, 1874-03-22

PROF. PEPPERS LECTURE,
Prot. PEPPER delivered the Last Of his seres of lee
lures yesterday evening The matinee lecture was only
fairly attended, IND the evening lecture showed
marked falling of in attendance from the audienct
thn. greeted the Professor his first appearance
The cause may be briefly stated None OF the lectures
we're interesting had been expected though had
they I'LL tept up to the standard OF the frat there would
have been for complaint. But the Lat two
lectures wcro undcnahy Of too primary character Ia
sepeutons OF those Of the first night, vera
not ESPECIALLY attractive: !, Besides, ths time
occupied g. IN hs de7ery Of these lectures was too
unless it Il continuous in character lihe opera or
drama, the spectator becomes esricd IN reasonable
time yet hs average tine aa2st BY Prof. Pepper ~as
Only synopsis Of the experiments Of yesterday even
ing can given, owing inck Of space Prof Pepper
said that sound 2s leard by tho ear depended partly
upon the density Of tho transmitting medium. As an
Illustration the lecturer aced small kei, which
gen The d. neity Of tho latter bei1R much less than
that Of sir the sound Of the bell auost wholly
destroyed Great amusement was also excited by the
vocal efforts Of the Professor when he had filed his
lungs with hydrogen gas hts voice being changed
from baritone to nervous, shr1u srebble.
By drawing violin low across the edge Of tnr
sound was rEodueeta and the lalls at tie time
few out in ali directions, showing that the sound was
not caused by electricity could 10 easily shown by
striking and applying tt to the jar when
The lec,ur.r theu showed the experiment Of the dis
turbed surface at waler making the surface
Eaa cassing the shadows on screen This system OF
wares precisely similar to that Of sound waves,
Tho former had their modal pontS or points ct rest
and Is water-w2ye, by coming in contact with an
other either augmented it or DESTROYED T. 50 atswayes
Tould act upon each other. Tnat is, two sounds
might he made to meet each other, 50 that sound
ut iii would be heard.
model points OF chord vibrating under the move
nlent OF violin bow. 4 beautiful experiment was
performed by attaching cord to l:ed point, and
,Ae o;her end to iaree tuningfork, On striking the
tuning fork the str7ng thrown Into violent vibra-
tions in number OF different sections throughout
its length. These sections vere equal u leugth but
cord.
Another similar experiment. applied to the vibration.
Plates Of brata, upon which fno sand had been scat
tered On drawing violin low acfoas the edge ct
the plsses the sand III. thrown in lines aud OF
more or less regular character, according to
the nate produced. To show that tue char
acter of aound depended upon the number
high rate Of rerolution Ia sound eroulue st shrer
aud shrier as the rapidity Increased. t.e iustru
meu caed the syrsn, ~4s a!so set III motion with the
tnIne eftc'.
Tho iectursr then explained the constructon Of tho
famous e cIancl ouliduch, which attracted much
attention among mechanics in EaEo1o. The principal
nj about It WAS colul inal1 OF whistle and lis
ton.T5d. TIE inter being drawn fl pushed out Of
the piston which formed the burrl OF the whistle the
produt cd.
Tue III which sound could b Al p1rent!y In
creased iu volume IL uslr4ted by l4c.us Frso-
nant nortar-snaped wi close 10 Azge, fiat bowl,
&C: oss the edge OF which violin had been draw1.
Tho Sound was greatly tnrezsed when the mouth of
the ntostar WIS turHsd toward II, but it
llso shown that tie vibrating bowl and the
ons used 10 throw the sound must # tho same or
nearly ths sanne tone. The experiment of the con-
ceated muslc-box w;s eatea With very long rod
md the result WAS highly satisfactory.
:, Frof. Pepper then spoke Of the various attempts
hat had Teen made to invent talking-machiues but
aala ths. almost .lvays they had been impos.ures.
It was TOO difficult to Keep the organs always in tile
same condition, and the talking head which was e1-
lihlted IN Loudou the nearest approach ever
made to SUCCESS. When the Professor hoard
bis head In London 1t could pronounce few wors,
,ut under the management Of atr. Brnutn, tho great
could talk quite well An Instrument was
Introduced to show how musical uots could 10 given
n optical expression. ray Of light reflected Il ON
mirror Was thrown upon screen, aud By making Tie
mirror vibrate under tho influence OF uotc, the
pot OF light waa elongated vertically. Another note
ade It extend itself horizontally, whio combine
ion Of the two, II they were in harmony, produced
ing of light The lecture closed with inevitable
host, which was fully explained to tho audience. |
In closing, Prot. Pepper slgutded possltIe nten-
lou of an early return 10 Chicago, lecturer.