"we" referred to two of Thévenot's protégés, the Dutchman Jan Swammerdam (1637–1680) and the Dane Niels Stensen ("Steno") (1638–86). Thévenot invented the spirit level (or bubble level) some time before 2 February 1661, which he filled with alcohol and mounted on a stone ruler fitted with a viewing lens. This date can be established from Thévenot's correspondence with scientist Christiaan Huygens. Within a year of this date, the inventor circulated details of his invention to others, including Robert Hooke in London and Vincenzo Viviani in Florence. It is occasionally argued that these bubble levels did not come into widespread use until the beginning of the 18th centurythe earliest surviving examples being from that timebut Adrien Auzout had recommended that the Académie Royale des Sciences take "levels of the Thévenot type" on its expedition to Madagascar in 1666. It is very likely that these levels were in use in France and elsewhere long before the beginning of the 18th century. Other works Many of Thévenot's maps of the Middle East were published in his (Paris, 1663), a collection of translations of voyages of discovery (such as that of Cosmas Indicopleustes). One of these was one of the earliest and most detailed depictions of southern Iraq (his nephew Jean de Thévenot later visited this region). Thévenot makes reference to the Mandaeans of the Basra region, and includes a printed page from one of this sect's holy books, one of the first printed appearances of the Mandaean language in Europe. The map by Thévenot, — in the , is a French version of the 1644 chart of Abel Tasman's discoveries using information from Dutch sources, notably Joan Blaeu's world map published in 1659. Although Thévenot said that he had taken his chart from the one inlaid into the floor of the Amsterdam Town Hall, in fact it appears to be an almost exact copy of that of Joan Blaeu in his published in 1659 in the (“Atlas of the Great Elector“). The map of the world set into the floor of the great hall of the Amsterdam Town Hall was drawn from Blaeu's world map of 1648. Once Blaeu's map of the world appeared other mapmakers, such as Thévenot, copied his depiction of New Holland. Hollandia Nova in the Kurfürsten Atlas is shown as it appears in Blaeu's world map of 1648, Nova et Accuratissima Terrarum Orbis Tabula. Thévenot divided the continent in