( 522 ) 



That ratio is constant tor different duration of vibration, as was 

 proved by the arrangement according to groups of mean equal 

 duration. 



When we wish to compare the values for the ratio of amplitudes 

 of magnetic force and earth-current of vibrations of shorter duration 

 with those of the six terms of the daily variation, it is best to inscribe 

 all values in one diagram with abscis ly Al and ordinate lyi/T. 



When now the formula A = 0.8 



V TM 



found above for the 6 



terms of the daily variation will still hold, then the values which 



lie on the same radius-vector through the origin must be the same. 



It is evident that this is only the case for the middle part of the 



diagram, namely for the radius-vector where 0.8 1/ == 150. 



The ratio P^ljT and t^M is therefore = 2. 



If the amplitude of the magnetic component is relatively larger, 

 then the radii with equal values are bent gradually to the axis of 



abscissae, and if — is relatively, larger, then they are bent to the 



axis of ordinates. 



For a great — ; i. e. for a duration of vibration of about one 



minute, they turn again to the axis of ordinates and a maximum 

 seems to be formed. 



It will be possible to force these curves in a formula, but we 



