130 



ON THE NUMERICAL RELATIONS OF GRAVITY AND MAGNETISM. 



X. 



In consequence of the cumulative tendency of partially obstructed waves, as illustrated 

 in the ocean tides, and in the occasional great breakers on a beach, the atmospheric cur- 

 rents are liable to disturbances, which, according to my theory, should produce the phe- 

 nomena known as " magnetic storms." Since the normal action which we have been 

 considering requires the employment of a constant portion of the magnetic force, the 

 aggregate excess should also be constant, and should therefore present analogous numeri- 

 cal relations. 



Mr. Airy, the British Astronomer Royal, has published a paper,* in which he presents 

 the sums and coefficients of magnetic irregularities, deduced from a long series of ob- 

 servations. His aggregates appear to indicate that the disturbing force is a third propor- 

 tional to two other forces, which may be called, respectively, central and tangential. 



Thus in his " Table II, Algebraic Sums of Magnetic Fluctuations (in terms of Hori- 

 zontal Force) for each Year, from 1841 to 1857, including all Days of Record of Great 

 Magnctical Disturbance," the Mean Disturbance is 



Westerly Force. 



— .00023 = M. 



Northerly Force. 



— .00146 = T. 



Nadir Force. 



-.00057 = 0. 



Here the proportion T : C : : C : M gives for M a 



Theoretical value, ....... 



Observed "........ 



.000222 

 .000228 



" Table III. Algebraic Sums of Magnetic Fluctuations (in terms of Horizontal Force) 

 for each Year, from 1841 to 1857, including only those days of Great Magnetic Dis- 

 turbance, in which Records were made by the three Instruments." 



Theoretical value of M, 

 ( Unserved " " 



.000287 

 .000257 



" Table VIII. Sums, without regard of sign, of Coefficients of Magnetic Irregularity 

 (in terms of Horizontal Force) for each Year, from 1841 to 1857, including all Days of 

 Record of Great Magnctical Disturbance." The proportion C : T : : T : M gives for M a 



Theoretical value, 001218 



Observed " 001203 



" Table IX. Sums, without regard of sign, of Coefficients of Magnetic Irregularity (in 



" First Analysis of One Hundred and Seventy-seven Magnetic Storms, registered by the Magnetic Instruments 

 in the Royal Observatory, Greenwich, from 1841 to 1857. By (jIeouof, BlDDEIA Airy, Astronomer Royal."— 

 Trans. Royal Soc, Vol. 153, Art. XXIX. 



