A rare and unusual French calendrical astrolabe, French, circa 1587,

Rete for 29 stars indicated by curving, slightly flame-like pointer and named, with their magnitudes, in punched capitals as are virtually all the other inscriptions on the instrument.



Cor Scorpio Spica Virginis 1



Lvcida Hydre 2 Canis maior



Cor leonis Canis minor 1



Dexter humerus orionis 1 Pes sinister ori[onis} 1



Ocvlvs tavri 1 Navis ceti 3



Venter ceti 3 Cavda ceti 3



Crvs aqvarii 1 Cavda capri[cornvs] 3



Dexter Hvm[ervs] Bootes 3



Cavda Leo 1 Lanceator 1



Corona septentri Pal sinis[ter] ser[pentis] 3



Caput Her[cules] 3 Lira 1



Aqvila 1 Cavda signi 2



Mvcida Pegasi Crvs Pegasi 2



Vmbilicvs Andro[meda] 3 Cap[ut] algor 2



Hircvs 1



Thick Capricorn band carrying a 24 hour scale reading to 30 minutes by a star division and, but with inverted reading sense, a month scale which forms a zodiacal calendar when used in conjunction with the ecliptic (0° Aries = 21 March, i.e. this is a Gregorian calendar). Although the star names are in Latin, the month names are given in French, short counter-changed east-west bar, the ecliptic ring with named signs. The rete has be cut from a recycled piece of brass originally intended for a similar purpose as is shown by the considerable quantity of punched inscriptions on the back..



Mater probably cast in one piece with the limb which carries



1 an hour scale divided to 4 minutes



2 a degree scale in four quadrants 90-0-90-0-90°



The interior of the mater is blank. Unusually the plates are held in pace not by a lug but by a screw passing through the limb directly opposite the shackle which blocks them in place. The edge of the limb is engraved with the latitudes of



Paris 48 Lion 45 Thovlovse 44



Nantes 50 Marseille 43 Mets 47 Bovrdeavs 45 Monpellier 42 Geneva [ ]



Nvrembert 49 Rome 41 Naples 40



Milan 44 Gennes 42 Londres 54



Sevillia 37 Lisbona 40 Barcelona 41



Back with degree scale in four quadrants on the edge surrounding an universal oçrthographic projection of the sphere of the type first described for astrolabes by Juan de Rojas in a work published at Paris in 1550.



Plate 1is a conventional projection for latitude 45° or slightly higher (calculated value) which would allow it to be used with acceptable error in most of the places listed on the limb. The twelve astrological ‘Houses of the Heavens’ are marked by dotted lines numbered in roman numerals, the unequal hours below the horizon are indicated by arabic numerals. Around the edge are the wind directions Septentrio, Boreas, Vvltvrvs, Svbsolanvs, Evrvs, Evroavster, Avster, Africvs, Zephirvs, Chorvs and Cirrcivs. On the reverse of this plate are the scales that would normally be found on the back of an astrolabe. These are :



around the edge, a zodiacal calendar (0° Aries = approximately 21 March)



in the upper two quadrants a llist of star names radiating from the centre which make a series of 15 names with others added elsewhere, each with its magnitude and identified by a letter of the alphabet.



lower left quadrant, a shadow square of twelve in numbered groups of three



lower right quadrant, an equal hour diagram in which the morning and afternoon hours are superimposed so that it will fit into a single quadrant used in conjunction with the scales on the alidade



Plate 2 has a central volvelle which rests in cut out in the centre of the disc, but can be made to rotate with its pointer traversing the remaining broad band of the plate if the astrolabe is assembled with this plate on top of plate 1 and the rete. To aid the function its edge is chamlfered so that it only nests into the centre of the plate in one direction. The outer band of the plate carries a liturgical calendar with saint’s days and dominical letters for six months on each side, the index disc is engraved on one side with a lunar aspectarium, a diagram showing the conjunctions, oppositions and other angular relations between the moon and other celestial bodies ; the other side carries tables of Les Festes mobiles de l’Année, explains their relative positions in the year, and has dominical letters and epacts from 1587.



There is a simple openwork, rectangular throne with flared sides, a shackle and ring. The alidade, although original, is not that which would have been placed on the back since it is non-functional with the orthographic projection. It was probably originally placed on the front of the instrument, the back being fitted with a right angled regulus now missing.



The instrument is now contained in a contemporary, green-baize lined shaped wooden box covered in black pigskin blind worked on the front with a symmetrical, slightly grotesque, flowing leaf design within a circle of half moons, the back with radiating line decoration. This box is not original to the instrument.



 



 



 



 



 

Time Museum, Christies South Kensington, 14th April 1988, lot 148

A highly unusual instrument with many uncommon features which looks back in style to the mid-century production of French astrolabes, often by clock-makers, using punches, rather than forward to the lighter, more elegant instruments associated with Philippe Danfrie and his contemporaries at the end of the century. Although the design of the rete within the ecliptic seems, for the moment, to be without parallel, the strapwork outside the ecliptic is identical with that of the rete illustrated in Jacque Focard’s Paraphrase de l’Astrolabe (1546, 1556) although there fewer stars are shown. The simple open throne is close to one on an unsigned and undated French astrolabe in the Geographical Society of Lisbon, while the radiating list of stars above the shadow square can be paralleled on an astrolabe dated 1548 by I. Galois (Gunther 204). A similar use of such a radiating list is also to be found on the remains of an astrolabe by Jacques de la Garde of 1547 (sold in these rooms 30 May 1991 lot 39). Here the diagram is used for supplying calendrical information similar to that contained on the volvelle disc in the present instrument. The throne of de la Garde’s instrument also employs open-work and there appear to be some stylistic resemblance’s among the punches. Since de la Garde was working until at least 1580 it is not impossible that the present instrument derives from his, or a successor workshop, but confirmation or rebuttal of this suggestion must wait until the two instruments can be compared side by side