AND OF TERRESTRIAL MAGNETISM. 



261 



very nearly for the ratios of the amplitudes of the three associated subsequent 



pulses : 



First : Second : Third : : 1 : 0'62 : (0'62) 8 . 



Thus the amplitudes of the successive associated pulses do, in this instance, decrease 

 nearly in geometrical progression. At this rate we should have had the amplitude of 

 the fourth associatx-d subsequent pulse in Table V. about GO. 



The remarks made on the sources of uncertainty affecting corresponding data in 

 12 apply here equally. 



14. It seemed desirable to make sure that no period shorter than 27 days was 

 indicated by days previous to the selected disturbed days. Mean "character" 

 figures were accordingly calculated for all days up to the 35th prior to the selected 

 disturbed days of the 11 years 1890 and 1900. The "character" figures thus 

 deduced appear in the first line of Table VI. The second line supplies for comparison 



TARLE VI. " Character " Figures on Previous and Subsequent Days associated 

 with the Selected Disturbed Days of the 11 years 1890 to 1900. 



the corresponding figures for the 35 days subsequent to the selected disturbed days, 

 as given in S.M. The "character" of the representative disturbed day was 1'51. 

 Figures in excess of the normal value 0'70 are in heavy type. 



