Retrospect of French Literature--- History. 687 
Vang. . This prince, one of the best 
who. ever. governed China, was also 
one of the most learned men of his 
time,and on both accounts his memory 
is still respected among his country- 
men. According to a tradition: at- 
tested by books anterior to the pre- 
scription, this prince determined the 
leneths. of the meridional shadows of 
the sun during the two solstices, and 
also, fixed the position of the solstices 
in the heavens.* The measures of the 
shadows detailed by Father _Gaubil 
were calculated by the learned Freret, 
in his ¢‘Dissertation sur la Certitude de 
la Chronologie Chinoise,” and have 
since undergone that process with still 
greater exactitude by M. Laplace, in 
his ‘« Exposition du Systeme du Mon- 
de.”+  Atter the necessary correc- 
tions, the latter found the latitude of. 
the city of Loyang, the place where 
the observations were made, to be 
precisely the same as that. ascertained 
by the missionaries; and the difference 
of the two solstitial heights then re. 
marked, made him acquainted with the 
obliquity of the ecliptic at the period 
when those remarks were made. He 
found it to be 23 deg. 53 min. 2 sec. 
The agreement of the latitude of 
Tcheon-Koung with that of the mis- 
‘sionaries, is a Very, important ve- 
rification. The epoch of the regency 
of Tcheon-Koung has been fixed by 
Freret between the years 1098 and 
1104, before our wra, and the obser- 
vation alluded to, took place in one of 
those six years. This determination 
relative to the ingenious calculations 
referred to above, perfectly agrees with 
those of P. Gaubil, and the tribunal of 
history, as well as ofthe lettered men 
among the Chinese. Now, if in con- 
formity to the present formule of ce- 
festial mechanism, we calculate the va-~ 
Jue of the obliquity of the ecliptic, 
for the epoch in question, it will be 
found equal to 23 deg. 51 min. 52 sec. 
being only two minutes less than what 
results from the shadows of the gno. 
mon. Now, there is here no interven. 
ing objection ; for the obliquity of the 
ecliptic has considerably changed since 
the time of Tcheon-Koung to our own 
days. It is at present 24 minutes 
(plus faible) less, than it was then, and 
* Gaubil, Connoissance des Temps de 
1809, p. 393. Lettres Edifi. tom, 27. p. 
124. : 
t Sme edit. in 8yo. &c, 2, p.269 & 400, 
\ 
most certainly neither Tcheoh-Koung” 
nor P. Gaubil, nor any of the other 
Missionaries, were acquainted with the 
laws ofits diminution; for eve when 
the last wrote, the existence of these 
chanzes were not as'yet fully proved. * 
According io thé same tradition 
Teheon-Koung had also determined 
the positiowof the winter solstice in’ 
the heavens, and fixed it at two Chi. 
nese degrees from the ‘constellation Vu, 
which commences with the star e Aqua. 
rius. “If we equally connect this ob- 
servation with the year 1100 before our 
era, and by means of the formule, 
of the celestial’ mechanism (mecha. ’ 
nique céleste) we caleulate the position 
of the solstice for that epoch, we shall 
discover that it only differs from that 
of Teheon-Koung to the amount of 
49 minutes of degrees, or about thirty 
minutes of time.t 
It suffices then, in order to make 
the observations and the theory agree, 
to’suppose that Tcheor-Koung may 
have deceived himself to the amount 
of that quantity relative to the time 
of the solstice: this is not at all incre- 
dible, when we recollect, that the Chi- 
ancse at the period alluded to, measur. 
ed time by clepsydra, according tothe 
suecessive heights of water in a’ vase, 
where it rose in the exact proportion as 
it descended from another vesse! which 
was more elevated. They détermined 
the place of the solstice by noting the 
Stars which passed the meridian 12 
hours after’the sun; and consequently 
it occurred, that they had measured 
this interval of 12 hours, within three 
tninutes, which, considering the mean: 
used, isa remarkable degree of pre- 
cision. It may, moreover, be sus- 
pected, that the little dif erence just 
alluded to, proceeds from an error 
in the probable epoch of this obser. 
vation, which we have fixed at the 
year 1100 before our wera; therefore 
it is sufficient in order to make the 
whole agree, merely’ to ascend 5% 
years higher. Whatever may be the 
case, the smallness of these differences 
is an undenimble proof of ihe excellency - 
of ourastronomicai tables, and the re- 
a a a a 
* Exposition du Systeme du Monde: 
According to the obliquity of the ecliptic, 
as certified by the tables for the year 1100 
before the Christian ara, the observations 
of I'cheon-Koung make the latitude cor. 
respond with the present determination 
of it. 
“+ Expositedu Syst. du Monde. 
ality 
