INTRODUCTION.

The rule for calculating the ahargana The total number of elapsed days from a fixed epoch to a given date. according to the Romaka A school of Indian astronomy influenced by Greek/Roman traditions. (I. 8—10), and so likewise the rules for finding the mean places of the sun and the moon (VIII. 1. 4) immediately follow from the constitution of the yuga A vast cycle of time or an astronomical era., and have been elucidated in the notes to the translation. The length of the periodical month would, according to the Romaka, amount to 27 days, 7 hours, 43 minutes, and 6.3 seconds.

To the apogee The point in an orbit where a celestial body is furthest from the Earth. of the sun the longitude of 75° is ascribed in VIII. 2. —The apogee of the moon and its periods of revolutions are not, in the usual Indian style, treated apart from the moon’s motion; the 8th chapter (stanza 5) rather contains a rule for calculating the moon’s position with regard to her apogee directly i. e. without any preliminary separate calculation of the apogee’s place. The kendra The "center" or anomaly; the angular distance of a planet from its apogee. mentioned there is the moon’s anomaly, and the rule implies that the anomaly revolves 110 times within 3031 days, in other words that the moon returns to her apogee, or performs one anomalistic revolution, in 27 days, 13 hours, 18 minutes, and 32.7 seconds.

By deducting the longitude of the sun’s apogee from the mean longitude of the sun we find the sun’s anomaly, and may then proceed to calculate his true longitude. For the latter process the Romaka Siddhânta A specific astronomical treatise; "Siddhânta" refers to a comprehensive scientific work. however does not supply any general rule, enabling us to deduce the required equation of the centre The correction needed to find a planet's true position based on its elliptical orbit. for any given anomaly; but contents itself with stating the amounts of the equation from 15 to 15 degrees of anomaly. These amounts are stated in VIII. 3, and it is of interest to note that they agree very closely with the corresponding amounts given by Ptolemy Claudius Ptolemy, the 2nd-century Greco-Egyptian astronomer.. The greatest equation of the centre, which according to the modern Sûrya Siddhânta The most famous and authoritative Indian astronomical text. amounts to 2° 10′ 13″, and which in no other Hindû text book known to me greatly differs from this latter value, according to the Romaka amounts to 2° 23′ 23″, while Ptolemy assigns to it the value of 2° 23′; and also the equations for the smaller anomalies show a pretty close agreement, as appears from the following tabular statement:

The values quoted from Ptolemy are those given by him for the quadrants of the apogee. The Romaka Siddhânta apparently makes no distinction of quadrants, but employs the same equations indiscriminately for all.