METEOROLOGY. 
from those bodies passing through a frozen 
medium of hail or snow ; and that this may 
be the case admits of very little doubt; but 
it is equally probable, that the rays of the sun 
breaking through an uniformly dense cloud, 
nearly exhausted by rain falling from it, may 
produce a similar etfect on moisture in a fluid 
state, and this is demonstrated frequently by 
the sun appearing through such clouds. The 
parhelia, or mock sim, is another phenome- 
non, effected by the rays of the sun dart- 
ed upon frozen or fluid particles of water 
on either side of that body ; but the exact 
manner in which this appearance originates 
cannot, for obvious reasons, he ascertained. 
A constant attendant upon each of the 
phenomena that we have attempted to illus- 
trate is wind, the doctrine of which deserves 
every possible attention, as much of our 
comfort, and health, and commerce wholly 
depends upon it. Were it not for this agi- 
tation of the air, putrid etfluvia arising from 
the habitations of man, and from vegetable 
substances, besides the exhalations from 
water, would soon render it unfit for respi- 
ration, and a general mortality would be the 
consequence. In this instance also the 
philosopher finds his progress arrested, and 
his research bounded by insurmountable 
obstacles; still, however, there are many facts 
established that are highly satisfactory. The 
temperate zones are not under the influence 
of as regular winds as between the tropics : 
the trade wind prevails annually and regu- 
larly in those parts of the Pacific and At- 
lantic oceans which lie near the equator; it 
blows from tlie north-east within a few 
points on the north side of the equator, and 
fi'om the south-east on the opposite side, 
and the interval space of these separate 
winds is from the second to the fifth degree 
of north l.ititude, and within the limits just 
mentioned, where the wind may be said 
never to blow from the north or the south ; 
but there are dreadful storms, and perfect 
calms, equally dangerous and perplexing to 
the mariner, who finds the force of the trade 
winds decline as he approaclies their boun- 
dary. Between the tenth and thirtieth de- 
grees of south latitude the trade vvind pre- 
vails in tlie Indian ocean ; but north of it 
there is a change every halfyear, when they 
blow in an opposite direction to tlieir pre- 
vious course : these are termed n:onsoons, 
and their change is constantly productive of 
variable airs and storms of extreme violence, 
which frequently continue from five to six 
weeks, during which period the navigation 
is very dangerous. The monsoons take 
place one on the south and the ottier on the 
north side of the equator in the Indian 
Ocean, and they extend to the eastern coast 
of China, and the longitude of New Hol- 
land, from Africa: they, however, suffer 
partial changes through local circumstances. 
They are, besides, not altogetlier confined 
to the space just mentioned, as the wind 
blows from the east or north-east between 
September and April, and for the remain- 
der of the year from the south-west on the 
coast of Brazil, between Cape St. Agustine 
and the isle of St. Catherine. Having thus 
directed the attention of the reader to this 
part of the subject, we shall pass to the pre- 
vailing winds of our native country, which 
were ascertained by order of the Royal 
Society of London, which learned body 
published the following result in their Transr 
actions. — At London. 
Winds. 
Days. 
Winds. 
Days. 
South-west... 
.. 112 
South-east. . 
.. 32 
North-east.. 
.. 58 
East 
North-west. . 
.. .50 
Soutli 
AFest 
.. 53 
North 
.. 16 
The same register shews, that the south- 
west wind blows more upon an average in 
each month of the year than any other, par- 
ticularly in July and August; that the north- 
east prevails during January, March, April, 
May, and June, and i.s most unfrequent in 
February, July, September, and December ; 
the north-west occurring more frequently 
from November to March, and lesis so in 
September and October than in any other 
months. In tlie fifth volume of the Statis- 
tical Account of Scotland there is a table of 
seven years close observation made by Dr. 
Meek, near Glasgow, the average ot which 
is stated as follows : 
"Winds. Days. '\y’inds. Pays. 
Southwest 174 North-east.. 104 
North-west. .. 40 South east... 47 
In Ireland the prevailing winds are the 
west and south-west. The different de- 
grees of its motion next excites our atten- 
tion; and it seems almost superfluous to 
observe, that it varies in gradations froin 
the gentlest zephyr, which plays upon the 
leaves of plants, gently undulating them, tp 
the furious tempest, calculated to inspire 
horror in the breast of the most callous: it 
is also a most remarkable fact, that violent 
currents of air pass along, as it were within 
a line, without sensibly agitating that be- 
yond them. An instance of tins kind oc- 
curred at Edinburgh, when the celebrated 
aeronaut Lunardi ascended in his balloon, 
which was conveyed with great velocity by 
