Bīrūnī, Muḥammad ibn Aḥmad, Alberuni's India (v. 2)

(London :  Kegan Paul, Trench, Trübner & Co.,  1910.)



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translated the passage to me. For a month has thirty
lunar days, and a twelfth part of the solar year has
30f|-^^ lunar days. This fraction, reckoned in day-
minutes, is equal to 55' 19" 22"^ 30'^ If we now, for
example, suppose a conjunction or new moon to take
place at 0° of a zodiacal sign, we add this fraction to
the time of the conjunction, and thereby we find the
times of the sun's entering the signs successively. As
now the difference between a lunar and a solar month
is only a fraction of a day, the sun's entering a new
sign may naturally take place on any of the days of the
month. It may even happen that the sun enters two
consecutive signs on the same month-day (e.g. on the
second or third of two consecutive months). This is
the case if in one month the sun enters a sign before
4' 40" 37"' 30'" have elapsed of it; for the next follow¬
ing entering a sign falls later by 55' 19'' 23*" 30''*', and
both these fractions [i.e. less than 4} 40" 37"' '^o^"' plus
the last-mentioned fraction) added together are not
sufficient to make up one complete day. Therefore
the quotation from the Veda is not correct.
Proposed          I supposc, howcvcr, that it may have the following

of thcfvedk: corrcct meaning :—If a month elapses in which the sun
passage. ^qqq ^ot march from one sign to another, this month is
disregarded in the calculation. For if the sun enters
a sign on the 29th of a month, when at least 4' 40" 37'"
30*^ have elapsed of it, this entering takes place before
the beginning of the succeeding month, and therefore
the latter month is without an entering of the sun into
a new sign, because the next following entering falls on
the first of the next but one or third month. If you
compute the consecutive enterings, beginning with a
conjunction taking place in 0° of a certain sign, you
Page 214. find that in the thirty-third month the sun enters a new
sign at 30' 20" of the twenty-ninth day, and that he
enters the next following sign at 25* 39" 22"' 30'" of the
first day of the thirty-fifth month.
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