Chase.] -^70 [-jan. 21, 



"subsidence" of Neptune from its secular aplielion, since \/grOZ t/g. 

 The quotient of Sun's mass by Earth's mass -^-hich will account for all 

 these accelerations, is therefore, f/ 1.0145 X 366.2565 X (30.034)'^ =331567, 

 a value which differs by only Jg of one per cent, from the one last obtained 

 by purely a priori indications, and ^ of one per cent, from the one which 

 was deduced from coronal oscillations. 



7. Photodynamic Limitation of Jupiter's Day. 



The centre of nebulosity (Jupiter) presents equally conclusive evidence 

 of photodj^namic acceleration, if we pay proper regard to the difference be- 

 tween the expansive reaction of elasticity and the gravitating action of con- 

 densation, with its consequent limitation of elasticit3\ If we take the 

 "centre of primitive annular condensation" (Neptune), at its rupturing 

 locus (secular perihelion == 29.5982^3), the photodynumic seat of rupturing 

 action* is at | of 29. 5982^)3 = 16. 4434o3 ; squaring and multiplying by Sun's 

 mass (1047.879), we get 10467 for the number of rotations in an orbital revo- 

 lution. Dividing Jupiter's year (4332.5848 dy) by 10467, we get 9h. 56m. 

 3.4s. for the length of Jupiter's day. Prof. Hall's recent estimate is 9h. 

 55m. 26.5s. 



8. Moon's Mass. 



In the third note of the present series, I have sliown some of the rela- 

 tions of Earth's orbital eccentricity to Jupiter's locus of rupturing oscilla- 

 tion, the masses of Sun and Jupiter, Earth's fall from the centre of the belt 

 of greatest condensation, and the height of Earth's homogeneous atmos- 

 phere. The atmospheric elasticity should evidently be in equilibrium, 

 between the mutual inter-actions of Earth and Moon, in the same way as 

 the fethereal elasticity is in equilibrium between solar and planetary actions 

 and reactions. The atmospheric eccentricity being .0012483, the ratio be- 

 tween the lunar and terrestrial masses, in order to be in equilibrium with 



this eccentricity, should be 7r^x.0012483, or Earth's mass should be 81.17 

 times Moon's mass. What slight modifications of this value may be re- 

 quired, in order to satisfy other conditions, must be left for further investi- 

 gation. 



9. Earth's Semi-axis Major. 



If we take the photodynamic estimate of the centre of the belt of greatest 



condensation (1.016895 ; Note 3), the ratio of ?"o to 7*3, as determined by the 



mean locus of solar and terrestrial action proportionate to mass, should be 



214.5516 

 1.016805 times ^ = 109.088. If we adopt Stockwell s computation 



of the secular centre of the belt of greatest condensation (1.016939^^3), the 

 ratio is 109.093. These estimates give, for Earth's semi-axis major, 

 92750000 and 92754000 miles respectively. 



* Proc. Amer. Phil. Soc, xii, 392-4; P. Mag., June, 1877, p. 353. 



