- Museum number
Gilt brass astronomical compendium. Comprising from the top:
b) table of latitudes of 30 towns
c) equinoctial sundial
d) magnetic compass
e) tide computer
a) At the edge is a 24-hour circle, divided in quarter hours, and labelled in Arabic numerals. There follows a large volvelle, with its rim divided in months, which are indicated by their full names, subdivided in 5-day intervals, not numbered. From the centre 12 radial lines are cut to intersect each month. By each line is the name of a star. Around the centre rotates an index, which could be of help if one of the possible stars were occluded. When one of the named stars is on the meridian, the volvelle is turned to match, when the day of the month gives the time.
b) The latitude table of 30 towns is on the inside of the lid, with six columns and five rows listing the latitudes in degrees and minutes.
c) When fully opened, the chapter ring in its cradle is erected, and the appropriate latitude set by a quadrant that turns to the vertical. The quadrant arc is divided in degrees, 0-90°, numbered every ten. The gnomon is attached to the quadrant, and erects with it. The upper, summer, side of the ring is numbered in hours, IV-VIII, and the lower, winter, VI-VI; the signature is on this rim. The inside of the ring has the divisions to half an hour.
d) The compass card has a diameter of 57 mm including the circle of degrees, twice 0-90°-0. This is divided to 2°, and labelled in tens. The pointers for the 32 wind directions are coloured in blue, faded red, pale green, white. The magnetic needle is straight at both ends, and is a replacement. The glass cover contains air bubbles.
e) The base is a tide computer. The outer circle gives the months, with the days in units of two, numbered in tens, followed by the Zodiac, each Sign shown by its sigil, divisions in 2° intervals, numbered in tens. Then comes a 24-hour scale divided in half hours, the hours in roman numerals. The innermost circle is a wind rose with 16 of the points labelled with initials of the wind directions. Rotating at the centre is a volvelle with a long index and a scale of the Moon's age; divided in 29½ days and labelled every 2 days. Finally, there is a lunar volvelle with a long index, phase aperture, and planetary aspects.
- Production date
1610-1615 (approximate dates attributed in Turner 2000)
Diameter: 60 millimetres
Thickness: 18 millimetres
- Curator's comments
The list of stars on the nocturnal resembles the 12 navigation stars (seven are identical) of William Bourne published in his 'Almanacke' (1571); reproduced in Taylor (Taylor, E.G.R. (ed.) (1963) 'A Regiment for the Sea and other writings on navigation by William Bourne of Gravesend, a gunner', Hakluyt Society, 2nd series, Vol. 121, Cambridge University Press, pp. 99-101).
The form and sequence of information on the tide computer is the same as on other Allen compendia, and the Charles Whitwell 1600 compendium (National Maritime Museum, Greenwich (AST 0468; old no. D.35/36-194C).
'The nocturnal is unusual in form, and is analogous to the pictorial type', see Turner 2000, p.258 with specific references to his cat.nos. 83 and 86.
The compass card is his type A-2; see Turner 2000, p. 64 and Plate 14 (c).
The sequence of information on the tide computer is the same as that on other Allen compendia, and the Charles Whitwell 1600 compendium [now in the Greenwich NMM, AST0468; Turner 2000, cat. no. 58]; see Turner 2000, p.259.
- Not on display
Latest: 2 (Mar 2017)
1 (Feb 1996)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number