193 Prof. P. E. Chase on the Co /'relations of Central Force. 



insulates the conducting wire therefrom. In this case, too, 

 we have consequently the conditions of a rapidly charged 

 and discharged condenser, giving rise to reciprocating induced 

 sparks. 



13. This conclusion can be directly proved by recurring to 

 the earlier experiments (fig. 2) and introducing across the 

 circuit a wire of suitable resistance to short-circuit the extra- 

 current so that it may complete its route without having to 

 overleap the break at the key. This is shown in diagram in 

 fig. 6, where R is a box of resistance-coils introduced between 

 a and a! . If the wire of which the electromagnet E is made 

 be stout, its resistance will be a mere trifle, and a resistance of 

 3 or 4 ohms at R will be sufficient. In some cases a drop of 

 pure water between the points of contact at K has also the 

 result of obviating the extra-current spark. And in every 

 case, when the conditions are so arranged as to obviate the 

 appearance, on breaking contact, of the extra-current spark 

 at K, no earth-wire, nor any conductor, will draw a spark 

 from the electromagnet-core — a decisive proof that the sparks 

 so drawn were due to induction by the statical charge of the 

 accumulating extra-current, and to that alone. 



XXV. On the Nebular Hypothesis. — IV. Correlations of Cen- 

 tral Force. By Pliny Earle Chase, LL.D., S.P.A.S., 

 Professor of Philosophy in Placer ford College. 



[Continued from p. 36.] 



THE various accordances of planetary mass and position 

 which have been pointed out in preceding papers, the 

 harmonic prediction of a source of planetary disturbance at 

 •269 Earth's radius vector which was confirmed by the sun- 

 spot observations of Messrs. De La Rue, Stewart, and Loewy, 

 the comparison of gravitating and chemical force by means 

 of the explosive energy of H 2 0, the measurement of gravita- 

 ting waves, the agreement between the ratio of selenium-con- 

 ductivity in sunlight to its conductivity in darkness and the 

 ratio of Sun's light-emitting to its earth-attracting energies, 

 and my various mechanical estimates of solar mass and dis- 

 tance seem to be dependent upon mathematical laws, among 

 which the following merit special consideration. 



Let/ = velocity communicable, at distance r, in time t, by 



any central force varying as -^> 



j\ = velocity communicated by a single impulse, or in a 

 single instant, 



