Early Dutch-German Altitude Dials

Click for a larger image suitable for printingAt the present I am studying a small group of 17th-century altimetric or vertical brass sundials of Dutch-German origin.

They measure about 60 mm in width (although at least one is known to be almost twice as wide) and are characterized by having their hour scale marked on a raised ear-lobe shaped extension to an otherwise circular flat disk (see illustration). They all feature a movable arm with a pinhole mounted on the reverse for adjusting the gnomon to the appropriate calendar date (the first half of the year is usually on the front, the other half on the back).

Many of these dials have a multi-rayed Sun as decorative motif and are stamped with a crown, indicating an Amsterdam origin. Most of them only function for one particular latitude (52;35°) but some can be adjusted for a range of latitudes.

At the moment I have been able to trace about twenty examples of this type of sundial in various collections:

As I am preparing a paper on this group of sundials, I would be very grateful to learn whether there are other sundials of this type preserved in private or institutional collections that I am unaware of.

Robert H. van Gent
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document last updated on June 7, 2006

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