t s N A T U R A L H I S T O R Y
the Comifh tongue, Lagas-aiief; that is, the weather’s eye; and
proiiounce it a certain fign of hard rain.. Notwithftanding this,
the Mercury fell only two tenths of an inch, and on Saturday
night there was no rain. Sunday morning was dry, but not clear ;
and about eleven it began to rain gently, about one, poft'rnerid. a
flood of rain came on, and continued all Sunday night, and till ten
the next morning.
se c t . dc. The conjundtions and oppofitions of the Sun and Moon would
inconflant,as have a regular effedt upon the Atmofphere of the Earth» and con-
fequendy influence the wind and rain in a regular manner at periodical
diftances of time, i f the Atmofphere was always in one fixed
equal temperature. This we fee plainly demonftrated in a. thicker
medium, by the regular influence of the Sun and moon upon the
Ocean, where the tides rife and fall as the Moon is perpendicular or
oblique, in its meridian or decline, and vary generally, . though not
exadfly, according as the Sim and Moon adt in concert of oppofitiohj’*
but the Atmofphere is a much more mixed and compfieated body,
as well as much eafier difturb’d, than the waters; and in;p>roportion
as the feveral aity, aqueous, feline, or fulphureous exhalations prevail
at any time, and in any place, the alterations which1 would
otherwife regularly follow the pofitions o f the Sim, Moon, and
Earth, are fufpended and controuled, and oftentimes totally prevented,
and the quite contrary effcdt produced, by the more powerful,
though fluctuating and uncertain, combinations^ the parts
o f the Atmofphere.
The weather is therefore inconftant every-where, but in feme
places more fb than in others. In hot countries it is more inconftant,
and the alterations more violent, ccetcris paribus, tiban in cold. In
the Torrid Zone there are more tornadoes and hurricanes than in
the Temperate Zone ; more inconflancy of weather again in
the temperate than within and near the Polar Circle, where by
reafbn that the Air is more condenfed, and the Atmofphere fuffers
fefs alteration from the Sun’s influence and the variety of vapours
that attend it, the weather is much more uniform, clear, and equable,
than in warmer climates. In Cornwall it may be reckoned in general
as unfettled and various, as to wind and rain, as any-where in
Britain, fuch fudden transitions there are from wet to dry, and from
calm to tempeft. One of the greateft variations which I have ob-
ferved in the Mercury of the Barometer, was April 3, 1753 ; when,
from Tuefday nine 0’ clock in the evening, to Wednefday ten
o’clock in the morning, the Mercury fell parts o f an inch,
the Mercury refting at 28 which is the loweft I have ever yet
noted. It then Hew a ftorm, with fbme fhowers of hail and rain;
and
O p C O R N W A L L . tg
and the vacuity of the Atmofphere, which occafioned this great
fubfidence of the. Mercury, drawing after it a guft of air, the Mercury
began to rife at one 0’ clock, poft merids and by ten at night
was r i f ehpar t s of.an inch.„| During all this month the greateft
variation ats London in -one day was but j||k parts of an inch, A
more furprifing variation ftill happened onWednefday, February; 18,
175,6,: the morning very dark, Wind at North Eaft, it fnowed
hard, and the wind blew a hurricane all the forenoon; my Diago-
nal/Barometer^'CQntinued at 28—-84: next morning, the Wind at
North;,, cold Hail, and men Sunlhine, the Mercury was rifen to
29—-84; ,a very extraordinary rife?for fb fhoft a time. At Lifkerd
about Mo -miles to the Eaftward >>of my houfe, from Wednefday
February 1 7 5b, 12 ,at noonji to Thurfday 19 at noon, (viz.
in 24 hours) the quickfilver rofe one iflcllM l p By this violent
and fudden alteration in the Mercury it appeafsthat the Atmofphere
at thefe times muft have been greatly agitated, and proceeded over
the earth in vaft waves; low, deep, and hollbw, when the Mercury
fell ; lofty and mountainous afterwards, which occafioned as fudden
a rife. This defoltoiy ftate of the Atmofphere will alfb account
for and confirm the; common obfervation, that when the Mercury
rifes. or falls quick, it is a certain fign of a fhoit continuance of fair
or foul Weather : the fluids over our head are agitated in like manner
as • thofe of the ocean, but, as being a thinner medium, much
fboner, eafier, and by lefs force; and when the column of air over
any place is fuddenly and greatly encreafed, that height muft be
quickly followed by a depreffion o f the next focceeding portion of
the Atmofphere, as furely as an elevated wave o f the fea leaves a
hollow to come after i t : but when the Mercury rifes or fells gradually,
or continues ftationary, then the Atmofphere being o f a
plain furfece, little agitated, die column of air is nearly the feme,
and the weather is likely to continue for fbme time.
"But though our weather, as to wind and fain, is fo inconftant, s e c t . x .
yet as to heat and Cold it is much more conftant and fettled than Heatairf^d
m the Eaftern parts o f England. Six feveral days in July; mare°1
1756, Farenheit’s Mercurial Thermometer altered only one degree;
two degrees nine days'; three degrees feven days; four degrees
three days; five degrees one day; and on five days there was no
variation: but the Thermometer at London on two days altered
one degree; two degrees on two days ; three degrees on fix days;
four degrees on four days; five degrees oh three days; fix degrees
« 'At London, if I am 'rightly informed, the ‘ RoyalSocidty was on this Wednefday felt fourteen
rife was ftill more precipitate j the Barometer at the hours riling one full inch.
on