42 PROCEEDINGS OF THE 



Velocity, 

 Calibres. Charge. feet per second. 



Cotton, length, 10 15'9 oz 1,426 



Powder, " 18^ 49 (normal powder charge.) ... 1,400 



Cotton, " 9 17 1,402 



— As to advantage in weight of guu, the fact of the recoil being less in the ratio 

 of 2 ; 3 enables a less weight of gun to be employed, as well as a shorter gun, 

 without the disadvantage to practice arising from lightness of gun. As regards 

 durance of gun, bronze and cast-iron guns have been fired 1,000 rounds without in 

 the least afifeeting the endurance of the gun. As regards its practical application 

 to destructive explosions of shells, it appears that from a difference in the law of 

 expansion, arising probably from the pressure of water in intensely-heated steam, 

 there is an extraordinary difference of result, namely, that the same shell is ex- 

 ploded by the same volume of gas into more than double the number of pieces. 

 This is to be accounted for by the greater velocity of explosion when the gun- 

 cotton is confined very closely in very small spaces. It is also a peculiarity that 

 the stronger the shell the smaller the fragments into which it is broken. As re- 

 gards mining uses, the fact that the action of gun-cotton is violent and rapid in 

 exact proportion to the resistance it encounters, tells us the secret of its far higher 

 efficiency in mining than gunpowder. The stronger the rock, the less gun-cotton, 

 comparatively with powder, is necessary for the effect ; so much so that while 

 gun-cotton is stronger than powder as 3 to 1 in artillery, it is stronger in the pro- 

 portion of 6 2'74 to 1 in a strong and solid rock, weight for weight. It is the 

 hollow rope form which it is used for blasting. Its power of splitting up the mate- 

 rial is regulated exactly as wished. As regards military and submarine explosion, 

 it is a well-known fact, that a bag of gunpowder nailed on the gates of a city will 

 blow them open. In this case gun-cotton would fail. A bag of gun-cotton explo- 

 ded in the same way is powerless. If one ounce of gunpowder is exploded in 

 scales, the balance is thrown down ; with an equal force of gun-cotton nothing 

 happens. To blow up the gate of a city a very few pound? of gun cotton, carried 

 in the hand of a single man, will be sufficient, only he must know its nature. In 

 a bag it is harmless ; exploded in a box it will shatter the gates to atoms. 

 Against the palisades of a fortification : a small square box containing 25 lb, 

 merely flung down close to it will open a passage for troops; in actual experience 

 on palisades a foot diameter and 8 feet high, piled in the ground, backed by a 

 second row of 8 inches diameter, a box of 25 lb. cut a clean opening 9 feet wide. 

 To this three times the weight of gunpowder produced no effect whatever, except 

 to blacken the piles. Against bridges : a strong bridge of oak, 24 feet span, was 

 shattered to atoms by a small box of 25 lb. laid on its centre ; the bridge was not 

 broken, it was shivered. As to its effect under water : in the case of two tiers of 

 piles, in water 13 feet deep, 10 inches apart, with stones between them, a barrel 

 of 100 lb. gun cotton, placed 3 feet from the face and 8 feet under water, made a 

 clean sweep through a radius of 15 feet, and raised the water 200 feet. In Venice 

 a barrel of 400 lb. placed near a sloop in 10 feet water, at 18 feet distance, threw 

 it in atoms to a height of 400 feet. All experiments made by the Austrian Artil- 

 lery Committee were conducted on a grand scale, — 36 batteries, six and twelre 

 pounders (gun cotton) having been constructed, and practised with that material. 



