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Day and Night

Day and Night

  • Exhibition Text

    • 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.

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In This Section

Horizontal Compass Dial (brass)

Horizontal Compass Dial (Brass)

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.

Polar Dial

Polar Dial

For use at different latitudes, rotating the dial’s vertical wheel changes the angle of the upper plate marked with hours.

Universal Ring Dial

Universal Ring Dial

The small suspension ring of this pocket dial slides to different latitudes marked on the large outer ring.

Book Dial (16th century)

Book Dial (16th Century)

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.

Book Dial (17th century)

Book Dial (17th Century)

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.

Open Block Dial

Open Block Dial

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.

Crescent Dial and Calendar

Crescent Dial and Calendar

Morning hours appear on one crescent of this dial, afternoon hours on the other; the central bar indicates months.

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