Manasara (English translation)

by Prasanna Kumar Acharya | 1933 | 201,051 words

This page describes “notes regarding apacchaya (light or dim shadow)” of the Manasara (English translation): an encyclopedic work dealing with the science of Indian architecture and sculptures. The Manasara was originaly written in Sanskrit (in roughly 10,000 verses) and dates to the 5th century A.D. or earlier.

Notes regarding Apacchāyā (light or dim shadow)

These notes are extracted from the Mānasāra chapter 6 (rules for erecting gnomoms and pegs):

“the length of the gnomon being divided into ninety-six parts, (and) the apacchāyā being left out of these parts, the (due) east should then be determined”

The term [apacchāyā] is interpreted ordinarily as ‘light or dim shadow’ which in astronomical language may be rendered by ‘penumbra,’ i.e., a partial or lighter shadow formed all round the perfect or darker shadow. But the ‘penumbra’ formed round the ‘umbra,’ of the gnomon can never be measured in aṅgula (of three-fourths inch) as given in tie lines immediately following (31—35, 50—76) with any scientific precision, because no accurate line could be drawn between umbra and penumbra to show their demarcation and consequently it cannot be subtracted from the shadow, either from beyond the length or side of its extreme point meeting the circumference of the circle.

Another possible meaning of the term would be the shadow which is deviated, declined, dislocated, displaced or wrongly placed, Though not distinctly mentioned in ordinary dictionaries or the literature accessible to the lexicographers ibis sense of the term is grammatically possible, and there are parallel terms like apa-devatā, apa-mṇi??u[?], apa-karman, etc., where the panicle apa, conveys similar connotations, Further, declination of the shadow is an astronomical fact in consequence of the processional declination of the sun. Taken in this sense the declined shadow will have to be deducted either by the circumference of the circle (as shown in plate VI, fig. 2) or from the top end of the length of the shadow (as in plate VI, fig. 3)

But in both cases the following are the grave objections:—

(i) The amount of corrections as given (in lines 81—78) are too large, the maximum correction possible, on account of the change of declination of the sun in the interval between the morning observation and the afternoon one, being less than 1/300th part of the length of the gnomon, i.e., less than ¼th aṅgula approximately, while it is stated to be 8 aṅgulas (in lines 35, 69, 70).

(ii) The maximum corrections between the times when the correction is zero should be the same, but they are not so as given in the text.

(iii) The times when the correction is zero should be solstices (June 21-22, December 21-22), tut it is not so as given in the text lines 31, 51, 52).

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