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The Encyclopedia of Horology

Tool · English astrolabe

Gilt Brass Astrolabe by Bastien Le Seney

Partially verified

This 85 mm diameter gilt brass astrolabe is signed by Bastien Le Seney, a clockmaker to Henry VIII. Produced circa 1545 in London, the instrument features a three-lobed throne decorated with foliate scrolls and a suspension ring that appears to be a replacement. The mater contains a degree scale and a small pin to secure the two provided plates. The rete includes an ecliptic ring with zodiacal engravings and twenty star pointers, eight of which are labeled. The back of the instrument displays a degree scale, zodiacal markings, a calendrical scale, shadow scales, and a double hour quadrant. It also features the coat of arms of Henry VIII, which includes heraldic inaccuracies, alongside the initials 'H' and 'R'. Additional inscriptions include the motto of the Order of the Garter and a royal dedication on the rule.

Front view of the gilt brass astrolabe showing the rete, rule, and alidade.
Front view of the gilt brass astrolabe showing the rete, rule, and alidade. — British Museum, London. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.mhs.ox.ac.uk
Category
Tool · English astrolabe
Maker / attribution
Bastien Le Seney
Reference
Not recorded
Catalogue / lot identifier
MLA 1878,11-1.113
Source-reported date
circa 1545
Source-reported place
London

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Construction and Mater

The astrolabe is constructed of gilt brass with a diameter of 85 mm. The mater features a degree scale numbered 0 to 360 clockwise by 5-degree increments. The rim is riveted to the mater, and a small pin at the bottom maintains the placement of the internal plates. The equal hour markings are present, though the numeral 9 is engraved in reverse. The outer edge of the mater bears the Latin names of the winds, including 'VELNOTVS' and 'AVSTER'.

The instrument features a three-lobed throne adorned with foliate scrolls. The suspension ring is identified as a replacement. Two plates are provided, each featuring varying thicknesses; one is double the thickness of the other. These plates are marked for latitudes of 52 degrees 30 minutes and 53 degrees, with crude almucantar and azimuth markings.

Evidence for this section
  • “The rim is riveted to the mater.”
  • “The three lobed throne is decorated with foliate scrolls.”
  • “The suspension ring appears to be a replacement.”
  • “There are two plates, both are marked on one side only, the other side being left blank.”

Back Plate Details and Inscriptions

The back of the astrolabe is engraved with a degree scale reading from 0 to 90 degrees in four segments. A zodiacal scale is included, as is an eccentric anticlockwise calendrical scale. The lower portion contains shadow scales and the signature of the maker, 'BASTIEN LE SENEY FACIT'. The top half features a double hour quadrant.

Central to the back is the coat of arms of Henry VIII, flanked by the letters 'H' and 'R' with two roses inscribed below. The heraldry contains noted inaccuracies, specifically the placement of the fleurs-de-lis and the direction of the lions in the first quarter. The alidade and rule display segments of the Order of the Garter motto and a royal inscription in French.

Evidence for this section
  • “The back bears has a degree scale clockwise 0 to 90 to 0 to 90 to 0”
  • “Underneath these scales is the signature 'BASTIEN LE SENEY FACIT'.”
  • “Inside is the coat of arms of Henry VIII, but the quartering is incorrect”
  • “The rule bears the inscription 'ROY HENRY PAR LA' / 'GRASE DE DEIV' along the arms.”

Rete and Alidade

The rete is characterized by an thick ecliptic ring featuring engraved zodiacal signs. It includes twenty star pointers, of which eight are specifically identified with labels such as 'CANIS MINOR' and 'SPICA VIR'. The alidade is counter-changed with a bevelled edge and two sighting vanes. One arm of the alidade and the central wedge are identified as replacements.

Despite the replacement of one arm, portions of the motto 'Honi Soit Qui Mal Y Pense' remain visible. Specifically, 'QUI' is near the center, with 'MAL Y PENCE' appearing on the remaining original arm. Both the alidade and the rule are finished with stepped pointers at their extremities.

Evidence for this section
  • “The rete with an unusually thick ecliptic ring, engraved with depictions of the zodiacal signs, is divided 12 times into 30?”
  • “There are 20 star pointers, but only 8 stars are labelled”
  • “The counter-changed alidade with a bevelled edge has two sighting vanes. One arm of this alidade is a replacement.”
  • “The wedge is a replacement.”

Open research questions

  • What is the significance of the specific latitude markings of 52 degrees 30 minutes and 53 degrees in the context of Bastien Le Seney's work?
  • Can the specific errors in the royal coat of arms be linked to a known workshop practice or a specific historical commission request?

Source evidence

Recorded claims and source quotations for Gilt Brass Astrolabe by Bastien Le Seney
FieldSource-reported valueSource quotation
MakerBastien Le Seney“Signed by Bastien Le Seney”
MaterialGilt brass“Gilt brass; 85 mm in diameter”
Datecirca 1545“circa 1545; London”
Inventory NumberMLA 1878,11-1.113“Registration no. MLA 1878,11-1.113”
ProvenanceAugustus W. H. Meyrick“The instrument was donated in 1878 by Augustus W. H. Meyrick”

Visible details

  • The coat of arms of Henry VIII shows reversed lions and incorrect quartering.
  • The rule is inscribed with 'ROY HENRY PAR LA' / 'GRASE DE DEIV'.
  • The rete contains twenty star pointers with eight labeled.
  • The Latin names of the winds are inscribed on the outside edge of the mater.

Research qualifications

  • The suspension ring is considered a replacement.
  • One arm of the alidade is a replacement, as is the wedge.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Astrolabe

Reviewed 2026-10-26 · Record 712725b27b

Terms in this record

Glossary explanations for terms named in this object’s record.

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