Evening star. [volume] (Washington, D.C.) 1854-1972, 1883-05-19
Heat from, the Sun.

William c. Wyckof in Harpers Magazine for June.
The Mount Whitney observations show the
sun to be hotter than was supposed. The heat
received at the earths surface is probably more
by One-haf than was estimated by Herschel
and POuillet, and even materially exceeds the
values assigned by more recent investigators
1t would in one year melt crust of ice over the
whole sunward half of the earth six hundred
feet thick. This is. of cOuse. a statement in
very round numbers. The scientific phrase
would be that the suns vertical energy could
raise the temperature of one gram Of distilled
water three degrees Centigrade per minute for
each centimeter of the earth's surface nominally
exposed.
Having supplied us with an increased amount
of heat, the Mount Whitney experiments also
favor us with new figures OF intenser cold. The
estimates OF Herschel and Pouillet made the
temperature of space 22io below the zero of
Fahrenheit. The new results carry it down
nearly to the calculations for the absolute zero.
the absence of all heat. say minus 1892 F. To
the non-scienttic mind the distinction between
such far-dOwn temperatures is not unlike that
between the pains of rheumatism and those of
gout-the first being as from a thumbscrew
twisted to the last point of human endurance,
the govt giving one turn more.
Further, it appears that the direct heating
power OF the sun cannot raise q thermometer
quite 500 F. above its surroundings whatever
they may be- If we suppose the whole globe a
thermometer, and without an atmosphere the
sun could only heat it fifty degrees above the
cold of space, leaving it at about minus 400 F.
under full sunshine. The internal heat of the
earth may be disregarded in these calculations
1t seems paradoXical to say that, if the atmOs-
pherc were removed from the earth. it's surface
would receive more heat and yet be much
colder. But this is a fact of the same kind as
our experience in ascending mountain. The
atmosphere does indeed cut off h great deal of
heat. but on the other hand it keeps great
deal of that which it permits to pass through.
When the air is heated up to its retaining capa-
city an equilibrium is established.
TO Illustrate: let us imagine q large empty.
windowless hall. with two doors partially OBJ
strncted by Centennial turnstiles one FOR entry
and one for exit. A procession of one hundred
persons enters per minute. At first there is
abundant room; few want to come out. At the
END OF the second or third minute perhaps only
three people are leaving for one hundred arriy
ing. After longer interval the number of de-
parting guests is much greater 1t last the hall
Is crowded. to its utmost capacity. and if we
still suppose one hundred per minute entering,
1t is absolutely certain that one hundred per
minute must be getting out This final cOndi-
ton IS one which we may call equilibrium. If
the turnSties of Centennial pattern record their
turnings, we can ascertain exactly how many
people are in the hall at any moment. Now to
apply the illustration to heatbearing rays enter
ing our atmosphere, we may suppose that
nearly all reach the soil through radiation;
hat ninety per cent go out through
he regular exit of convection;
nine per cent squeeze back through the turn
stile by which they entered radiation and
one per cent climb out through the chimney of
'cOnductOn." 1t follows that by merely regu-
latin@ the turnsties, by modifying this capacity
for selecting and holding rays Of certain wave
lengths, atmospheres could be constructed
which would keep the planet Mercury COOL or
the iar-of Neptune comfortably warm. Here is
q hint for rOmanCerS who wish to plant their
drdn,atis persOnB in some other world
The Allegheny and Mount Whitney observa-
tions firmly establish the fact that the sun is
blue. The particular shade OF color which it has,
II viewed without intervening atmosphere, may
be laid down as that on the border of the blue
near the green. about where the line appears
in the spectrum. Sad to say this is not an
''esthetic' hue; 1t is more like that referred to
in one of Southey's poems: 'YOu could almost
smell birthstone, their breath was so blue, for