Manasara Series (I. A Dictionary of Hindu Architecture; II. Indian Architecture according to Manasara-Shilpashastra; III. Manasara on Architecture and Sculpture: Sanskrit Text; IV. Architecture of Manasara: Translation; V. Architecture of Manasara: Illustrations; VI. Hindu Architecture in India and Abroad; VII. An Encyclopaedia of Hindu Architecture) v4.c30.s1.224

v4.c30.s1.224

⁴ The ordinary mode of finding out cardinal points by means of a gnomon is simple. A gnomon of 24, 18 or 12 *aṅgulas* in length, 6, 5 or 4 *aṅgulas* at the base and 2, 1 or ¾ *aṅgula* at the top which is shaped like an umbrella, is fixed on the selected ground levelled with water. A circle is described from the bottom of the gnomon with radius twice the length of the gnomon. Two points are marked on the circumference of the circle when the shadow of the gnomon meets it before and after noon. The straight line joining these two points is roughly taken to be the east-west line (vide lines 30, 37, 42, 84). The line which bisects the east-west line would be the north-south line. The bisecting is done in the usual way. With each end of the east-west line as centre and the length of the line as radius two circles are drawn which intersect each other at two points forming a fish-like common segment; the straight line joining these points of intersection bisects the east-west line at right angles and indicates the north-south line. The intermediate quarters are found out in the same way by constructing the fish between the points of the determined quarters (see plate VI, fig. I). The inaccuracy in the precise determination of the east and west points is caused by the variation of the shadow in consequence of declination of the sun during the interval between the two instants in the forenoon and afternoon when the shadow is observed. For the purpose of rectifying the inevitable variation of the shadow *apa-chchhāyā* is stated to be deducted from the shadow (see note under line 29-30). The subject has been discussed more or less elaborately by all the other leading authorities of astronomy and architecture, for instance,
(1) Sūrya-siddhānta of Bhāskarāchārya (III, 1—51).
(2) Brahma-sphuṭa-siddhānta of Brahmagupta (XIX, 1—20).
(3) Līlāvatī of Bhāskarāchārya (XI, 1—10; part II, chapter II, section 4)
(4) Siddhānta-śiromaṇi of Bhāskarāchārya (VII, 36—29).
(5) Pañcha-siddhāntikā of Varāhamihira (II, 10—13, XIV, 1—11, 14—22).
(6) Mayamata (VI, 1—28).
(7) Śilparatna of Śrīkumāra (XI, 1—22).
(8) Kāśyapa-śilpa (I, 60—70).
(9) Vāstu-vidyā (III, 7—10).
(10) Manushyālaya-chandrikā (II, 1—4).
(11) Vitruvius (Book I, chapter VI, Book IX, chapters IV, VIII, IX)