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quite hidden ; still the gun and syren-sounds reached on the 
bearing of the Yarne light- vessel to a distance of 11-J miles. 
The syren was heard through the paddle-noises at 9^ miles, 
while at 8J miles it became efficient as a signal with the 
paddles going. The horns were heard at 65 miles. This was 
during calm. Subsequently, with a wind from the N.N.W., no 
sounds were heard at 6 J miles. On land, the wind being across 
the direction of the sound, the syren was heard only to a 
distance of 3 miles N.E. of the Foreland ; in the other direc- 
tion it was heard plainly on Folkestone Pier, 8 miles distant. 
Both gun and horns failed to reach Folkestone. 
Wind, rain, a rough sea, and great acoustic opacity, charac- 
terized October 31. Both gun and horns were unheard 3 miles 
away, the syren at the same time being clearly heard. It after- 
wards forced its sound with great power through a violent rain- 
squall. Wishing the same individual judgment to be brought 
to bear upon the sounds on both sides of the Foreland, in the 
absence of our steamer, which had quitted us for safety, I com- 
mitted the observations to Mr. Douglass. He heard them at 
2 miles on the Dover side, and on the Sandwich side, with the 
same intensity, at 6 miles. 
A gap (employed by the engineers in making arrangements 
for pointing the syren in any required direction) here occurred 
in our observations. They were resumed, however, on Novem- 
ber 21, when comparative experiments were made upon the gun 
and syren. Both sources of sound, when employed as fog-sig- 
nals, will not unfrequently have to cover an arc of 1 80° ; and 
it was desirable to know with greater precision how the sound 
is affected by the direction in which the gun or syren is pointed. 
The gun, therefore, was in the first instance pointed on us 
and fired, then turned and fired along a line perpendicular to 
that joining us and it. There was a sensible, though small, 
difference between the sounds which reached us in the two 
cases. A similar experiment was made with the syren; and 
here the falling off when the instrument was pointed perpen- 
dicular to the line joining us and it was very considerable. 
This is what is to be expected ; for the trumpet associated with 
the syren is expressly intended to gather up the sound and pro- 
ject it in a certain direction, while no such object is in view in 
the construction of the gun. The experiments here referred to 
were amply corroborated by others made on November 22 and 23. 
On both of these days the Galatea's guns were fired to 
windward and to leeward. The aerial echoes in the latter case 
were distinctly louder and longer than in the former. The ex- 
periment has been repeated many times, and always with the 
same result. 
In front of the Cornhill Coastguard Station, and only 1£ 
mile from the Foreland, the syren, on the 21st, though pointed 
