The proper season is when the weather is very dry; the special days
are those when the moon is in the constellations of the Sieve, the
Wall, the Wing or the Cross-bar;
These are, respectively, the 7th, 14th, 27th, and 28th of the
二十八宮 Twenty-eight Stellar Mansions, corresponding roughly
to Sagittarius, Pegasus, Crater and Corvus. The original text,
followed by the _T‘u Shu_, has 月 in place of 宿; the present
reading rests on the authority of the _T‘ung Tien_ and _Yü Lan_.
Tu Mu says: 宿者月之所宿也. For 箕壁, both _T‘ung Tien_ and _Yü Lan_
give the more precise location 戊箕東壁. Mei Yao-ch‘ên tells us
that by 箕 is meant the tail of the 龍 Dragon; by 壁, the eastern
part of that constellation; by 翼 and 軫, the tail of the 鶉 Quail.
for these four are all days of rising wind.
此四宿者 is elliptical for 月在此四宿之日. 蕭繹 Hsiao I (afterwards
fourth Emperor of the Liang dynasty, A.D. 552–555) is quoted by Tu
Yu as saying that the days 丙丁 of spring, 戊已 of summer, 壬癸 of
autumn, and 甲乙 of winter bring fierce gales of wind and rain.