204 



Dr. Gr. Thibaut — On t\e Suri/aprajnapti, 



[No. 4, 



solstice they have reached the original minimum. On the day of the win- 

 ter solstice the diameter ot" the solar circle amounts to 476,000 li (the li is 

 a certain Chinese measure of length) ; its circumference to 3 x 476,000= 

 1,428,000 li. The corresponding numbers for the circle, described on the 

 day of the summer solstice, are 238,000 and 714,000. Between the inner- 

 most and the outermost circle there lie five other circles, which the sun 

 describes in the months intervening between the two solstices, so that there 

 are altogether seven circles ; the six intervals between these are said to 

 correspond to the months of the year (2x6 = 12). So it appears that 

 the Tcheou-Pei assumes separate solar circles for each month only, not for 

 each day. Each circle is at the distance of 19,833^ li from the two neigh- 

 bouring circles. 



The terrestrial place for which all the calculations of the Tcheou-pei 

 are made is said to have such a situation that it is distant 16,000 li from 

 the spot lying perpendicularly under the sun on the day of the summer 

 solstice and 185,000 li from the spot lying perpendicularly under the sun 

 on the day of the winter solstice ; the distance of the place of observation 

 from the pole, i. e., the spot at the centre of the earth which lies perpendi- 

 cularly under the celestial pole, is said to amount to 103,000 li. Round the 

 terrestrial pole there extends a circle of 11,500 li radius, which is the terres- 

 trial counterpart of the circle described by the polar star round the celes- 

 tial pole. The light of the sun extends 167,000 li in each direction, so 

 that on the day of the winter solstice when the sun moves in the exterior 

 circle it extends at midday only 32,000 li beyond the place of observation 

 and so does not reach up to the polar circle. On the days of the two 

 equinoxes when the sun is moving in the fourth circle — the diameter of 

 •which amounts to 357,000 li— the rays of the sun just reach up to the 

 polar circle. On the day of the summer solstice when the sun moves in 

 the interior circle his raj's reach beyond the pole to the extent of 48,000 li, 

 so that then the whole polar circle is continually illuminated. When the 

 sun in his daily revolution has reached the extreme north point, it is midday 

 in the northern region and midnight in the southern region ; when he has 

 reached the east point, it is midday in the eastern, midnight in the western 

 region ; when he has reached the south point, it is midday in the southern, 

 midnight in the northern region ; when he has reached the west point, it is 

 midday in the western, midnight in the eastern region. As the light of 

 the sun always reaches 167,000 li each way, we must add 2 x 167,000 to 

 the diameter of the circle, described on the day of the winter solstice, in 

 order to obtain the diameter of the circle representing the outmost limit 

 reached by the rays of the sun ; the diameter of this circle is therefore 

 810,000 li. 



On the day of the winter solstice the space illuminated by the sun 



