The independent press. (Abbeville C.H., S.C.) 1853-1860, 1855-07-20
From the Cassville Stnndard.7
The Science of Heat.

Heat IS the sensation Of warmth. The sun
is the principal source of heat The heat
of the Supid:tfers from artificial heat, in that
of the for" er passes readily througssglass
while the i5ster possesses the property only
in small segree. Sunshine is detrimental
to combustion the reason why is not known
with any degree Of certainty, but fires are
never SO bright when the Sun shines on
them. II IS supposed by some writer's that
chemical effect is produced upon the air
in contact with the fire which iInpedes the
progress O: the combustion.
Cdlo,ic-When we touch substance
hotter than ourselves, a subtle invisible
stream flows from the hotter substance and
produces On our nerves the sensation of
warmth This stream is called caloric, and
is the agc't which produces the sensation Of
warmth, but heat is the sensation Of itself.
This .caloric is not equally distributed over
the globe. for at the equator the medium or
average temperature is 50 1-2 degrees while
at the po!es it is believed to be about 3 de-
grces bel,w zero.
Elect$<city, the second source of heat.-
Electricity, like heat, exists in all matter :;
but it is frequently in concealed state and
can onlyo developed by friction; hence, its
name fr,m the Greek word electron signify
ing amt.r, which, it was discovered by the
Greeks, possessed when rubbed the proper
ty of attracting other bodies. This proper
ty is possessed by many other bodies. IF
you ruba piece Of paper with India rubber
the rubber will adhere to the table. A piece
Of common brown paper may be made to
stick fast to the wall by drying it for mo-
ment al the fire and then drawing it once or
twice between your knees. In both cases
electricity is excited by friction. Brushing
the hair for long time produces an itching
Of the head, because the friction of the hair
brush excites electricity in the hair, which
consequently becomes over charged and ir-
ritates the skin. Cats rub their ears before
a rain, becsusc the air is full of vapor and
its humidity (piercing between the hairs Of
the' - P!oauoes un itching sensation, or. it
may be because the air is oyer-charged with
electricity, producing a corresponding over
charge in the hair Of the cat. This over
charge gives the hair perpetual tendency
to become ruffled and the cat keeps rubbing
her coat and ears to smooth the hair down.
Electricity, like heat, is in itself invisible,
though it is often accompanied by both light
and heat. 1t is sometimes attended BY a
peculiar odor known as Ozone, resembling
sulphur and phosphorus. This odor has
been observed in the air during thunder
storms.
The Aurora Borealis is supposed to be
produced by the electric fluid passing
through air Of different densites. The
most rarified air produces aOhite light, the
drycst air, rcd, and the dampest ycllov
streaks.
Lightning.-Lightning is accumulated
electricity discharged from the clouds.
There are three causes which produce this
electricity in the clouds: the evaporation
from the earth's surface, the chemical
changes which take place on the earth's sur
face, and currents of air of unequal temper
ature, which excite electricity by friction, as
they come in contact with each other. When
cloud overchu,yed with electric fluid, ap-
proaches another which is undcrcharged,
the fluid rushcs from the former into the
latter, until both are equally charged. Some
times mountains, trees and steeples will
discharge the lightning from cloud float
ing near, and the electric fluid sometimes
rushes out of the earth into the clouds.
Lightning clouds are Of various heights
from the earth, some of them actually touch
ing it with one Of their edges, while others
are as high as four or five miles above it.
Those from which electricity is discharged
during thunder storm are, however, rare
y more than seven hundred yards above
the surface of the earth. On a fair day,
the.clouds are often four or five miles above
our heads, but their average height is from
one and half to two miles.
Lightning is sometimes forked because
the lightning cloud is at great distance,
and the electrical current is diverted into a
ziz-zag course by the powerful resistance Of
the air, the current flying from side to side
10 order to pass where there is least resist
ance. Sometimes, in very severe storms,
the flash will divide into two or more parts,
and there will be as many flashes of forked
lightning seen at the same time. When the
cloud is near the earth and the current
meets with but little resistance, it is not
divided, and the flash is straight. Sheet
lightning is either the reflection of distant
flashes not distinctly visible, or else several
flashes intermingled. Sometimes the flash
es assumes globular form, which is the
most dangerous form Of lightning -
x fash Of lightning is generally followed
BY pouring rain, because the flash produ-
ces change in the physical condition oi
the air, rendering it unable to hold as much
water in.solution as it could before; conse.
Equently, q part is given off in heavy rain,
It's generally followed BY . gust Of wind