336 
only at Mulheim the vanes indicated the 
change of the wind 14 to 2 hours too late; 
which muft be afcribed either to their not 
being fufficiently fenfible to its imprefhion, 
er to the change in the arr not having till 
then reached fo high. Zhe other 16 ob- 
fexvations were, on five other days, made 
during. the’ prevalency- of winds ircm the 
Arik quarter; the fmatlett height obtained 
is 94.6,9, the greateft 933,6; difference 
26,7. The mean elevation obtained from 
the latter obfervations amounted to 965, 
that from the former to only $94,6. .Con- 
fequently the difference of the winds cauled 
here a difference of 70,4. in the average 
amount of the elevation. _ Five ae a 
tions on-one day, the winds being S. SSE. 
‘and E. which mut have produce ed a me- 
dium effect, a&tually gave likewife a 
number between the higheft and, loweft 
elevation, viz. 938,5.. In lrke manner, 
nine obfervations on three cther days when 
the wind was W. SW: WSW. and NE. 
gave a medium of 940,:. Finally, we 
abtained from four cblervations on one 
day, when NNW. and NO. NNO. winds 
prevailed » the medium number 951,8, 
which approaches fo near the greater ele- 
vations becaule the barometer is here but 
wery hittle affected’ by the Weft wind, 
which occafions the lef ,desrees of eleva- 
tion. » , 
This remarkable influence of the winds 
on the barometer induced me to tape the 
ee iarnes of the elevations between 
Aftulheim and Carliruhe; with che view, 
partly to find a-more exact mean eleva- 
mean 
tion, by arranging thedifferent obfer vations 
according to the winds prevalent. when 
they were made, and by rejecting fuch as 
Speed to be erroneous ; partly to dif 
cover here likewile the difference between 
the ‘medium of the {maller elevations du- 
ring the prevalence of winds from the third 
quarter, “atid that of the greater when = 
wind blew from the fird ; that’ is, to diic 
ver the effect of the einds. This differ. 
ence amounts here to only about 47 feet ; 
but the difference for Muiheim and Bern, 
te 70,4. Bern is about as: high again 
above Miulheim, as Millheim is above 
Carlffuhe. 
Now Carlfruh ey Miulheim and Bern are 
fo fituated, from North to South, that their 
meridians do not much differ from one 
another: they may, then, be here confi- 
dered as lyingunder the fame meridian; 
confequently they are not ‘at the fame 
time, but gradually one after the other, 
expofed to a current of ‘@ir from North 
to South or frem South to Northe. In hike 
manner they are only fuce eflively, 2 althoug gh 
The Influence of the Winds on the Barometer. 
[May ty 
in an oblique direction, vifited Ly ‘the | 
winds which blow from the firft quarter — 
towards the third, or from the third to- 
wards the firfts - And in thefe fucceflive — 
effe&s of a current of air on the above- — 
named places, would feem to lie the caufe 
of the difference in the elevations obtained — 
by barometrical obfervations ; which firtt 
becomes obfervable at a confider-ble dif. — é 
tance, and muft be ftill more obfervable ee 
when thefe confiderably diftant places are 
moreover very diffimilarly fituated with | 
refpe&i to height. 
The North and Baw winds are, it is : 
well known, not only dry, but likewife — 
drying 5 3 that is, on account of their dry- — 
neis and the ealy folubility.of water in at- ~ 
mofpheric aie they take up and carry — 
along with them the vapours which they ~ 
find in their way. But it may eafily be ~ 
fuppofed, that they do not always retain — 
this property in an equal degree, but that — 
it varies in-proportion as in their progrefs — 
they become loaded with vapours, or gra-_ 
dually from the low grounds atcend the — 
mountains into a more elevated region, 
and fo become changed into a mafs of air | 
lefs denfe and capable of imbibing ya- © 
pours, or pafs over diftrifts from which’ . 
fewer exhalations arife, &c. But thefe 
winds are likewife at the fame time cold oj 
cool; confequently .they bring along with ; 
them a denfer air, whofe oreater denfity 
‘renders it capable of taking up and hold-— 
ing in folution a greater quantity” of van 
pours, a 
On the.contrary, winds from the quar- 
ter-from South to Weft, blowing over the ~ 
not fo far diftant fea, are already loaded 
with vapours. ‘They would therefore, ta 
their paflage over the land, impart a fhare *. 
¥ them to a merely dry: land-air: but- 
‘ey oftentimes occagon an accumulation | 
ce by means of the heat which they — 
bring along with them from a warmer re=— 
gion. This heat premotes the exhalation 
of the ground and of plants, and the air 
becomes overloaded with vapours ; which, | 
befides other co-operating caules, i is fue 
ficient to produce, frequently and in an ir- 
regular manner, a dinking of the mercury 
in the barometer. 
Tf we adopt the opinion of De Luc, that 
air mixed with vapours is lighter than | 
pure dry air; the variations in the eleva- 
tions between Carlfruhe, Miilheim and 
Bern may perhaps be thus accounted for: 
—the air always arrived more loaded with 
vapours, » at the’ place more diftant from 
the point whence the winds originated, 
and cauled the Mercury to fall ; which, 
when the wind blew from the fick quarter, _ 
gave 
