M. Kreil's Magnetic Observations, 



247 



than they had done in 1837, as is shown by the following 

 comparison : 





Jan. 



Feb. 



Mar. 



April. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Dec. 



1837. 

 1838. 



25 

 28 



13 18 

 16 21 



22 

 17 



6 22 27 

 11 29 30 



2 

 4 



2 28 

 12 34 



25 

 23 



14 16 

 14 15 16 



18 

 17 



14 19 

 20 28 



These coincidences would show a new fact, namely, the 

 periodical nature of these phaenomena, if equally considerable 

 disturbances had not occurred, (ex.gr. those of the 12th, 14th, 

 and 15th November 1837, and of the 17th January 1838,) 

 without any corresponding disturbances being traceable in 

 other years. The subject requires to be further elucidated 

 by continued observation. 



Another point to which the attention of the observer should 

 also be directed is, the symmetrical arrangement of these dis- 

 turbances in the same year, many of them being nearly six 

 months apart, for example : 

 In the year 1836 and 



1837 the disturbances on the 22nd April and 18th Oct. 



1838 — — 17th Jan. and 12th July. 

 do. — — 2 1 St Feb. and 23rd August. 

 do. — — 29th April and 3 1st October, 

 do. — — 4th June and 5th December. 



18. All hours of the day do not appear to be equally fa- 

 vourable to the development of this phaenomenon, at least its 

 first indications occur much more frequently in the evening 

 than in the morning hours. If we take from the 105 dis- 

 turbances marked in our day-book, those which were ob- 

 viously continuations of perturbations which had begun on 

 preceding days, as well as those which were first remarked 

 during the intervals between the regular hours of observa- 

 tion, then the first indications of 



19 were at 20^ O' 



1 - 



- at 22 30 



9 - 



- at 1 



21 - 



- at 4 30 



16 - 



- at 7 30 



11 - 



- at 11 



Here it is to be remarked, that the observation hour, 11, 

 precedes the longest interval namely, the night, and that the 

 greater number of the more considerable disturbances ex* 

 tend over several hours or even days; therefore perturbations 

 which may have begun in the early hours of the night ought 



