Natyashastra
चतुरर्धकलं वा स्यात् तदर्धकलमेव च । अवस्थान्तरमासाद्य कुर्याद् गतिविचेष्टितम् ॥ ३१॥
The duration of the gait may be four, two, one, or even half a Kalā; upon a change of condition, the gait should be suitably adjusted.
english translation
caturardhakalaM vA syAt tadardhakalameva ca । avasthAntaramAsAdya kuryAd gativiceSTitam ॥ 31॥
hk transliteration by Sanscript