ABSTRACT
Giacomo Rho 羅雅谷, who hailed from Milan, studied mathematics and entered the Society of Jesus at the age of twenty-two. He left Europe for China in 1618 when his fellow Jesuit Nicolas Trigault 金尼閣 (1577-1628) returned to the mission with a group of new recruits. He reached Macau in 1622 and stayed there for two years. He then accompanied Alfonso Vagnoni (or Vagnone) 高一志 (1566/8-1640) to Shanxi, where he preached for five or six years. In 1630, he was sent for to proceed to Beijing to assist Johann Adam Schall von Bell 湯若望 (1591-1666) in his efforts to improve the calendar under the direction of Xu Guangqi 徐光啟 (1562-1633). The task was completed in 1634, when the 137 volumes of Books on the Calendar and Astronomy from the Chongzhen Reign 崇禎曆書 (Chongzhen lishu), were presented to the emperor. Giacomo Rho was among those responsible for ensuring that the work adopted the cosmology of Tycho Brahe, which still placed the earth at the centre of the universe but explained the orbits of the five planets by means of a heliocentric model.
