This section is from the book "The Brihat Jataka Of Varaha Mihira", by N. Chidambaram Aiyar. Also available from Amazon: Brihat Jataka of Varahamihira.
4. The Learned Brahmins in the Science of Horoscopy say, that the number of degrees passed over by the Sun in any particular sign represents the lunar day at the time of birth (a). If the Prasna Lagna be a day sign, the birth will have occurred at night and if it be a night sign, the birth will have occurred by day; the ghatika of birth shall be determined from the portion of the rising sign that has risen above the horizon (b).
(a) Beginning from the first lunar day in the Moon's increase, suppose the Sun to occupy the 24th degree of Sagittari at the time of birth. The lunar day or Tithi at the time of birth is the 24th day counted from the first day in the Moon's increase or 24 - 15 or the 9th day in her wane.
(b) The length of the day or night of birth being known it is represented by the rising sign and the Lagna Sphuta will give us the exact proportion of the Sign that has risen above the horizon. By the Rule of Three, we can arrive at the exact time of birth from Sun-rise or Sunset. When this is known, the Horoscope may be cast with the help of the Astronomical Tables or the Almanac. The first four stanzas, therefore, give us a complete process for the discovery of the time of birth of a person from the Prasna Lagna.
5. According to some, the lunar month of birth shall be determined from the Navamsa occupied by the Moon at the time of query (a). Again, the sign occupied by the Moon at the time of birth will be either the Prasna Lagna or the 5th house or 9th house from it, whichever is most powerful. If it be difficult to determine which of the three signs is most powerful, the sign occupied by the Moon will be the sign represented by the part of body of Kalapurusha that may happen to be touched by a person at the time of query or the sign may be determined from the like indications occurring at the time of query (b),
(a) The rule stated in the Text is very vague. What the Author means is thus explained by the Commentator.
Suppose each Navamsa to be divided into 9 equal parts; then, if at the time of query the place occupied by the Moon be,
Beyond the | And within the | The lunar month will be |
(1) 8th part of the Navamsa of Aries. | 7th part of the Navamsa of Taurus. | Kartika. |
(2) 7th part of the Navamsa of Taurus. | 6th part of the Navamsa of Gemini. | Margasira. |
(3) 6th part of the Navamsa of Gemini. | 5th part of the Navamsa of Cancer. | Poushya, |
(4) 5th part of the Navamsa of Cancer. | 4th part of the Navamsa of Leo. | Magha. |
(5) 4th part of the Navamsa of Leo. | 7th part of the Navamsa of Virgo. | Phalguna, |
(6) 7th part of the Navamsa of Virgo. | 6th part of the Navamsa of Libra. | Chaitra. |
(7) 6th part of the Navamsa of Libra. | 5th part of the Navamsa of Scorpio. | Vaisakha, |
(8) 5th part of the Navamsa of Scorpio. | 1th part of the Navamsa of Sagittari. | Jyeshtha. |
(9) 4th part of the Navamsa of Sagittari. | 3rd part of the Na vamsa of Capricorn, | Ashadha. |
(10) 3rd part of the Navamsa of Capricorn | 2nd part of the N vamsa of Aquarius. | Sravana, |
(11) 2nd part of the Navamsa of Aquarius.. | 5th part of the Navamsa of Pisces ... | Bhadra - pada. |
(12) 5th part of the Navamsaof Pisces ... | 8th part of the Navamsa of Aries. | Aswayu - ja |
(b) For instance, if, at the time, creatures representing any of the signs of the Zodiac be seen or their sounds heard, the Moon will occupy such sign at the time of birth.
6. The sign occupied by the Moon at tire time of birth of a person will be as many signs removed from the sign occupied by the Moon at the time of query as the Moon is removed from the rising sign at the time of query (a). But if the rising sign be Pisces, then Pisces will be the sign occupied by the Moon at the time.of birth. (In case of doubt), the sign shall be determined by any articles of food that may be brought, any figures that may appear or by any sounds that may be heard at the time (b).
(a) For instance, suppose Scorpio is the rising sign and Pisces the sign occupied by the Moon at the time of query. From Scorpio to Pisces is 5 signs; the 5th sign from Pisces is Cancer. Cancer will, therefore, be the sign occupied by the Moon at the time of birth of a person.
(b) From articles having the shape of, or in any way connected with the creatures representing the signs of the Zodiac and from the sounds of the like creature, the sign occupied by the Moon may be determined. In all these cases, it is assumed, that an All-pervading Intelligent Being helps an astrologer by various signs and. suggestions.
7. The rising sign at the time of birth will be the sign of the lord of the rising Navamsa at the time of query (a). Or, the rising sign at the time of birth will be as many signs removed from Prasna Lagna as the Drekkana occupied by the Sun is removed from the risingDrek - kana at the time of query (b).
(a) Supposing the rising Navamsa at the time of query to be that of Sagittari, the rising sign at the time of birth is Sagittari.
(b) Suppose the rising Drekkana at the time of query to be the 2nd Drekkana of sign Gemini and the Drekkana occupied by the Sun at the same time to be the 3rd Drekkana of Sagittari. The number of Drekkanas from the one to the other is 20. Therefore, the rising sign at the time of birth is the 20th sign from Gemini; subtracting 12 from 20 it is the 8th sign from Gemini, i.e, signCapricorn.
8. Or, multiply the Sphuta (Longitude) of the planet or of the most powerful planet occupying the rising sign by the number of inches in the length of the shadow of a twelve inch Sanku (a straight rod) placed vertically on a horizontal surface and in the Sun; divide the product by 12. The remainder will give the rising sign at the time of birth (a). According to others, if the querent be seated at the time of query, the 7th house from the rising sign at the time will be the Lagnaat the time of birth; if the querent be lying at the time, the 4th house from the rising sign will be the Lagua at the time of birth; if the querent be standing at the time, then, the 10th house will be the Lagna; and if he be rising from his seat, then the rising sign itself will be the Lagna at the time of birth (b).
(a) Suppose the longitude of the planet, or, (where there are several planets) of the most powerful planet occupying the rising sign to be 4 signs 10 degrees and 20 minutes and suppose the length of the shadow to be 4 1/2 inches; the product of the two numbers is 19 signs 16 degrees and 30 minutes. This, divided by 12, gives as remainder, 7 signs, 16 degrees and 30 minutes. The Lagna at the time of birth is therefore the 8th sign from Aries, i.e., sign Scorpio.
(b) According to Subhodhini, the 7th, 4th, 10th and 1st houses are not with reference to the Prasna Lagna as explained by Bhatta-Utpala but with reference to the Lagna obtained from the procees given in the first half of the text, that is, from sign Scorpio in the instance quoted in note (a).
 
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