50 ANNUAL OF SCIENTIFIC DISCOVERY. 



cotton on the projectile any law of force he pleases. Its cost of pro- 

 duction is considerably less than that of gunpowder, the price of quan- 

 tities which will produce equal effects being compared. Gun-cotton is 

 used for artillery in the form of a gun-cotton thread or spun yarn. In 

 this simple form it will conduct combustion slowly in the open air, at a 

 rate of not more than one foot per second. This thread is woven into 

 a texture or circular web. These webs are made of various diame- 

 ters, and it is out of these webs that common rifle cartridges are made, 

 merely by cutting them into the proper lengths, and inclosing them in 

 stiif cylinders of pasteboard, which form the cartridges. (In this shape 

 its combustion in the open air takes place at a speed of ten feet per 

 second.) In these cylindrical webs it is also used to fill explosive 

 shells, as it can be conveniently employed in this shape to pass in 

 'through the neck of the shell. Gun-cotton thread is spun into ropes in 

 the usual way up to two inches diameter, hollow in the centre. This 

 is the form used for blasting and mining purposes ; it combines great 

 density with speedy explosion. The gun-cotton yarn is used directly 

 to form cartridges for large guns by being wound round a bobbin so as 

 to form a spindle like that used in spinning-mills. The bobbin is a hol- 

 low tube of paper or wood, the object of the wooden rod is to secure in 

 all cases the necessary length of chajnber in the gun required for the 

 most effective explosion. The gun-cotton circular web is inclosed in 

 close tubes of India-rubber cloth, to form a match line, in which form it 

 is most convenient, and travels with speed and certainty. In large 

 quantities, for the explosion of mines, it is used in the form of rope, and 

 in this form it is conveniently coiled in casks and stowed in boxes. As 

 regards conveyance and storage of gun-cotton : it results from the fore- 

 going facts, that one pound of gun-cotton produces an effect exceeding 

 three pounds of gunpowder in artillery. This is a material advantage, 

 whether it be carried by men, by horses, or in wagons. It may be 

 placed in store, and preserved with great safety. The danger from 

 explosion does not arise until it is confined. It may become damp and 

 even perfectly wet without injury, and may be dried by mere exposure 

 to the air. This is of great value in ships of war, and in case of danger 

 from fire, the magazine may be submerged without injury. As regards 

 its practical use in artillery, it is easy to gather from the foregoing gen- 

 eral facts how gun-cotton keeps the gun clean and requires less wind- 

 age, and therefore performs much better in continuous firing. In gun- 

 powder there is sixty-eight per cent, of refuse, or the matter of fouling. 

 In gun-cotton there is no residuum, and therefore no fouling. Exper- 

 iments made by the Austrian committee proved that one hundred 

 rounds could be fired with gun-cotton, against thirty rounds of gun- 

 powder. From the low temperature produced by gun-cotton, the gun 

 does not heat. Experiments showed that one. hundred rounds were 

 tired with a six-pounder in thirty-four minutes, and the gun was raised 

 by gun-cotton to only 122 Fahrenheit, whilst one hundred rounds 

 with gunpowder took one hundred minutes, and raised the temperature 

 to such a degree that water was instantly evaporated. The firing with 

 the gunpowder was, therefore, discontinued ; but the rapid firing with 

 the gun-cotton was continued up to one hundred and eighty rounds 

 without any inconveniencc > . The absence of fouling allows all the 

 mechanism of a gun to have much more exactness than where allow- 



