Instruments · Horary quadrant - gunter
Armillary / astronomical instrument, England, 1623-1700
- Maker / attribution
- Unrecorded in source
- Date
- 1623-1700
- Historical period
- Early Modern Horology (1600 – 1750)
- Country of origin
- England
- Place
- England, England
- Object type
- Horary quadrant - gunter
- Dimensions
- overall: 5 x 115 x 115 mm
- Holding institution
- Science Museum Group, London
- Accession / object no.
- 1889-51
- Credit line
- Taylor, C.P.
- Catalogue title (original)
- English horary quadrant, 1623-1700
Record summary
Held and catalogued by Science Museum Group, London (object number 1889-51), this is a horary quadrant - gunter, made in England, England, dated 1623-1700. The Atlas places it in the Early Modern Horology period (1600 – 1750) of its Instruments collection. Recorded dimensions: overall: 5 x 115 x 115 mm. The record is illustrated with 1 photograph.
Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.
Catalogue description
Science Museum Group description
This unsigned English horary quadrant was made during the latter part of the seventeenth century. Made of brass the quadrant has engraved scales to a design conceived by the English mathematician Edmund Gunter in 1623. The horary quadrant was used for finding local time by sighting either the Sun or a bright star at night. Held vertically, a measurement could be taken from the position on the scale of a moveable bead on the thread of the instrument's plumb bob. The instrument was derived from the astrolabe and first appeared during the Medieval Period. Like its predecessor it includes a two-dimensional depiction of the heavens that is reduced to a quarter.
Historical context
Early Modern Horology (1600 – 1750)
Huygens' pendulum and balance spring transform accuracy; English makers develop the anchor and deadbeat escapements.
Pocket sundials, Butterfield dials and sandglasses remained essential companions to imperfect clocks; navigators used sandglasses and the log line; observatories began to combine telescopes with pendulum clocks.
Read the period in the timelineMore instruments from this periodEarlier: Renaissance Horology
Atlas type guide
Astrolabes, quadrants and astronomical compendia
The planispheric astrolabe is a two-dimensional model of the sky. A pierced rotating star map (the rete) turns over a plate engraved for a particular latitude; by aligning a star or the sun with its observed altitude, the user can read the time of day or night, the time of sunrise and sunset, and solve many other astronomical problems. Developed in the Hellenistic world and refined by astronomers in the Islamic world from the eighth century, it reached Latin Europe through al-Andalus.
Quadrants, compendia, armillary spheres and later orreries belong to the same family of instruments that model the heavens. They were teaching tools, status objects and practical time-finders. Many surviving examples are signed and dated, which makes them important evidence for the history of instrument-making workshops in Baghdad, Isfahan, Lahore, Toledo, Louvain, Nuremberg, London and elsewhere.
What to look for
- The latitudes engraved on the plates — they show which cities the instrument was made for.
- The script and calendar used: Arabic or Persian inscriptions, abjad numerals, Hebrew or Latin text indicate tradition and region.
- The design of the rete: the number of named stars and the style of the star pointers changes by region and period.
- Shadow squares, unequal-hour lines and zodiac scales on the back (dorsum).
- Signatures, dedications and dates, often hidden on the throne (kursi) or the back.
Dating clues
- Signed and dated astrolabes allow precise dating; undated ones are attributed by star positions on the rete, which shift slowly through precession.
- Gothic-style retes with tracery are typical of European instruments of the fourteenth and fifteenth centuries.
- Printed paper astrolabes and planispheres became common from the sixteenth century onward.
General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.
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