590 



Prof. B. Stewart on the Daily 



E. Possible Yariation of the Lunar Effect with the Sun-spot Period. 



15. In order to determine this point as well as we can from the ob- 

 servations, let us consider as minimum solar years the years 1855-57, 

 1862-67, 1873-75, and as maximum solar years the years 1858-61, 

 1868-72, and we thus obtain two values for the winter variation, one 

 corresponding to minima and the other to maxima solar years. Sub- 

 tracting from these the mean winter variation (E), the residual difference, 

 if any, may be supposed to represent an effect possibly due to the solar 

 period. 



By these means the following results have been obtained : — 



Phase oflunation... (0) (1) (2) (3) (4) (5) (6) (7) 

 Winter variation "j 



(min. period), j- 1075 io-86 io'99 io"58 io"i3 10 33 10*56 10-83 

 corrected for (E) J 



Deduct (F) ii-i8 ii'37 ii'32 io-88 10-52 10-49 ^°'19 ii'o5 



Supposed effect of 1 _ ^ _ _^ _ 



solar minimum. J tjj jjj j \/ 



and in like manner — 



Phase of lunation.., (0) (1) (2) (3) (4) (5) (6) (7) 

 Winter variation 1 



(max. period), I 11-76 12-05 1175 11-29 ii-o6 10-69 11-12 ii'34 



corrected for (E) J 



Deduct (F) ii-i8 11-37 11-32 io-88 10-52 10-49 io79 H'OS 



Supposed effect of I g ^ ^ ^.^^ ^. ^. 



solar maximum, J ' J ' • tj -r jt 



There would thus appear to be, judging by the winter observations, two 

 effects of a solar minimum and maximum. 



The first of these is a general decrease for minimum years and increase 

 for maximum years of the temperature-range, a result already indicated 

 by Tables I. and II. 



The second of these is a general decrease for minimum years and in- 

 crease for maximum years of the difference in temperature-range caused 

 by the varying positions of the moon. 



Thus it wiU be seen from (N) that the minimum range lags most 

 behind the average range at the point (1), for which the average range 

 is highest ; while it lags least behind the average range at the point (5), 

 for which the average range is lowest. (P), of course, indicates a beha- 

 viour of exactly the opposite description. 



16. Let us now direct attention to the prominent character of the 

 winter lunar effect. 



Gathering together the various values of this effect, we obtain as 

 follows : — 



