AbstractAccording to post‐Vedānga pre‐Siddhāntic Jaina canonical texts, 18 muhūrtas (1 muhūrta = 48 minutes) and 12 muhūrtas are respectively the greatest and the smallest lengths of daylight. The length of any day (daylight) of the year can be computed therefrom through a simple linear zigzag function. However, the ratio 3: 2 between the greatest and the smallest length of daylight holds good for a latitude 35° north very near to that of Babylon. This ratio is also propounded in Jyotisa Vedāngam. It is exposed here that the ratio 3: 2 holds equally good for Gandhāra, a renowned seat of ancient Indian culture. Gandhāra might have been used for purposes like those of a standard station for purposes of time‐reckoning in ancient India. However, by applying a correction for the variable rate of flow of water through the orifice of a water‐clock, it has been exposed that the actual ratio of maximum and minimum lengths of daylight measured in time‐units is different from the ratio of the amounts of water to be poured into the water‐clock on the respective days. It is revealed that the ratio 3:2 of the amounts of water to be poured into the water‐clock on the longest and shortest days (daylights) is equivalent to the ratio √3: √2 of the actual time‐lengths of the longest and the shortest days respectively. It refers to a latitude 19° 6 north, very near to that of Ujjainī, another renowned