PHYSICAL AND MATHEMATICAL SCIENCES. 15
All this certainly indicates a greater advance than wasmade by the western nations even at a much later period.*
The Egyptians.
The Egyptians seem to have obtained considerablecelebrity for astronomical knowledge at a remote period.Hut little, if any thing, of their astronomy has beenpreserved ; for Hipparchus and Ptolemy , though col-lecting ancient observations, give none from Egyptian astronomers, but have recourse to those of the Chal-deans. Diodorus Siculus informs us that the Egyptianswere able to calculate eclipses ; and other writers speakof the records of observed eclipses. They must havecollected observations to assign the recurring period bywhich their predictions were framed. One of theirearly kings, Osymandyas (whose date is uncertain), issaid to have constructed a large circle marked with thesigns of the zodiac. Their religious solemnities wereregulated by the lunar revolutions ; while their civilyear consisted of 365 days. They soon found thatneither of these accorded with the true solar year: butwithout caring to obtain an agreement between the reli-gious or civil periods of the year with the physicalseasons, they contented themselves with remarking therecurrence of a period of 1461 such years at which thesuccession of months and festivals returned to the sameseasons. This was called the Sothaic period ; and theoccurrence of one such epoch is mentioned in a. d. 13,9.The preceding was therefore in the year b. c. 1322.Some writers have even contended that there was onebefore this.
It appears from good authority that the Egyptiansconceived the two inferior planets, Mercury and Venus,to revolve round the sun, accompanying him in hisannual revolution round the earth, f The invention of
* See Prof. Playfair’s Memoir on the Astronomy of the Brahmins,Edinb. Trans. 17^2." ii.