Instruments · Models (representations); sundials; astronomical instruments
Model of North equinoctral dial (Ayn Yantra), scale 1:24 in the Jaipur Observatory
- Maker / attribution
- Jai Singh II, Maharaja of Jaipur, 1686-1743 (maker); Jai Singh (maker)
- Date
- 1884-1886
- Historical period
- Industrial Revolution (1850 – 1900)
- Country of origin
- India
- Place
- India, Jaipur, Rajasthan, Asia, Jaipur; Rajasthan; India; Asia
- Object type
- Models (representations); sundials; astronomical instruments
- Holding institution
- Science Museum Group, London
- Accession / object no.
- 1887-12
- Credit line
- Colonial and Indian Exhibition 1886
- Catalogue title (original)
- Model of Ayn Yantra at Jaipur Observatory, 1884-1886
Record summary
Held and catalogued by Science Museum Group, London (object number 1887-12), this is a models (representations); sundials; astronomical instruments by Jai Singh II, Maharaja of Jaipur, 1686-1743, made in India, Jaipur, Rajasthan, Asia, Jaipur; Rajasthan; India; Asia, dated 1884-1886. The Atlas places it in the Industrial Revolution period (1850 – 1900) of its Instruments collection. The record is illustrated with 4 photographs.
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 is one of a series of models made 1884-6, showing the astronomical instruments of the Jaipur Observatory, India. These were exhibited in 1886 at the Colonial and Indian Exhibition, London. Built of masonry the Jaipur instruments were used to accurately measure the position of the Sun, stars, moon and planets. Lacking telescopes these devices used naked eye sights and massive but precise construction. Known as Ayn Yantra (North Equinoctral Dial), it was built and designed under the supervision of Maharajah jai Singh II. Finding European, Islamic and Hindu astronomical tables inaccurate, Singh decided to make his own observations to improve matters. As ruler of Rajastan, he built several observatories starting in 1724 with one near Delhi.
Historical context
Industrial Revolution (1850 – 1900)
American interchangeable-parts manufacture; railroad time standards; Swiss and German factory systems.
Instruments spread into industry, science and sport: stopwatches, chronoscopes, metronomes, watchmen's clocks and time recorders.
Read the period in the timelineMore instruments from this periodEarlier: Precision & Scientific Horology
Atlas type guide
Sundials and solar time-finders
A sundial tells time from the position of a shadow cast by a gnomon or style. Because the sun's apparent motion depends on latitude, every fixed dial is laid out for a particular latitude, and portable dials either carry a latitude scale or are made for one region. Sundials show local apparent solar time, which drifts against mean (clock) time by up to about sixteen minutes over the year — the equation of time.
Portable dials were the pocket instruments of the sixteenth to eighteenth centuries. Nuremberg and Augsburg workshops produced folding ivory diptych dials with inset compasses; English and French makers sold brass horizontal dials, ring dials and the Butterfield type; Japanese and Chinese makers had their own traditions of compass dials. After mechanical watches became reliable, dials remained in use for setting them, and nineteenth-century heliochronometers were built to correct directly for the equation of time.
What to look for
- The latitude engraved on the dial plate or a latitude arc on the gnomon — it shows where the dial was meant to be used.
- The type of hour lines: equal (equinoctial) hours, Italian or Babylonian hours counted from sunset or sunrise, or unequal temporal hours on early and Islamic instruments.
- An inset magnetic compass and whether a magnetic-declination mark is drawn on its card — a useful dating clue because declination changes over time.
- Maker's signatures and town marks: Nuremberg compass-makers (Kompassmacher) often struck a personal mark and the town's punch.
- Additional scales such as lunar volvelles, wind roses, perpetual calendars or lists of cities with their latitudes.
Dating clues
- Ivory diptych dials are characteristic of Nuremberg between about 1500 and 1700.
- Butterfield-type dials with a bird-shaped adjustable gnomon point to Paris workshops from the late seventeenth century onward.
- Equation-of-time tables engraved on the plate became common after the mid-seventeenth century, once pendulum clocks made the difference between solar and mean time obvious.
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.
Read next:The history timeline
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