पञ्चसिद्धान्तिका (आचार्य वराहमिहिर - सूर्य, रोमक, पौलिश, वासिष्ठ एवं पितामह सिद्धान्त)

IV. 50 IV. THREE PROBLEMS 123 mid-day shadow to the result and deduct 12. The shadow of the gnomon, caused by the Sun, is got. This means: Shadow at any time = 6 × daytime ÷ the time taken + midday shadow − 12. Example 19. Given daytime = nā. 33-20, mid-day shadow = aṅg. 2-50, find the shadow at nā. 8-0 from sunrise. Shadow = 6 × 33 1/3 ÷ 8 + 2 5/6 − 12 = 25 + 2 5/6 − 12 = aṅg. 15-50. (Actually the shadow is aṅg. 13-56, which can be seen from the previous examples). But if the constants in the popular verse, 5 and 10, are used, then the rule becomes, Shadow = 5 × daytime ÷ taken time + mid-day shadow − 10. Using this, the shadow = 5 × 33 1/3 ÷ 8 + 2 5/6 − 10 = 20 5/6 + 2 5/6 − 10 = aṅg. 13-40. See how close this is to the correct, 13-56. Being the inverse of the operation of finding the time from the shadow, this rule can be derived from the previous rule, viz, 6 × daytime ÷ (shadow − mid-day shadow + 12) = time in nāḍis. ∴ 6 x daytime ÷ time = shadow − mid-day shadow + 12. ∴ shadow = 6 x daytime ÷ time + mid-day shadow − 12, which is the present rule. [चन्द्रच्छाया] (इ)ष्टा नाड्यो द्युनिशं चन्द्रोदयनाडि[का]युतविही(नाः) । ताभिस्तत्कालेन्दोर्भानोरिव चिन्तये(च्छा)याम् ॥ ५० ॥ Moon's shadow 50. To compute the Moon's shadow at any time in the night, the time after sunset is to be added to the nāḍīs from moonrise to sunset if the Moon rises in the day. If the Moon rises after sunset, the time of moonrise after sunset is to be subtracted from the taken time. This is to be used as the time taken for computation, and work done as in the case of the Sun to get the Moon's shadow. The work is to be done thus: Upto the desired time after sunset, the time after moonrise is to be found, and this time is to take the place of the time after sunrise in the work of finding the shadow as in IV. 41-44. So, for the desired time the Moon's true declination and day-diameter have to be found and these are to be used in the place of the Sun's declination and day-diameter. The required cara etc. are to be found using these. As the nāḍis pertain to the solar day, they should be made lunar and used. The two examples given hereunder will make the work clear. The author's intention is 49. Quoted by Utpala on BS 2, p.62 49a. A. नाडिभि b. A. षट्समु. A1. द्वरेतत्र; A2. द्वारेतत्र 50a. A.C.D. दृष्टा. A. द्युनिशे b. A. नाडियुत. A1. विहीना; A2. विहिना c. A. कालेंदो d. A. छायां