Note 86 — Chapter VII · THE TIME AND PERIOD OF THE EVENT

Equatorial hours are the twenty-four hours of the earth’s revolution on its axis. Each of them is equal in duration to the passage of 15 degrees of the Equator; and they are numbered from noon to noon. A particular explanation of the astronomical use, both of temporal and equatorial hours, is to be found in the 9th Chapter of the second Book of the Almagest; an extract from which is given in the Appendix.