1877.] 



Range of Magnetic Declination. 



119 



appears to be in the march of the declination-range from year to year 

 (Pig. II.) traces of a force which prevents this range from being strictly 

 comparable with that of sun-spots. It will be seen that after the date of 

 peculiarity a (Figs, I. and II.) the sun-spot curve marches rapidly up, while 

 the declination-range curve does not so mount ; also, after the maximum 6, 

 the sun-spot curve falls more rapidly than the declination-curve. Similar 

 remarks will apply to other points ; in fine we have grounds for supposing 

 the declination-range to be acted upon by some other influence than one 

 so represented by sun-spots as to follow their increase and diminution. 



"Mr. J. A. Broun, in a series of interesting investigations, has indicated 

 the probability that there is an influence of this nature ; and it may fairly 

 be said that the results of this paper are at least consistent with such an 

 hypothesis. 



20. I would next remark that the hypothesis asserting a connexion of 

 some kind between magnetical and meteorological phenomena appears to 

 be borne out by the results of this paper*. 



It will be noticed from Figs. XI., XII. (p. 120), that there is a striking 

 likeness between the winter lunar variation for the decimation and 

 temperature ranges. There is also a likeness between the summer lunar 

 variation for these two elements, not so striking to the eye, but which 

 will nevertheless be seen from the following comparison : — 



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



Summer lunar yaria- 1 



tion temperature- j- 16-96 17*02 17*23 I7"22 1 7*35 17*15 17*24 I7'27 

 range J 



Summer lunar yaria- "1 



tion declination- J- '620 -6oo '578 '586 '609 '604 '584 -596 

 range J 



Eoth of these, the first imperfectly and the latter fully, exhibit maxima 

 at or near new and full moon. Again, while on the whole there is a like- 

 ness between the curves representing the annual variation for these two 

 elements, yet there is also a dissimilarity, inasmuch as the declination- 

 curve (Pig. IX.) has apparently a strong reference to the equinoxes, which 

 is absent, or nearly so, in the temperature-curve. But it may be taken for 

 granted that if there be a connexion between magnetism and meteorology, 

 it certainly cannot be of such a nature that all the meteorological pecu- 

 liarities of a place are reproduced in its magnetic phenomena, for all 

 observation is against a connexion of this description. Indeed any hypo- 

 thesis of a connexion between these two must, in order to be consistent 

 with facts, assume that the magnet averages things so as to be free, in a 

 great measure if not completely, from local peculiarities. 



* Mr. Baxendell, of Manchester, was the first to direct attention to this subject in 

 a paper " On a Diurnal Inequality in the Direction and Velocity of the Wind," appa- 

 rently connected with the daily changes of magnetic declination. See Memoirs of the 

 Lit. and Phil. Society of Manchester, vol. iy. ser. 3, p. 210. 



