A late 16th/early 17th century astrolabe, not signed, Flemish, possibly from the workshop of Michel Coignet.

Brass, D. 267mm.

The rete composed of simple strap-work carries pointers for 34 named stars for each of which the magnitude and astrological domiciliation are given. For each star within the circle of the Tropic of Cancer only, the first word of the star name is capitalised, the rest of the name  being engraved in italic. The stars are:



Engraved name                                 Identification
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Cor Scorpi                                          Alpha scorpii
Lucida lancis austr                          Gamma scorpii
Spica virginis                                     Alpha virginis
In Basi  Crateris                                Crateris
Lucida Hyare                                      Alpha hydrae
Canis maior                                       Alpha canis maioris
Austuria Cornu tauri                          Zeta tauri
Post intervallum fluuij                       Theta eridani
In australi cauda ceti                         Beta ceti
Crus aquarii                                        Delta aquarii
Cor leo                                                 Alpha leonis
Canis minor                                        Alpha canis minoris
Media cin oriionis                               Epsilon orionis
Oculus tauri                                         Alpha tauri
Hirc[us] Capella                                  Alpha aurigae
Caput algol                                          Beta persei
Dex hum Pegasi                                 Beta pegasi
Rictus pega                                         Epsilon Pegasi
Prima antinoi                                       Alpha antinoi
Sinist genu                                           Zeta ophiuchi
Cauda                                                    Beta leonis
Arcturus                                                 Alpha bootis
Vlt cauda vrsae                                    Eta Ursae majoris
Hirc[us] capellae                                  Alpha auriga
Dext[er] latus persei                            Alpha perseiPectus Cassiopeia                                           Alpha Cassiopeae
A Cinguli Andromedae                        Beta Andromedae
Cauda cigni                                           Alpha cygni
Rostrum galinae                                   Beta cygni
Caput Herculis                                      Alpha Herculis
Aquila v olans                                        Alpha aqilae
Dextrum genu Ophiuci                         Eta ophiuchi
Vlt cauda vrsae                                      Eta Ursa maioris
Caput algol                                            Beta persei
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The North-South and East-West bars are straight, the North-South  bar being present only inside the arcs of the tropic of Capricorn. The ecliptic circle carries the names of the signs each of which is divided and numbered 10, 20, 30. The reverse of the rete has the ecliptic fully divided and olther construction lines. There are some minor metal flaws and corrosion and the central roundel which receives the axis pin has been reinforced by the riveting to it of a disc slightly less than 1mm thick. Whether this was done to strengthen this area or to take up  free space following the loss of a plate, the result is that the rete can no longer lie perfectly flat against the plate below.



A small magnetic compass, with the cardinal points marked by the initials of their Latin names, is incorporated in the lobed throne to which the shackle is attached through an horizontal plate rivetted to the ears of the throne. Engraved on the edge of this plate is '1631', a date of  which the significance now eludes commentary. The ring is present and the face and back of the throne are engraved with geometrical and symmetrical foliate decoration. The cast limb is separately attached to the back plate to form the mater. This is engraved with the cardinal points indicated by the initials of their Latin names and joined by crossed lines within an equal arm cross with arched ends. The intervening quadrants are divided by a series of triangles the points of which, being radial from the centre, represent 64 compass directions. The limb carries a degree scale in four quadrants (90-0-90-0-90) divided into groups of 5 numbered in tens, the second group of five in each ten having the divisions alternately hatched and not hatched, and a double12 hour scale similarly divided reading to 2 minutes and numbered in 20 minute groups.



The back of the instrument is engraved on the outer edge with a degree scale numbered 90-0-90-0-90 by groups of ten with every other division hatched. Within this is a zodiacal calendar (eccentric-type) with the signs and months named and numbered in groups of ten. The centre upper half carries an unequal hour scale numbered 1-6-1 drawn around circle of formal wheat-sheaf decoration, while in the lower half is a decimal double shadow square of ten divisions of five numbered by groups of twenty 20-100. The labels for the shadow square 'Umbra recta' and Umbra versa' have been interchanged. Within the shadow square is a double quadrant of degrees 90-0-90 reading from the meridian line of the instrument surrounding in the band of 23.5° part of an orthographic projection of the sphere labelled 'HORA PRO LONGITVDINE DIERVM / AD VNIVERSALI ALTITVDINEM POLI (hour of the length of   day at all latitudes). The remaining free space in the lower half of the instrument is filled with symmetrical foliate decoration.



There is one plate for latitudes 42° and 48° and one plate missing.
The locking lug is placed as an extension of the meridian line at the bottom of the instrument, the azimuths and almucantars are both numbered in groups of ten. The tropics, equator and the crepuscular line are all so named, and the unequal hours are drawn in beneath the horizon numbered I – XII in roman numerals. To these are added on the plate for 42° the lines of the Great Houses, or houses of the heavens



The alidade is named in Arabic form 'Alhidada', is counter-changed, and marked 'LINEA FIDUCIAE'. It is attached by a screw, with foliate decorated head, and a wing-nut. The half rule on the face is engraved with a scale 'PRO LOCO SOLIS',  (for the place of the Sun) and engraved with a zodiac scale.

An elegant instrument extremely close in style and  layout to a similarly unsigned astrolabe now in the collection of the Adler History of Astronomy Museum in the Adler planetarium, Chicago (see Webster & Webster, 106- 8, no 24).  Of the Flemish origin of both there can be no doubt and this has to be in Catholic Flanders since the date of 0 Aries, 21 March, implies that the Gregorian calendar was accepted. Although some elements of the engraving suggest that they were made within the orbit of the workshop of Michel Coignet (1549-1623) at Antwerp, a firm attribution is not yet possible especially as the instrument which the astrolabe most resembles  in its decoration – a surveying plate now in the Musée de la Renaissance, Ecouen – is signed only by a monogram 'MC 1590'. The areas for which the latitudes of the two plates are most appropriate are Northern Spain, Rome and Central Italy for the 42° plate, the Nantes – Paris region, Munich, southern Germany and Bavaria.