Naval Mariner's Sundial

A horizontal sundial consists of one dial plate, marked off in hours, and the gnomon which sits on the noon line and projects out from the dial plate.

In order to tell the correct local time, the gnomon must be parallel with the Earth's axis, or, in other words, that it should point towards the celestial pole. In the northern hemisphere, this means, for practical purposes, that the gnomon should point at the Pole Star.

The chief advantages of the horizontal sundial are that it is easy to read, and the sun lights the face throughout the year. All the hour-lines intersect at the point where the gnomon's style crosses the horizontal plane. Since the style is aligned with the Earth's rotational axis, the style points true North and its angle with the horizontal equals the sundial's geographical latitude.

Made of wood and brass, this historically accurate sundial, based off an original in the Naval Museum of Madrid, features a compass and beautifully printed sundial faces. The exterior cover is topped with a list of major port cities and their latitude, handy reference for any navigator. The perfect item for those with the spirit of discovery. 

Historical Example

Diptych Dial, by Stockert, 18th Century - Oxford Museum

Dimensions
Length: 3 in
Width: 2 in
Height: 0.8 in