AS A VEHICLE OF SOUND. 
229 
c. Its liability to be quenched or deflected by an opposing wind, so as to be practically 
useless at a very short distance to windward, is very remarkable. A case has been cited 
in which the gun failed to be heard against a violent wind at a distance of 550 yards 
from the place of firing, the sound of the syren at the same time reaching us with great 
intensity. 
Still, notwithstanding these drawbacks, I think the gun is entitled to rank as a first- 
class signal. I have had occasion myself to observe its extreme utility at Holyhead and 
the Kish light-vessel. The commanders of the Holyhead boats, moreover, are unanimous 
in their commendation of the gun. An important addition in its favour is the fact that 
the flash often comes to the aid of the sound : on this point the evidence cited in the 
Appendix is quite conclusive. 
There may be cases in which the combination of the gun with one of the other signals 
may be desirable. Where it is wished to confer an unmistakable individuality on a fog- 
signal station, such a combination might with advantage be resorted to. 
If the gun be retained as one form of fog-signal (and I should be sorry, at present, 
to recommend its total abolition) it ought to be of the most suitable description. Our 
experiments prove the sound of the gun to be dependent on its shape ; but we do not 
know that we have employed the best shape. This suggests the desirability of con- 
structing a gun with special reference to the production of sound*. 
An absolutely uniform superiority on all days cannot be conceded to any one of the 
instruments subjected to examination ; still our observations have been so numerous and 
long-continued as to enable us to come to the sure conclusion that, on the whole, the 
steam-syren is, beyond question, the most powerful fog-signal which has hitherto been 
tried in England. It is specially powerful when local noises, such as those of wind, 
rigging, breaking waves, shore-surf, and the rattle of pebbles, have to be overcome. Its 
density, quality, pitch, and penetration render it dominant over such noises after all 
other signal-sounds have succumbed. 
I have not, therefore, hesitated to recommend the introduction of the syren as a coast 
signal. 
It will be desirable in each case to confer upon the instrument a power of rotation, so 
as to enable the person in charge of it to point its trumpet against the wind or in any 
other required direction. This arrangement has been made at the South Foreland, and 
it presents no mechanical difficulty. It is also desirable to mount the syren so as to 
permit of the depression of its trumpet fifteen or twenty degrees below the horizon. 
In selecting the position at which a fog-signal is to be mounted, the possible influence 
of a sound-shadow, and the possible extinction of the sound by the interference of the 
direct waves with waves reflected from the shore, must form the subject of the gravest 
consideration. Preliminary trials may, in most cases, be necessary before fixing on the 
precise point at which the instrument is to be placed. 
The syren, it will be remembered, has been hitherto worked with steam of 70 lbs. 
* The Elder Brethren have already acted upon this suggestion, and have had plans of a new signal-gun laid 
before them by the constructors of the War Department. 
