Greetings to all readers, At the present I am studying a small group of 17th-century altimetric brass sundials of Dutch 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 an ear-lobe shaped extension to an otherwise circular flat disk. An illustration can be found in:
http://www.fys.ruu.nl/~vgent/sundial/sundial.htm They all feature a movable pinhole arm mounted on the reverse for adjusting the gnomon to the appropriate calendar date. Many of them have a multirayed Sun as motif and are stamped with a crown. Most of them only function at one particular latitude (52;35°) but some can be adjusted to a whole range of latitudes. At the moment I have been able to trace twelve examples of this type of sundial in various collections: 1 Museum Boerhaave (Leiden), unsigned, dated 1615 2 National(?) Museum (Gdansk), made(?) by Johannes Hevelius in 1638 (lost since 1945?) 3 Eise Eisinga Planetarium (Franeker), made by Jan Roelas van Vries in 1642 4 Dutch Maritime Museum (Amsterdam), made by François van Oerle in 1660 5 Private Dutch collection, made by Jan van Call (< 1667) 6 Joseph Drecker collection (Harvard?), made by 'IW' (or 'IVV') in 1672 7 Sotheby Mak van Waay Amsterdam (1984), made by 'IW' (or 'IVV') in 1680 8 Dutch Maritime Museum (Amsterdam), made by Willem Sneewins in 1700 9 Joseph Drecker collection (Harvard?), made by 'PLK' in 1755 10 British Museum (London), made by 'HWW', not dated 11 Dutch Maritime Museum (Amsterdam), unsigned, not dated 12 Museum for the History of Science (Oxford), unsigned, not dated As I am preparing a paper on these 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 Zaagmolenkade 50 3515 AE Utrecht The Netherlands Tel./fax: 00-31-30-2720269
