On Eapid Periodic Variations ef Terrestrial Magnetism. 



43 



As may be seen, the cases where X-waves are alone conspicuous, 



or in other words, the disturbing field is directed nearly in the 



meridian, are most frequent near midnight and noon, while the 



opposite cases, i.e. those in which the disturbance occurs nearly in 



the WE direction, are most frequent in the morning and 



evening. 



Fig. 14. 



Parallel. 



Inverted. 



iOO 



80 



<oO 



40 



20 



^ 8 IZ 16 20 Zf 



Fig. 15. 



X alone. 



Y alone. 



C Z 4- G 



10 11 14- 16 IS 20 22 2.4 



