1. For recent publications on the subject of solar activity -and atmospheric electricity the interested reader may be referred to the following: Bauer, L. A., , ( Terr. Mag., , vol. 26, , 1921, , pp. 63, 64, 67 and 68; Terr. Mag., vol, 27, 1922, pp. 27, 28 and 30; Nature, Aug. 11, 1923, pp. 203–205; and Nature, Nov. 10, 1923, p. 686); C. Chree (Proc. Phys. Soc., London, vol, 35, part 3, Apr. 15, 1923, pp. 129–136; Nature, Sept. 8, 1923 pp. 361–362).
2. Blumenschein, A., , , Sitz. ber. Akad. Wiss, , Wien, , Mathem.-naturw, Klasse, Bd. CXXI, , Abt. IIa, , 1912, , Tabelle II, p. 32 .
3. Bauer, L. A., , Terr. Mag., 26, 47 1921,
4. Die interdiurne Veräinderlichkeit der Horizontal-Intenstät als Mass für die erdmagnetische Aktivität;Bartels;Meteorol, ZS.,1923
5. Absolute daily range of magnetic declination at Kew Observatory, Richmond, 1858 to 1900, Meteorological Office;Chree;Geophysical Memoirs,1923