1904. Xo. 2. THE DIURNAL VARIATION OF TERRESTRIAL MAGNETISM. 27 



VI. 



Of the stations dealt with in this paper that are situated in the anti- 

 polar section of the northern hemisphere. Pawlowsk, Vienna, and Zi-Ka- 

 "Wei have had self-registering vertical variometers. Xovaja Zemlja and Tiflis 

 have had Lloyd's balance, Cape Thordsen, Ssagastyr, Bossekop, and So- 

 dankylä, unifilars with iron bars, while from Wilhelmshaven no obsen'ations 

 of the vertical force have been published. 



On going very carefully over the series of observations now before 

 me, I am convinced that it will scarcely be advisable to use other obser- 

 vations than those received from Pawlowsk, Vienna, Tiflis and Zi-Ka-Wei, 

 whose excellently-equipped obser^'atories, having long been in operation, 

 may be assumed to have had perfect control of the instruments employed 

 for the difficult observation of vertical force. A reser\'ation regarding 

 Vienna's vertical variometer will be mentioned later on. 



