Year: 1869

From the London Daily News.l ga


It would scarcely be thought BY most
persons (says our contemporary, that
the stars supply the earth with an appre-
eiable amount Of heat Even on the
darkest and clearest night, when the
whole heavens seem lit up by a multi
tude Of sparkling orbs, the idea of heat
is not suggested by their splendor. It
will, therefore, seem surprising to many
that men eff science should assign no
incOnsiderable portion Of our terrestrial
heat supply to those distant twinkling
lamps. 1t is not many years since Pro
fessOr Hopkins, of Cambridge, went even
farther, and expressed his belief that if
the earth atmosphere were but increased
some $4,000 yards in hight, SO as to
have an increased power Of retaining the
warmth poured upon it from outer space,
we might do without the sun altogether,
so far as heat supply is concerned. As
a glass-house collects the suns heat and
renders it available during the time that
the sun is below the horizon, so he held
that the additional layer of air would
serve to garner the warmth of the stars
in quantities sufficient for all of our
requirements. But until lately all these
views, however plausible they might
have seemed, had not been founded upon
facts actually observed. 1t has been
reserved for these days in which discove-
ries Of the most unexpected kind are
daily rewarding the labOrs of our physie-
lists to see that established as a certainty
which had before been founded merely
upon considerations of probability. Mr..
Higgins, the physicist and astronomer,
has just published the results of a series
of inquiries addressed to the actual
measurement of the heat which we
receive from the leading brilliants of
the nocturnal sky. The instrument called
the galyanometer, which has been made
more or less familiar to many of US by
the researches and lectures of Mr. Tyn-
dali, was made use of by Mr. Huggins in
these Investigations The instrument
was fixed by Mr. Higgins large refrac-
tor, so that the image of a star formed
by the S-ineh object glass might fail
upon the surface of the thermopile. 1t
will give some token of the care required
in researches of the sort to mention that
the apparatus had to be left attached to
the telescope for hours, sometimes for
Ssss, until the needle, whose motion
marks the action of the heat, had come
to perfect rest. When the time came for
making an observation, the shutter Of
the dome which covers the telescope was
opened, and the telescope was turned
upon a part of the sky near to some
bright star, but not actually under the
star Then the needle was watched to
determine whether the change Of posi-
ton had produced any effect. IF in four
or five minutes no signs Of change were
shown, the telescope was moved the
small distance necessary to bring the
image of the star directly on the face Of
the pole. Almost always the needle
began to move as soon as the image of
the star fell upon it. The telescope was
then moved slightly away again from
the star the needle was then seen to
return to Its place. In this way from
twelve to twenty observations would be
made upon the same star, so that DO
doubt might remain as to the motion
being really due to the stars heat. In
this way it was found that the bright
Arcturus moved the needle three degrees
in about a quarter of an hour. So did
Regulus. the leading brilliant of Leo,
the constellation at present adorned by
the splendor of ruddy Mars. Pollux
gave a DETECTION of one degree and a
half; but, singularly enough, his twin
brother, Castor produced noefect at all
upon the needle. The splendid Sirius
gave detection of only two degrees /;
but as this star is always low down, and
SO shines through greater proportion
of the denser atmospheric strata, it is
not surprising that its heat should not
be proportioned to its brilliapcy.