The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1870-03-05

the scientific world. Mr.. Stone hoped to be
able to announce the actual amount of heat
which the irst-class stars send to this globe
on which we live.
little consideration will show the enor-
nous difficulty of the problem. A very deli
cate thermometer placed at night in the
open air responds to thousand influences
which the ordinary observer would be inclined
wholly to disregard. Long ago, Gilbert
White, of Selborne, noticed how the ther-
mometer rises at night as clouds pass over
head, and sinks as the heavens grow clearer.
But as the science of meteorology has pro-
gressed, men have recognized the fact that
changes much less obvious than these affect
the thermometer. On each of two different
nights the sky may be beautifully clear,
the floor of heaven ''thick inlaid with
patines of bright gold, and yet the con-
dition of the air may be so different
that on one night the earth's heat may be
rapidly radiating into space, while on the
other an unseen presence in mid-air checks
the escaping heat, and makes the weather
warm and genial. Though on each night
''the heavens break open to their highest"
there is thus the most essential difference in
the circumstances under which the stellar
heat would be measured since the same aque-
GUS but unseen veil which cuts off the
escaping earth-heat, must in part, at least,
influence the heat which is sent to the earth
from beyond the stellar spaces.
By an ingenious arrangement Mr.. Stone
was enabled to overcome this difficulty in
great part, and to secure that which so de-
lighteth the soul of the man of science, a
reliable zero. Let not the uninitiated be
confounded by this mystic word-it implies
merely that which may be compared to the
end of a rule or measuring-tape To know if
a star sends us heat at any moment we must
know what heat our instruments would show
before receiving the stars heat; otherwise,
what are we to measure from E? But, as we
have said, this initial heat is continually vary
ing. What Mr.. Stone had first to do, then,
was to master this difficulty. Others remained
which we have not space to specify, but these
also he overcame.
At last, after enormous labor, the heat re-
ceived from two well-known stars has been
measured. Arcturus, the leading brilliant of
the Herdsman, and Vega, the chief star of
the Lyre, are the two orbs dealt with by Mr..
Stone. From a careful measurement of their
light, Sir John Herschel long since deter
mined that these stars are of equal splendor;
but Arcturus shines with ruddy yellow light,
while Vega exhibits a color which has been
compared to the CLEAN Of highly-polished
steel. The estimates of their heat CORE
spond with the aspect of these orbs. The
fiery Arcturus sends us about twice as much
heat as the blush Vega. Minute indeed is
the quantity of heat received from either
star, even Arcturus having a direct heating
effect correspondence to but about the 800, ,000th
part of degree Fahrenheit. Or, Mr.. Stone
remarks, the result may be otherwise stated
as follows:-The heat received from Arcturus
is sensibly the same as that from the face of
three-inch iron cube full of boiling water at
| a distance of 383 yards.
To the worlds which circle around these
| brilliant stars our sun doubtless supplies no
| larger degree of heat; nay, we have good
| reason to believe that ne is relatively an in
| significant orb. Around Arcturus are we'll
| warmed worlds, nourished by the rays which
| belong to the red end of the spectrum. Those
| which circle around Vega, if equally distant,
are less plentifully supplied with heat. On
| the other hand, if one may speculate so con-
| fidently as to the state of these worlds as to
| regard photography as an art practised among
| their inhabitants, then must the people
warmed by Arcturus sit longer for their por-
| traits than those on whom the brilliant Vega
| pours his powerful actinic rays Seriously,
| the researches we have been dealing with
suggest strange thoughts for our considera-
tion. The question of the plurality of worlds
had seemed perplexing enough when we con-
sidered merely the strangely various condi-
tions under which living creatures must sub
sist in the different orbs which circle round
our sun. But when we contemplate the varie-
ties presented among the fixed stars, the
mind is lost in the attempt to conceive the
enormous range of variety which must char
acterize the races of living creatures subsist
ing in the systems of which those stars are
the central luminaries.