80 



of 1*563 feet per second was obtained; with a 12-pounder the results 

 were — 



Calibres. Charge. Velocity, feet per second. 



Cotton, length, . . 10 . . , . 15'9 oz 1426 



Powder, 13| . . . . 49 (normal powder charge) 1400 



Cotton, 9 ....17 1402* 



Captain Maury, U. S. JS"., says that iron-clads at Charleston have re- 

 mained for several hours under fire, the decks not becoming in any way 

 foul, from the entire absence of smoke. I think the foregoing evidence 

 of some of the leading men of science will show that, while it possesses the 

 disadvantage of ignition at a comparatively low temperature, it has the 

 advantages of lightness, freedom from damp, lessening of recoil, not heat- 

 ing or fouling, cheapness of production, and great diminution in weight ; 

 and, to sum up all, can be submerged in water, and dried for use accord- 

 ing as wanted ; for cupola-ships it seems to be especially adapted, as it 

 would to a great extent obviate the fouling in the turrets. Sir W. 

 Armstrong, indeed, is of opinion that where there is no heat in the gases, 

 there can be no projectile force : the initial velocity, however, has been 

 proved to be greater than in the case of powder. Mr. Siemens, having 

 considered the question, is of opinion that the greater heat imparted to the 

 gun by gunpowder is owing to the greater amount of solid matter, which, 

 involving the heat of the gases under a pressure of some 400 atmo- 

 spheres, imparts a portion of the same by radiation to the side of the 

 gun, while in the case of gun-cotton gases only are produced, which 

 could only impart heat by the slower process of conduction, and leave a 

 larger margin of heat to be developed in force by expansion ; while Ad- 

 miral Sir Edward Belcher supposes it to be owing to the greater rapidity 

 of the explosion, and the absence of fouling matter, which contains and 

 retains the heat. And it is to be hoped that the requisition of the Bri- 

 tish Association for a Government Commission to inquire into the de- 

 tails of this interesting subject will be granted. In the recent duel 

 between the "Alabama" and "Kearsage," great stress has been laid on 

 the chain armour with which her sides were in a measure protected. 

 "William Eowan, Esq., C. E., of Belfast, claims the merit of its inven- 

 tion ; he laid, some years ago, a table of results obtained from a target 

 composed of suspended chains, before the government. Now, no doubt, 

 under certain circumstances it may be of benefit — for instance, as Cap- 

 tain Blakely observes, in the case of cast iron shot. Strange to say, it 

 was known well in the reign of Elizabeth : a Captain John Yonge, an 

 officer of, we are told, forty years' experience, suspended chains round 



* Professor Abel, F. P. S., has shown that the formation of trinitrocellulose may be 

 represented by the equation : — 



> Cotton. Nitric Acid. Gun Cotton. Water. 



C G H 10 O 5 + 3 { } O = C G { ffa } 0 5 + 3 I } O . 



