The Ancient Egyptian Calendar and Its Revision by J. Norman Lockyer is a comprehensive study of the calendar system used by the ancient Egyptians. The book provides an in-depth analysis of the various methods used by the Egyptians to measure time, including the lunar and solar calendars, as well as the Sothic cycle. Lockyer also explores the revision of the Egyptian calendar system during the reign of Pharaoh Ptolemy III, which resulted in the creation...