Contact goniometer with separate arms

S.L. Penfield, New Haven, Conn., U.S.A.
Contact goniometer (cardboard 15 x 7.7 cm and separate celluloid arms) with instruction leaflet in stiff paper envelope (16 x 8.7 cm).
Signed "CONTACT GONIOMETER | MODEL A. | Designed by S.L. Penfield." and "Patented | July 31st, 1900. | Made in New Haven, Conn., U.S.A."
Samuel Lewis Penfield died in 1906 at the age of 50. The instruction leaflet mentions "Late Professor in Yale University" which dates the set after 1906.

private collection