Surya Siddhanta
ततो लग्नान्तरप्राणाह् कालाम्शाः षष्टिभाजिताः। प्रतीच्याम् षड्भयुतयोस् तद्वल् लग्नान्तरासवः॥
In the east, longtitudes of the sun and of the planet, determine the interval in respirations between the two lagnas (lagnantarapräëa). This divided by 60 will give the time (kälangça). In the west, determine the interval in respirations of the two after adding six räçis (signs) to both.
english translation
tato lagnAntaraprANAh kAlAmzAH SaSTibhAjitAH। pratIcyAm SaDbhayutayos tadval lagnAntarAsavaH॥
hk transliteration by Sanscript