408 [May 16, 
Ohase. ] 
elasticity, Professor Norton has found* that ‘‘at the distance 807 the 
repulsion becomes very nearly the same for all the assumed values of 
Wy, : : LOE ; c : oe 
”? 7 and m being centres of origination for the interior and exterior 
Me 
wave systems of the wthereal atomic envelopes. Now if 7—Sun’s radius, 
L 
4 
and 7! —Mereury’s orbital radius, 7’ is nearly equivalent to 807 (see. 3f le 
mm 
he second factor may be deduced in the following manner : 
If we suppose a collection of spherical atoms of equal magnitude, ea sh 
of which has condensed around it an wthereal envelope, to be arranged 
in the most compact manner possible, the lines joining the centres of 
three contiguous particles will form an equilateral triangle. If the 
envelope is of such density as to allow the indefinite rectilinear trans- 
mission of waves between adjacent particles, one-half the distance 
between the centres of two adjacent atoms, will be a mean proportional 
between the radius of the atom and the distance between an atomic 
centre and an adjacent sthereal centre ; the ratio of the atomic radius to 
the half-distance, and of the half-distance to the inter-central distance, 
being each equal to the ratio of radius to sec. 30°. In the accompanying 
figure, 
ABYAC ss: ACG: AD: > rad. ; 
According to the hypothesis of Mossotti, that the ethereal particles are 
infinitesimal in proportion to the atoms, the sphericity of the atomic 
surface may be disregarded, and the virtual radius of the ewthereally- 
enveloped atom may be supposed to vary asthe mass. But in atoms of 
* Amer. Jour. Sci., May, 1872, p. 340. 
