The daily intelligencer. [volume] (Seattle, Wash. Territory [i.e. Wash.]) 1876-1881, 1879-09-18

rejecting On the keepers Of Tatooch
liCh. for an alleged neglect Of duty IN
not sounding the fog whistle At times
which were stated TO have occurred on
three or four days If the previous week,
during which several vessels were OF
the islard in fog. As 1t can be shown
ard satisfactorily proved that during
the time specified. and on all occasions
Of fog, the whistle has been sounded in
strict accordance with the orders Of the
Lighthouse Board, and as there have
been other aud equally unjust com
plants made against the keeper Of
Dungeness light although the persons
making complaint have done so ur-
doubtedly in good faith Il wish to show
from the hishes: authority those natural
causes in the transmission Of sounds
that have produced effect. which. if
unexplained, would seem to show q
neglect Of duty on the part OF men who
are known 10 the Lighthouse Board IS
among the best and most efficient men
in the whole lighthouse service of the
United States.
In the report CT the Smithsonian In
s.itute for 1917, page 81, the late Prof.
Joseph Henry. Secretary of IT, Insti-
.ute and President Of the Lighthouse
Board, says IL conclusion: For several
years past the Secretary has devoted the
greater part Of the summer to insesti-
cations Oh sound in tie application OF
fog signals, 10 connection with the
Lighthouse Board. These investisa-
tious have been made along the coas!
on lighthouse steamers, with the assist
ance of members and officers of the
Lighthouse establishment. During the
last year series Of experiments were
made along the coast Of Maine, which
served to establish some new principles
as well as to confirm previous results"
From oil the experiments made by the
Lighthouse Board III regard to the trans
mission Of sound in free air, the follow
ing conclusions may be considered es-
tablished
The audibility Of sound at distance
depends on the character Of the sound,
which must not be too high or shrill.
otherwise the amplitude Of vibration
will be too small to allow sufficient
quantity Of air to be put in motion;
neither must tue pitch be too low, for
in this case the motion Of the atoms of
DIR in the sound wave will not be suffi-
GENTLY rapid to convey the impulse TO
great distance. The results are de-
rived from observations on the siren.
the reed trumpet and the automatic
buoy. The effect of quantity of sound
is shown in tho fact that. in sounding
different instruments ut the same time,
it was found that two sounds apparently
of the Same loudness were heard al very
different distances The audiblity Of
sound depends upon the state u the
atmosphere. The most efficien. cause
of the loss of audibili,y is the direct
effect produced by the wind. AS gen
ersl rule. a sound is heard farther when
moving with tho wind tran when NOV
ing against it. This effect, which is in
conformity with ordinary observation,
is not due to an increase Of velocity Of
the sound wave in one direction and q
diminution in the other by the motion
of the wind except ia an imperceptible
| degree; for since sound moves at the
vata 81 al, II l. \
of seven and half miles an hour woald
| increase OR diminish the velocity Of the
sound wave only one per cent 1t is
due. however, to change in its direc-
ton. Sound moving with the wind is
refracted or thrown down toward the
earth; while moving against the wind
it is refracted upward and passes over
the head of the observer, so as to be
heard at n distance NJ all elevation of
several hundred feet when in,udible at
the surface Of the earth.
Although, as n general rule, the sound
is heard farther when moving with the
wind than when moving against it, yet
in some instances the sound is heard
farthest against the wind. but this phe-
nomenon Is shown TO DO due 10 domi-
nant upper wind, blowing at the time
in an opposite direction to that at the
surface of the earth These winds are
not imaginary productions inveuted to
explain the phenomenon, but actual ex-
istences. established by observation, as
~ the case Of the experiments made OF
Sandy Hook in 1874, by means OF bal
looms, and FROM the actual motion Of
the air in the case Of northeast storms,
as observed at stations on the coast Of
Maine.
1t has been established, contrary to
what has formerly been thought to be
the case, that neither fog, snow, hail nor
rain materially interferes with the trans
mission of loud sounds. Tho siren has
been heard at = greater distance during
the prevalence OF q dense AMI widely
extended fog than during aay other
condition Of the atmosphere This
may. however, be attributed TO the uni
form density and stiffness Of the mir q,
the time. which is most favorable 10 the
transmission Of sound, as shown by the
observations Of Parry and other Arctic
explorers. Air, however, is seldom in
a state Of uniform density, but is per-
vaded by local currents, due TO coutsc.
with portions of the earth une1uaily
heated, and from the retractions and
reflections 10 which the sound wave is
subjected in its passage through such
medium, i. Is broken up and los, 10 the
car at less distance.
In some CASES sound-sha1ows ara