196 FRAGMENTS OF SCIENCE. 



ally upon the best possible shape, arrangements were made 

 with the War Office for the construction of a gun specially 

 calculated to produce the loudest sound attainable from 

 the combustion of 3 Ibs. of powder. To prevent the 

 unnecessary landward waste of the sound, the gun was 

 furnished with a parabolic muzzle, intended to project 

 the sound over the sea, where it was most needed. The 

 construction of this gun was based on a searching series 

 of experiments executed at Woolwich with small models, 

 provided with muzzles of various kinds. A drawing 

 of the gun is annexed (p. 197). It was constructed 

 on the principle of the revolver, its various chambers 

 being loaded and brought in rapid succession into the 

 firing position. The performance of the gun proved the 

 correctness of the principles on which its construction was 

 based. 



An incidental point of some interest was decided bv the 

 earliest Woolwich experiments. It had been a widely 

 spread opinion among artillerists, that a bronze gun pro- 

 duces a specially loud report. I doubted from the outset 

 whether this would help us; and in a letter dated April 

 22d, 1874, I ventured to express myself thus: " The 

 report of a gun, as affecting an observer close at hand, is 

 made up of two factors the sound due to the shock of the 

 air by the violently expanding gas, and the sound derived 

 from the vibrations of the gun, which, to some extent, 

 rings like a bell. This latter, I apprehend, will disappear 

 at considerable distances." The result of subsequent trial, 

 as reported by General Campbell, is, " that the sonorous 

 qualities of bronze are greatly superior to those of cast iron 

 at short distances, but thai, the advantage lies with the 

 baser metal at long ranges."* 



Coincident with these trials of guns at Woolwich, gun- 

 cotton was thought of as a probably effective sound-produ- 

 cer. From the first, indeed, theoretic considerations caused 

 me to fix my attention persistently on this substance; for 

 the remarkable experiments of Mr. Abel, whereby its ra- 

 pidity of combustion and violently explosive energy are 



* General Campbell assigns a true cause for this difference. TLe 

 ring of the bronze gun represents so much energy withdrawn from 

 the explosive force of the gunpowder. Further experiments would, 

 however, be needed to place the superiority of the cast-iron gun at a 

 distance beyond question. 



