260 



Mr. C. Chambers. 





(0) 



(1) 



(2) 



(3) 

 



(4) 



(5) 



(6) 



(7) 



Summer variation (minimum 

























4-83 



4-77 



4-39 



4-46 



4-83 



4-85 



4-50 



4-47 



Deduct (D) 



5-52 



5-52 



5-18 



5-18 



5-56 



5-56 



5-13 



5-19 



Supposed effect of solar mini- 





















-0-69 



-0-75 



-0-79 



-0-72 



-0-73 



-0-71 



-0-63 



-0-72 



and 





(0) 



(1) 



(2) 



(3) 



(4) 



(5) 



(6) 



(7) 



Summer variation (maximum 





















6-11 



6-17 





5-79 



6-23 



6-21 



5-77 



5-81 



Deduct (D) 



5*52 



5'52 



5-18 



5-18 



5-56 



5-56 



5-13 



5-19 



Supposed effect of solar maxi- 





















+ 0-59 



+ 0-65 



+ 0-61 



+ 0-61 



+ 0-67 



+0-65 



+ 0-64 



+0-62 



8. The series (Gr), (I), (G')> (10, (K), and (M), are curved in figs. 

 5 to 10 in order, and their respective mean values are — '26, +'36, 

 — '24, + *20, — '72 and +'63. These numbers imply that the result 

 already found, that years about the time of maximum sun-spots have 

 a larger declination-range than years about the time of minimum sun- 

 spots, holds also for the winter and summer half-years separately. 



The amplitude of the variation corresponding to the sun-spot varia- 

 tion is like the absolute declination-range, and even in greater propor- 

 tion, much greater in summer than in winter. On the other hand, 

 the supposed sun-spot effect on the lunar variation is greater in winter 

 than in summer, the winter curves (figs. 5 to 8) being much bolder 

 than the summer curves (figs. 9 and 10) : the former are, indeed, of 

 greater range and equally definite, though different, in character with 

 the absolute winter variation shown in fig. 2. 



E. Variations ivhicli seem to depend on Planetary Configurations. 



9. The periods chosen for examination with respect to variation 

 of declination-range are the same as were selected by Dr. Stewart in 

 our model paper, viz : (a) the period of conjunction of Venus and Mer- 

 cury, (/3) the solar period of Mercury, and (7) the period of conjunc- 

 tion of Mercury and Jupiter. Assuming with Dr. Stewart, that as the 

 periods differ little from three months,* three-monthly values of the 

 phenomenon will be nearly free from any inequality depending on the 

 periods, and that differences between the monthly and the three-monthly 

 values will exhibit any such inequality as may exist, we have sub- 

 tracted the three-monthly values from the monthly values referred to 



* The assumption, as regards the period of conjunction of Venus and Mercury, is 

 not very exact, and this may be the reason why the variation found in this case is 

 of less simple character than that of the other two periods. 



