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



4th and 15th of September. 

 18th, 22nd, and 23rd of October. 



23rd of November. 



4th and 18th of January. 

 6th, 7th, and 9th of February. 

 29th and 30th of May. 



II. The days of disturbance are more numerous in the 

 horizontal intensity than in the declination. 



III. In this year also several great perturbations were ob- 

 served to occur on the same days on which the same phe- 

 nomenon had taken place in preceding years. The days 

 which particularly deserve notice in this respect, are about 

 the 18th of January, from the 18th to the 22nd of February, 

 and the 18th of October. 



Great disturbances were observed in 



1837. January 16th. 1837. February 18th. 



1838. 17th. 1838. 16th and 21st. 



1839. — 19th. 1839. 18th and 21st. 



1840. 18th. 1840. 18th and 21st. 



1836. February 17th. 



In February, 1840, the disturbance of the horizontal inten- 

 sity was but feebly marked, probably in consequence of the 

 very great perturbations which took place in the same month 

 on the 6th, 7th, and 9th. 



The recurrence in October is a particularly marked one ; 



1836. October 18th. 



1837. 18th. 



1838. 17th. 



1839. . 18th. 



The two periods, February and October, are about equi- 

 distant from the winter solstice. 



8. If we put together, without respect to signs, the shocks 

 which occur at the different hours of the day, both on the 

 perturbation days and on others, we obtain as a final result 

 the following table, exhibiting the number of scale-divisions 

 by which the needles were displaced by disturbances. 



Sum of the Displacements. 



Hours. 



Declination. 



Horizontal Intensity. 



17 to 19 



536-44 



1373-36 



20 to 22 



463-90 



1746-14 



23 to 1 



497-95 



1425-33 



2 to 4 



69776 



1472-05 



5 to 7 



147516 



1911-15 



8 to 10 



1481-17 



2964-23 



