National Republican. (Washington City (D.C.)) 1872-1888, 1880-08-28
SCIENTISTS IN COUNCIL.
Interesting Proceedings in Convention and
In Sections,

In Sections.
BosrON, Aug. 27.-The members of the
American Association of Science after heir eX-
haustiyo labors Of sightseeing and attending
receptions at Cambridge yesterday appeared
Ia full numbers this morning mt the institute
Of Technology. Tho association met in gem
eral session in Huntington hall at 10 o'clock
and after tr1usactiug a small amount Of busi-
ness, adjourned, The various sections of sub
sections then met In the rooms assigned them.
Section 4 was presided over by tho president,
Prof. Asaph Hall of Washington, ID. c., and
tho first paper road was The determination
Of the rotation time of Jupiter from obscrva-
lions OF tho red spots in lS19-S0 together
with the physical character aud changes of tho
spot" by Prof II. S. Poitchett. This was fol.
lowed by n paper on "rho determination of the
comparative dimensions Of intimate molecules
and tho reduction of the specific properties of
substances" by Prof w. A. Norton.
Mr. c. j. II. Woodbury. gave his deductions
from scientific experiments with lubrcatiug
oils, aud Mr., Thomas Craig spoke upon the
steady and vortex motion III Viscous COM
pressibe fluids.
Mr. Leonard Waldo gave an interesting dis.
course upon bptcroscopic observations, prim.
clpally solar.
In section B, where Prof Alexander
Agassiz presided napers were read as follows
medical curriculum" by Mr. Harrison Allen;
Distinguishing the species Of populus and
juglaus by young nndul and juelaus by young
naked branches" by Mr.. w. J. Bell.
AT the evening session Prof. AloXan-
der Graham Bell lectured on "The production
aud reproduction of sound by light" based on
discoveries made by Sumner Tainter and him
self He described tho remarkable substance,
selenum, and the manipulation devised In
previous experiments. Tho fual result" he
said, ''oI our researches has widenod the class
| of substances sensitive to light vibrations
until We can PROFOUND the fact of such sensa.
tlveness being general property Of all matter
We have found this property 10 gold, silver
platinum, iron, steel, brass, copper, zine
lead, antimony, German silver jenkins
metal, Rabbits metal, ivory, celluloid gutta
pcrcha, hard rubber, soft vulcanized rubber
paper, parchment, wood, mica aud silvered
glass, and the only substances from which we
have not obtained results are carbon and thin
microscopic glass. We find that when o vibra.
tory beam of light falls upon these substances
they emit sounds, the pitch Of which depends
upon the frequency OF the vibratory change
| In light. We find further that when we con.
| trOl tho form or character Of light vibrations
on scinum and probably on the other sub
stances we control the quality Of the sound
aud obtain all varieties Of artlculata sTGcGh,
We can thus, without conducting wire, as
In electric telephony, speak from station to
slaii2I whenever we can project beam of
/ light. We have not had an opportunity of
testing tho limit to which this photophonIo
Influence can DO extended, but we have spoken
about 500 feet apart and there seems no reason
to doubt that the results will be obtained at
whatever distance u beam of light can be
flashed from one observatory to another. The
necessary privacy Of our experiments hitherto
has prevented an attempt al determining the
0NtremO distance at which this new method of
vocal communication will be available"