196 Some Principles and Results of Harmonie Motion. 
The influence of luminous undulation. upon the actions and 
reactions between the chief centre of nucleation and the chief 
centre of condensation (Sun and Earth) seems to be indicated 
by the following tendencies :-— 
t, in the conversion of circular motion into simple harmonic 
:; 2 2 
motion, « ace d; representing such conversion, «(= d. 
The radius of mean condensation (46) is 2* times the radius 
2\3 
of actual condensation ; 365°256 x (=) = 95-9) 4°54 ge 
apparent solar semidiameter which corresponds to this value 
is 961/43, which differs by less than 5!5 of 1 per cent. from 
the British Nautical Almanac estimate, 961/82. Dr. Fuhg’s 
estimate (Astron. Nachr. 2040), 961/495, is still closer. 
Tendencies to solar equatorial acceleration and polar retar- 
dation, such as are shown by the sun-spots, are indicated 
by the following approximations to the period of solar rota- 
tion :— 
t, ca/d3; (36°3514 x 430891)+(6°6 x 3962°8) = (24-472), 
2 d; 430891 (3962'8 x 3°92295)= 27-7174. 
ts x/5; (36°3514+6'6)? x 392295 = (25°602)?, 
t, ocd’; (36°3514+-6-6)? =30°336. 
The secular influence of the chief centres of nucleation and 
nebulosity (Sun and Jupiter) on the chief centre of conden- 
sation (Harth), as well as the cyclical actions and reactions 
between Harth and Jupiter, are shown by the equation 
Os Psp 9p Psa= bata 
In this equation 6;, 6) are the mean Kantian densities of 
Jupiter, Sun; pg, Psa, the nearest secular approaches of Harth 
to Jupiter, Sun; ¢,, orbital period of Jupiter ; ¢,, Kantian or 
rotational period of Harth. The secular eccentricity of Harth 
which satisfies this equation is ‘06543. Stockwell’s estimate 
is (06774. 
