The early Jesuit missionaries had already endeavoured to make known to Europe the true geography of China, of which at the end of the 16th century even the best cartographers were utterly ignorant.
In 1701 the great work of the general map of the empire, begun by the topographical drawing of the capital city of Beijing and its environs, including the ancient summer residences of the emperors and 1700 towns or villages, was assigned to Antoine Thomas, a Belgian of Namur, and three Frenchmen, Joachim Bouvet, Jean Baptiste Régis and Dominique Parrenin.
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.
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 Régis.
Régis and Cardoso drew the map of Shandong; Jartoux, Fridelli and Bonjour traversed Mongolia as far as Lake Baikal in the north and the Zunghar Khanate to the west.
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.
Jartoux, who with Régis and Fridelli had the largest share in it, sent a copy to France, where it was published by Jean-Baptiste du Halde with the assistance of the celebrated geographer Jean Baptiste Bourguignon d'Anville in the Description de la Chine (1735).
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".