The Massachusetts spy, and Worcester County advertiser. [volume] ([Worcester, Mass.]) 1825-1831, 1831-06-01

IN heaven.
IRANsNIssToN OF SOUND. The propagation
OF sound through water presents many inter.
estlng points Of consideration. The velocity
with which it moves was found by nj. Beudant
to be about 1921 feet per second; and by still
more accurate experiments, made in the Lake
OF Geneva, NM. Coladon and Sturm found it
10 DC Aus feet per second, when the tempera-
ture was 40. 6. of Fahrenheit. The series of
experiments performed by these two able phi
losophers We're made with much care and sa-
gacIty, and have afforded many very innortant
and instructive results After trying various
methods Of producing sound under water, they
adopted the continuance of striking bell with
metallic lever, about yard below the sur
lace; the signals were made by the explosion
OF gunpowder which was effected by the same
blow of the hammer which struck the bell, and
the interval which elapsed between the appear
ance of the fash and the arrival of the sound
was reckoned by quarter of a second stop
watch. The experiments were made in the
pure water of the Lake of Geneva, between
kole and Thonon, distance of nine miles
When the bell was struck beneath the water, it
was distinctly heard by an observer in the air
and directly above the bell but when the OBJ.
server was 200 or 300 yards distant from the
point above the bell, the sound of it could no
longer be heard. This remarkable fact requires
some explanation. IT, in a dark night, we
place in glass bell bright flame like that of
an argand lamp, and sink it foot or two be-
meath the surface of pool of clear and still
water, the light will be readily seen when the
eye is nearly above it; but if the eye is at such
distance, that the line joining it and the Ii ght
is inclined Al. or less tothe surface of the pool
not single ray of the light of the lamp will
ieach the eye, even If it were as intense as the
light of tropical sun. The whole of the LIGHT
suffers what is termed total reflection from the
inner surface of the water. From the above
experiment of NM. Colladon and Sturm. this
curious property of light seems to hold also in
the case OF sound, which appears to have been
totally reflected from the surface of the water
Now, IN the case of light, we could see the
amp under water by putting pane of glass at
the end of tube, and thrusting that end under
the surface. five point the tube to the lamp,
It's rays will fall nearly perpendiculary upon
the pane of glass, and they will be freely trans
mltted to the eye. In this experiment we have
done nothing more than substitute for the OBJ.
lique surface of water, which is incapable of
transmitting light, less oblque surface Of glass
which is capable of transmitting it. In like
manner, NM Colladon and Sturm conceived
the happy idea of plunging tube into the wa.
ter, at any distance from the bell, to receive
the vibrations which the surface of the water
would not allow to escape, and to transmit them
to the ear of an observer out of the water With
this view, they plunged vertically into the lake
a thin tin cylinder, about three yards long and
eight inches wide, closed at the lower end and
open above, and the sonorous vibrations propa.
gated under the water were thus stopped, and
made to enter the air in the tube, which trans.
mitted them to the ear of the observer By
means of this beautiful contrivance, they were
enabled to hear the strokes of the bell under
water at a distance of nine nlileS-across the
whole breadth of the Lake of Geneva. In the
course Of these experiments NJ Coladon OBJ.
served that the sound of hell, struck under
water, had, ata distance, no resemblance what
ever to its sound in air. It gave sound like
that of two knife blades struck against each
other. When the distance became so small as
the eighth part of mile, the musical tone of
the bell could be distinguished after the blow of
the hammer, a result which is the reverse of
what takes place in air, where the first impulse
of the hammer is heard only in the immediate
vicinity OF the bell.
HerschclPS Treatise on Sound