Compasses – Schmalcalder Prismatic Compass by Ross Ltd. circa 1897-1907

German-born Charles Augustus Schmalcalder, a “mathematical and philosophical instrument maker” living in Middlesex in England, patented the first prismatic sighting compass in 1812.

schmalcalder 1812 patent drawings
Drawings from Schmalcalder’s 1812 patent.

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