Horizontal and analemmatic sundial

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Horizontal and analemmatic sundial
Manufacturer	Engelbrecht, Beraunae
Production years	1784
Production location	Bohemia

With a combination of these two types of dials it is possible, by turning the instrument until both dials indicate the same time, to dispense with the use of a compass for setting. It is, however, necessary to know whether the sun is east or west of the meridian as similar readings on the two dials can be obtained in two positions corresponding to equal altitudes of the sun.

[edit] How it works

The horizontal dial has a folding gnomon for a latitude of 510 and, in addition to the ordinary hour-lines, there are curves indicating the paths at different times of the year of the shadow of a notch in the edge of the gnomon. In an analemmatic dial the hours are indicated by the intersection of the shadow of a vertical gnomon and an elliptical scale of hours. The gnomon has, however, to be adjusted in a north and south direction according to the time of the year. A plummet and scale allows the instrument to be set for latitudes between 400 and 600. This sundial was made by Engelbrecht, Beraunae in Bohemia, 1784.

[edit] Memories

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[edit] In the Science Museum's Records

Inv. No: 1894-10