New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1881-04-22
SOUND PRODUCED BY LIGHT.


WASHINGTON. April 21.-At the meeting of
the National Academy OF Sciences this afternoon
Professor George r. Barker described briefly
interesting experiments with the carbon lamp More
in the therno balance The result Of his experiments
the discovery that the carbon fibre II remarkably
sensitive TO heat It's variations being eNhhed III ne
creased resistance Of tho fibre to the passage Of electrical
| currents With single cell Of Daniels or Lclanchc
battery so arranged in circuit that only about one
three hundrcth OF it, current passed through tho hbre
| the resistance reduced maximum OF Two ohInS.
Professor Barker expressed the opinion that carbon
would prove valuable substance Tor dehoHo eAIeri
| rncnts In the measurement Of heat.
Professor Barker was followed by Professor Alexander
Graham Bell who read paper OF absorbing hler'Nt
upon the production Of sound by radiant energy Ills
| remarks were lu-trated by sketches when were eA-
! bidtcd npon large screen by means OF camera
lie was frequently interrupted by rounds Of applause
and ppon his conclusion was the recipient OF ringing
euocy from the president Of the association PROFESSOR
william b. Rogers who asked the members u" JOIN nun
IN an accanation ~ thanks" 10 Professor Bel for the
interesting and valuable contribution he had made To
tho proceedings OF the association The following are
tho r,osi nuortanf points in Professor Bells paper:
I'M paper read before the American Association for
the advancement ~ science last August Professor bc
described certain experiments made ly Mt summer
Tainer and himself which had resulted IN the c"nHFuc
ton of phoiophoue" apparatus for the production
Of sound by light The discovery WAS announcer
that thin disks ~ very many diereh'
substances emitted sounds when exposed to the H'U'h
Of rapidly interrupted beam "f Snh"Eh' i"' .''"'
variety ~ material used In these experiment" "" '' "
the belof that snnorou.uess under such circumstances
would hc found lr general property "i hl m"'''''
At that time he had failed 10 obtain audible 'hc''7 from
1nas OF the various substances which became son"r"n-
i'm the condition Of thin diaphraens; t ms '"u'o WI"
explained upon the suppo-iun that the molecular us
turhance produced ~ the light was chrHy Hu''"'e 10"
tom and tho circumstance OF the experiment
, yirotnu had fu Dee transmitted through the mass OF
the substance order 10 ac the ear II was there
fore supposed that n air that was directly IN contact
with the Illuminated surface could be led to TIE ear
louder sounds might hc obtained and solid m"-'H 'e
found 10 Dee ~ souorous as thin dithmgmN
At this stage the experiments were interrupted - CIR
c,m.t,pc,- called Professor Bell to Europe While IN
Paris new form % the apartment occurred To his NINA
which would not only enable him to Investigate the
sound produced by masses, but would also permit MN
IN t,si the more general proposition that souorousc-r
under the influence Of intermittent hEh la property
common 10 All matter Professor Ben being unable to
pur.uc nj. apartments 10 Pans wrote To- Mr. fainter
sugce-tns that they Dee carried ou here which was Zone
with remarkable results He had begun 10y examining
tho sonorous prupsrtc- OF vast number ~ substances
inc oscd IN test tubes simple empirical search Tor
loud crcis tus led gradually &" The discovery
that cotton WOOL wor-tcd ak and nr""s materials
generally produced much louder sounds than hard
r-1d bodies ike crystals or dmphrnems such n" hnd
hitherto been uscd.
Mr. Tnpier next collected silks and wor-trds Of differ
, .,,,., f.,,l that thu d,rlr.t slndrs
ch' '"'"'H' ""' 'l' Wy $1,000.
produced the best circir bAfA ""rHHH '7'''"N b"'o
AN rAtrrmrly loud sound. As white cotton wool had
.t ,,.f e,u,l u mt siltt Nor 10 ANY other white
hbrous material before tucd Dee wa- anN"u. O." obtain
color,d specimens FOR comparison. Not hh'int any al
.-...t ,,... ...r..., ~ d,ft,nt,e ..rur
manu- """'' ''' Nv | .
! cotton wool with nmpo.a'h 0"'h W'IN'' ''''
f,rc,,,.ut r,.ult.d that Dee wns induced tn trl
go. ......oo,f.l ~ hmm,
Mulhid'h h"n'- N""'' % ''"'''
black MAS placed 300 % test tuh" ava c'p"-'d !"