8 Memoir on the Diminution of the 
of Chinese astronomy, and particularly of Cocheou- King’s, 
all the details they will be able to get at. 
Let us first discuss such of the enomon’s observations as 
were not’ made on the solstices. “These observations re- 
duced to feet, containing a great number of decimals , appear 
to have been Haas or at “least set down, with more precision 
than those of the solstices. i, 
The three noon observations made about the solstices are 
those of the 10th June 1278, 29th June 1279, and 29th Nov. 
1279. The corresponding lengths of shadow observed were 
11 feet 7775; 12 ft. 264; 76 ft. 74, 
which give for the corresponding distance of the sun from 
the zenith, corrected by refraction and parallax, and reduced 
to the poiee: 
16° 20/ 35",6; 10° 20'38",0 63° 24457". 
The mean of the two first observations gives ie: 20' 37”,2 
for the sun’s distance from the zenith in the summer sol- 
stice ; which being subtracted -from the sun’s distance from 
the zenith in the. winter solstice, half the difference will 
give 23° 32'9",9 for the apparent obliquity of the ecliptic, 
The putation was then — 7,4; so that the true obliquity 
was 23° 32’ 25” in 12979... According to the new Tables, 
this obliquity should have been 23° 39’ 98” 593 the dif- 
ference 20” is within the limits of errors in observations. 
Half the sum of the two distances of the san to the zenith 
gives 39° 52’ 47,1 for the apparent distance of the equator 
from the zenith, or for the apparent altitude of the pole. 
Subtracting 7,4 on account of the nutation, about the 
middle of 1279, we shall have 39? 52’ 39”,7 for the true 
altitude of the pole. ' 
The two lengths of solstitial shadows, eleven feet seven 
inches, and 79 feet eizht inches, give for the respective di- 
stances of the sun from the zenith, after being corrected 
for the refraction and parallax, ‘ 
16° 18' 28,9, and 63° 24' 24”, 
whence is found 93° 32’ 57,5 for the ecliptic’s obliquity, 
and 39° 51’ 26",5 ‘for the altitude of the pole. These re- 
sults difier a little from the preceding; but it may be sup- 
posed with some probability that the difference is Gwing to 
some decimal that has been omitted in the solstitial lengths 
of the shadows, in which it.appears that the first decimal 
only was preserved. » Ae 
Ceinsideline now the observations made towards. the 
equipoxes ; that is to say, those made on the 15th March, 
20th March, and 29th August, the lengths of the observed 
shadows 
