HEA T. 
tay (which is of — aves age being put for radius, 
de force of the fun the horizontal furtace of the earth 
et be to that, as he Acie’ of nin Tan” s altitude at any other 
ae it fellows, that the time of the continuance of the 
e: that i is, the fine of 23 de- 
of radius, as 8. into 12 
tin nuing 12 hours above the” horizon at 
équino 
hat whereas the nature of heat is to remain in the fub- 
ject, after the luminary that occafioned its being heated is 
removed, and particularly in the air, under the equinoétial 
the twelve hours abfence of the fun does but little diminifh 
the motion ‘impreffed by the paft action of his ray wherein 
heat confifts, before he rifes again; but under the pole, the 
mae abfence of the fun for fix sioihe: wherein the extre- 
mity of cold d doés ebtain, hath fo chi gis the air, that it is, 
-as i 
é fun has got ae 
towards it, be any ways fenfible of his ‘piclencs; his beam 
a obftrudted is thick clouds, and perpetual fogs and 
in lat. 11° AL the 
» and t colour of the foi Ge "he 
ft, erect Bey ‘are lofty and covered with 
fhow, greatly =e to chill the air by the winds which come 
wey Sh hich blow in eddies through the levels 
» to extend 
point every morning before ees and hence at 
a certain height, which varies in- latitude, it 
ly freezes at night in every fe ay though in the 
uel 
in Tat 28°, he thinks hat it thou 
Ste pate, ei y at vacgistet from the sa the level ited 
> concave or sates 
vex parts penta either oy refraétion or refleétion. And 
fome have even taken thete to be foie kindle the ex- 
halations lodged in the 4 
warm clit ! ree the next pa _ This al 
héight he calls the * lower term o ‘conyelatica,” he altitude 
between the ead at the height ¢ of jo lee Fests ut but | 
As to foils: a ftony, fandy, or chalky earth, it is known, 
reflects hic of the rays into ains but 
This the prot eee inhabié the ak fe Veenen, 
where turf is dug, are very fenfible of: walking there but.a 
little while, the feet ut the face. 
not.at all; on the conteatyy in a 
It is : rertain, that heat unccien by the fun to bo- 
dies on the earth, depends much upon other circimitances * 
befides the-dire&t force Thefe mult be modified. 
by our atmofphere, na Soot reflected and combined by 
the aétion of the furface of the earth itfelf,, to produce any 
remarkable effects of heat; fo that if it were not for thefe 
additional circumflances, it is much te be queftioned whe- 
ther the. naked heat of the fun would be very fenitble. 
this purpofe, it is obferved by Ulloa, .in his Voyage 
Peru, that on-the weftern fhore of that kingdom, from “yn 
Maria de Ia Parilla to Lima, it is winter.on the mountains 
to June,.whilft it is: fummer. in: 
om January or Februar 
the vallies ; ; but iy June to November or December, it ig: 
winter in the v , and fummer ia the mountains. See on: 
this fabjeét the siele Temperature of the flees: 
The following table gives the heat to every tenth degree 
of latitude to the equinoGtial and tropical fun, by which an > 
eftimate may be made of the intermediate Segre sd ; 
~— 
Lat. Sun im” Sun’ in Sun in 
goes SB W 
co) 20000 18341 T8341 
oe x) 19696 20290 15834 
20 18794 21737 13166 
30 17321 22651 Jo124 
40. 15321 23048 6944 
50 12855) 22091 3798 
60 10000 22773 1075 s 
7° 6840 23543 000 
80 3473 24673 000 at 
- af 25955: eg OS See 
For an account of the a tin and roplea: ¥e | 
which - = table is calcu Phil a abr. vol, ii, 
pet 
1. That she equi 
is as twice the fquare © 
- Phat under 238 os the heat j is as. ie fine of, 
di Tan’ 3 declination 
goed 1 zones, when’ the fun fets not, the’ 
heat is as the ‘ire > of a circle into the fine of the 
ofldetacn's anid, at eta 
as the fines of ‘le latitudes, ees Eid they are as the 
fines of the latitudes into into the fines of declination, 
. That the sequinoGtial day's sehetiiiiae where a the 
of the ao 
gal pliner with etsy the diference Sides: 
ac ‘fatnmes end he. declinations: are- 
yi equal to 
6, in th ume pall ani ny confequentys thofe differ- 
