426 Prof. Kreil's Deductions from thejirst Year's Observations 



does take place, though considerably less than the one indi- 

 cated above. 



The results as to the horizontal intensity are contained in 

 the following table : 



II. Horizontal Intensity. 



From this table it appears: 



I. That the intensity is stronger when the moon is west of 

 the magnetic meridian, for the sum of the intensities corre- 

 sponding to western horary angles exceeds by 5'14 scale-di- 

 visions the sum of the intensities corresponding to eastern 

 horary angles. 



II. The intensity is decidedly greater when the moon is in 

 the neighbourhood of the inferior meridian than when she is 

 near the superior meridian, for the horary angles from 6 h to 

 17 h give a sum greater by 28-08 scale-divisions than do the 

 horary angles from 18 h to 5 h . 



7. The increased frequency and the greater number of the 

 Prague observations enabled us to pursue the interesting phae- 

 nomena of the magnetic perturbations with more exactness 

 than we had been able to do at Milan. We proceeded in 

 the following manner with both the horizontal elements. 

 The changes were noted which had taken place between each 

 observation and the next, and the sum of these () was taken 

 for each day without reference to their signs. The monthly 

 mean of these sums was taken and called 2. Now if on any 



y 

 day the quotient was found greater than 2, that day was 



2* 



reckoned one of disturbance. 



It hence appeared that the magnetic elements frequently 

 sustain a very considerable change of brief duration ; though 



