A fine late 16th-Century brass Italian astrolabe,

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細節

A fine late 16th-Century brass Italian astrolabe,
unsigned but datable to 1590 -- 7in. (17.8cm.) diamter

The limb (7.6 to 8.0mm wide) is divided into 24 hours and 360 degrees, both scales numbered with punched arabic numerals. The degree scale is marked every ten from 0-90° consecutively in four quarters. The mater has been turned from a brass disc leaving the raised limb at the edge (combined thickness 6.0mm). The mater is blank, and shows only marks due to lathe judder, filing marks, scratches and small casting fissures. The throne is small and roughly-shaped, with rotating pin and ring.

Fitted into the mater are two plates, held in position by lugs:
Plate A (163mm diameter; 1.1 to 1.8mm thick) is inscribed for the latitude 45° on one side; the reverse has a universal projection. Altitude lines are marked every 5° and numbered in tens. The azimuths are at 10° intervals, each numbered. Additional lines indicate the tropics, equator, planetary hours, crepuscular line (punched LINE AVRORE); a set of dot-punched lines mark the twelve Houses of Heaven. On the reverse is the universal astrolabe projection known as the Saphea. Both latitude and longitude lines are at 5° intervals, unlabelled. On the outer edge is an unnumbered 360° scale. The hour angles (every 15°) are cut deeper, and are numbered with the hour engraved in large arabic numerals. The ecliptic line crossing the centre is divided to 5°, and at each 30° the sigil of the Zodiac is engraved. The names of 17 stars are punched (see below). The lug is inset and held in place by solder. This may indicate that the cumbersome process of trimming off the edge of the disc to leave a proud lug has been abandoned for adding a lug to a simply formed disc of brass.

Plate B (163mm diameter; 0.8 to 1.4mm thick) is inscribed for the latitude of 44°, which number is inexpertly engraved below the centre. The altitude lines are cut every 3°, and only two of these are labelled, on the left: 6; 12. Azimuth lines are at 5° intervals, unlabelled. The tropics, equinoctial circle, crepuscular line and planetary hour lines are engraved, and are also not labelled. Indicated just with punched dots are two lines that are part of the Houses of Heaven, unlabelled, but corresponding to lines 3/9 and 5/11. Because these lines are punched, and the plate is very thin, an impression has been made that is visible on the other side. The reverse is blank, but shows a large fissure and filing marks. The lug is inset in the same way as on the accompanying plate.

The shape of the rete is a simple one favoured by some Italian makers of the sixteenth century. Wide bands are provided for both the equatorial lines and the ecliptic. The equatorial is divided into single degrees, numbered in tens. The ecliptic is marked in single degrees divided in tens to thirty for each sign of the Zodiac. All numbers on these bands are punched. The name and sigil for each of the signs are engraved between guide lines. The central crossbars are counterchanged. The front of the rete shows some layout lines; the back shows only filing marks. The star pointers are formed from arcs of a circle, cut as needed, except for cavda cigni, which has a notch. There are sixteen stars, their names engraved as listed below.

The outer edge of the back begins with a degree scale marked in tens 0-90° in four quarters. There follow a Zodiac scale and a concentric calendar scale, both with the names of the Signs and of the months (in Latin) engraved in capitals over guide lettering scratched in place. For obvious examples, see SAGITARIVS and DECEMBBR; this did not, however, prevent the incorrect spelling of December. The numerals are punched. The space inside these scales has in the lower half a shadow square to 12 units at the apex, alternately shaded. Concentric with the plates are seven bands that give, first, the names of eight winds in Italian, followed by a perpetual calendar which begins with the year 1590 and ends with 1626. All the letters and numbers are punched. The calendar begins with the names of the bands:
NVMER ANNOR 1590
INDEX PASCHA 7 A
LITERA DOMINI G
CYRCLVS SOLARIS 3
AVRE NVMER 14
EPATAE 24

This table shows the New Style, or Gregorian calendar, with the year Anno Domini, date of Easter (March or April), Dominical Letter, Solar Cycle, Golden Number, Epact. Easter fell on 22 April 1590, not 7 April as marked. Two more incorrect Easter dates are in 1599 and 1602.

Both the alidade and the rule are counterchanged. The top surfaces are bright; the undersides show casting flaws and file marks. Alidade: 73mm long; 10mm wide; 1.8 to 2.0mm thick. Rule: 75mm long; 7mm wide; 2.1 to 2.2mm thick

The pin: all parts are held in place by a central bolt with a wide (16mm) stepped head and an octagonal nut with a pair of notches.

See Colour Illustrations

注意事項

No VAT will be charged on the hammer price, but VAT at 17.5% will be added to the buyer's premium which is invoiced on a VAT inclusive basis.

拍品專文

Plate A is designed for the latitude of 45° (Milan region) for use with the rete, the reverse being a universal projection, that is, suitable for any latitude. Although this is not unusual, it shows that the maker was trying to be abreast of the times. Plate B seems to be a special order, being one-sided, and for a latitude of 44°, this number being roughly engraved, not punched. This is just north of Florence, the coordinate of which is 43°40'. The star names are what one would expect for the late sixteenth century. However, some of the names are unusual, and may be particular to the craftsman or to his patron. For example: CATORVELAPOLO ( And); PICIS NOTIVS ( PsA); FIDICV. ( Lyr); CENTAV ( UMa, at the end of the Bear's tail, the Chief of the Mourners).

THE STARS ON THE RETE
Inscribed Designation Name
CAP. ANDR. a And Alpheratz
CASSIOP PECTVS a Cas Schedar
Ocul. Tau a Tau Aldebaran
PES. SIN. ORIO b Ori Rigel
CANIS MA a CMa Sirius
CAN. M a CMi Procyon
COR. HYDRE a Hya Alphard
Cor. Leon a Leo Regulus
Spic. Vir a Vir Spica
ARCTV a Boo Arcturus
CENTAV m UMa Alkaid/Benetnash
Cor Scor a Sco Antares
FIDICV. a Lyr Vega
AQVILLA a Aql Altair
CAVDA CIGNI a Cyg Deneb
CAV. CETI b Ceti Diphda

THE STARS ON THE SAPHEA
Inscribed Designation Name
CATORVELAPOLO a And Alpheratz
ERIDANVS a Eri Alchernar
VENTER CETI x Cet Baten Kaitos
OCVLUS TAVRI a Tau Aldebaran
HIRCVS a Aur Capella
SINISTER HVMERVS ORIONIS y Ori Bellatrix
CANIS MAIOR a CMa Sirius
CANICVLA a CMi Procyon
COR LEO a Leo Regulus
ALIOT e UMa Alioth
SPICA VIRGINIS a Vir Spica
LVCIDA CORONE a CrB Alphecca
COR SCORPII a Sco Antares
LYRA a Lyr Vega
AQVILA a Aql Altair
CAVDA SIGNI a Cyg Deneb
PICIS NOTIVS a PsA Formalhaut