Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 13, MAT-MIC

Jritr»(l sif¬
t-ion.
C 7°S ]
METEOROLOGY.
Introduc¬
tion.
INTRODUCTION.
i
Objedt of -Jl yiETEOROLOGY is that part of natural fcience
meteoro- XVI w’nich treats of the changes that take place in our
atmofphere, as they are perceptible to our fenfes, or as
they are indicated by certain inftruments which the in¬
genuity of man or accident has difcovered to anfwer
that purpofe. In as far as it defcribes the phenomena
produced by fueh changes, meteorology is a depart¬
ment of natural hiftory ; but in its attempts to account
for the appearances, it is almoft entirely dependent on
t Natural Philosophy and Chemistry.
Its connec- The connexion of METEOROLOGY with CHEMISTRY
lion with js fufiiciently evident to thofe who take only a fuper-
rfiemiftry. gcjaj vjew Qf tj}e fubjeft, though it has only of late at-
tracled the notice of rhilofophers. That the air is
fometimes hotter and fometimes colder than ufual j that
it is at one time much rarefied, and at another greatly
condenfed 5 now uncommonly dry, and now' furcharged
■with moifture—are circumftances that daily meet the
fenfes of the moft cafual obferver, as they are circum¬
ftances that powerfully, and often unplealantly, arreft
his attention. That thefe changes are the refult of de-
compolitions and combinations that are continually go¬
ing on in the atmofphere, and of new modifications of
its component principles, is manifeft to him who is ac¬
quainted merely with the firft elements of modern che-
miftry.
3 Indeed to modern chemiftry this fcience is indebted
for the progrefs it has made within the laft 50 years j
a period which may be confidered as the fecond epoch
of meteorology. In fa£t, this fcience is ftill in its in¬
fancy ■, but from the ardour with which it is now culti¬
vated, from the abilities of the philofophers who are en¬
gaged in the ftudy, and from the progrefs that is daily
making in the kindred feiences, we may reafonably
look forward to a period, at no great diftance, when it
ftiall pleafe the great Author of nature to unveil many
of thofe wonders which are now involved in darknefs
and obfeurity, and permit us to controul the jarring
elements, as lie has allowed us to exercife dominion over
the beafts of the earth, the fowls of the air, and the
fifties of the fea.
M 4 uf A late ingenious writer on the climate of Britain has
improving fuggefted fome ufeful hints for the improvement of me-
meteoro- teorulogy, which we (hall here extrafl. “ With this
fogy* view, our firft ftep muft be that recommended by Mr
Kirwan and others, to eftablifti correfponding focieties
in different parts of the world j thefe focieties muft be
furnithed with fimilar apparatus, equally adjufted, mid
graduated in their conftruftion, for making obfervations
on the weather. In our own ifland it will be necefiary
to procure regifters, carefully kept, from the different
parts of the fea coaft, and from thofe parts of the coun¬
try fituated in the interior. The various ftates of the
barometer, thermometer, hygrometer, and ele&rofcope,
fhould be carefully noted j with the variations and the
degrees of wind, as well as the diurnal and nocturnal
Tol. XIII. Part II.
afpeft of the heavens diferiminately marked ; the ap¬
pearance of the fky ; and in familiar language, fuch as
might be underftood by the refpeftive and diftant ob-
fervers 5 for inftance, whether the fun is totally or par¬
tially obfeured by vapour ;—whether the clouds are
mottled, or fleaky 5—whether they affume the appear¬
ance of horizontal ftreaks, or appear in radii apparently
from a centre—or in maffes of denfe vapour—or
loofe and fleecy—or thofe familiarly known by the
name of mare-tail clouds.—with any other new or ac-
cuftomed phenomena. The common terms/«/;*, cloudy,
or wet, are infufficient for forming a judgment of the
weather 5 as the term fair is generally at prefent ex-
preffed only in oppolition to rain, without diftinguifh-
ing whether the atmolphere is obfeure, dull, or bright.
The appearance of the ftratum of air on the earth’s fur-
face, that is, the /pace between the clouds and the earth,
fhould be always accurately deferibed. Is there a blue
haze, white miff, and denfe fog ? or is the air tranfpa-
rent ? which is the cafe when diftant objefts appear
more than commonly diftincl and near to the eye of the
obferver : the temperature of the ocean at/?/// tide fhould
be frequently afeertained, as it wrill be found to have
confiderable influence in thefe refpecls on an infular coun¬
try. By the remarks of obfervers, ftationed in various
parts of our coafts, we fhould foon be enabled to difeo-
ver when vapour is wafted in from the fea, or genera¬
ted by the aqueous and vegetable furface of our ifland.
During a north-weft wind, which is frequently attend¬
ed with ft or ms of hail and rain, and ufually experienced
in the fpring, an obferver ftationed on the coaft of Sligo
in Ireland, or Denbighfhire in Wales, might afeertain
whether the difpofition of the atmofphere to ftorm and
cloud came in with the air from the Atlantic ocean,
or was generated by the vapours of our own ifland. It
would be defirable alfo again, that the temperature and
blue hazy appearance of the atmofphere curing the
north-eaft winds, fo common in May and June, fhould be
noticed by obfervers on the north-eaft coaft, in the coun¬
ties of York, Lincoln, Effex, and Kent; and by others,
on the oppofite weftern coafts of Pembroke, Devon, and
Cornwall, fo as to determine what changes in tempera¬
ture this w ind undergoes in its paffage over the ifland j
and wrhether or not the degree of haze increafes or dir
minilhes by its progrefs from either quarter *, and whe¬
ther the vapour is more or lefs difpofed to produce florms ?
By fuch comparative obfervations on the coaft, con¬
joined with thofe made by others in the central parts
of the kingdom, we might rapidly proceed in meteo¬
rological fcience, or, as it is commonly called, a know¬
ledge of the weather. The obfervations made in the
interior of the country would enable us at all times to
trace the origin and progrefs of ftorms : in fituations
where tillage or pafturage is moft attended to, the ef-
fedls of fpring frofts and blights ftiould be particularly
noticed, as well as the firft appearance of the aphis and
coccus, the caterpillar and larvae of other infedts, on
fruit trees, and particularly thofe peculiar to the hop
plantations. The firft opening of the vernal foliage on
4 U trees