A S A VEHICLE OE SOUND. 
231 
len thened interval between the blasts of the trumpet or syren. My own small expe- 
rience as a sailor has shown me how harassing to the mariner are some of our revolving 
lights with a long period of rotation. No light, in my opinion, ought to be obscured 
for a period exceeding- 30 seconds ; and the interval between two blasts of our fog-signal 
ought, in general, not to be longer. 
With the instruments now at our disposal, wisely established along coasts, I venture 
to think that the saving of property in ten years will be an exceedingly large multiple 
of the outlay necessary for the establishment of such signals. The saving of life appeals 
to the higher motives of humanity. 
In a Report written for the Trinity House on the subject of fog-signals, my excellent 
predecessor, Professor Faraday, expresses the opinion that a false promise to the 
mariner would be worse than no promise at all. Casting our eyes back upon the 
observations here recorded, we find the sound-range on clear, calm days varying from 2 \ 
miles to 16^ miles. It must be evident that an instruction founded on the latter 
observation would be fraught with peril in weather corresponding to the former. Not 
the maximum but the minimum sound-range should be impressed upon the mariner. 
Want of attention to this point may be followed by disastrous consequences. 
This remark is not made without cause. I have before me a Notice to Mariners issued 
by the Board of Trade regarding a fog- whistle recently mounted ’ at Cape Race, and 
which is reputed to have a range of 20 miles in calm weather, 30 miles with the wind, 
and in stormy weather or against the wind 7 to 10 miles. Now, considering the distance 
reached by sound in our observations, I should be willing to concede the possibility, 
in a more homogeneous atmosphere than ours, of a sound-range on some calm days of 
20 miles, and on some light windy days of 30 miles to a powerful whistle ; but I 
entertain a strong belief that the stating of these distances, or of the distance 7 to 10 miles 
against a storm, without any qualification, is simply calculated to inspire the mariner 
with a false confidence which may lead him to ruin. I would venture to affirm that at 
Cape Race calm days might be found in which the range of the sound will be less than 
one fourth of what this notice states it to be. Such publications do not fulfil their 
proper object if they are made the vehicle by which inventors vaunt the performance of 
their instruments ; they ought to be without a trace of exaggeration, and furnish only 
data on which the mariner may with perfect confidence rely. The object which I had 
in view in extending these observations over so long a period was to make evident to 
all how fallacious it would be, and how mischievous it might be, to draw general con- 
clusions from observations made in weather of great acoustic transparency. The mariner 
when he hears a fog-signal ought, as just stated, to assume the minimum rather than 
the maximum distance, and to take his measures accordingly. 
Thus ends, for the present at all events, an inquiry which I trust will prove of some 
importance, scientific as well as practical. In conducting it I have had to congratulate 
myself on the unfailing aid of the Elder Brethren of the Trinity House. Captain Drew, 
Captain Close, Captain Were, Captain Ateiins, and the Deputy Master have all from 
