The Units of Time in Ancient and Medieval India
By Takao Hayashi
History of Science in South Asia, Vol.5 (2017)
Introduction: This is a preliminary survey of time units used or mentioned in ancient and medieval works written in Sanskrit and other Indian languages. The fields of the works surveyed are Jyautiṣa, Paurāṇika, Uttara-vaidika, Smārta, Bauddha, and Jaina literatures, including Chinese translations of Bauddha works. No small portion of the data presented in the following sections has already been taken up and explained in the works mentioned at the end of this section, but I newly collected the data from the original sources and arranged them in my own way according to my own interest.
My main interest lies in the great variety of the names of the units and of the conversion ratios between them that these texts exhibit. In these texts, they are mostly given in metrical languages. In this paper, I often put them together in a table, which is useful for showing the numerical structure of the given time units. The tabular presentation, however, excludes everything in the texts other than the names and ratios. I have therefore supplied other important information also from the texts, if any.
For the yuga-manvantara-kalpa system described in the purāṇas, I often abandoned the tabular presentation because the mode of the description itself is interesting even if the resulting table would turn out to be the same. In such cases I have closely followed the text line-by-line in reproducing the given numerical relationships.
Top Image: India shown in the 16th century Atlas Cosmographicae