RARE LATE 17TH CENTURY DANISH CROSS-STAFF BY ABRAHAM TADE
Dated 1699
Signed and dated on the side of the ebony shaft "A Tade * 1699", approx. 5" up from the square end. Sides with graduated scales for altitude and zenith distances. Four pearwood vanes with wing-shaped brass set screws. Smallest vane is 3.5" in length and 1.5" wide and has an elk horn sighting vane required when using the instrument as a backstaff. Two largest vanes are 15.25" and 24.125" in length and 1.5" wide. The second-smallest vane is 7.5" in length and 1.5" wide and is original to the instrument, signed in ink "D de Waay", believed to be that of an owner. The vane has a replacement brass aperture disc fitted to one end for using the instrument as a backstaff. The brass set screw is also a replacement.
Shaft .53" x 32.5". Height on stand 24". Length on stand 32.5".
Provenance:
A private collection.
Antiquairs, Grijpma & Van Hoogen, Groningen, purchased from the above circa 1990.
Hyland Granby Antiques, Hyannisport, Massachusetts, purchased from the above circa 1997.
Purchased from the above 1998.
The Kelton Collection of Marine Art & Artifacts.

References:
"The Cross-Staff, History and Development of a Navigational Instrument" by Willem F.J. Mˆrzer Bruyns, Rijksmuseum Nederlands Scheepvaart Museum; Zutphen, Walburg Institute, 1994. Historical information on p. 14-16, 20-30 and 53.
"Bulletin #80 of the Scientific Instrument Society" by Willem F.J. Mˆrzer Bruyns, March 2004.

Notes:
The definitive treatise on these instruments, "The Cross-Staff, History and Development of a Navigational Instrument" by W.F.J. Mˆrzer Bruyns, contains a list of all known instruments extant. This instrument is listed on p. 53, number 15 in oldest date order, and is the only known cross-staff by this maker. There are only four older instruments in good or very good condition and this is the only 17th Century example in private hands. Less than 100 cross-staffs exist in any condition throughout the world. Of these, only about 40 are in good to very good condition with at least one original vane. Of these, most are in institutions.

Cross-staffs were first described and probably invented around 1342 by the Catalan-born Jewish philosopher and scientist Levi Ben Gerson (1288-1344), then living in Avignon. It was then used only by astronomers. Its use was introduced at sea by the Portuguese around 1515, about 50 years after the quadrant and the astrolabe, probably inspired by Vasco da Gama's observing the Arab's use of the kamal in 1498. Initially the Portuguese used it to measure the altitude of the Pole star, preferring the mariner's astrolabe or the nautical quadrant for sun sights. In the southern hemisphere they observed a star in the Southern Cross, although this required the application of a much larger correction than that of the North Star observation.

While the backstaff was developed by Davis in 1595, and was popular for almost 200 years, the cross-staff continued in active use. Many, especially the Dutch, considered its ease and accuracy of construction and its ability to make accurate sights preferable to the backstaff. The cross-staff was finally supplanted in the Dutch East India Company ships about 1750 by the octant and later the sextant.

Overall condition is excellent. The shaft is original and in excellent condition, with one original vane, and fitted with three additional modern ones.

The absence of a condition report does not imply an object is free of defects. All items may have normal signs of age and wear commensurate with their
age; these issues will likely not be mentioned in the condition report. Please contact Eldred's before the auction with any condition questions. Questions about condition will not be answered after purchase. Condition reports are provided as a courtesy, and we are not responsible for any errors or omissions. Important note on frames: Frames are not guaranteed to be in the same condition as they are in the item photograph. Due to handling and shipping, many frames, especially antique ones, are prone to losses. If you have questions about the condition of a frame, please contact us prior to the auction.