बृहत्संहिता (आचार्य वराहमिहिर - स्थापत्य, खगोल, मौसम व जल विज्ञान)

Adh. II. 8-10] द्वितीयोऽध्यायः 9
In the case of the several systems of measurements
of time, viz., Solar, Savana, Lunar, etc., he must be
able to distinguish what are similar and what are not
similar; and also be conversant with the aptness or
otherwise of each for (being used for) any particular
purpose.
८. सिद्धान्तभेदेऽप्ययननिवृत्तौ प्रत्यक्षसममण्डललेखासंप्रयोगा-
भ्युदितांशकानां छायाजलयन्त्रदृग्गणितसाम्येन प्रतिपादनकुशलः ।
8 In cases of difference of opinion among the
Siddhantas regarding the actual termination of an
Ayana, he should be able to reconcile them by showing
the agreement between accurate calculation and what
has been actually observed in the circle drawn on the
ground through shadow and water-appliances.
९. सूर्यादीनां च ग्रहाणां शीघ्रमन्दयाम्योत्तरनीचोच्चगतिकार-
णाभिज्ञः ।
9. He should also be conversant with the causes
that lead the planets from the Sun onwards to proceed
in different kinds of motions—rapid, slow, southerly,
northerly, towards apojee, perijee, etc.
Vide Sripatipaddhati—P. 48.
१०. सूर्याचन्द्रमसोश्च ग्रहणे ग्रहणादिमोक्षकालदिक्प्रमाणस्थिति-
विमर्दवर्णदेशानामनागतग्रहसमागमयुद्धानामादेष्टा ।
10 In the matter of the Solar and Lunar eclipses,
he should be able to predict by calculation the times
of their commencement, cessation, direction, magnitude,
duration, intensity and color as well as the Moon's
prospective conjunctions with the non-luminous planets
and their warfare.
ब्र. सं. २