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. 
1. Leigh . . . 
2. Girdler Light- 
vessel . . 
3. Reculvers 
4. St. Nicholas 
5. Epple Bay . 
6. Westgate 
7. Kingsgate . 
6$m 
12 
17* 
20 
22 
23 
25 
les W.N.W. 24 
S.E. by E. 5 
S.E. by S. 18 
S.E. . 3 
S.E. by E. 19 
S.E. by E. 9 
S.E. by E. 8 
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 Slioeburyness. 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 
