66 Professor Ahel [March 21, 



It has been stated that detonation can be transmitted from one 

 maes of gun-cotton or dynamite to another through intervening air- 

 spaces. The extent to which such spaces can be introduced without 

 checking detonation is obviously regulated by the size of the masses 

 of explosive detonated ; but the distances of air-space through which 

 the detonation of a moderate quantity of the explosive agent will 

 communicate to similar masses, are very limited, a space of 2 inches 

 being sufficient to prevent the detonation produced by a mass of 

 8 oz. of gun-cotton, freely exposed, from communicating to con- 

 tiguous ones. If the dispersion of the force is prevented in part, and 

 direction is given to the gases violently projected from the centre of 

 detonation, the power of transmitting detonation to separated masses 

 of explosive is increased to a remarkable degree. This is readily 

 accomplished through the agency of tubes, the charge first detonated 

 being just inserted into one extremity, while that to which the 

 detonation is to be transmitted is inserted into the other ; or separate 

 charges may be placed at different distances inside a long tube, with 

 long intervening spaces, the initiative charge being inserted at one 

 end. A few illustrations of the results thus obtained may be given. 

 The detonation of a 1-oz. disk of gun-cotton in open air will not 

 transmit detonation with certainty to other disks placed at a greater 

 distance than half an inch from it ; but if it be just inserted into one 

 end of an iron tube 2 feet long and 1*25 inch in diameter, a 

 similar disk, or even a plug of loose gun-cotton inserted into 

 the other extremity of the tube, will invariably be detonated. 

 With employment of 2 oz. of gun-cotton, in a tube of the same 

 material, thickness, and diameter, detonation was transmitted to a 

 distance of 5 feet. In tubes of the same kind, of very considerable 

 length, 2-oz. disks of gun-cotton placed at intervals of 2 feet, 

 were detonated through the initiative detonation of one such disk 

 inserted into one extremity of the tube. In other experiments a long 

 tube of this kind was fitted with branch pipes, 2 feet long, at those 

 parts where the intermediate disks were placed, and charges of 

 gun-cotton were placed at the extremities of these pipes. By the 

 initiative detonation of 1 oz. of gun - cotton all the charges were 

 detonated, the effect on the air being that of one single explosion. 

 The results obtained with equal quantities of gun-cotton varied with 

 the diameter, strength, and nature of the material of the tubes used. 

 Dynamite and mercuric fulminate, applied to their own detonation, 

 furnished results quite analogous to those obtained with gun-cotton ; 

 but in applying fulminate to the detonation of gun-cotton through 

 the agency of tubes, some singular and instructive results were 

 obtained, for an account of which the lecturer referred to his Memoir 

 on this subject. 



Silver fulminate was employed for the purpose of instituting 

 more precise experiments than could be made in operating on a 

 larger scale, with gun-cotton, on the influence of the material com- 

 posing the tubes, of the condition of their inner surfaces, and of 



