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

144 PAÑCASIDDHĀNTIKĀ V. 7 सविता यतः शशाङ्कात् कोट्या परिकल्पितस्ततः कोटिः । देयांशकाङ्गुलसमा भुजकर्णौ चाङ्गुलैरेव ॥ ६ ॥ शशिमध्यात् प्राक् कर्णः कोटिरतोऽतो भुजः शशाङ्कगतः । परिधावक्षो(न्ना)मः शौक्ल्यं मध्याद्धनुस्तत्र ॥ ७ ॥ 6. The ‘Koṭi’ is to be drawn on that side of the Moon towards the Sun, north or south, which is got in computing it, using the scale, one aṅgula = one degree of ‘Koṭi’. The Bhuja and the Hypotenuse also should be drawn to the same scale. 7. Thus, first there is the Hypotenuse from the centre of the Moon to that of the Sun. From the centre of the Sun the ‘Koṭi’ is laid in the direction com- puted for it. Then from its termination the ‘Bhuja’ is laid towards the Moon’s centre. On the rim of the Moon represented by a circle of fifteen aṅgulas, the raising of the horn in aṅgulas due to the latitude of the place is to be done. At the centre of the two ends of the horn the illumination in digits is to be represented on the diameter. There the arc (forming the upper boundary of the illumination) is to be drawn (by making the arc pass through the two ends of the horn and the point in the middle to which the illumination extends). Though it is plain that these four verses give instructions for the graphical representation of the Moon at the times of visibility, (specifically its first visibility in the evening in the west), yet on account of possible incorrect copyings, and because we are not sure of the degree of roughness of the result intended by the Siddhānta, we encounter a lot of difficulty in ordering the words and interpretting them. The author has not given the diameter of the Moon in aṅgulas, which is neces- sary to draw the orb, and represent in it the illumination and the uplifting of the horn. But we can infer the diameter to be fifteen aṅgulas thus: On Aṣṭamī, at the middle of either fortnight, when the hypotenuse is 90°, according to the rule for getting the illumination, we have 90/12 = 7½ aṅgulas of illumination. We know that half the Moon is illuminated then, and therefore the whole Moon should have a diameter of fifteen aṅgulas, as we have stated. This agrees also with the ‘elevation of the horn’ due to the latitude, which can be shown thus: The line joining the tips of the horn seen horizontal by a person on the equator, is seen vertical by a person at the pole, i.e. at 90° latitude, because the celestial equator is inclined by 90° there, so as to be coincident with the horizon. As the hypotenuse at the time for which the elevation is required is small, we can take it that the elevation of the horā is proportionate to the degrees of latitude. According to the rule for elevation given by the author, it is for 90° and 90 × 2 ÷ 15 = 12 aṅgulas, along the rim of the quadrant, from the horizontal to the vertical. Therefore the whole rim, i.e. the circumference, is 4 × 12 = aṅgulas and this shows that the diameter must be 48 × 7/22 = fifteen aṅgulas very nearly. This agreement in the diameter, as calculated by the two rules, itself is a criterion for the correctness of the rules. 7c. A.°वक्षोनामः; C.D.U.°वक्षो नाम d. D.शौक्ल्यमध्यात्॰ 6b. A.कोज्यापरिकल्पितकोटिः A.तदनु सूत्रं; D.तदनु [च] सूत्रम्’