MEMOIR OF DANIEL TREADWELL. 



481 



strength of the materials to which it was applied. Tims, lie takes the force which acted 

 upon it at 100,000 pounds to the square inch. Now the instrument was held to the gun by a 

 screw formed in the cast iron body of the gun, one and a half inches in diameter, and one 

 and a half inches deep. This gives an area of the plug of the instrument of 1.75 square 

 inches, which received the full pressure of the fired powder. The pressure upon the end of 

 the instrument, then, was 1.75 X 100,000 = 175,000 pounds, or about eighty tons. He must 

 be a very bold engineer who would sleep under a weight of ten tons suspended over him 

 by a bolt tapped into a hole in a cast iron plate one and a half inches in diameter, and one 

 and a half inches deep, and yet it does not seem to have occurred to Captain Rodman, that 

 eighty tons' pressure must have driven his instrument from its place." 



In 1862 Mr. Tread well invented and completed the construction of a device or 

 apparatus for firing cannon, and at the same time closing the vent and keeping it 

 closed during the discharge of the gun. It is described as follows : 



" This invention relates to the construction of apparatus for discharging guns or ordnance, 

 and is designed to obviate certain difficulties attending the mode of construction now usually 

 employed, which will be briefly noticed in order to afford a better understanding of the 

 conditions to which the improvements more particularly apply. 



" In the guns now used, the fire for igniting the charge is communicated to it through an ori- 

 fice in the walls of the chamber in which the charge is placed, called the ' vent,' or ' touch-hole,' 

 by means of priming which is ignited by fulminating powder of some kind, or by the direct 

 application of some incandescent body to the priming powder. When the explosion of the 

 charge takes place, the vent, being open, permits a portion of the gas produced from the charge 

 to escape through it during the whole time that the projectile is within the gun. This gives rise 

 to certain difficulties which it is the object of this invention to remove. The gases within the 

 gun thus escaping through the vent at the moment of explosion under an enormous pressure, and 

 perhaps also by their chemical agency, produce corrosion of the surface of the metal within the 

 vent, and rapidly wear and enlarge it so as to require it to be replaced after a few hundred dis- 

 charges by an operation well known as ' touching.' The vent when new has to be sufficiently 

 large to insure its being easily kept free from clogging, and from its further rapid enlargement ; 

 the proportion of the charge that escapes through it becomes very considerable in guns firing the 

 ordinary round shot with windage, and the evil is greatly aggravated both as to the amount 

 of waste of charge and wear of vent by the greater pressure of the gases in the gun when an 

 elongated projectile is fired without windage, as is the case with modern rifled guns. The escape 

 of this amount of gas from the vent, in addition to the wear and waste produced, is also very pre- 

 judicial when the gun is fired with the breech in some confined space, such as the casemate of 

 a fort, or the between-decks of a ship of war, where the fire is dangerous, and the smoke becomes 

 a serious inconvenience to the gunners." 



" On the Construction of Improved Ordnance as proposed in a Letter to the Secretaries of War and of 

 the Navy, and the Chiefs of the Bureaus of Engineers and of Ordnance of the United States/ 7 by Daniel Tread- 

 well. Cambridge, 18(!*-i. 



Mr, TreadwelTs conclusions are fully confirmed by Captain C. S. Smith's experiments at Sandy Hook, in 

 1881, by dropping from a height Captain Rodman's instrument. "Gun-making in the United States, by Cap- 

 tain Rogers Birnie, Jr., Ordnance Department, U. S. Army." Monograph VIIL, Military Service Institution, 

 New York, 1888, p. 54. See also Report of the Chief of Ordnance for 1882 (twenty years after Mr. Tread- 

 weirs publication), p. 124. 



