• ( % ) 
Perpendiculars^ and a Curve drawn through the Extre- 
mities of thole Perpendiculars, the Area comprehended 
ft all :>e proportionate to the Colle&ion of the Heat of 
all the Beams of the Sun in that fpace of time. Hence 
it will folio w,that under the Pole the CoSledion of all the 
Heat of a tropical Day, is proportionate to a Redangle 
of the Sine of 23|gr.into 24 Hours or the Circumference 
of a Circle,- that is, the Sine of 23 \ gr. being nearly 
4 tenths of Radius; as * 0 into ix Hours. Or the Polar 
Heat is equal to that of the Sun continuing iz Hours 
above the Horizon, at 53 gr. height, than which the 
Sun is not j Hours more elevated under the Equina- 
But that this matter may be the better underftood^ 
I have exemplied it by a Scheme (Fig. 8.) wherein the 
Area ZG H H, is equal to the Area of all the Sines of 
the Sun's Altitide under the Equino&ial, ere&ed on the 
refpe&ive Hours from Sun- rife to the Zenith ; and the 
Area s H H s is in the fame proportion to the Heat 
for the fame 6 Hours under the Pole on the Tropical 
Day ,* and Q H HQ^ is proportional to the coileded 
Heat 9f i2 Hours, or half a Day under the Pole,which 
fpace Q H HCL is vifibly greater than the other Area 
H2,GH, by as much as the Area HGQ^ls greater 
than the Area Z G Q) ; which, that it it fo, is vifible 
to fight, by a great excefs ; and fo much in proportion 
does the Heat of 1 the 24 Hours Sun illine under the 
Pole, exceed that of the twelve Hours under the Equi- 
noctial : whence Ceteris paribus, it is reafonable to con- 
clude, that were the Sun perpetually under the Tropick, 
the Pole would be atieaft as warm, as it is now under 
the Line it fclf. 
But whereas the Nature of Heat is to remain in the 
Subje<9\ after the Caufe that heated is removed, and 
particularly in the Air; under the Equhio&ial the twelve 
Hours abfence of the Sun does very little flill the Mo- 
Y y z tion 
