Dài Jìnxián 戴進賢 / Ignaz Kögler, S.J.
Bavarian Jesuit. Born Landsberg am Lech (Electorate of Bavaria, Holy Roman Empire), 11 May 1680; died Beijing, 30 March 1746. The Chinese name Dài Jìnxián was given according to the conventional pattern: Dài surname (free choice), Jìnxián “Advancing-Worthiness” as personal name.
Educated at the Jesuit college in Munich; entered the Society of Jesus 1696. Trained in mathematics and astronomy at Bavarian Jesuit institutions; sent to the China mission 1715, arriving Beijing 1716.
Appointed almost immediately to the Qīntiānjiān (Imperial Astronomical Bureau): from 1717 he served on the Bureau staff under Bernard-Kilian Stumpf 紀理安; on Stumpf’s death in 1720, Kögler was appointed Director of the Qīntiānjiān (jiānzhèng 監正), succeeding to the Jesuit-held office that descended from Adam Schall von Bell (湯若望) through Ferdinand Verbiest 南懷仁, Antoine Thomas 安多, Stumpf, and now Kögler. He held the directorship for 26 years (1720–1746), the longest tenure of any of the Jesuit Bureau directors and one of the longest of any Bureau Director regardless of nationality.
Kögler’s principal scientific contribution was the proposal — formally accepted by the Yōngzhèng emperor — to revise the KR3f0018 Lìxiàng kǎochéng (then only six years from its 1724 publication) on the basis of post-1720s European astronomical data, in particular the new measurements of the solar parallax and atmospheric refraction by the Cassini-Lahire (Giovanni Domenico Cassini and Philippe de la Hire) Paris-observatory tradition, and the Keplerian-elliptical-orbit reformulation that had become the European standard since Kepler’s Astronomia nova (1609) and Tabulae Rudolphinae (1627). The Kepler theory had been left out of the 1635 Chóngzhēn lìshū (Schreck-Terrentius had had access to it but had not had time to integrate it before his death) and had also been bypassed by the Kāngxī-period Lìxiàng kǎochéng, both of which retained Tycho’s geo-heliocentric model with uniform circular orbits.
After Kögler’s 1730 (Yōngzhèng 8, sixth-month shuò) successful prediction of a solar eclipse using the new methods — predicted with greater precision than the Lìxiàng kǎochéng’s prediction — the Yōngzhèng emperor approved his proposal to “correct the sun-and-moon two tables” continuing on from the Lìxiàng kǎochéng. The work begun under Yōngzhèng was completed under Qiánlóng as the KR3f0019 Yùzhì lìxiàng kǎochéng hòubiān (1742, 10 juàn) — the first Chinese-language astronomical work to systematically employ Keplerian elliptical orbits, and through which the post-Tychonic European astronomical synthesis entered the Qīng official calendar.
Kögler also served as principal European-mathematical-staff editor on the KR3f0020 Qīndìng yíxiàng kǎochéng (1744, 30 juàn), the Qián-lóng-period instrument-and-star catalog. His Beijing-period observation of stellar positions — using both the Schall-Verbiest Beijing instruments and the new Western telescopes-and-pendulum-clocks brought to Beijing through the Lazarist-and-Jesuit network from the 1720s — supplied the empirical foundation for both works.
Kögler’s death in 1746, two years after the Yíxiàng kǎochéng publication, marked the end of the Kepler-era Jesuit synthesis at Beijing. He is buried at Zhalan 柵欄 cemetery in Beijing alongside Ricci, Schall, Verbiest, Pereira, and the long line of Jesuit Bureau directors.