In the Indian tradition the purāṇas are supposed to discuss certain mandatory themes. These form the five characteristics (Lakṣaṇas) of a Purāṇa. One of them is to elaborately describe the origin of the Universe. Obviously notion of time becomes important to discuss origin of the Universe. Also we need use of large numbers to measure time. In book three, chapter 11 of Bhāgavata-purāṇa there is an elaborate discussion of time. The time units describes in this chapter covers an astonishingly wide range. These descriptions form part of the discussions on the origin of the Universe.
It is always the practice to first define a unit and create additional units by establishing its linkage with it. For example, in the modern parlance we define a metre. Further we define a centimetre to be 1/100th of a metre, a kilometre to be 1,000 metres and so on. In chapter 11 of Bhāgavata-purāṇa we see a similar approach to define time. See below the table for details (Although the chapter has all contiguous measures of time, I have skipped the measures in between Prahara and Masa (Month):
We shall see how the first unit of measure for time has been defined. The definition is by way of the following verse:
द्वादशार्धपलोन्मानं चतुर्भिश्चतुरङ्गुलैः ।
स्वर्णमाषैः कृतच्छिद्रं यावत् प्रस्थजलप्लुतम् ॥
dvādaśārdha palonmānam caturbhiś-caturangulaiḥ
svarna-māshaiḥ kṛtac-chidram yāvat prastha jala-plutam
This verse in a way sets up an experiment described as follows. Take a copper pot weighing six palas (1 pala = 48 gms), which can hold water of one prastha (1 prastha = 640 gms; in the case of water it is 640 ml). The vessel shall be bored at the bottom with a golden needle weighing four maṣas (1 māśa = 1 gm) and of length four aṅgulas. (Interestingly, from modern physics we know that if the weight, length and the type of material is known, then it is possible to compute the diameter of the rod!) Leave the pot in water and start a stopwatch. Wait until the vessel is filled fully with water and it just submerges in the water. Stop the watch and record the time. This elapsed time is nāḍika.
Once we have this measurement, then we can get all other measures of time from the table above. Is it not interesting?
Reproduced with permission from Prof. Mahadevan B.
More in our book Introduction to Indian Knowledge System by Prof. B. Mahadevan, Vinayak Rajat Bhat and Nagendra Pavana R. N.