Indian Science and Technology in the Eighteenth Century: Some Contemporary European Accounts c9.18

c9.18

From the epoch above mentioned, the mean place of the sun for any other time is deduced, on the supposition that in 800 years, there are contained 292,207 days.⁹ This supposition involves in it the length of the sydereal year, or the time that the sun takes to return to the beginning of the moveable Zodiac, and makes it consist of 365ᵈ, 6ʰ, 12′, 36″.¹⁰ From this, in order to find the tropical year, or that which regulates the seasons, we must take away 21′, 55″, as the time which the sun takes to move over the 54″, that the stars are supposed to have advanced in the year; there will remain 365ᵈ, 5ʰ, 50′, 41″, which is the length of the tropical year that is involved, not only in the tables of Siam, but likewise, very nearly, in all the rest.¹¹ This determination of the length of the year is but 1′, 53″, greater than that of De La Caille, which is a degree of accuracy beyond what is to be found in the more ancient tables of our astronomy.