Day and Night
Before the invention of reliable clocks, people measured the time of day by observing the changing length and position of a shadow cast by a fixed object during the Sun’s daily passage from east to west. Many merchants, soldiers and other travelers carried pocket sundials, sometimes designed for use at more than one latitude.
In place of the marked circle used on many European dials, this dial has hours marked on arc.
As with the dial at left, the hours here are marked on an arc, but this dial uses a string rather than a pin to cast the shadow.
For use at different latitudes, rotating the dial’s vertical wheel changes the angle of the upper plate marked with hours.
The small suspension ring of this pocket dial slides to different latitudes marked on the large outer ring.
The angle formed by the dial’s cover and base allows a central string connecting them to cast shadows that mark the time at 48 degrees latitude.
As a traveler moved about, he could set the brace at the side of this dial to prop open the cover at angles match different latitudes.
The back of this handsomely crafted dial is designed for use at night.
The long pin at the dial’s center can cast a shadow on any of the four inner walls marked with hours as the Sun moves during the day.
Morning hours appear on one crescent of this dial, afternoon hours on the other; the central bar indicates months.
For orientation, a tiny compass is set in a covered box at the edge of this round dial.