Signed: Butterfield AParis
Fig. 47 (left).
Not all pocket-sized instruments incorporated both a level and sight. The observing part of this instrument by the Paris-based English maker Michael Butterfield consists only of a level. The decorated steel plummet moves over a scale of 45° whose arc is hinged to fold into alignment with the upright. As Nicolas Bion noted when describing and illustrating this form of instrument, the folding construction simply made the instrument more compact and easier to fit into a case (catalogue no. 32).
The reverse of the upright carries gauge scales. There is a joint scale for 'Calibres des Pieces' and 'Diamettres et Poids des Boulets' which allows for windage and provides the weight of shot from ¼ to 5 pounds. There is also a scale for powder calibrated over the same range and marked 'Demy Diamettres des Spheres des Poudres'.
Height: 102 mm
Inventory no. 52,788