Early Dutch-German Altitude Dials

At 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:

• Museum Boerhaave (Leiden, NL) – unsigned, features an epact scale for 1615 to 1634
• Muzeum Pomorski (Gdansk, P) – unsigned, owned by Johannes Hevelius in 1638(?), lost since 1945(?)
• Eise Eisinga Planetarium (Franeker, NL) – made by Jan Roelas van Vries in 1642
• Private collection (NL) – made by Jan Backer van Kall in 1644
• Private collection (NL) – made by Jan van Call (before 1667)
• Private collection (NL) – made by Pieter van Call, not dated
• Netherlands Maritime Museum (Amsterdam, NL) – made by François van Oerle in 1660
• Collection of Historical Scientific Instruments (Harvard, USA) – made by ‘IW’ (or ‘IVV’) in 1672
• Musee d’Histoire des Sciences (Geneva, CH) – made by ‘IW’ (or ‘IVV’) in 1680
• Formerly in the Arthur Frank collection, auctioned by Sotheby’s in 1986 – made by ‘IW’ (or ‘IVV’) in 1680 (for an image of the front, click here)
• Private collection (NL) – made by ‘IW’ (or ‘IVV’) in 16?? (same as previous entry?)
• Netherlands Maritime Museum (Amsterdam, NL) – made by Willem Sneewins, features a tide predictor, an epact scale and a perpetual calendar for 1700 to 1728 (for an image, click here for the front or the back)
• Collection of Historical Scientific Instruments (Harvard, USA) – made by ‘PLK’ in 1755

• Private collection (NL) – unsigned, not dated
• British Museum (London, GB) – made by a German instrument maker ‘HW/W’, not dated
• Metropolitan Museum of Art (New York, USA) – made by a German instrument maker ‘HW/W’, not dated
• Museum of Applied Arts (Budapest, H) – probably German, not dated
• Netherlands Maritime Museum (Amsterdam, NL) – unsigned, not dated
• Museum for the History of Science (Oxford, GB) – unsigned, not dated
• Collection of Historical Scientific Instruments (Harvard, USA) – unsigned, not dated
• Auctioned by Van Glerum (The Hague, NL) in 1992/93, now probably in a German private collection – no further details known

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.

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document last updated on June 7, 2006

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