Fig. 46

Bion's text was intended to provide a survey of the full range of mathematical instruments then available, and it included a section on gunnery. His well-illustrated work served as a standard reference not just through its several 18th-century French editions, but on a more international stage too. A German edition was published in 1712 and frequently reissued and an English translation by Edmund Stone appeared in 1723. Stone's edition is particularly interesting for it adds specifically English instrument types absent in the French original. Thus a description and engraving of English gunner's calipers (see catalogue no. 10) were added to the account of French gunnery instruments. The second English edition of 1758 further supplemented the original offering, in effect proclaiming the superiority of the latest English innovations.

In the original text Bion described the construction and use of various calipers and levelling instruments for guns. In addition to levels using rigid plummets moving over an arc scale (such as catalogue no. 26), he shows a folding square set up on a breech (catalogue nos 33 and 34). His engraved plate also gives readers unacquainted with warfare a general sense of the different trajectories typical for cannons and mortars and provides a graphical display of the variation of range with elevation.

Although Bion is now probably best known as an author he was equally recognized as an instrument maker in his own day (cf. catalogue no. 9). He achieved an official position as royal instrument maker, with the title 'ingénieur du roi pour les instruments de mathématique'.