Book Dial (Rosewood)
Rosewood, silver, gilded brass
The back of this handsomely crafted dial is designed for use at night. The user held the dial vertically, adjusted the shorter sighting rule to align with the pointer stars of the Big Dipper and noted where the edge of this rule lay on the hours marked near the rim. Other nighttime observations could also be made.
AMNH Hayden Planetarium Collection 2010