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Auktionsarchiv: Los-Nr. 24

An English brass universal equinoctial ring dial Unsigned, mid to late 18th century …

Auction 29.03.2016
29.03.2016
Schätzpreis
600 £ - 800 £
ca. 853 $ - 1.138 $
Zuschlagspreis:
650 £
ca. 924 $
Auktionsarchiv: Los-Nr. 24

An English brass universal equinoctial ring dial Unsigned, mid to late 18th century …

Auction 29.03.2016
29.03.2016
Schätzpreis
600 £ - 800 £
ca. 853 $ - 1.138 $
Zuschlagspreis:
650 £
ca. 924 $
Beschreibung:

An English brass universal equinoctial ring dial Unsigned, mid to late 18th century The outer meridian ring with two quadrants divided into degrees annotated 0-90 in two directions to one side opposing engraved quadrant of degrees for altitude also annotated 0-90 to be used in conjunction with a pin (missing) to be placed in a hole opposing the scale, the pivoted inner ring is engraved with Roman numeral chapter ring annotated I-XII twice divided into five minute intervals and with tied lozenge half hour markers, the rotating bridge with central slot fitted with pinhole slider and finely engraved with a zodiacal scale with corresponding signs over declination scale in degrees opposing calendar to other side, the outer rim with adjustable bracket fitted with suspension ring, diameter 10cm (4ins); with an English mahogany pocket compass, unsigned, late 18th century, the circular paper scale printed with rose within band annotated with the cardinal points sub-divided into four within outer scale calibrated in degrees, fitted with locking pointer beneath glass secured by a brass bezel in simple square case with hinged cover, 5.5cm (2.125ins) wide. The equinoctial ring dial is generally thought to have been developed from the mariner's astrolabe by William Oughtred in around 1600. To use an equinoctial ring dial the suspension ring bracket must be first slackened and moved to line up with the scale at a position corresponding to the latitude of the location from where the reading is being taken. The sliding pin-hole curser to the bridge needs then to be positioned to correspond with the date. Ensuring that hour ring is fully opened (ie. at ninety degrees to the outer ring) the instrument then can be suspended in sunlight and orientated until the pin hole projects onto the inner edge of the hour ring thus providing a reading for local solar time. When correctly orientated the outer ring will be aligned with the north-south direction, the hour ring with the equator and the bridge will be parallel with the access of the earth. The fact that the current lot has a calendar annotated in English as well as typical tied lozenge half-hour markers to the hour ring confirms it origins. With regards to dating the instrument, the calendar is divided so that the sign of Aries commences on the 20th of March, this indicates that the current lot was made to operate under the Gregorian calendar which was adopted in England in 1752.

Auktionsarchiv: Los-Nr. 24
Auktion:
Datum:
29.03.2016
Auktionshaus:
Dreweatts & Bloomsbury Auctions
16-17 Pall Mall
St James’s
London, SW1Y 5LU
Großbritannien und Nordirland
info@dreweatts.com
+44 (0)20 78398880
Beschreibung:

An English brass universal equinoctial ring dial Unsigned, mid to late 18th century The outer meridian ring with two quadrants divided into degrees annotated 0-90 in two directions to one side opposing engraved quadrant of degrees for altitude also annotated 0-90 to be used in conjunction with a pin (missing) to be placed in a hole opposing the scale, the pivoted inner ring is engraved with Roman numeral chapter ring annotated I-XII twice divided into five minute intervals and with tied lozenge half hour markers, the rotating bridge with central slot fitted with pinhole slider and finely engraved with a zodiacal scale with corresponding signs over declination scale in degrees opposing calendar to other side, the outer rim with adjustable bracket fitted with suspension ring, diameter 10cm (4ins); with an English mahogany pocket compass, unsigned, late 18th century, the circular paper scale printed with rose within band annotated with the cardinal points sub-divided into four within outer scale calibrated in degrees, fitted with locking pointer beneath glass secured by a brass bezel in simple square case with hinged cover, 5.5cm (2.125ins) wide. The equinoctial ring dial is generally thought to have been developed from the mariner's astrolabe by William Oughtred in around 1600. To use an equinoctial ring dial the suspension ring bracket must be first slackened and moved to line up with the scale at a position corresponding to the latitude of the location from where the reading is being taken. The sliding pin-hole curser to the bridge needs then to be positioned to correspond with the date. Ensuring that hour ring is fully opened (ie. at ninety degrees to the outer ring) the instrument then can be suspended in sunlight and orientated until the pin hole projects onto the inner edge of the hour ring thus providing a reading for local solar time. When correctly orientated the outer ring will be aligned with the north-south direction, the hour ring with the equator and the bridge will be parallel with the access of the earth. The fact that the current lot has a calendar annotated in English as well as typical tied lozenge half-hour markers to the hour ring confirms it origins. With regards to dating the instrument, the calendar is divided so that the sign of Aries commences on the 20th of March, this indicates that the current lot was made to operate under the Gregorian calendar which was adopted in England in 1752.

Auktionsarchiv: Los-Nr. 24
Auktion:
Datum:
29.03.2016
Auktionshaus:
Dreweatts & Bloomsbury Auctions
16-17 Pall Mall
St James’s
London, SW1Y 5LU
Großbritannien und Nordirland
info@dreweatts.com
+44 (0)20 78398880
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