________________
86
this field. But it is convincing that dimensions of Meru except those of its culikā form a consistent picture. AED represents the approximate cone of Meru. The traditional mount Meru GEDB is represented by the frustrum of cones.
Now let us assume
that the observer is situated at 0 lying at the circumference of Jambudvipa whose radius19 is 50000 y.
that OGK represents the true horizontal plane of the observer* and it meets the direction of earth's axis at G as such that P lies at the true celestial north pole and OW represents a plane parallel to the equatorial plane.
that OAK' represents the apparent horizontal plane of the ob
server.
that P' is chosen as such that its apparent altitude <P'OK' is equal to <PGK (the angle of inclination of the axis of the earth to the true horizontal plane OGK of the observer).
Now join P' with A, the point of intersection of the apparent horizontal plane with axis of earth. Extend P'A till it meets perpendicularly the plane OFJC at J. The plane OFJC is inclined to the equatorial plane at <FOW which is equal to <FAJ, for the angle between two planes is equal to the angle between their perpendiculars. The imaginary locus of revolution of P round P' is projected on flat earth as the locus of F revolving round J. This produces the cone AFC. This cone is cut at G ty a plane GHB parallel to flat earth. The true horizontal plane OGK meets the axis of Meru at N.
(i)
(ii)
(iii)
(iv)
Now because earth is regarded as made up of concentric rings of land masses alternatively surrounded by ocean rings with the mount Meru placed at centre of the central island Jambudvipa 20 so OJ forms the radius of Jambudvipa.
Radius of Jambudvipa, 21 OJ Now in ANOJ,
NH GH
JAIN JOURNAL
NJ
50000 y GH || OJ,
DJ
19 Gupta, R. C. (1975) 'Circumference of Jambudvipa in Jaina Cosmography', IJHS, Vol. 10 No. 1, pp. 38-45.
20 See f.n. 13.
21 See f.n. 19.
Jain Education International
* Apparent and true horizontal planes (see fig. No. 3) actually denote the respective tangential planes to the earth's sphere at the point of the observer's position on it. They should not be confused with the modern astronomical sense of horizontal plane passing through the centre of the celestial sphere. Be it mentioned here that our work is in progress to study the development of notion of spherical earth in Jaina astronomy.
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