342 {March 1, 
Chase, | 
nebular layers ; that their studies were limited to the direct action of living 
forces; that they used no adequate criteria for distinguishing between 
nebular and meteoric influences ; and that their methods often, if not al- 
ways, virtually assumed the very principles which they sought to prove. 
Herschel,* somewhat obscurely, intimated the possibility that nuclei 
might be simultaneously formed, at different points within the body of the 
nebula, by the action of particles of different densities. Peirce, Alexander, 
Hill, Wright, Kirkwood, and myself, discovered various planetary har- 
monies which point, unmistakably, to such synchronous internal and ex- 
ternal activities. Yet no one seems to have thought of the likelihood that 
interior portions could acquire a greater angular velocity than the nebular 
surface, so that a planet might revolve in less time than its Sun rotated, or 
a satellite in less time than its primary, until I called attention to the fact 
that the time of nucleal rotation must vary as the 4 power of the time of 
superficial nebular revolution. 
The significance of this relation does not seem, even now, to be gene- 
rally understood. For, when Professor Hall found that the inner satellite 
of Mars actually revolved with such unprecedented rapidity, Kirkwood 
asked, in the American Journal of Science and Art, ‘‘ How is this remark- 
able fact to be reconciled with the cosmogony of Laplace?’ The same 
question has been asked by others, and variously answered. It may, 
therefore, be a fitting time to state, more explicitly, some obvious evi- 
dences of present nebular activity, such as are shown in the following 
comparative synopsis : 
M = n n? = — oo, 
7 | xn = a ‘a zn? = IY, = 201) 
x mn = 63;=2hk3 | reW=d4 | 
a xin = 2Q, ORT si 
m= 93,—= 28; | . 
M = modulus of light at Sun’s surface = 2204.95 x Earth’s mean radius- 
vector, a quantity of which I have already shown the importance ; (1) by 
identifying the velocity of light with the limiting velocity toward which 
the mean solar centrifugal and centripetal forces both tend ; (2) by show- 
ing that the same harmonic progression is manifested in the Fraunhofer 
lines and in planetary distances ; (3) by tracing numerous harmonic ar- 
* Outlines of Astronomy, 2 871-2. 
