[13] Report for 1906, App. 4, see also (3) p. 102.
[14] (1) p. 166.
[15] Ergebnisse der mag. Beobachtungen in Potsdam, 1901, p. xxxvi.
[16] U.S. Coast and Geodetic Survey Report for 1895, App. 1, &c.
[17] T.M. 1, pp. 62, 89, and 2, p. 68.
[18] (3) p. 45.
[19] Die Elemente des Erdmagnetismus, pp. 104.108.
[20] Zur täglichen Variation der mag. Deklination (aus Heft II. des Archivs des Erdmagnetismus) (Potsdam, 1906).
[21] M.Z. 1888, 5, p. 225.
[22] M.Z. 1904, 21, p. 129.