RECENT EXPERIMENTS ON FOG SIGNALS. 207 



On the 17th of October, 1877, another series of experi- 

 ments with howitzers and rockets was carried out at Shoe- 

 buryness. The charge of the howitzer was 3 Ibs. of L. G. 

 powder. The charges of the rockets were 12 oz., 8 oz., 4 

 oz., and 2 oz. of gun-cotton respectively. The gun and 

 the four rockets constituted a series, and eight series were 

 fired during the afternoon of the 17th. The observations 

 were made from the Vestal and the Galatea, positions 

 being successively assumed which permitted the sound to 

 reach the observers with the wind, against the wind, and 

 across the wind. The distance of the Galatea varied 

 from 3 to 7 miles, that of the Vestal, which was more 

 restricted in her movements, being 2 to 3 miles. Briefly 

 summed up, the result is that the howitzer, firing a 3-lb. 

 charge, which it will be remembered was our best gun at 

 the South Foreland, was beaten by the 12-oz. rocket, by 

 the 8-oz. rocket, and by the 4-oz. rocket. The 2-oz. 

 rocket alone fell behind the howitzer. 



It is worth while recording the distances at which some 

 of the sounds were heard on the day now referred to: 



24 out of 40 sounds heard. 



The day was cloudy, with occasional showers of drizzling 

 rain; the wind about N.W. by N. all day; at times squally, 

 rising to a force of 6 or 7 and sometimes dropping to a 

 force of 2 or 3. The station at Leigh excepted, all these 

 places were to le ward of Shoeburyness. At four other 

 stations to leeward, varying in distance from 15^ to 

 24 miles, nothing was heard, while at eleven stations 

 to windward, varying from 8 to 26 miles, the sounds were 

 also inaudible. It was found, indeed, that the sounds 

 proceeding directly against the wind did not penetrate 

 much beyond 3 miles. 



On the following day, viz., October 18th, we pro- 

 ceeded to Dungeness with the view of making a series of 

 strict comparative experiments with gun-cotton and cotton- 

 powder. Rockets containing 8 oz., 4 oz., and 2 oz. of gun- 

 cotton had been prepared at the Royal Arsenal; while 



