RECENT EXPERIMENTS ON FOG-SIGNALS. 25? 



gun produces a specially loud report. I doubted from 

 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 



Breech-loading Foz-Bijrnal Gun, with Bell Mouth,* proposed by 

 Major Maitland, K. A., Assistant Superintendent 



latter, I apprehend, will disappear at considerable dis- 

 tances.' 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.' f 



* The carriage of this gun has been modified in construction 

 since this drawing was made. 



f General Campbell assigns a tnie cause for this difference. 

 The ring of the bronze gun represents so much energy withdrawn 



