Matsya Purana — Solar–Lunar Motions
उत्तरायाः प्रमाणं तु काष्ठाया मण्डलस्य तु दक्षिणोत्तरमध्यानि तानि विन्द्याद् यथाक्रमम् //
uttarāyāḥ pramāṇaṃ tu kāṣṭhāyā maṇḍalasya tu dakṣiṇottaramadhyāni tāni vindyād yathākramam //
One should, in proper sequence, ascertain the correct measure of the northern side of the wooden measure, and then accordingly determine the southern, northern, and central divisions of the (Vāstu) maṇḍala.
This verse is not about Pralaya; it belongs to the Vāstuvidyā material, focusing on practical measurement and directional layout of the Vāstu maṇḍala.
It supports the dharmic duty of building correctly—whether a king planning settlements/temples or a householder constructing a home—by insisting on accurate, orderly measurement and proper orientation (north/south/center).
It instructs how to establish the maṇḍala’s directional and central divisions using a standard wooden measure, a core step in Vāstu and temple-site preparation before placing structures or altars.