Sector, by Butterfield, Paris, 18th Century

Brass sector. On the signature side are sectoral scales of chords and metals, with a single scale of the weight of shot. There is a label for a scale of solids in the usual place before the metal scale, but no actual scale. The reverse carries equal parts and polygons, with a single scale of the calibre of artillery.

The extraneous label for a scale of solids suggests uncomprehending rote manufacture at best. This may be an instrument to which Butterfield's well-known name was falsely applied.