A fine Demi Pied De Roi by Lasnier Paris ca. 1750. This compact 11cm instrument combines all of the calculating features of a sector (lines, chords, metals, and polygons) with a plumb bob and level. The joint’s atypical engraving, which vaguely resembles palm leaves, can be seen on other sectors by Lasnier.
There were several manufacturers in the 17th and 18th Centuries named Lasnier. This sector is most likely by Pierre Alexis Lasnier (Birthdate unknown, Active by 1734 – Death in 1777). According to Marcelin he took over the sign of J. Lefebvre Aux Deux Globes around 1734. His brother Charles-Henri (Born 1709) apprenticed to him. He is recorded working in Paris at the Rue de la Pelleterie in 1734 and Quai de l’Horloge in 1735.
A similar sector, without level, can be seen in the Harvard collection:
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