Jean-Baptiste Régis (died 1738) was a French Jesuit missionary in imperial China.
He was born at Istres in Provence on 11 June 1663, or 29 January 1664; died at Peking on 24 November 1738. He was received into the Society of Jesus on 14 September 1683, or 13 September 1679, and in 1698 went on the Chinese mission, where he served science and the Catholic religion for forty years, and took the chief share in the making of the general map of the Chinese Empire.
The early Jesuit missionaries had already endeavoured to make known to Europe the true geography of China, of which at the end of the sixteenth century even the best cartographers were utterly ignorant. Their achievements up to the middle of the seventeenth century are summed up in the "Novus Atlas Sinensis" published by Father Martin Martini (Amsterdam, 1655). He was greatly assisted in this work by Chinese books of geography, where he found a mass of descriptive information, the distances between important places, and even maps which however were very crude, the distances having been measured with little exactitude. These imperfect data he supplemented and completed by astronomical observations made in the chief towns by himself and his associates; hence the positions of his Atlas are remarkably accurate. The favour enjoyed by the missionaries with the Chinese emperor K'ang-hi (1662–1722) made it possible for them to improve on this. Father Ferdinand Verbiest collected the earliest ideas of 'Tatary' (i.e. the Mongol Empire) during two journeys made to that country with the emperor (1682-3).
The arrival in China in 1687 of French Jesuits sent by king Louis XIV gave new impetus to scholarly labours in the mission, especially to geography. Provided with perfected instruments and trained in the methods of the astronomers of the observatory of Paris, the new missionaries were able to determine more correctly locations already calculated. The "Mémoires" and the "Histoire de l'Academie des Sciences" record their observations. Father Jean-François Gerbillion made eight journeys through Tatary and Mongolia (1688–98) acquiring more geographical information concerning them. In 1701 the great work of the general map of the empire, begun by the topographical drawing of the capital city of Peking and its environs, including the ancient summer residences of the emperors and 1700 towns or villages, was assigned to Father Antoine Thomas, a Belgian of Namur, and three Frenchmen, Joachim Bouvet, Jean Baptiste Régis and Dominique Parennin. Ming Emperor K'ang-hi, who wished to take measures against the periodic overflow of the rivers of Zhili, was satisfied.
Fr. Parennin then induced him to consent to a map of the Great Wall of China. Fathers Bouvet, Régis and Pierre Jartoux measured their route to the eastern extremity of the famous rampart by means of regularly divided cords, keeping track of directions with the assistance of a compass, and frequently observing the meridian of the sun in order to calculate latitudes. In four days they reached the Gulf of Zhili (8 June 1708) and began operations on the great Wall. On 16 October they estimated its extent to be 21° long., or almost half the widest breadth of the United States from east to west and had determined the positions of the fortified towns "by which it was flanked", according to Fr. Régis. At the end of two months, Bouvet, being ill, retired to Peking. Régis and Jartoux reached the western edge of the Great Wall at Kia-yu-Koan (modern Jiayuguan) and completed their work by the mensuration of an interior lateral wall which had brought them to Si-ning (Xining), on the frontier of Tibet, near Lake Kukunor. They returned to Peking on 10 January 1709. Their map pleased the emperor, who requested the continuation of the work for the provinces outside the Great Wall and for China proper.
Régis, Jartoux and Fr. Ernbert Fridelli, from the Austrian Tyrol, set out for the northeast. In two expeditions (8 May - 17 December 1709; 22 July - 14 December 1710) they made the map of Liaodong and Manchuria, and during the interval drew the province of Chi-li, in which Peking is situated. In 1711 Father Francis Cardoso, a Portuguese, and the Augustinian Father Guillaume Bonjour, the only non-Jesuit, joined the geographers. Régis and Cardoso drew the map of Shang-tung; Jartoux, Fridelli and Bonjour traversed Mongolia as far as Lake Baikal in the north and the entrance of eastern Turkistan to the west. The year 1712 brought a new reinforcement; Frs. Vincent de Tartre and Cardoso made the maps of Shan-si and Shen-si (1712–14), Kiang-si and Kwang-tung, and Kwang-si; Frs. Anne-Marie de Mailla, Roman Hinderer, an Alsatian, and Régis laboured (1712–15) on the maps of Hu-nan, Kiang-nan, Che-kiang, Fu-kien and the Island of Formosa. Meanwhile Fridelli and Bonjour were at Sze-chuan, where Fr. Bonjour died on 23 December 1714, and was replaced by Régis on 24 March 1715. He assisted Fridelli with the maps of Yun-nan, Kwei-chow (Guizhou) and Hu-kwang. After ten years' labour the new map of China was completed on 1 January 1717. The fundamental method employed was the exact measurement of distances from which was obtained the longitude and latitude of places; this, supplemented and controlled by the observations of the meridians of the sun and the polar stars, directly gave the latitude. The missionaries were sometimes assisted by the observation of eclipses of the moon and the satellites of Jupiter, of which more perfect process they desired to make use to obtain longitudes, but conditions did not permit.
In reply to a criticism of Féret, the learned secretary of the Académie des Inscriptions et Belles-Lettres, Antoine Gaubil wrote (5 November 1736):
Ferdinand de Richthofer, the geologist and explorer of China, wrote "If we consider the time at which it was made, the map of the Jesuits, as a whole, may be called a masterpiece" (China, I, 686).
Father Jartoux, who with Frs. Régis and Fridelli had the largest share in it, sent a copy to France, where it was published by Fr. Jean-Baptiste du Halde with the assistance of the celebrated geographer Jean Baptiste Bourguignon d'Anville in the "Description de la Chine" (1735). Régis composed a short commentary on it under the name of "Nouvelle géographie de la Chine et de la Tartarie orientale", which is preserved in the Bibliothèque Nationale, Paris, fr. MS. 17, 242; Father Du Halde availed himself of the writing to a great extent but would have done better to publish it entire.
Régis also turned his attention to the ancient Chinese books (king). Fr. Gaubil praises his "sane criticism" on the subject, and the English sinologist James Legge writes: "Régis is known as the interpreter of the Yih-king (ie the Yijing or Book of Changes) . His work was edited at Stuttgart, in 1864, by Julius Mol. One part of the first volume is occupied with Prolegomena which contain the most valuable introduction to the Chinese higher classics that has yet been published" ("Notions of the Chinese concerning God and the spirits", 1852, 69).
Father Gaubil describes his great virtue as humility and modesty, and says: "He was universally esteemed and loved by the missionaries of various bodies, Christians and the people of the Court who associated with him".