Kugler 7 that the various periods underlying their lunar predictions were identical with those heretofore believed to have been independently arrived at by Hipparchus, who accordingly must be held to have borrowed from Chaldaea the lengths of the synodic, sidereal, **anomalistic** and draconitic months.

The **anomalistic** revolution of a planet or other heavenly body is the revolution between two consecutive passages through the pericentre.

If the pericentre is fixed, this is an actual revolution; but if it moves the **anomalistic** revolution is greater or less than a complete circumference.

An **Anomalistic** year is the time (365 days, 6 hours, 13 minutes, 48 seconds) in which the earth (and similarly for any other planet) passes from perihelion to perihelion, or from any given value of the anomaly to the same again.

The terms synodical, sidereal, tropical, **anomalistic**, nodical, are applied respectively to these months, of which the lengths are as follow: - N This diagram is a key to some of the features reproduced in the photograph.

The **anomalistic** month is the mean time taken by the moon in passing from one perigee to the next; the sidereal month is the mean time in which the moon makes a circuit among the stars; the tropical month is the mean time in which the moon traverses 360° of longitude; the nodical or draconic month is the mean time taken by the moon in passing from one rising node to the next; the solar month is one-twelfth of a tropical year.

The lengths of the various months are: synodic = 29.53059 days; **anomalistic** = 2 7.554 60, sidereal = 27 32166, tropical = 27.32156, nodical = 27.21222, solar= 30.43685.

An **Anomalistic** month is the time in which the moon passes from perigee to perigee, &c.