Accession No

0731

Brief Description

navicula, ship-shaped dial, possibly by SF, English, 1620

Origin

England [presumed]

Maker

SF [maker or former owner]

Class

dials

Earliest Date

1620

Latest Date

1620

Inscription Date

1620

Material

metal (brass)

Dimensions

Special Collection

Robert Whipple collection

Provenance

Purchased from Somalvico, Hatton Garden, London, England, on 07/07/1933.

Inscription

‘SF’ (reverse)
‘1620’

Description Notes

Navicula, ship-shaped dial, in brass, [English], 1620.

Brass ship-shaped dial with pivoting mast carrying latitude scale, divided 10˚ - 66 1/2˚, numbered by 10˚, subdivided to 1˚. Sliding index on mast lacks plumb line and thumb screw. Reverse of mast carries a second latitude scale (later addition for use near the solstices) divided 40˚ - 60˚, numbered by 10˚, subdivided to 1˚. Lower end of mast decorated by fleur-de-lys. Mast dated 1620 on obverse.
Obverse of ship: hour lines divided 1 - 12 in both directions, numbered by 1. RHS has a zodiac scale divided to sign and subdivided to 10˚. A similar scale appears along the keel for the alignment of the mast. Decorated ‘poop’ and ‘forecastle’ with pinhole sights.
Reverse of ship: degree scale around edge divided 90˚ - 0 - 90˚, numbered by 10˚, subdivided to 1˚. Lefthand quadrant carries geometric square divided [0] - 12 - [0], numbered by 3, subdivided to 1. Righthand quadrant carries scale of unequal hours, divided [1] - 6 - [12], numbered by 1. Inscription on reverse: ‘SF’.

Condition: good.

[NOTE: On 14/07/2015 XRF analysis was conducted on this instrument. Results and analysis are given in the ‘Notes’ field.]

References

Catherine Eagleton; 'A ship-shaped sundial; dated 1620'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2017: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/astronomy/ship-shaped-sundial

Events

Description
The navicula is a rare and intriguing form of portable sundial, designed to resemble the shape of a ship. The earliest known examples date from the late Middle Ages, of which only five examples survive. This instrument is a later seventeenth-century copy.

The dial tells time at any latitude between the tropic of Cancer and the Arctic circle in equal hours, and all of the known examples have an unequal hour diagram on the back. There is also a shadow square, which enables the user to calculate the linear height of an object. Some scholars believe that the Zaouraq, a type of astrolabe described in early modern Arabic manuscripts, was the navicula’s precursor; however, it remains unclear who invented the first instrument and recent scholarship persuasively suggests an English origin for the navicula, perhaps in East Anglia. In 1560, the French mathematician Oronce Fine published a book about sundials that included descriptions of how to make a Regiomontanus dial and a ship-shaped dial. This instrument is an exact copy of the diagram given in Fine's book. It is therefore possible that an educated English gentleman read Fine's book and commissioned an instrument just like the one in the diagrams.
08/07/2014
Created by: Allison Ksiazkiewicz on 08/07/2014

FM:39985