KECENT EXPERIMENTS ON FOG-SIGNALS. 309 



the outset whether this would help us ; and in a letter 

 dated 22nd April, 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.' 



FIG. 8. 



Breech-loading Fog-signal Gun, with Bell Mouth, 1 proposed by 

 Major Maitland, K.A., Assistant Superintendent. 



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 that the advantage lies with the baser metal at 

 long ranges.' 2 



1 The carriage of this gun has been modified in construction 

 since this drawing was made. 



3 General Campbell assigns a true cause for this difference. 

 The ring of the bronze gun represents so much energy withdrawn 



