The Sun.
London, England, 1849-12-08 00:00:00

HISTORY OF METEOROLOGY.

Some of the earliest records of attention to the
Causes of atmospherical phenomena are to be found in
the writings of Aratus, a Greek poet, who flourished
nearly three hundred years before the Christian era,
chi, fly in his " Diosemia." But the principles he
de,cribes were those to which Diodorus, the historian,
alludes in his accounts of the Egyptians; and they
had 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 a; art 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 priests. They enjoyed large revenues, and
received an education to fit them fur 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 himself. 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
spcuous for a knowledge of optics, geography, and
astronomy. Among the Remens there were several
who wrote on the subject, especially Matnlius, also
Virgil in his " Georgics ;" Lut I.e (as did Piling)
made the works of Aratus the basis of his doctrines,
nor did the cause of meteorology derive much benefit
from the masters of the world.
In the middle ages science fled to the colleges of
Arabia, aid not only do we owe the figures of arith-
metic and the basis of algebraical analysis, but also
all the improvements in the Eeience of meteorology,
which it could boast previously to the sixteenth cen-
tury, are due to Alctiindue, Albarnazer, and other
famous Arabian philosophers, whose works have
been too much neglected, because of a prejudice
against their opinions on other subjects. During the
last two centuries, Bacon, li'-pier, and other master
minds turned their attention to the subject, and many
valuable observations' were cede, in Germany
especially by Hyriander, in Italy by Toaldo and
Becaria, and in England by Dr. Goad, who was phy-
eician to Charles the Second. It is well known that
during the last century the subject languished in the
feeb!e hands of would-he meteorol"gists, such as
the editors of Moore's Almanack, whose gross cor-
ruptions of the original doctrines of the Egyptians,
as contain( d iu the works of Claudius Ptolemy, have
spread a worse than E,uptian darkness over the land
as to the plainest facts of meteorology ; and it is onl)
at the present era that the British Association is
engaged in making observations to determine facts,
which have been recently observed, but have nu
claim to novelty. I may 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
by Dr. 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 regards the present state of meteorology, I
may say that the only facts well attested in modern
days are, first, that no change whatever has"taken
place in the climate of Europe since ancient times.
This point has been satisfactorily determined by M.
Schonw and M. Arago. Secondly, that the mean
temperature at the equator is about SI 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 zero of F., or forty-two degrees below the
freezing 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 Forbes, that " with regard to the
course of the hororary oscillations of the barometer
we are very much in the dark," may undoubtedly be
extended to the causes of massy of the phenomena of
the atmosphere.

OF THE CoNtTITUTION AND PRCPEETIES or THE

ATMOSPHERE.

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
gaseous compounds, of various qualities, the most im-
portant of which is atmospheric air; which, by
chemical 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
bring one square inch in measure, as follows :
Nitrogen, 2i37aisn, o.o3.ches; oxygen, 6.3; vapour, 0.4;
carbonic
The leading qualities of the air may be thus ex-
pressed :—lt 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 elastic, or capable of expansion and compression,
as shown 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 thay be compressed, or made to occupy a
smaller space. That it is ponderable is shown by its
bearing 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,
Scc., shows it to be a substance, and capable of resist-
ance. The temperature of the air is found to vary
continually in almost all situations, being very rarely
stationary for a single hour. Its density also varies
continually, being affected by temperature, by dis•
tance from the level of the sea, and other causes, one
of which is the direction of the wind. Thus Dr.
I'rout found that 100 cubic inches of dry air, at the
temperature of 60 degrees, weighed about 14 grains
less than the same quantity at the temperature of
32 degrees ; and that the same quantity of air
weighed about 1 500th of a grain more when the
wind was from the west. 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
may be 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 bell may be shaken, without emitting
any sound when the air is exhausted; and it is els()
proved by the fact that sound is conveyed with
difficulty in the upper and more rarified regions of
the air. Lastly, the air is known to be a non-con-

ducter of electriuity ict, °via:Lay b ate, tuP, whal
rarified, tF, elvetrie fluid passes truly through it.

FXTUNT OF THE ATMO.iPIERE,

Ihe height of atmosphurtc air (which must always
be distinguishtd from the atmo,phere itself) has been
caricusly (stimw.td, the general t•pinion being that
it exttnds about fifty milts fain the surface; 1 think,
hcvt ever, kr tonecusly. •