Chase.] ^^^ [Jan. 21, 



sethereal or luminiferous atmosphere as homogeneous. Therefore, if we 

 consider Earth's mean orbital eccentricity as due to tlie elastic reaction of 

 the nebular centre of oscillation (Jupiter) against the nucleal centre (Sun), 

 we find : 



Earth's mean atmospheric ecc'y : Earth's mean orbital ecc'y :: (Earth's 

 semi-axis major)- : (Jupiter's semi axis major)^; wlilch gives .0012483 : 

 .0033789 :: 1 : 5.2028'-. In order to acquire the velocity due to this eccen- 

 tricitj', there should be a fall of the centre of condensation (Earth) from 

 the centre of the dense belt of planets, through one-half the height, or 

 .016895 Earth's semi-axis major. In order to make the efficient wave 

 producing vis viva at Earth equivalent to that at Sun's surface, we should 

 take account both of Earth's (1.) and Jupiter's (.033789) action, as is done 



at 



in the equation 1.033789^::= i/</o''o- Substituting g= 33.088 -- 5280, 



and t = 86164 sec, this gives 270.67 miles = x^go^'o- From this velocity 

 we can readily deduce Earth's orbital velocity, Avhich, being multiplied by 

 the number of seconds in a sidereal year and divided by 2-, gives 270.67 

 -f- v/ 214.55 X 31558150 -4- 2- = 92812000 miles, for Earth's semi-axis 

 major. The closeness of agreement between these photodynamic results 

 and other estimated values is shown in the following table : 



Jupiter's secular range, 



" minimum ecc'y. 

 Mass, Sun -^ Jupiter, 

 Theoretical vel. of sound. 

 Homogeneous atmosphere, 

 Earth's mean ecc'y, 



'• " orbital fall, 



" semi-axis major, 



4. Cosmical and Molecular Densities and Velocities. 



We have seen that the function i oc -^/— is independent of any other 



element than d, when /is a maximum, or when comparisons are made at 

 distances from the centre of force which are proportionate to their respec- 

 tive nucleal or atmospheiic diameters. This renders the proportionality 



t cc -» / — an important one. For example, it is safe to predict that if the 

 time of rotation of any single star should ever be discovered, it will be 

 found to be such that i- will not differ perceptibly from the velocity of 



light ; and from the times of rotation we can readily calculate the ratios of 

 stellar I0 solar density. In binary and multiple stars, or in planetary sys- 

 tems where the planetary reactions are so important as either to retard or 

 accelerate the rotary velocity of the nucleal mass, the value of the modulus 

 velocity must still be some function of the velocity of light, although it 

 may be so changed as to leave room for much interesting and perplexing 

 study in seeking the causes and amounts of perturbation. In considering 



