THE TECHNOLOGIST. [Sept. 1, 1864. 



54 ON THE MECHANICAL NATURE AND 



place. Air left in a gunpowder barrel is often supposed to burst the 

 gun ; in a gun-cotton barrel, it only mitigates the effect of the charge. 

 The object of enclosing the gun-cotton charge in a hard strong paste- 

 board cartridge, is to keep the cotton from compression and give it room 

 to do its work. 



It is a, fourth discovery of General Lenk, that to enable gun-cotton to 

 perform its work in artillery practice, the one thing to be done is to 

 " give it room." Don't press it together — don't cram it into small bulk ; 

 give it at least as much room as gunpowder in the gun, even though 

 there be only one-third or one-fourth of the quantity (measured by 

 weight). One pound of gun-cotton will carry a shot as far as 3 or 4 lbs. of 

 gunpowder ; but that pound should have at least a space of 160 cubic 

 inches in which to work. 



This law rules the practical application of gun-cotton to artillery. 

 A cartridge must not be compact, it must be spread out or expanded to 

 the full room it requires. For this purpose, a hollow space is preserved 

 in the centre of the cartridge by some means or other. The best means 

 is to use a hollow thin wooden tube to form a core ; this tube should be 

 as long as to leave a sufficient space behind the shot for the gun-cotton. 

 On this long core the simple cotton yarn is wound round like thread on 

 a bobbin, and sufficiently thick to fill the chamber of the gun ; indeed, 

 a lady's bobbin of cotton thread is the innocent type of the most 

 destructive power of modern times — only the wood in the bobbin must 

 be small in quantity in proportion to the gun-cotton in the charge. 

 There is no other precaution requisite except to enclose the whole in the 

 usual flannel bag. 



The artillerist who uses gun-cotton has, therefore, a tolerably simple 

 task to perform if he merely wants gun-cotton to do the duty of gun- 

 powder. He has only to occupy the same space as the gunpowder with 

 one-fourth of the weight of gun-cotton made up in the bobbin as 

 described, and he will fire the same shot at the same speed. This is 

 speaking in a general way, for it may require in some guns as much as 

 one-third of the weight of gunpowder and seven-tenths the bulk of 

 charge to do the same work ; a little experience will settle the exact 

 point, and greater experience may enable the gun-cotton to exceed the 

 performance of the gunpowder in every way. 



The fifth principle in the use of gun-cotton is that involved in its 

 application to bursting uses. The miner wants the stratum of coal torn 

 from its bed, or the fragment of ore riven from its lair ; the civil 

 engineer wishes to remove a mountain of stone out of the way of a 

 locomotive engine ; and the military engineer to drive his way into 

 the fortress of an enemy, or to destroy the obstacles purposely laid in 

 his way. This is a new phase of duty for gun-cotton — it is the work 

 of direct destruction. In artillery you do not want to destroy directly, 

 but indirectly. You don't want to burst your gun, nor even to injure it ; 

 and we have seen, in order to secure this, you have only to give it room. 



