1-863.] 567 



May 21, 1863. 



Major-General SABINE, President, in the Chair. 

 The following communications were read : 



I. "On the Nature of the Sun's Magnetic Action upon the 



Earth." By CHARLES CHAMBERS, Esq. Communicated 

 by the President. Received April 30, 1863. 

 (Abstract.) 



If the sun were a magnet of sufficient power to exert a sensible 

 attraction upon a small magnet at the distance of the earth, it would 

 have a real influence on the earth by inducing magnetism in its soft 

 iron, and an apparent one due to the direct action of the sun upon 

 the magnets used for measuring the earth's variations of force. As 

 the earth rotates upon its axis, producing a varying relation, as to 

 position, of the place of observation with respect to the sun, a diurnal 

 variation will thus be produced in the forces which act upon the 

 magnetometers, which variation is shown to follow the simple law 

 #= A sin (A -fa), x being the deviation of the magnet from its normal 

 position, h the hour-angle of the sun (and for a single day), A a con- 

 stant coefficient, and a a constant angle. A comparison of this result 

 with the laws of the observed diurnal variations shows that direct and 

 inducing action of the sun is not the sole cause of the variations. 



An endeavour is then made to prove that if any part of the observed 

 diurnal variations is due to this cause, it is small in comparison with 

 that produced by other forces in operation. This is done by sepa- 

 rating from the observed variations the part of them which obeys the 

 law #'=Bsin(A-f /3), and comparing the variations in the values of 

 B and j3 from month to month with those of A and a, when it is 

 seen that the former obey a law which has but little similarity to the 

 law of variation of the latter. 



II. "Numerical Elements of Indian Meteorology/' Series I. 



By Dr. HERMANN DE SCHLAGINTWEIT, Corr. Memb. of the 

 Academies of Sciences of Munich, Madrid, Lisbon, &c. 

 Communicated by the President. Received May 4, 1863. 



(Abstract.) 



In this paper the author communicates Plates in which the iso- 



2s2 



