M E T E O I 
ether bodies. It is an equality of heat, and not an equality 
of temperature, that nature tends to reftore. 
“ The atmofphere, indeed, prefents a ftriking pecu¬ 
liarity to us in regard to heat: we fee in a perpendicular 
column of air, a body without any change of form, llowly 
and gradually changing its capacity for heat from a let's 
to a greater ; but all other bodies retain a uniform capa¬ 
city throughout their fubftance. If it be afked why an 
equilibrium of heat Ihould turn upon the equality in quan¬ 
tity rather than in temperature1 I anfwer, that I do not 
know ; but I reft the proof of it upon the faft of the in¬ 
equality of temperature obferved in afcending into the 
atmofphere. If the natural tendency of the atmofphere 
was to an equality of temperature, there does not appear 
to me any reafon why the fuperior regions of the air 
Ihould not be at leaft as warm as the inferior. 
« The arguments already advanced on behalf of the 
principle we are endeavouring to eftablilh, are powerfully 
corroborated by the following facts : By the obfervations 
of Bouguer, Sauffure, and Gay Luflac, we find that the 
temperature of the air at an elevation where its weight - 
js that at the furface is about 50 0 Fahrenheit lefs than 
that at the furface; and from my experiments (Manch. 
Memoirs, vol. v. p. 525.) it appears that air being fud- 
denly ratified from 2 to 1, produces 50° of cold. Whence 
we may infer, that a meafure of air at the earth’s furface 
being taken up to the height above-mentioned, preferv- 
ing its original temperature, and fullered to expand, 
would become tu'o meafures, and be reduced to the fame 
temperature as the lurrounding air ; or, vice verfa, if two 
mealures of air at the propoled height were condenfed 
into one meafure, their temperature would be railed 50 0 , 
and they would become the fame in deniity and tempera¬ 
ture as the like volume of air at the earth’s furface. In 
like manner we may infer, that if a column of air from the 
earth’s furface to the fummit of the atmofphere were con- 
denied, and brought into an horizontal pofition on the 
earth’s furface, it would become of the fame denfity and 
temperature as the air around it, without receiving or 
parting with any heat whatever. 
“ Another important argument in favour of the theory 
here propofed, may be derived from the contemplation of 
an atmofphere of vapour. Suppofe the prelent aerial at¬ 
mofphere were ton nnihilated, and one of fteam or 
aqueous vapour were bftituted in the place ; and fup- 
pofe, further, that th temperature of this atmofphere 
at the earth’s furface were every-where 211°, and its 
■weight equal to 30 inches of mercury. Now at the ele¬ 
vation of about fix miles the weight would be 15 inches, 
or one-half of that below; at twelve miles it would be 
7-5 inches, or one quarter that at the furface, &c. and the 
temperature would probably diminilh 25 0 degrees at each 
of thefe intervals. It could not diminilh more ; for we 
have feen (p. 14.) that a diminution of temperature of 25 0 
reduces the force of vapour one-half; if, therefore, a 
greater reduction of temperature were to take place, the 
■weight of the incumbent atmolphere would condenle a 
portion of the vapour into water, and the general equili¬ 
brium would thus be difturbed perpetually from conden- 
fation in the upper regions. But if we luppofe, on the 
other hand, that the diminution of temperature in each 
of thefe intervals is lefs than 25 0 , then the upper regions 
would admit of more vapour without condenfation ; but it 
muft take place at the furface, becaufe vapour at 212 0 can¬ 
not fuftain more than the weight of thirty inches of mer¬ 
cury.” Dalton's New Syjlem of Chemical Philofophy, p.'i2 3. 
The connection of Meteorology with Chemistry is 
fufficiently evident to thofe who take even a fuperficial 
view of the fubjeft, though it has only of late attracted 
the notice of philofophers. That the air is fometimes 
hotter and fometimes colder than ufual; that it is at one 
time much rarefied, and at another greatly condenfed; 
now uncommonly dry, and now lurcharged with moif- 
ture—are circumftances that daily meet the fenles of the 
t O L O G Y. 251 
moft cafual obferver, as they are circumftance.s that 
powerfully, and often unpleafantly, arrelt his attention. 
That thefe changes are the refult of decompositions 
and combinations that are continually going on in the 
atmofphere, and of new modifications of its component- 
principles, is manifeft to him who is acquainted merely 
with the firft elements of modern chemiftry. 
Indeed to modern'chemiftry this fcience is indebted 
for the progrefs it has made within the Lift fifty years; 
a period which may be coniidered as the fecond epoch 
of meteorology. In faft, 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 
engaged in the ftudy, and from the progrefs that is daily 
making in the kindred fciences, we may reafonably 
look forward to a period, at no great diftance, when 
it fhall pleafe the great Author of Nature to unveil many 
of thofe wonders which are now' involved in darknefs 
and obfcurity, and permit us to controul the jarrino- 
elements, as he has allowed us to exercife dominion 
over the beafts of the earth, the fowls of the air, and the 
fillies of the fea. 
A late ingenious writer on the climate of Britain has- 
fuggefted fome ufeful hints for the improvement of me¬ 
teorology, which we lhail here extraft. “ With this 
view', our firft ftep muft be that recommended by Mr. 
Kirwan and others, to eftablilh correfponding focieties in 
different parts of the world; thefe focieties muft be fur- 
nilhed with fimilar apparatus, equally adjufted, and gra¬ 
duated in their conftu&ion, for making obfervations on 
the weather. In our own illand it will be necelfary to 
procure regifters, carefully kept, from the different parts 
of the fea-coaft, and from thofe parts of the country fi- 
tuated in the interior. The various ftates of the baro¬ 
meter, thermometer, hygrometer, and eleftrofcope, ihould 
be carefully noted ; with the variations and the degrees 
of wind, as well as the diurnal and nodturnal afpedt of 
the heavens indifcriminately marked ; the appearance of 
the Iky ; and in familiar language, luch as might be un- 
derftood by the respective and diftant obfervers ; for in- 
ftance, w'hether the fun is totally or partially obfcured 
by vapour; whether the clouds are mottled, or fleaky; 
whether they alfume the appearance of horizontal ftreaks, 
or appear in radii apparently from a centre—or in mafles 
of denfe vapour—or loofe and fleecy—or thofe familiarly 
knowm by the name of mare-tail clouds—with any other 
new or accuftomed phenomena. The common terms 
fair, cloudy, or wet, are inlufficient for forming a judgment 
of the weather; as the term fair is generally at prelent 
exprefled only in oppplition to rain, without diftinguilh- 
ing whether the atmofphere is obfcure, 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, Ihould 
be always accurately defcribed. Is there a blue haze, 
white mill:, and denfe fog ? or is the air tranfparent ? 
which is the cafe when diftant objects appear more than, 
commonly diftindt and near to the eye of the obferver. The 
temperature of the ocean at full tide Ihould be frequently 
afcertained, as it will be found to have conliderable in¬ 
fluence in thefe refpedts on an infular country. By the 
remarks of obfervers, ftationed in various parts of our 
colls, w'e Ihould loon be enabled to difcover when vapour 
is wafted in from the fea, or generated -by the aqueous 
and vegetable furface of our illand. During a north-weft 
wind, which is frequently attended with ltorms of hail 
and rain, and ufually experienced in the fpring, an ob¬ 
ferver ftationed on the coaft of Sligo in Ireland, or Den- 
bighlhire in Wales, might afcertain whether the difpoll- 
tion 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 illand. It would be defirable alfo 
again, that the temperature and blue hazy appearance of 
the atmofphere during the north-eaft winds, fo common 
in May and June, Ihould be noticed by obfervers on the 
2 north- 
