1878.] 



Magnetic Declination at Prague. 



401 



have three epochs in each case, while only two of these are common to 

 both solar and magnetic observations. This comparison is made in 

 the following table. 



Table XII. In which observed and calculated declination-range in- 

 equalities are compared together for selected periods. 



Period of Mercury (one revolution). 



o 







Observed. 



Calculated. 



and 



30 



+ 11 -48 



+ 10 -42 



30 „ 



60 



+ 3-62 



+ 7-25 



60 „ 



90 



- 3-50 



+ 2-25 



90 „ 



120 



- 6-91 



- 3 25 



120 „ 



150 



- 9 13 



- 8 16 



150 „ 



180 



-12-37 



-11 -67 



180 „ 



210 



-13 -72 



-1212 



210 „ 



240 



-10 -44 



- 8-68 



240 „ 



270 



- 2 -45 



- 2-62 



270 „ 



300 



+ 7 73 



+ 4-10 



300 „ 



330 



+ 15 14 



+ 9-26 



330 „ 



360 



+ 16 -20 



+ 11-27 



Mercury and Jupiter together (one revolution). 



o 



o 



Observed. 



Calculated. 



and 



30 



+ 11 -87 



+ 11 -61 



30 „ 



60 



+ 2-56 



+ 8-07 



60 „ 



90 



- 4-26 



+ 2-75 



90 „ 



120 



- 8-72 . 



- 2-45 



120 „ 



150 



-13-85 



- 7-93 



150 „ 



180 



-16 -24 



-11 -97 



180 „ 



210 



-13 44 



-11 -80 



210 „ 



240 



- 8-32 



- 8-71 



240 „ 



270 



+ -51 



- 3 11 



270 „ 



300 



-11 -39 



+ 3-44 



300 „ 



330 



+ 16-91 



+ 8-74 



330 „ 



360 



+ 17 -06 



+ 11 -89 



The results of Table XII are exhibited in Diagram II, in which fig. 8 

 exhibits the observed and calculated magnetic inequalities for the 

 period of Mercury, and fig. 10 the same for the period of Mercury and 

 Jupiter. 



17. It thus appears that in the case of the magnetic declination 

 periods there is (as in those of sun-spots) an exaltation of the observed 

 over the calculated values during times of maximum sun-spot fre- 

 quency, but this exaltation is not so marked as in the case of sun-spots. 

 l\ow, without pretending to know in what way the sun influences 



