OF CORNWALL. Ig 
and the vacuity of the Atmofphere, which occafioned this great 
lubfidence of the Mercury, drawing after it a guft of air, the Mer- 
cury began to rife at one o’ clock, poft merid. and by ten at night 
was ri en paits of an inch. During all this month the created: 
variation at London in one day was but ^ paits of an inch. A 
more inrprihng variation dill happened onWednefday, February 18, 
,’7 5 , b: morning very dark, Wind at North Eaft, it fnowed 
, ’ and tne wind blew a hurricane all the forenoon; my Diago- 
Norrb ar ° m M er „ C T tmU ! d , at 28 -' 8 4 : next morning, the Wind at 
North cold Hail, and then Sunlhine, the Mercury was rifen to 
T~ i ; a T 7 extraordina ry rife for fo flrort a time. At Lilkerd 
a out o miles to t le Eaftward of my houle, from Wednelday 
e ruary i 175 , 12 at noon, to Thurfday 19 at noon, (viz. 
m 2+ hours the qmckfdver rofe one inch i*. By this violent 
and hidden alteration in the Mercury it appears that the Atmofphere 
iele times mud have been greatly agitated, and proceeded over 
' Car “ m vaft wares ; fow, deep, and hollow, when the Mercury 
' U , lofty and mountainous afterwards, which occafioned as fudden 
a me. This defultory date of the Atmofphere will alfo account 
for and confirm the common obfervation, that when the Mercury 
n es or alls quick it is a certain fign of a lhort continuance of fair 
foul weather : the fluids over our head are agitated in like manner 
f inner °r ’* .“f!’ b “ t > as bein S a thinner medium, much 
r ’: fier V^ 7 efs force; and when the column of air over 
X P ! 1S foddenly and greatly encreafed, that height mud be 
th^A? f °f r ed ^ r d fP reffion of the next fucceeding portion of 
hollo® 1 ’ f fUre ‘ y “ 311 elevated wave of the l! leaves a 
hollow to come after it : but when the Mercury rifes or falls gra- 
dually, or continues flationary, then the Atmofphere being of a 
pmm funace, httle agitated, the column of air is nearly the fame, 
and the weather is likely to continue for fome time. 
yet as to’heft' 1 an” raffT’ “ t0 7‘ nd and ra ”’ is fo inc onftant, SECT !C . 
in the E-'fte ^ r 1S muc ^ more c °nftant and fettled than 
“ T r i, v P t? of . En S Iand - Six feveral days in Tuly, 
'j ““ S , ercuna ’ Thermometer altered only one degree; 
leed^s fi mn A. yS; thrCe de S reeS feren d ays; four degre^ 
variation* V, /h ° nC da ^ ; and 011 bve da y s tbere was no 
one' Ho but the Thermometer at London on two days altered 
four rf? r6e ’ t C ^ ees 011 tw0 days ; three degrees on fix days ; 
degrees on four days; five degrees on three days; fix degLl 
e At London if T • , , . 
on 
