[1] My lectures, given in November, 1890, were printed in Nature, April-July, 1891, under the title "On some Points in the Early History of Astronomy," with the following note:—"From shorthand notes of a course of lectures to working men delivered at the Museum of Practical Geology, Jermyn Street, in November, 1890. The notes were revised by me at Aswân during the month of January. I have found, since my return from Egypt in March, that part of the subject-matter of the lectures had been previously discussed by Professor Nissen, who has employed the same materials as myself. To him, therefore, so far as I at present know, belongs the credit of having first made the suggestion that ancient temples were oriented on an astronomical basis. His articles are to be found in the Rheinisches Museum für Philologie, 1885."
[2] Maspero, "Histoire ancienne des Peuples de l'Orient." p. 136.
[3] Hibbert Lectures, 1879.
[4] See Rawlinson's "History of Egypt," Vol. II., p. 134, for references on this subject.
[5] "The temples of the gods ought to be so placed that the statue, which has its station in cella, should, if there be nothing to interfere with such a disposition, face the west; in order that those who come to make oblations and offer sacrifices may face the east.... When temples are built in the neighbourhood of a river, they should command a view of its banks, like the temples of Egypt upon the borders of the Nile."—Vitruvius, Civil Architecture, Section I., Chapter V.
[6] See Biot, "Études sur l'Astronomie Indienne," p. 293.
[7] See Biot, "Sur divers points d'Astronomie ancienne: Mémoires, Académie des Sciences," 1846, p. 47.
[8] For a detailed account of the way in which the formula in use has been obtained, the reader had better turn to Vol. I., p. 253, of Chauvenet's "Spherical and Practical Astronomy."
If we denote the latitude by φ,
and let p = the star's polar distance,
a = " " right ascension,
Θ = sidereal time of observation,
h = the star's altitude,
t = " " hour angle;