On Five Circular Parts of Jambudvipa

Summary

Sajjan Singh Lishk’s paper ‘On Five Circular Parts of Jambudvipa’ delves into the cosmological speculations of the Sūrya‑prajñapti, a Jain astronomical treatise. The third prabhṛt of the text concerns the dimensions of the region illuminated by the sun and divides Jambudvipa into five circular bands. Lishk begins by reviewing diverse opinions that circulated among different schools of thought before the composition of the Sūrya‑prajñapti. Some commentators claimed that the sun and moon shine upon only one island and ocean, while others asserted that their heat and light reach three islands and three oceans; yet another opinion held that they illuminate three and a half islands and seas. The author explains that the compilers of the Sūrya‑prajñapti synthesised these views and proposed a unique scheme based on the ratio of the maximum to minimum lengths of daylight. In this model the ratio 3:2 becomes fundamental: the longest day is one and a half times the shortest. Lishk conjectures that such a ratio might have been derived from experiments with water clocks (clepsydras) used to measure flows of water over different periods. The article discusses how converting the ratio of daylight durations into areal parameters yields a latitude of thirty‑five degrees north, which coincides with Ujjain, an important centre of Jain astronomy. The author argues that the simplest conceptual division of Jambudvipa into five circular parts likely emerged from such empirical observations and arithmetic reasoning. He acknowledges that no textual evidence shows that ancient astronomers measured the actual areas of illuminated land in relation to daylight, but he suggests that they could have adapted quantities derived from water measurements. The discussion links the cosmological model to earlier studies by Malaya Giri, Dr S. D. Sharma and others, emphasising that the Sūrya‑prajñapti is the seventh Upanga of the Jain canon and was redacted at the council of Valabhi. Lishk also indicates that the modern astronomer uses correction factors such as Bernoulli’s theorem when dealing with variable flow rates. By integrating historical commentary with scientific interpretation, the paper illustrates how Jain scholars combined speculative cosmology with observational data. The conclusion notes that the ratio 3:2, though seemingly simple, represents a profound attempt to harmonise cosmological geography with the realities of astronomical observation. Through this exploration, the article highlights the ingenuity of ancient Jain astronomers and the methodological continuity between their work and later scientific thought.