Evening star. [volume] (Washington, D.C.) 1854-1972, 1890-11-15
LIGHT AS A GENERATOR OF
SOUND.
Justice to Distinguished Washington
Scientist.

Scientist.
To the Editor Of THE EVENING STAR:
The following appeared in your issue of Tues
day last:
"A wonderful discovery has been attracting
the attention of scientists says the Chicago
Mai. beam Of sunlight is made to pass
through prism so as to produce the solar
spectrum or Rainbow. A disk, having Sits or
openings cut In it, is made to revolve and the
colored light Of the rainbow is made to break
through 1T and fall ON silk, wool or other ma
terial contained in glass vessel. As the
colored lights fall upon il sounds will DO given
by the different parts of the spectrum, and
there will be silence in other parts If the
vessel contains red worsted and the green
light flashes upon it loud sounds will be given
Only feeble sounds will be heard when the rcd
and blue parts OF the rainbow fall upon the
vessel. and other colors make no sound at ALL"
wonderful discovery" certainly but by
no means so recent rs the Chicago editor ap-
pears to suppose, The paragraph quoted is an
exact description Of apparatus. experiments
and result Is which, with other interesting mat
tiers in relation to the generation of sound by
the action of light, were brought to the atten-
ton OF the scientific world about ten years ago
by Prof. Alexander Graham Bell Of this city
This eminent Washing tonian was the first to
announce, and SO far as the facts have ap-
peared the hrst to conceive, the idea OF pro-
ducing sound by the action Of light. In lee
ture delivered May, 1878, before the Royal In
stitution Of Great Britain he declared .the
possibility Of hearing shadow by means of in
terrupting the action of light upon selepium."
In October. 1880, having originated the strik-
ing scientific hypothesis that ''sonorousness
under the influence of intermittent light is q
property common to all matter" he laid the
results OF numerous experiments before the
French Academy, arresting thereby the atten-
ton of scientists in both hemispheres. In his
investigations and experiments Prof. Bell was
largely assisted by Mr.. c. s. Taintor, whose aid
he ungrudgingy acknowledged. The JOINT
labors OF these gentlemen resulted in the con-
struction OF the "photophone," an apparatus
for the production Of sound by light, and the
''spectrophone," an instrument for use In spec
trum analysis its purpose being to determine
the audibility Of different substances in the
spectrum. These instruments, together with
various experiments bearing on the general
subject, will be found fully described in two
very interesting addresses by Prof. Bell. one
read August 81, 1880. before the American As
ISOLATION for the Advancement Of Science, and
the other read April II, 1881, before the Ma
tional Academy OF Sciences ANY one who has
a fancy for the wonders Of science can learn
from these addresses the means by which
beam OF light, having an undulatory character
impaired to it by the human voice, can be re-
Elected so as to reproduce at q distant station
the spoken sounds Thus, as a voice carrier, q
ray OF light may in a certain sense fulfill the
function OF telephone wire. In this way
vocal communication between stations about
$50 yards distant was successfully maintained
by these two experimenters. and in the Ian
guage of Prof. Bell there seems no reason to
doubt that the results may be obtained at what
ever distance q beam of light can be flashed
from one observatory to another"
This communication is written without con-
sultation with Prof. Bell and in the interest
simply Of justice and truth.
DAVID WOLFE BRowN.