it SPHERICAL BODIES. i age 
long as the intenfity and magnitude of the central fire conti- 
nue the fame. 
9. Ir remains for us to determine the value of a’, which, 
though conftant, is not yet given, or known from obferva- 
tion. 
At the furface of the globe we may fappote the mean tem- 
perature to be known: let T be that temperature, and let R = 
the radius of the globe. Then, when x =R, b= tr, and by 
fubftituting in the general formula, we have T=H+— ae —), 
3(T—H) _ ag Rep (Eb T) 
and a = Tot ae 
1 era 
Kongens a 2 G- *) 
enh = onan 
Hence alfo by reduction 
RT—7H Rr(Ai—T) 
hie R—r_ a v(R—r) *- 
Rr(H —T 
Es gear a lec ua game 
From this equation, it is evident, that ) — potion or 
—r 
the excefs of the temperature at any diftance x from the 
centre, above a certain given temperature, is inverfely as a. 
But the conftruction of the hyperbola which is the locus of the 
preceding 
