1862.] and Military Applications of Explosions, 441 



If a slowly burning powder be employed in such arms, a portion of the 

 unexploded charge is expelled together with the projectile, the period 

 between the first ignition of the powder, and the expulsion of the shot 

 or shell from the gun, being insufficient for the combustion of the 

 entire charge. In long guns and in rifled cannon it is very impor- 

 tant, on the other hand, that the ignition of the charge of powder 

 should take place gradually, so that the pressure exerted thereby upon 

 the gun and the projectile should, after the first ignition, be as far as 

 possible uniformly continuous during the passage of the shot or shell 

 along the principal portion, if not the entire length, of the gun's bore. 

 With the gunpowder which has been, until quite recently, in general 

 use for large cannon, the actual explosion of a charge is almost 

 entirely accomplished before the projectile has passed beyond the 

 trunnions of the gun. Hence the rear portion of the weapon is sub- 

 ject to a strain wliich is enormous as compared to that sustained by 

 the front part of the cannon. Numerous important advantages natu- 

 rally result from a more uniform distribution of the pressure over the 

 interior of the gun ; for instance, the necessity of constructing the 

 part reaching from the breech to the trunnions of very much greater 

 strength than the remainder (a measure which, in the production of 

 cast-iron cannon, involves considerable difficulties) is greatly dimi- 

 nished, and the risk of fracture of guns, or of their serious injury from 

 submission to excessive strain, is considerably lessened. The explosive 

 action of gunpowder may, it need hardly be observed, be easily regu- 

 lated by the introduction of modifications in the proportions of the 

 carbon, sulphur, and saltpetre employed in its manufacture, and in the 

 degree of intimacy with which the ingredients are mixed. Both of 

 these expedients interfere, however, with the extent of force ultimately 

 exerted by a given weight of the gunpowder ; since, in either case, the 

 chemical action between the ingredients would be modified. The 

 rapidity of combustion of gunpowder may, however, be admirably 

 regulated, without introducing any alteration in its composition or in 

 the perfection of its manufacture, simply by increasing or diminishing 

 the size of the particles or grains constituting a charge ; and also by 

 modifying the degree of compression to which the gunpowder is 

 subject before, or at the time of, its conversion into grains or pellets. 



By combining the application of uniform and accurately regulated 

 pressure with modifications in the composition of gunpowder, and by 

 thoroughly confining the material within a case or receptacle, so that, 

 if ignited, it can only burn in one direction, admirable and valuable 

 arrangements (known as Fuzes and Time-Fuzes) are obtained for 

 igniting charges of gunpowder in shells at any period, during their 

 flight, which may have been determined upon previous to the loading 

 of the gun. By simple mechanical arrangements, regulating the 

 amount of the compressed gunpowder which shall burn before the 

 flame reaches the charge in the shell, the time of explosion is readily 

 adjusted with the greatest nicety (subject, however, to variations 

 depending upon the degree of density of the atmosphere, as recently 



