[81] Sitz. k. Akad. der Wiss. (Berlin), 1897, no. xviii., also T.M. 3, p. 191.
[82] T.M. 2, p. 11.
[83] Die Elemente des Erdmagnetismus (St Petersburg, 1899), p. 103.
[84] T.M. 9, p. 113.
[85] T.M. 1, p. 77, and Nature, 57, pp. 160 and 180.
[86] M.Z. 15, p. 175.
[86a] Sitz, der k. k. Akad. der Wiss. Wien, math. nat. Classe, 1898, Bd. cvii., Abth. ii.
[87] P.T. (A) 180, p. 467.
[88] Die Tägliche Periode der erdmagnetischen Elemente (St Petersburg, 1902).
[89] R. Accad. Lincei Atti, viii. 1899, pp. 69, 121, 176, 269 and previous volumes, see also Séances de la Soc. Franc. de Physique, 1899, p. 118.