— 229 — 



Calling the hourly values of the horizontal intensitj' and 

 (leclination on the first or second day following on a day ot' 



distiirbance h^. h^, h,^ h^,^; d^, d,, d.^ d^^ and on 



the second, or third day or still later on 



h^, h,, h, h,^; d;, d,, d^ d,^ 



then for a number of cases was compiited 



(h-h,), (h-h,)----(d-d,).---(d,-dj 

 and the averages of these respect, values 



H,, H, H,„ D,, D, D,,. 



Calling the averages of these latter values (H) and (D), 

 than by taking the differences 



A K =H, -(H), A cl, =D, -(D) 

 A h, =H, -(H) A tl, =D, -(D) 



etc. etc. 



A h,, = H,,-(H), A d,, = D,,-(D) 



a system of hourly values was found for the components of 



that vector, which represents the daily inequality of the vector 



of disturbance. 



Vectordiagrams were drawn according to these values 

 computed for a certain number of stations, but tliough they 

 were pointing to a real influence of terrestrial rotation, they 

 were mostly too irregular to allow any conclusions as to the 

 nature of this influence. 



Now in 19ul Dr. Lüdklincï ') showed, that, in following 

 Wild's device by taking the difference between corresponding 

 hourly values, computed from all days without exclusion of 

 disturbed days, and derived from quiet or normal days only, 

 regular vectordiagrams were to be obtained. 



In his paper Dr. Lüdhling gives the hourly values of the 

 horizontal component, after the N/S and E/W directions, 

 for the arctic stations and for Faidotrsk , and reproductions 

 of the diagrams. He remarks, that at these stations, with 

 the exception of Kingna Fjord and partially Godthaah, the 



1) Terrestrial Magnetism, IV, p. 245. 



