Of the nine instruments originally contained in the case only a sector [Inv. MdS-84] has survived; its use is accurately described by Bion himself - engineer to the King for mathematical instruments and one of the best known names of his time - in his Traité de la construction et des principaux usages des instruments de mathématique, the first edition of which dates from 1709. This text provides complete tables of all the articles Bion’s workshop could supply its customers, even though certain instruments, such as telescopes, microscopes and micrometers, are only briefly described, probably to protect design details and prevent plagiarism. On the frontispiece of Bion’s books appears the address of his workshop, first as Quai de l’Horloge à l’enseigne du Soleil d’or, and then as Au Quart de cercle.
According to Daumas (op. cit.) very few of Bion’s instruments have survived which makes this case, even if incomplete, decidedly rare, as too the astronomical ring described in file 6.
The case is wooden, covered in black skin with printed Fleurs-de-lis. The six-inch (c. 15 cm) sector bears on one of its faces the words N. Bion in Paris.
The six basic scales are engraved as was the case in most of these instruments: on one side, the line of equal parts, that of planes and polygons; on the other the line of chords, that of solids and metals. On one edge is added a line used for measuring the caliber of cannons, on the other a line for computing the diameter and weight of artillery bullets.

N. Bion (1709), table 6 of IV edition.
F. Farinelli (1979), p. 193.
M. Daumas (1953), p. 109.