Kautilya's Arthashastra 2.20.37

2.20.37

pañcadaśamuhūrto divaso rātriś ca caitre cāśvayuje ca māsi bhavataḥ //

(The divisions of time are) a truti, lava, nimesha, káshthá, kalá, náliká, muhúrta, forenoon, afternoon, day, night, paksha, month, ritu (season), ayana (solstice); samvatsara (year), and yuga. 2 trutis are equal to 1 lava. 2 lavas are equal to 1 nimesha. 5 nimeshas are equal to 1 káshthá. 30 káshthás are equal to 1 kalá. 40 kalás are equal to 1 náliká, or the time during which one ádhaka of water passes out of a pot through an aperture of the same diameter as that of a wire of 4 angulas in length and made of 4 máshas of gold. 2 nálikas are equal to 1 muhúrta. 15 muhúrtas are equal to 1 day or 1 night.

Such a day and night happen in the months of Chaitra and Asvayuja. Then after the period of six months it increases or diminishes by three muhúrtas.