On the Equilibrating Forces of the Solar System, 315 

 Fig. 1. Angles:— B = 120°; C = 90°; D = 105°. BE = f, 

 and is parallel to CD; BC = i; BA= -^ = 1'15 ; AE is un- 

 polished. 

 The angle between B A and D E = 45°. 



Fig. 2. Angles:— A = 60°; B = 150°; = 90°. BE=^; 

 the perpendicular from B on CD=J; the perpendicular 

 from BonAD = l; DC is not less than 1 ; C E is unpolished. 



The angle between B E and D C = 60°. 



Fig. 3. 



c 



\ ^^S^ 



jS? 





JD 



Q, 



Fig. 3. 

 OD=l; DA= 



Angles:— A = 60°; C = 120° 



7 . __ . „ 2 



37 3 = 1-35;AB = 



V3 



D=90°. CE=J; 

 = 145; BE is un- 



polished. 



The angle between A B and C E = 90°. 



In the scale to which the figures are drawn the unit is one 

 inch. If desirable the sides D E in fig. 1, and D A in figs. 2 

 and 3, may be silvered, as they are only used for reflection. 



24 Hyde Terrace, Leeds. 



XXXVII. " In the Beginning." — I. Mass and Position. By 

 Pliny Eakle Chase, Professor of Mathematics in Haver- 

 ford College*. 



IN tracing the influence of undulations, propagated with the 

 velocity of light, upon cosmical aggregation and dissocia- 

 tion, I have shown that the ratio of the limiting velocity of in- 

 cipient dissociation to the limiting velocity of incipient aggre- 



* Communicated by the Author. 



