[4] His life changed radically in 1725 when he was called by the Russian czar Peter the Great to Saint Petersburg to create and run the school of astronomy.

In 1760 he proposed that the international scientific community co-ordinate observations of the 1761 Transit of Venus to determine the absolute distance of the Earth from the Sun.

[6] Delisle and his party set out from St. Petersburg on 28 February 1740, arriving in Beryozovo, on the bank of the River Ob, on 9 April, having travelled via Moscow, the Volga, and Tyumen.

In the "Extrait d'un voyage fait en 1740 à Beresow en Sibérie" published in the Histoire Générale des Voyages, Delisle's ethnographic observations on the native peoples he encountered (the Votyaks,[9] Ostyaks,[10] Tartars,[11] Voguls,[12] and Chuvash)[13] include details of their religious beliefs, marital customs, means of subsistence, diet, and costume.

[14] In Delisle's unpublished papers there is a document entitled "Ordre des informations à faire sur chaque différente nation", which gives a structured outline of the ethnographic data to be collected for each particular Siberian nation: its history, geographical area, relations with other ruling powers, system of government, religion (e.g. belief in God, the Devil, life after death), knowledge in the arts and sciences, physical characteristics, costume, occupations, tools, mores, dwellings, and language.

[14] On 30 June 1740, Delisle visited a monastery in Tobolsk, where in addition to Russian and Old Church Slavonic manuscripts he was shown a mammoth tusk and other bones "d'une grandeur extraordinaire".

[15] The abbot recounted to Delisle that the previous year (1739) a Siberian merchant by the name of Fugla, already famous for his prodigious strength (he had fought and killed a bear with his bare hands), further added to his fame when he found near Yeniseisk an intact mammoth head "d'une grosseur étonnante.

[17] Ivan Kirilov (1689–1737), the first director of the imperial Cartographic Office, had Delisle officially invited to Russia with a view to his collaborating on the proposed map of the empire.

[18] For this reason, in 1740, while he was absent from the capital, undertaking his expedition to Siberia, Delisle was officially dismissed from the supervisory board in charge of the atlas.