BRITISH ASSOCIATION. 41 



speedy explosion. The gun-eotton 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 hollow tube of paper or wood, the object of 

 the wooden rod is to secure in all cases the necessary length of chamber 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 conve- 

 niently coiled in casks and stowed in boxes. As regards conveyance and storage 

 of gun-cotton : it results from the foregoing facts, that 1 lb. of gun-cotton produces 

 an effect exceeding 3 lb. of gunpowder in artillery. This is a material advantage^ 

 whether it be carried by men, by horses, or in waggons. 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 general facts how gun-cotton keeps the gun clean and requires less 

 windage, and therefore performs much better in continuous firing. In gunpowder 

 there is 68 per cent, of refuse, or the matter of fouling. In gun-cotton there is no 

 residuum, and therefore no fouling. Experiments made by the Austrian Com- 

 mittee proved that 100 rounds could be fired with gun-cotton, against 30 rounds 

 of gunpowder. From the low temperature produced by gun-cotton the gun does 

 not heat. Experiments showed that 100 rounds were fired with a 6-pounder in 

 36 minutes, and the gun was raised by gun-cotton to only 122° Fahrenheit, whilst 

 100 rounds with gunpowder took 100 minutes, and raised the temperature to 

 such a degree that water was instantly evaporated. The firing with the gun- 

 powder was, therefore, discontinued ; but the rapid firing with the gun-cotton was 

 continued up to 180 rounds without any inconvenience. The absence of fouling 

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

 ance is made for fouling. The absence of smoke promotes rapid firing and exact 

 aim. There are no poisonous gases, and the men suffer less inconvenience from 

 firing in casemates, under hatches, or in closed chambers. The fact of smaller 

 recoil from a gun charged with gun-cotton is established by direct experiment: its 

 value is f of the recoil from gun-powder, projectile effect being equal. To under- 

 stand this may not be easy The waste of the solids of gunpowder accounts for 

 one part of the saving, as in 100 lb. of gunpowder 68 lb. have to be projected in 

 addition to the shot, and at a much higher speed. The remainder. General von 

 Lenk attributes to the different law of combustion. But the fact is established. 

 The comparative advantages of gun-cotton and gunpowder for producing high 

 velocities, are shewn in the followiug experiment with a Krupp's cast-steel gun, 

 6-pounder. With ordinary charge 30 oz. of powder produced 1,338 feet per 

 second. With charge of 13^ oz., gun-cotton produced 1,563 feet. The compara- 

 tive advantages in shortness of gun are shown in the following experiments, 

 12-pounder : — 



/ 



