New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-10-31
ACADEMY OF SCIENCES.
THE CLOSE OF THE SESSION.


or NEw,JERsEY MOSQUITOES INvEsTIGATED-THE
.Nryyr@ on THE MALE MUsQuTro vIBRATE IN
rHtsoN WITH THE NOTE OF AIR FEMALES WINGS
= p1sCovFRIEs IN FLU0REsCENT SUBSTANCES
BY PROF MORTON - ADJOURNMENT OF Tux
ACADEMY.
The Academy of Sciences met yesterday. by
tsvatiou at the stevens Institute. Hoboken The great
facilities offered for experimental research by that ins'
tu.iop make its vast halls. whore every variety OF
Isoderu scientific apparatus is TO nc found an approp
ate place Tor the meeting of such body. II was Wills
pored about among members that Prof Mayer had some
aiscoyeros TO tell Of which, while they added fups
tally TO our scientific knowledge, we're 10 themselves
rurionsly mtoustnC. With ludcrous sppropil"Vnos'
of locality tho discovery Of an entire ne" oias "
respecting tho Inusquto has been reserved lol o
sl Prof Mayer and the shores Of R0ooken' o'
,,,ncpt Ma oecastonea during the reading OF the
paper, W verbal ambiguity 10 "is uoe'l .S
ue anteunG OF the mnedutoesoD WHICH "' Na"
by which he was understood 10 STARE tn'' 'u0 =. &c.,
fn question were precisely Similar III elne ~
piue rods two three feet long NC suSeoq .oo
70 oYelau upoD this sOin at the request o'
Who oxpected 70 spend nghI IN NewJersey'
..Kw nr,,,op on ANALYSIS OF COMPOSITE e0oNpS-b'
PROF. AIFRTD A. MAYER
tn, naper euahied Prof Mayer 20 exhibit an expert
,ncataI conaruatOD OF the heorem OF Fourier as ny
ored br hi In his propositions relating to the nature
.fasimple so,md aad the analysis by the car ora
lions. and 10 show experiments elucdating the ny
pothesis Of addition OF Helmbo.tz
Al VIC represent any composite SOUND by apenome
.tve Fourier has aud states in his theoren that
snch curve always be reproduced by conpouuuihE
harmonic curves ()teD Infinite IN NUMBER having the
same axis a given curve and having the lengths OF
their recurrent periods AZ T, II, 81, a &c.
The above the0Tem Is tho statement Of mathematical
pos,ihty and Il does necessarily follow that 1t can
he translated into the language OF dynamics
without experimental confirmation; for, ~ hehnhoi'z
Remarks, "That mode Of decomposition OF VlDra'ory
fors such as the theOrem OF Fourier describes aud rem
dcrs pOssibies It only mathematical hoiion, admiIa
le because II renders computation face but not corre-
sponding necessarily anything IN reality Why con
sdtr the penduOus vibration as the DedueDle element OF
anyIbratOry motoui We can imagine whole divided
~ "a multitude Of different ways; In ~ calculation We
may nd lt 70 replace the nnmber III r .
iu order to bring view; but 1t does not follow that
"a should always ana necessarily considered as inc
sum offs In other cases it may be more advantage
eus 10 consider the nuIobor as the sum of + g.
''rhe mathematical possibility, established by Fourier,
@! decomposng any sunorOus motion into simple uora-
Ions cannot authorize conclude that this is the only
admissible mode Of decomposition, if VIC cannot prove
that II has adjudication essentially real The fact that
tho ear effects that decomposition induces one, never
Iheess 10 believe that this analyst has adjudication
independont OF all hypothesis In the exterior world
Ihs opinion Is also confirmed precisely by the fact stated
above that this mode Of decomposition IL more adNan-
tageous than any other in mathematical researches.
For the methods Of demonstration which agree with
cue Intimate nature Of things are naturally those which
Icad 60 teorehe results The most convenient and the
most clear"
But although Uemholtz thus states the Importance OF
an experimental confirmation Of this thecren yet he
Esd attempt test Ito truth 10y course OF rigorous
sxltrImeuts This 1 have succeeded in doing, by the
sid Of new method Of sonOrOus auaiyb "hiSn VIII
presently proceed 10 describe.
II is well known that II . surface advance regularly
under point OF u body having pendulum vibration
Ga plano parallel TO the surface, tins point
will describe the surface bDurOldal
ior' as Il more generally oai!od) "a
harmonic curve O1n states that such vibration, and
only sucb produce the ear the sensation OF sim
pt souua--iu other words, Of sound which has one
npd only one pitch. point OF the sOnorous
body whether IL be point Of membrane OF the drum
OF the ear OF the end OF vibrating rod. or OF the air
t,sslf may be ECtuated by motion which, when II is
caused 20 describe Itself the aforementioned sur
face may depart greatly In is form from the simple
harmonic curve. Yet in this ease, according to Ohm,
the ear will THIS composite motion as the analysis
~ the mathematician can act on lie corresponding
rQrye, aud WILL decOnpOse IT INTO The simple
harmonic vibrations which compose IT, There
fore the car win this perceive several sounds
each having deuIIe pitch ana with the proper de-
gree Of attention take oOgui1Ince o. any one OF
1bem 70 the exclusion less Of all Of the other
cog4pCncnts.
hut OhIns proposition h. true, then there must be
reason for &c IL the very dynamic constitution Of the
ear. This Ueluhoiz cav. and the discovery OF the
IoS cords o. cortl in the oochea and OF schultse's
brisues IN the ampuG led him 20 suppose that these
bodies effected the analysis OF the sound vibrating with
alphabetically its simple eomponeDts. Thus BE
founded his theory % addition, which az once led hun
HIS ply Biological theory Of music contained In his
renowned work Die Lehre con den Io"emRf"d'mge""
a. which he reveals the hidden causes OF musical
harmony, witch bad remained for zoos yesrs
secret and problem 20 tho mind OF man
But many difficulties present themselves when would
IIug 10 the test OF experiment the propositions Of Ohm
and uClmh0ltz's ingenious hypothesis OF addition
First the complex sound Oh which we would experiment
tpanates from multitude Of vibrating points, mud the
points OF the resultant suffice differ IN their
RmpItaGes OF vibration, while points equally removed
from the geometrc eeuter OF the differ In THEN
phases Of vibration, 40 that when such wave falls at
al angle alphabetically vibrating bodies which
present any surface the effects produced are the results
" extreDey complex motions. The mind sees Ut once
the difference between this complex conception
spd Ohm's simple statement o. his application
Of Fourters theorem. The only experiment, in-
deed, which HelmhOitz addnces in support
OF his aooustica applications of Fourier's theorem
D. precisely in the condition OF tue relations have
Just described viz thar in which tho cords OF piano
arc caused 10 y1brate sympatheucay To tue elements
which may exist ~ the note we sing over the strings OF
The instrument.
AZ the mathematician In mia analysts deeomposos seri
attn every point Of the recurring curve into its Gle
ments, the physcist. In combining the theorem OF
Fourier should deeompose INTO its elementary harmonic
vibrations, the motions which such curve rep
resents and indeed reproduces when IL drawn under
ALT In piece paper which exposes only point OF the
az To GO this IL Is required that only
vibrating point Of the ibody should be experimental
and that the composite Vioraory motion ~ this point
sbond be conveyed along lines 10 bodies vibrating SYM