Kautilya's Arthashastra 1.19.8

1.19.8

taiḥ paścimā vyākhyātāḥ //

He shall divide both the day and the night into eight nálikas (1½ hours), or according to the length of the shadow (cast by a gnomon standing in the sun): the shadow of three purushás (36 angulás or inches), of one purushá (12 inches), of four angulás (4 inches), and absence of shadow denoting midday are the four one-eighth divisions of the forenoon; like divisions (in the reverse order) in the afternoon.