The Sun.
London, England, 1849-12-10 00:00:00

11L3TORY OP METEOROLOGY.

Some of the earliest records of attention •to the
causes of atmospherical phenomena are to be found in
the writ.ing., of Aratus, a Greek poet, who flourished
nearly three hundred years before the Christian era,
enik tly in his " Diosemia." But the principles he
describes were those to which Diodoru9, the historian,
alludes in his accounts of the Egyptians ; and they
ha l been imitated by the Grecian poet, as was the
case with everything the Greeks observed among
other nations. In Egypt a certain class of persons
were set apart for the express purpose of observing
the state of the atmosphere ; these persons were not
shepherds, as it is often erroneously imagined, but the
suns of the pfests. They enjoyed large revenues, and
rec4ived an education to fit them for the undertaking.
Owing to their observations and discoveries
the agriculture of Egypt (an art so highly dependent
on a foreknowledge of the state of the atmosphere)
made advances unknown to other countries, as testi-
fied by Diodorus hitnsfAf. The results of the Egyp•
tian's meteorological knowledge were embodied in the
" Tetra•biblos," of Claudius Ptolemy, in the second
century ; the man who, of all others, was most con-
spicuous for a knowledge of optics, geography, and
astronomy. Among the Romans there were several
who wrote on the subject, especially Matnlius, also
Virgil in his " Georgics ;" but he (as did Phing)
made the works of Aratus the basis of his doctrines,
nor did the cause of meteorology derive much benefit
froth she masters of the world.

In the middle ages science fled to the colleges of
Arabia, and not only do we owe the figures of arith-
metic and the basis of algebraical analysis, but also
all the improvements in the science of meteorology,
which it could boast previously to the sixteenth cen-
tur;•, are due to .Alchindu3, Albarnazer, and other
fanous Arabian philosophers, whose works have
been too much neglected, because of a prejudice
apainst tinir opinions on other subjects. During the
last two centuries, Bacon, Kepler, and other master
minds turned their attention to the subject, and many
valuable observations were made, in Germany
especially by llvriander, in Italy by Tualdo and
Becaria, and in England by Dr. Goad, who was phy-
sician to Charles the Second. It is well known that
d.ring the last century the subject languished in the
feeble hands of would-be meteorologists, such as
the editors of ilfoore's Altnanack, whose gross cor-
ruptions of the original doctrines of the Egyptians,
as contained in the works of Claudius Ptolemy, have
spread a worse than Egyptian darkness over the land
as to the plainest facts of meteorology; and it is only
at the present era that the British Association is
engiged in making obs?rvations to determine facts,
which have been recent:y observed, but have no
claim to novelty. I m3y instance particularly the
pointing out, at page 250 of their " Report on
Meteorology," the curious fact, that more rain falls
or may be caught near the ground than at a higher
point, which it is said " has met with no satisfactory,
explanation," while not only was the fact well deter-
mined, but a most simple and (to ray mind) satis-
factory explanation of it given above thirty years ago
byDr. Rutherford.

- The result of all this is that I believe I am war-
ranted in observing that very few principles are as
yet determined in the modern science of meteorology.
And as reg trds the present state of meteorology, I
may say that the only facts well attested in modern
digs are, first, that no change whatever has:taken
pla2e in the clircate of Europe since ancient times.
This point has been sltisfactorily determined by M.
Schonw and M. Arago. Secondly, that the mean
temperature at the equator is about 81 deg. F., and that
there are certain isothermal lines, or curves of mean
temperature, pretty well determined, and that at the
pole the mean temperature is about nine or ten degrees
below v?ro of F., or forty-two degrees below the
fi.ezing point.
Independent of the above, the whole mass of modern
meteorological science consists of isolated facts, which,
though connected in nature, await the discovery of
any known bond of connexion. In short, the observa-
tion of Professor Forbas, that " with regard to the
course of the honorary oscillations of the barometer
we are very much in the dark," may undoubtedly be
extended to the causes of many of the phenomena of
the atmosphere.

OF TUE CONSTITUTION AND PROPERTIES OF THE

AT NIOSPIIERS.

Meteorology teaches us that the portion of space
which surrounds the body in which our benevolent
Creator has placed us consists of several strata of
r.seous compounds, of various qualities, the most im-
portant of which is atmospheric air; which, by
charnical operations, has been repeatedly decomposed
and discovered to consist of oxygen, nitrogen, car-
bonic acid ,:gas, aqueous vapour, and electric fluid.
These substances (excepting the latter, which is im-
ponderable) press upon the earth in the ratio of
their volumes, their proportionate pressure being
equal to the weight of a column of mercury, its base
hying one square inch in measure, as follows :
Nitrogen, 23.7 inches ; oxygen, 6.3 ; vapour, 0.4 ;
carbonic acid gas, 0.03.
The leading qualities of the air may be thus ex-
pressed :--It is a transparent, elastic, ponderable,
gaseous fluid, capable of resistance, variable in its
temperature, density, and humidity, and a conductor
of sound only when dense, and of electricity only
when rarified.

It is transparent, as being the medium of vision;
it is deltic, or capable of expansion and compression,
as hewn by the action of heat upon confined air,
and by the removal of heat being followed by its
condensation ; also by the air-pump forcing an addi-
tional quantity of air into a given space, we see that
its particles they be compressed, or made to occupy a
smaller space. That it is ponderable is shown by its
hearing up solids immersed in it, as do other fluids,
and by its being weighed in a balance. It is found to
be a gaseous fluid, consisting in chief of 79 parts in
100 of nitrogen, 21 of oxygen gas. The force of a
strong wind which propels ships, overthrows trees,
&c., shows it to be a substance, and cap able of resist-
ance. The temperature of the air is found to vary
continually in almost all situaaions, being very rarely
stationary for a single hour. Its density also varies
continually, being afF.eted by temperature, by dis-
tance from the level.ot the sea, and other causes
nn
of v Lich is the direction of the wind. Thus, Dr.
Pewit found that 100 cu!:ie inches of dry air, at the
te-orature of GO df-grees,. weighed about 1:1 grains
),.a. than the slime cro,ntity at the temperature of
degrees ; and that the same. quantity of air
weighed about 1.500 th of a grain when !nor° when tt
wind was from the wast. The difference of the
weight of 100 cubic inches of air at different times
amounts to over 1-20th of a grain.
The humidity of the air varies continually also, as
vhe proved by several simple experiments. That
when the air is not dense it will not convey sound, is
shown by placing a bell within the receiver of an air-
pump, which hell may be shaken, without emitting
any sound when the air is exhaustld; and it is also
proved by the fact that sound is conveyed with
difficulty in the upper and more rarified regions of
the air. J..astly, the air is known to be a non con-