33 3 2014 285 297 Studies in the History of Natural Sciences Vol. 33 No. 3 2014 210008 N092 P1-092 A 1000-0224 2014 03-0285-13 0 1437 ~ 1442 1 1261 1931 1 2 2014-03-12 2014-05-09 1943 1971 11020302

286 33 1 1 2 2 2 2 2 2

3 287 3 1 2 2 80 4 2 923 955 786 24 10 1. 5 88 40 3 1. 8 1. 9 3

288 33 2 4 4 2 2 1 2 1 3 12

3 289 120 λ t t 0 λ 0 t t 0 Δt t 0 = t + Δt 1 Δt Δt = λ 0 - λ = Δλ 2 λ 0 λ λ 0 > λ Δλ = λ 0 - λ = Δt > 0 t 0 > t Δλ Δλ 5 λ λ λ 0 Δλ = λ 0 - λ Δλ = λ 0 - λ 2

290 33 2 1. 8 2 4 2 5 λ = 118 48' 116 24' Δλ = 118 48' - 116 24' = 2 24' = 2. 4 5 2 118 48' 2 1

3 291 2 3 4 5 5. 1 1 1268 5. 2 1 1268 5. 3 1368 1644 276 5. 4 1562 ~ 1633 1576 ~ 1630 1559 ~ 1654 1591 ~ 1666 1593 ~ 1638

292 33 6 6. 1 1399 1403 1421 1408 1441 6. 2 276 1 1449 1403 1449 6 2 1449 6

3 293 3 1635 1635 1635 6 4 1643 6 7 7. 1-7. 2 1 2 1630

294 33 1633 3 1629 1 1268 1634 1 1268 1629 1634 1644 7. 3 8 1 2-3 5 40' 1 1263

3 295 8. 1 8. 2 2. 4 1. 8 8. 3 - λ λ 0 Δλ = λ 0 - λ 1. 8-2001 6 λ = 120 E λ = 114 30' E Δλ = 120-114 30' = 5 30' 6 5 30' Δt = 22

296 33 6 Δt = 22 5 30' - 1 M / /. 1975. 2. M. 1989. 1783. 3. J. 1934 5 5 67 ~ 71. 4. M. 2011. 326. 5. M. 1985. 6 M / /. 1975. 3527 ~ 3553.

3 297 A Textual Research about the Deviation of the Scribed Scale Lines on the Horizontal Sundial Attached to the Abridged Armilla Built during the Ming Dynasty and the Correction for the Longitude Difference LIU Yan ZHANG Yang Purple Mountain Observatory CAS Nanjing 210008 China Abstract There is a horizontal sundial built according to Western astronomy as an attachment of the Abridged Armilla now preserved by the Purple Mountain Observatory. The Abridged Armilla is a famous ancient Chinese astronomical instrument built during the Ming Dynasty. As for the past history of this horizontal sundial most scholars over the last 100 years believed that it was added during the Qing Dynasty. There remains a major unresolved question about the scribed scale lines on the surface of this horizontal sundial. Between the scale lines for the high noon and the meridian there is an angle of deviation. The high noon line is deviated eastwards from the meridian line for about 2 degrees. The doubt is why there is such a deviation angle With a comprehensive textual research on this doubt the authors conclude that the deviation angle of about 2 degrees corresponds to the difference between the geographical longitudes of Nanjing and Beijing cities and it must be designed by the maker intentionally. The authors note that during the whole Ming Dynasty the official China standard time was Nanjing local time named as Time of Ying-tian rather than Beijing local time named as Time of Shun-tian. In order to directly and conveniently readout Nanjing local time through the scribed scale lines on this sundial in the city of Beijing the longitude difference of the two cities must be taken into consideration when building the sundial. Such a longitude difference is just in accordance with the deviation angle of about 2 degrees as expressed by the scribed scale lines on above-mentioned sundial. During the last stage of the Ming Dynasty the Chinese astronomers had already known something about geographical longitude and set up the concept of time difference between locations of different geographical longitudes. So it is reasonable to conclude that this sundial must have been built in Beijing during the last stage of the Ming Dynasty rather than during the Qing Dynasty. Keywords the Abridged Armilla horizontal sundial deviation of scribed scale lines correction for the time difference