January 5, 1894.] 
Weather Bureau. The balloon which the Secretary of 
the Treasury had asked the Secretary of Agriculture to 
permit the Weather Bureau to lend us, and which had 
been shipped to us, did not arrive. Had it come we might 
have had Professor Hazen looking down upon us from a 
great height, and we should have had him at the end of a 
rope, recording temperature, air currents, moisture, wind 
and sound from 1,000 feet above, and at intervals of 
25 feet, till we landed him on our deck or in the water. 
Major Livermore, however, used toy balloons, with which 
to ascertain the force and direction of the upper air cur- 
rents. The paper balloons were, say, four feet high, and 
one foot in diameter, at the widest part. They had an in- 
genious attachment for producing hot air, which, at night, 
lighted them, and made them for a while clearly visible. 
The longest flight I saw one of these make was 1514 min- 
utes. Then the Major had spherical rubber balloons of, 
say, nine inches through, which he filled with hydrogen 
generated on the Myrtle, which were also quite useful. 
The fog-signals we were sent to observe were three 
steam sirens and a steam whistle. Hach signal has its 
own peculiar characteristic. The second-class siren at 
Little Gull Island, for instance, gave, during a fog, a blast 
of five seconds, and then after a silent interval of 40 sec- 
onds, and another blast of five seconds, and it continued 
this alternation of blast and interval while the fog contin- 
ued. This blast and interval served to differentiate this 
signal from other signals within ear-shot, and especially 
that at New London light-house, which was a six seconds 
blast, alternating with a silent interval of thirty seconds. 
The siren is the most powerful fog-signal in existence. 
The English Government adopted it after a favorable re- 
port on it made by a commission sent to this country headed 
by Sir Frederick Arrow, and also after a report by Pro- 
fessor Tyndall, who then bore the same relation to the 
English lighthouse establishment that Professor Henry 
did to the United States lighthouse establishment, that is, 
of scientific adviser. 
Tyndall says of the siren in his book on “Sound,” third 
edition, p. 316: “The steam siren is the most powerful 
fog-signal which has been tried in England.” Again 
Tyndall says on p. 318: “We find the sound range on 
clear calm days varying from 21/2 to 16 1/2 miles.” 
Again he says on page 319: “It may be relied upon at a 
distance of two miles; in a great majority of cases it may 
be relied upon at a distance of three miles, and in a major- 
ity of cases at a distance greater than three miles.” 
Now as to the full range of the instrument, Tyndall 
says on page 321 of the same book: “The most conflict- 
ing results were at first obtained. On the 19th of May, 
1873, the sound range was 3 1/3 miles; on the 20th it was 
5 1/2 miles; on the 2nd of June, 6 miles; on the 3rd, more 
than 9 miles; on the 10th, 9 miles; on the 25th, 6 miles; 
on the 26th, 914 miles; on the Ist of July, 1234 miles; on 
the 2nd, 4 miles; while on the 3rd, with a clear, calm at- 
mosphere and smooth sea, it was less than 3 miles.” 
I have quoted this much from Tyndall, for while he ac- 
cepts the siren, he damns it with faint praise, and what 
he says is about the worst that has been said of it. The 
French, who also adopted it, speak in much higher terms 
of it, and the Light House Board, while constantly search- 
ing, has found nothing better. It remains the best fog- 
signal in the world, and it may be regarded as a constant 
memorial of the work of Professor Henry, who, for light- 
house purposes, was its inventor. 
But good as the siren is, it leaves much to be desired. 
It is a great big clumsy, ugly machine, expensive to make, 
expensive to run, and expensive to keep in repair. It is 
maintained to make a great big ugly noise continuously, 
and of a certain kind and atcertain intervals. It makes the 
noise, without regard to ethics or esthetics; but it might 
SCIENCE. 5 
keep its pitch better; and it might maintain its intervals 
better. Itis not an instrument of precision. It has its 
limitations. They are not entirely unconnected with the 
pressure of its steam; in other words, with its manage- 
ment. But it approximates exactness sufficiently near to 
answer the purposes for which it is intended. When the 
mariner hears it, and hears it aright, he knows where he 
is. The question we are discussing is not so much con- 
nected with the sound made as with the sound heard. It 
is not the aberration of the sound, but the aberration of 
the audition of the sound with which we are concerned. 
Now as to the method used to determine the intensity 
of the sounds of the fog-signal we tested. ‘This we did, 
on this cruise, by ear,and on the same scale and in the 
same way in which it was done in observations made in 
1881 and 1885. 
Each of the party on the Clover used the scale of 10. 
It was understood that 10 was the sound of the highest 
intensity, and 0+ the lowest sound observable. We divided 
the scale, however, thus: 11 plus, 1%, 2 minus, and 
then 2. Mr. Wallace, Major Livermore’s assistant, used 
the scale of 100. I have no doubt that is just as good as 
my scale, but as I had commenced my observations on the 
scale of 10, I carried that scale through these observations 
in order that those made in 93 might be comparable with 
those made in 85 andin ’81. The question of personal 
equation has arisen, but I have carefully avoided any 
comparison of the mode of hearing, or rather accuracy of 
hearing, between members of my party. My direction to 
each was to record 10 as the highest sound of the fog- 
signal that could be heard on board of the vessel in which 
he was making observations. When they were as near 
as they could get the vessel to the source of sound, the 
distance was, as a rule, not more than one-fourth of a 
mile. The minimum sound was 0. plus. One-half 
of the sound between 0+ and 10, I considered as 5, and 
half-way between that and maximum was called 7%, and 
half-way between 5 and 0+ was regarded as 24, and 
then we divided still finer between those points. In that 
way I think we got a practical solution of the question, 
and are as nearly accurate as it is practicable for 
observers to be, that is, for practical, but not for scientific, 
purposes. 
Each person preserves his own scale throughout, re- 
cording the maximum and minimum and medium, and 
dividing between those points according to the accuracy 
of his own ear. I noticed that different members of my 
party, and of Major Livermore’s party, did not mark in- 
stances the same under some circumstances; but the dif- 
ferences were slight, and they could be accounted for by 
interfering noises in different parts of the ship, which 
affected different hearers in those parts of the ship, so 
that their hearing of the same noise was to a certain ex- 
tent interfered with. I think the results reached were of 
a practical character, although they were not such as 
might be considered severely, or even scientifically, accu- 
rate. They were not such as would have been recorded 
by a self-registering machine, that is, they were not as 
finely phrased. _I tried to put myself in the place of the 
mariner, who might hear a fog signal without knowing 
what it was, and who might be forced to determine its 
identity by the character of its blast, the intensity of its 
blast, and the continuation of the silent interval between 
blasts. 
Major Livermore has a large number of observations 
which haye been plotted, and I think will be comparable 
with ours when ours are plotted. 
We are now having very delicate instruments made 
_with which to measure the character and the intersity of 
the sounds made by fog-signals; and thus I hope that 
