A Popular History of Astronomy During the Nineteenth Century / Fourth Edition

by Agnes M. Clerke

[61] R. Wolf, Gesch. der Astron., p. 518.

[62] Bessel, Pop. Vorl., p. 22.

[63] A new reduction of the observations upon which they were founded was undertaken in 1896 by Herman S. Davis, of the U.S. Coast Survey.

[64] Bessel, Pop. Vorl., p. 440.

[65] Durège, Bessel's Leben und Wirken, p. 28.

[66] Bonner Beobachtungen, Bd. iii.-v., 1859-62.

[67] Bessel, Pop. Vorl., p. 238.

[68] The heads of the screws applied to move the halves of the object-glass in the Königsberg heliometer are of so considerable a size that a thousandth part of a revolution, equivalent to 1/20 of a second of arc, can be measured with the utmost accuracy. Main, R. A. S. Mem., vol. xii., p. 53.

[69] Specola Astronomica di Palermo, lib. vi., p. 10, note.

[70] Monatliche Correspondenz, vol. xxvi., p. 162.