Bīrūnī, Muḥammad ibn Aḥmad, Alberuni's India (v. 1)

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



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  Page 347  

CHAPTER XXXV.                           347

develop periodically and parallel with the moon's
phases, all this is well known to the inhabitants of sea¬
shores and seafaring people. Likewise physicians are
well aware that she affects the humores of sick people,
and that the fever-days revolve parallel with the moon's
course. Physical scholars know that the life of animals
and plants depends upon the moon, and experimen¬
talists know that she influences marrow and brain,
eggs and the sediments of wine in casks and jugs, that
she excites the minds of people who sleep in full moon¬
light, and that she affects (?) linen clothes which are
exposed to it. Peasants know how the moon acts upon
fields of cucumbers, melons, cotton, &c., and even make
the times for the various kinds of sowing, planting, and
grafting, and for the covering of the cattle depend upon
the course of the moon. Lastly, astronomers know that ^^^'^ ^76.
meteorologic occurrences depend upon the various phases
through which the moon passes in her revolutions.

This is the month, and twelve of them are in tech¬
nical language called a lunar year.

The natural year is the period of a revolution of the Soiar

,      ,                             .                                                   .     month.

sun in the ecliptic. We call it the natural, because it
comprehends all the stages in the process of generation
which revolve through the four seasons of the year.
In the course of it, the rays of the sun as passing
through a window-glass and the shadows of the sun¬
dials reassume the same size, position, and direction in
which, or from which, they commenced. This is the
year, and is called the solar one, in antithesis to the
lunar year. As the lunar month is the twelfth part of
the lunar year, the twelfth part of the solar year is a
solar month in theory, the calculation being based on
the mean rotation of the sun. If, however, the calcula¬
tion is based on his varying rotation, a solar month is
the period of his staying in one sign of the zodiac.

These are the well-known two kinds of months and
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