Description and Notes:
The above picture shows the two sides of the sector. Although there is no maker's name or signature engraved on this instrument, but according to the 1758 edition of The Construction and Principal Uses of Mathematical Instruments, by M. Bion, it is similar to typical eighteenth century French made sector. It is made of nickel silver, which has been known in the eighteenth century but not commonly used on mathematical instruments until the nineteenth century. Therefore this sector may be dated to the end of the eighteenth or the beginning of the nineteenth century. It has been engraved with the six types of lines which are common to French sectors of the same period, namely, line of equal parts (les parties egales), line of planes (les plans), line of polygons (les polygones), line of chords (les cordes), line of solids (les solides), and line of metals (les Metaux). However, in addition to these common lines, this sector also has the line of weight of the ball (poids des boulets) and that of the size of rooms (calibre des pieces) engraved on the edge of the legs.
This sector is very well made and is in a near fine condition.