The Kenosha telegraph. [volume] (Kenosha, Wis.) 1860-1888, 1875-06-24
From the Now York Times.
ASTRONOMICAL DISCOVERIES.
THE SUN NOT so FAR AWAY AS HERETO
FORE T--MECHANICAL FORCE
OF LIGBT.

HE SUN MOI 81 FAX AWAY AS abnhAO-
FORE TAUGHT MECHANICAL FORCE
OF LIGBT.
The year 1876 seems likely to be dis
ltinguished III the annals Of astronomy
for the new evidence it is perfecting of
two important facts, both of which
have been held probable but have hith-
erto lacked complete demonstration.
| The first of these facts is that we are
some 100000 or 100000 Of miles
nearer to the sun than we had beer
taught BY our old text books on astrono
my to believe, and that consequently the
distances of the planets from the sun
and from each other require to be cal
cHlated over again and set down at much
lower figures. The evidence which the
recent observation of the transit of
Venus have contributed to this impor-
tant subject is we'll known TO our read
ers, and is brought forcibly to mind by
l
YORK with the transit expedition. The
second Of the demonstrations we have
referred to Is that Of the motive force
Of light. At a meeting of the Royal
Society Of Great Britain, few weeks
ago, Mr.. William Crookes, Fellow Royal
Society, who had previously communi
Gated some interesting facts on this sub
ject, read paper which may give rise
to much more important discoveries
perhaps than any contribution to Celes-
tial mechanics since the lew of gravita-
tion was demonstrated by Newton.
1t has always been assumed. and DR..
Belfour Stewart and other authorities
have affirmed, that light, apart from
heat, has no mechanical force whatever.
This old theory is overthIown by Mr..
Crookea, who fo2 some years past has
been making experiments, and has at
last constructed an ingenious apparatus,
by which he shows the power of iumi-
nous rays to drive round and roLnd al
little vane when the heat rays are ex-l
Guided, being tflofoughly sifted out BY
means of a screen ofalum We abridge
from the London Telegraph the follow
ing account of one Of the experiments
and regret that our space does not allow
a more extended notice cf the phenom-
ena submitted to examination before
the Royal Society. With an air pump
Mr.. Crookes first exhausts tube with
a bulb at its end and in the bulb he
mounts Upon delicate pivot little
Yane of glass or straw. This yane is
made in the form Of the letter Y, and
on each OF its four arms is mounted
disc Of pith blackened on one side.
TIE use of this blackened surface is in
genious, as will be presently seen. AS
soon as the machine is ready, it is expos.
ed to the sunshine, when its discs imme-
diately become endued, as it were, with
life. They revolve around their com.
mon axis just as the planets revolve
about the sun in the orrery. What isl
the motive force in this beautiful expert
ment? It is. not heat; for, as before |
observed the heat rays can be sifted
out by the alum screen without stop
ping the motion of the machine. The
atmosphere and its changes have Meth
ing to do with producing the motion.
Professor Osborne Reynolds some time
ago suggested that the disks revolyed !
because there was a latent moisture IN
them which, being evaporated in the
experiment, gave resilient impulse to /
the little errery To refute this theory,
and, at the same time, to show that the
sole motive force engaged ia driving
the orrery was the luminous rays of the
sun, Mr.. Cookies exhibited machine |
made wholly of platinum, which had
been heated to redness while under con-
tinuous and absolute exhaustion. The
discs being made of platinum, instead
of pith, as before, reviewed as obed-
iently as the disks of piths. Inasmuch |
as they could contain no apprcciable
amount of latent moisture, the theory |
of Professor Reynolds was, of course,
exploded.
The final result was that lighJ is now
acknowledged for the first time as one
of the mechanical forces, and such emil
rent men as Professors Stokes and
Huxley, DR.. Carpenter, Mr.. Norman