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JANUARY, 1980
reckoning of the first point of zodiacal circumference was shifted from winter solstice to Vernal equinox and consequently Abhijit ( « Lyrae) was replaced by Asvini (B Arietis) to head the list of nakşatras. 23
9. Set Theoretic Approach
The notion of set theoretic approach as developed by Jainas is exhibited in the classification of Jyotişikas (astral bodies). Besides, L.C. Jain has clearly exposed the set theoretic approach in Jaina School of Mathematics. Such an approach had also diffused into the Jaina School of Astronomy.24 10. Measurement of Celestial Distances
Celestial angular distances were measured in yojanas (basically, linear measures of length) in terms of corresponding distances projected over the surface of the earth, e.g. celestial latitudes of the Moon and other planets have been determined in terms of earth distances in yojanas expressed as heights of astral bodies from samatala bhūmi (earth having a plane surface, denoting a circular area with centre at the projection of pole of ecliptic).25 It is, however, worthy of note that the Babylonian ephemerides of 'System A' measure the latitude of the Moon in units called "Barley Corn” (Se) related by 72 Se = 1°. Similarly all other units of angular measurements are originally measures of length.26
11. Use of Zigzag Functions
Jainas had made an extensive use of linear zigzag functions, e.g., in the computation of length of the day as the Sun moves southward or northward. The Babylonian influence upon the use of linear zigzag functions is quite questionable. However, more researches are still in progress.
12. Observation of the Celestial Phenomena
Jainas had a keen sense of observation. They measured precisely the time as a function of shadow and determined time of the day through shadow-lengths of a gnomon. They had observed linear occultations, determined Summer solstice upto thirty muhūrtas or one day only, studied the phenomena of heliacal combustion of Venus, determined
28 Lishk, S.S. and Sharma, S.D.(1976), 'Chatratichatra Yoga in Surya Prajnapti',
Tirthankar, Vol.2, No.1, pp. 27-35, 41. Lishk, S.S. and Sharma, S.D. (1977), 'Classification of Jyotisikas in Jaina
Cosmology', Dilip, Vol. 14, No.2, pp.29-31. 25 See ref. No.9. 26 Neugebauer, O. (1975), A History of Ancient Mathematical Astronomy, p.514.
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