Chicago eagle. [volume] (Chicago, Ill.) 1889-19??, 1908-08-08
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The singular phenomenon Of hard
steel being cut BY 4 rapidly revolving
disc Of soft steel has been somewhat
puxzling. A microscopic examination
By an English engineer, r. W. Har.
bord. has now shown that the metal
acted upon 10 heated nearly or quite to
the melting point Of steel, but only at
the poiat Of contact with the disc.
In the absence Of other water sterilisa.
tion DR.. Ricgel Of the Austrian Army
finds citric acid effective. In q shall.
low vessel In sunshine Cloth Of citric
acid killed cholera germs In ave min.
utes and the typhus In an hour and q
half.
At the recent meeting Of the Amsri
can Association for the Advancement
Of Science, In Chicago. attention was
called to the interesting fact that the
work on the Panama Canal 10 changing
biological conditions in Panama, and
that its completion will enable the
fresh.water fauna Of the Atlantic and
Pacince slopes to intermingle. I'm.
doubtedly. many marine animals will
pass from one ocean 10 the other. Thus
permanent change Of conditions will
DO brought about, which may or may
not possess much practical importance;
but Ito scientific interest IL very great.
In View Of these facts. the association
resolved to urge upon Congress the no.
cessity Of an immediate biological sur.
vey Of the Panama Canal zone.
The question Of the possibility Of life
on the planet Mars continues to excite
wide interest. Recently DR.. Alfred
Russell Wallace has combated Prof.
Percival Lowell's conclusion that such
life exists. Among the objections urged
against the theory Of the habitability
Of Mars are the rSrity Of ito atmos-
phcre and the probably excessive frigid.
ity Of Ito climate. Dr. J. w. Evans OF
the Imperial Institute. London. re-
marks. In regard to this point. that tho
influence Of carb0nic acid on atmos-
pheric temperature seems not to have
been sufficiently considered. A slight
variation in the amount Of this constit.
uent has IN important effect upon the
retention OF heat. With relatively
large proportion Of carbonic acid. the
atmospheric temperature rises DR..
Evans suggests. rs IN interesting specu.
lation, that such condition may exist
upon Mars. and no thinks that the
quantity Of carbonic acid required to
make tho temperature endurable would
not be % great a. to be injurious to
animal life. Plant life would flourish
luxuriantly In II.
Architects ind no more difficult prob
lem than that presented by the acous.
tics Of lecture and concert halls. The
subject has been investigated BY Prof.
Wallace G. Sabine Of Harvard. who
presents some Interesting conclusions
The acoustic properties Of a hall de-
pend upon Two vas!sbles form and
the materials. The essential features
Of the materials are their absorbing
and reflective powers. The Fogg Art
Museum lecture hall was modelled after
the Sanders Theater In Cambridge, but
failed to reproduce its excellent acous.
tic properties. The reverberation OF
sound lasted 6.62 secOnds-an intoler-
able length. BY putting Sanders Thea
ter cushions on the seats. floor and
part Of the wall. the reverberation pc
riod was reduced to LA seconds. An
open window Is an absorbent Of sound.
An audience absorbs, per square meter.
OF as much as an open window. An
isolated woman In the auditorium alb
sorbed 81 as much as window, and
an isolated man As. apparently trib.
ute to the superior excellence Of female
apparel. Hair felt on the wall ab-
sorbed. per square meter, rs as much
as window.