4 SCIENCE. 
powerful fog-signal in operation at Point Judith could 
not be heard. ‘That area was soon marked by a whistling 
buoy. A similar area was found and plotted five miles 
from Block Island, and a whistling buoy was placed in the 
centre of that silent spot. 
A curious state of things was found off the light house 
on Little Brewster Island, Boston Harbor. Complaint 
had been made as to the action of the fog-signal there, 
which was a Daboll trumpet, and another and better fog- 
signal was wanted. Some asked for a siren, some for a 
steam whistle, and some for a larger and better Daboll. 
So a battery of fog-signals, one of each kind, was 
placed there, and I was appointed, with others, on 
an informal sort of a board to ascertain and re- 
port which of the three was best adapted to the 
place. It was found that the siren gave the best ef- 
fect, and it was duly established there, and is there yet. 
But it was also found that there were several areas of 
silence within normal ear-shot of that fog-signal which 
were constant as to their. general position, but which were 
floating or variable in their actual positions. There were 
already so many lights, buoys, spindles, etc., in that 
vicinity it was recommended that no more be established 
there lest it cause confusion. It was deemed the most 
curious concatenation of peculiar phenomena yet met. 
In observing ail these peculiar phases of non-audition 
of fog-signals at points where they should be heard, only 
one vessel had been used at a time. Hence, we had no 
record as to the sound at more than one place at a time, 
of a fog-signal. It had been a favorite plan of Professor 
Henry to use several vessels simultaneously about the 
same fog-signal, so as to learn where its sound was heard, 
as well as where it was not heard, at the same moment. 
The board decided to follow that plan this fall and in this 
way to re examine, with several vessels at the same time, 
the sound of the fog signal, which had heretofore been 
examined with but one vessel at a time. 
This duty was devolved on me, and I was ordered to 
the Clover, a fast-sailing schooner, to carry it into effect. 
I was permitted to invite two members of this society, 
Prof. C. A. White, LL. D., Member National Academy of 
Sciences, and Prof. H. A. Hazen, Forecaster of the Weath- 
er Bureau, to go with me on this cruise, and the invita- 
tion was afterwards formally repeated by the board. It 
was planned that when I had reached a scene of opera- 
tion and a proper day. was found, I was to impress 
any other light house vessel within reach for that day, 
and the hight house district officers were directed to give 
every practical aid to the expedition. This they did with 
great readiness and good effect. 
Thus it has happened that observations have been made 
recently from three vessels simultaneously, at three dif- 
ferent places, of the sound of a number of fog-signals at 
which abnormal phenomena had been observed and re- 
ported before; and the recent observations have been 
made, and have been plotted on the same scale as previous 
observations; so that all the observations made at each 
place whether in 1881, 1885 or 1893 are now comparable. 
The methods used at Little Gull light house and fog- 
signal station, for instance, were as follows: 
The Clover arrived at New London Harbor on the 
morning of Oct. 19. Leaving her trying to work yp to 
the city, against a headwind, I went ahead in the steam 
launch. At the light house depot I found the light house 
steamer, Cactus, with banked fires. In half an hour she 
was under way, and towing the Clover toward Little Gull. 
light station. Dr. White, Professor Hazen and I went on 
shore and the light keeper was directed 10 start up his 
fog-signal. Dr. White remained on the islet to see that 
the orders were carried out and to note any variations 
made from any cause in the usual sound. ‘Then Profes- 
xx II 
j Vo: ©. 579 
sor Hazen went on board of the Clover and I returned to 
the Cactus, and each vessel ran over prescribed courses. 
Observations of the intensity of the sound were made on 
each vessel each minute. The direction and force of the 
wind, the temperature by wet and dry bulb thermometer, 
and the pressure of the atmosphere, as shown by the bar- 
ometer, were duly recorded. ‘The appearance of the sea 
and the sky were also noted. 
The next day the Cactus was engaged on other impera- 
tive duty and the Clover went out from New London 
Harbor, where we had spent the night, without her. But 
Professor Hazen made a rather adventurous cruise in an 
open steam launch about the fog-signal, with excellent 
results. 
On the third day Professor Hazen was on the schooner 
Clover, and I was on the steamer Cactus. Dr. White was 
landed on Great Gull Island, which is small, treeless, and 
uninhabited, where he had large opportunity, which he 
fully used, to get the sound of the fog-signal under. cir- 
cumstances not had before. Here Dr. White noted the 
action and the result of peculiar echoes, and his studies 
of these echoes have developed an important factor in the 
discussion. 
Off Point Judith we had very light wind, almost no sea, 
though there was a heavy swell rolling in, and a fair sky; 
in other words, we had an excellent day for hearing. 
The Cactus being again with us, I went on her, Dr. 
White stayed with the Clover, and Professor Hazen, in spite 
of the bad character of that vicinity for quick and severe 
changes of weather, again took to the steam launch; so we 
got simultaneous observations of the sound of the fog- 
signal at Point Judith from three vessels, each cruising 
about on different lines. 
In our work about the ight on Little Brewster Island, 
at the entrance to Boston Bay, which occupied two days, 
we had the help of two other steamers. Major Livermore, 
of the Corps of Engineers, U. 8. A., and Engineer of the 
First and Second Light House Districts, went with us on 
his steam propeller, the Myrtle, and Lieutenant Com- 
mander Colby, U. S. N., assistant to the Inspector of the 
Second Light House District, accompanied us on the side- 
wheel steamer, Geranium. On the first day I was with 
Major Livermore on the Myrtle, Dr. White was in charge 
of the work on the Clover, and Professor Hazen went with 
Lieutenant Commander Colby on the Geranium. On the 
second day Dr. White went with Major Livermore; I 
stayed on the Clover, and Professor Hazen roe 
Lieutenant Commander Colby on the Geranium. Hach 
vessel ran on different courses on different days, and we 
got many simultaneous observations from the three ves- 
sels. Most of the time was spent on the open ocean be- 
tween Boston ight and Minot’s Ledge light, or beyond, 
or between Boston light and Egg Rock light. Part of 
each day, as we were going and coming from Boston Har- 
bor, was spent in the Narrows, or in Broad Sound, at the 
rear of the fog-signal we were observing. - 
Now, as to our tools. We had on the Clover an anno- 
meter at the foremast head, and another at the end of the 
jib-boom. Both were connected by electric two-conduc- 
tor cables with self-registering apparatus in the cabin. 
We also had a barograph which registered the pressure 
of the atmosphere, and we had a very delicate barometer 
by which to check the barograph These had been lent 
to the expedition by the Weather Bureau, and were under 
the charge of Professor Hazen, who looked after our me- 
teorology. In addition to these, the Professor had brought 
his own sling pschycometer, an ingenious arrangement 
of wet and dry bulb thermometers, which he managed 
with great skill, and clung to with much affection. The 
Clover had her own complement of thermometers, barom- 
eters, etc., in addition to what had come to us from the 
