[ M6 3 
vapours to afcend, that it will be found, that tht 
mercury rather afcends. 
There is a phaenomenon, which has puzzled many j 
that is, Why the mercury falls before the rain falls ? 
This may be explained by the column of air’s being 
leffened gradually, by the condenfation of the elec- 
trical fluid from the flrfl; defcent of the vapours till 
they fall in rain. 
I fhall now fay fomething of land-breezes and 
fea-breezes, a phaenomenon, which fometimes hap- 
pens in fair fettled weather, that the wind blows out 
from the land at night, and in from the fea at 
day-time. The land-breeze is occafioned by the de- 
fcent of the clouds, and the particular formation of 
the land j for if the land rife into a hilly country 
from the fea, when the clouds and vapours defcend 
at night, which they often do by the eledrical fluids- 
being condenfed, they mufl: prefs the air down the 
land toward the fea in their fall ; as may appear 
from the fmoke of any fire running down the fide of 
a hill, in the evening of a damp day, when the 
clouds are upon the defcent. And the fea-breeze h 
occafioned by the clouds afcending in the day-time,, 
which mufl: impel the incumbent air upwards, and 
make room for the fea-breeze to flow in : but, be- 
fide the mere afcent of clouds, there is an exceeding 
greater quantity of vapour raifed from the land than 
from the fea. For the fame extent of land has an 
exceeding greater furface than the fame extent of 
fea ; which may appear from the various forms of 
vegetables and animals, ^c. and the greater the fur- 
face, the greater will the evaporation be. Befide, the 
more irregular thefe furfaces are, the greater will be 
the 
