5'0 



NA TURE 



[September 24, 1908 



21° 20° 19° 18° \T 



Fig. 9.— The western magnetic variation in N. Britain and N. Ireland in 15 



Flo. 10.— The western magnetic variation in S. Britain and in S. Ireland in 1907. 



NO. 2030, VOL. 78] 



