Natyashastra
लयस्य वर्धनाच्चापि वर्धमानकमुच्यते । कृत्त्वा कुतपविन्यासं यथावद्द्विजसत्तमाः ॥ २७१॥
The Vardhamānaka is also called so due to the increase of tempo. After setting the musical instruments as prescribed, the procedure is followed accordingly by the expert performers.
english translation
layasya vardhanAccApi vardhamAnakamucyate । kRttvA kutapavinyAsaM yathAvaddvijasattamAH ॥ 271॥
hk transliteration by Sanscript