to defensive war, a great advantage over 

 offensive war, a fact that may be greatly in favor of civilization and humanity." 



The following letters indicate the value placed upon Professor Treadwell's labors 

 by the Instructor of Ordnance at the "West Point Military Academy. 



To Professor Daniel Treadwell. 



West Point, N. Y., January 21, 1865. 

 Dear Sir, — Being the Instructor of Ordnance and Gunnery at this place, I am, of course 

 much interested in the projrress of the art of making guns of great endurance. I have read your 

 pamphlet on the " Practicability of constructing Guns of Great Cahbre," and your printed letter 

 of December 23, 1861, addressed to the Secretaries of War and Navy, with interest, and am sat- 

 isfied that in this matter of built-up gims, made on scientific principles and carried out practi- 

 cally, you are without doubt entitled to the credit of being the first in this country to succeed 

 in solving the problem, and so far as I know were in advance of any one in England. In 

 order that I may fully understand all that you have accomplished, and be able to give my 



