170 On the History of Explosive Agents. [Feb. 5, 



mean rate at which velocity was transmitted along the spaced masses of 

 dynamite (in an experiment remarkable for the great uniformity of the 

 records at different parts of the train) was only =6239 feet (1896 metres) 

 per second ; the mean rate of transmission along masses of gun-cotton of 

 the same weight and length as the dynamite cartridges, and separated by 

 0-5 inch spaces, was (in two experiments) nearly = 17,000 feet 

 (5179*9 metres) per second. "When nitroglycerine was employed in the 

 pure and, therefore, liquid state, detonation being established at one ex- 

 tremity of the trains by means of a cartridge of dynamite, the mean rate 

 at which it was transmitted was only about 5500 feet (1672 metres) 

 per second, the same result being obtained in two experiments, in one of 

 which the quantity of nitroglycerine, in a given length of the train, was 

 double that employed in the other*. It may be possible that, by very 

 greatly increasing the quantity of nitroglycerine used, the rate of trans- 

 mission of detonation would be increased ; but there is no doubt that the 

 mobility and elasticity of the liquid, and the consequent facility with 

 which it yields to mechanical force when unconfined, act antagonistically 

 to the transmission of detonation in a mass of freely exposed nitrogly- 

 cerine. The author hopes that he may have the means and opportunity 

 of extending these interesting experiments, by ascertaining the effect of 

 confinement, both of nitroglycerine and gun-cotton, on the transmission 

 of detonation along continuous masses of the explosive agent. 



The numerical details given in the memoir afford proof of the trust- 

 worthiness of the results obtained in the velocity determinations, and of 

 the uniform rate at which detonation is transmitted along rows of con- 

 siderable length, composed of distinct masses of the explosive material, 

 even when these are separated from each other by spaces. "With trains 

 12-16 metres to 15-20 metres (40 to 50 feet) in length, the rate at which 

 detonation travelled along the last few feet was equal to that observed in 

 the first portion of the train. This was not the case with the transmission 

 of detonation through tubes to ividely separated masses of gun-cotton. The 

 time intervening between the detonation of the initiative charge at one 

 extremity of the tube and that of the first distinct charge (separated by a 

 space of 3 feet 3 inches, or 1 metre) was somewhat variable, and ranged 

 between 10,000 and 13,000 feet (3000 to 3900 metres) per second ; the 

 subsequent transmission, from charge to charge, along the tubes proceeded 

 at a tolerably uniform but considerably reduced rate, the average being 

 1800 metres (6000 feet) per second. In one experiment, with reduced 

 charges, the detonation was transmitted, as usual, to the first three separate 

 masses but the fourth and succeeding charges, though they exploded, did 

 not detonate ; the tube containing them was uninjured at those parts, but 

 the wires were severed at the seat of each charge, and the records ob- 



* The amount of nitroglycerine employed in a given length of the train corre- 

 sponded to that used in certain of the gun-cotton experiments, in which the rate of 

 transmission of detonation ranged between 18,000 and 21,000 feet. 





