324 



Intelligence and Miscellaneous Articles. 



lutions, and not, as I contended, the (axial) rotations, of bodies of 

 such size as to make the resultant of the resisting pressures pass 

 otherwise than infinitesimally near the centre of gravity of the whole 

 body. Professor Challis in particular finds this non-resistance of the 

 rether to the orbital motions of the planets a problem requiring a 

 special solution (Phil. Mag., May 1859). 



As to Professor Guthrie's hypothesis of " the inequality of sethereal 

 resistance being the real and only cause of the earth's axial rota- 

 tion," I may add that, in the communication above referred to, I 

 ventured to remark that " In the actual case of the planets, their 

 masses and velocities of rotation are such that the solar medium can 

 be of course conceived, not as causing, but only as tending slightly 

 to accelerate their rotations." Were it the cause of such rotations, 

 there would be such acceleration as, in the case of the earth at least, 

 I think I may say that we know there is not. 



But, in the hope that this short note may be yet in time for inser- 

 tion in your next issue, I shall add nothing further on the equally 

 difficult and interesting problem of Compound Translation and Ro- 



tation - I am, Gentlemen, 



Your obedient Servant, 

 Stone Buildings, Lincoln's Inn, J. S. Stuart Glennie. 



March 21, 1866. 



RELATION BETWEEN THE VARIATION OF SUN-SPOTS AND THAT 

 OF THE AMPLITUDE OF MAGNETIC OSCILLATION. BY FATHER 

 SECCHI. 



I have just completed the reduction of the magnetic observations 

 made during the years 1859-65, and of the sun-spots during the 

 same period. The results are interesting, as showing the reciprocal 

 influence of the two periodic variations, of the spots and of the am- 

 plitudes of the daily magnetic oscillation in our climates. The fol- 

 lowing is a summary : — 





Days of obser- 



Number of 



Daily varia- 

 tion of the 

 magnetic 

 declination. 



Variation of 



Years. 



vation of the 



groups ob- 



the horizontal 





sun-spots. 



served. 



intensity. 









div. 



div. 



1859. 



164 



257 



8-105 



9-53 



1860. 



122 



251 



8-025 



9-59 



1861. 



124 



269 



7-011 



9-42 



1862. 



49 



102 



6-572 



9 03 



1863. 



126 



105 



5-579 



9-31 



1864. 



100 



97 



6121 



9-18 



1865. 



181 



86 



5-547 



9-00 



(Each division of declination is equal to l'*34l, and of horizontal 

 force is equal to O'*00019.) 



The year 1862 is poor in observations. It is seen from this list 

 that a minimum of spots corresponds to a minimum of magnetic 

 variation. — Comptes Rendus, January 29, 1866. 



