[ 43 ] of the second half amounts to 199 only. So; while the mean precession for all is about 20", that for As vini (a Arietes) and Uttara-bhádrapada ( Andromeda.), the two stars on either side of Revati, is about 24' each. The question becomes more perplexing when we remember that Bhaskara, who certainly made a few corrections, has given in most cases the same longi- tudes as we have in the current Súrya-Siddhanta. Our identification of some of the stars may be doubtful.* But, taking all the star-longitudes into consideration, we aro forced to admit that somehow or other there were errors of observation. Possibly, these errors were partly due to the rude means of observation, increasing the errors with the increase of the zenith distance of the stars, and partly to azimuth errors, One or all of the explanations must be accepted as true, and we cannot suppose that any one having the slightest pretension to practical astronomy, however rough the instrument might be, could make such. gross errors in the simple measurements required. To take the mean of the star-longitudes for a solution of our prob. lem is therefore a wrong procedure, inasmuch as, we are entire- ly in the dark as to the weight to be attached to the determina tions. We shall, however, make use of them in another way later on We now proceed to consider the third method, which consists in analysing the dates in which there was no ayanáins aFor this purpose, we require not only the dates but also the rates of
- Thue, if Abviai be identified with B Aristos aod Uttara-blsádrapade
with y Pegasi, the amount of precession deduced from them becomes nearly equal and agrecs with that obtained from Magoe. Digitized by Google
