ITS EFFECT ON TEMPERATURE AND ITS PRESSURE ON SMALL BODIES. 54i) 
Substituting in (4) 
dd 
> I 
+ W — 
A 
(0 - Tey 
This can proi^ahlv only be integrated by approximation. We can see the effect on 
the motion at the beginning by putting 
dhi I A 
9 + C? 
1 + 
since T/C is small if we begin at the distance of the earth and with a particle having 
the velocity of the earth. 
An integral of this is 
A 
The complementary function will be periodic and may be omitted, 
approximation adopted 
CW. 2T. 
Then initially 
and /■ = 
r/r = - (2T/C) 6. 
2CT 
A 
0 . 
To the order of 
In applying these results, we may note that 1 = is constant fur all 
distances, and that b, the earth’s distance, is 4'Jo U. Inserting the value of the 
solar constant, 0’175 X Uff, and taking p — 5‘5, we get 
T = 3-9 X 10^^ ir\ 
C will depend on the initial conditions. Assuming that tlie body considered is 
initially moving in a circle, then, at the beginning 
since at r = b the acceleration to the centre is U'G. 
Then _ 
C = r^O = \/ 0’66V. 
Substituting these values in rjr we have 
r _ _ 7-8 X 10^'^ _ 
r r^a 
This gives only the initial value of - and cannot be taken to hold for a time which 
will make T~6'VC- appreciable. But by (3) we see that r = 0 if ^ = C/T, so that 
