Pseudo-equinoctial (seasonal inclining) dial

Date19th century

Object number00029991

NameCompass

MediumWood, copper alloy

DimensionsOverall: 25 x 70 x 100 mm, 100 g

ClassificationsTools and equipment

Credit LineANMM Collection Gift from Mary Bayldon

Terms

DescriptionThis portable Chinese pseudo-equinoctial (or seasonal inclining) dial comprises a rectangular hour dial-plate hinged to a base-plate. The dial is surrounded by three circles of Chinese characters, which indicate the hour, and subdivide into 30 minute and 15 minute intervals. The base-plate features 13 grooved divisions marked in black, in which the strut on the back of the hour-plate is set according to the season. This changes the angle of the hour dial. The base-plate also features a small geomantic compass with a glass face and plain silver dial, surrounded by rings which indicate traditional directions.HistoryPortable dials were made in China as early as the 14th century, and dramatically increased in production in the 16th century after the arrival of the Jesuits. There were two general types of portable dials: 'pseudo-equinoctial' or seasonally inclining dials, and diptych dials. Chinese 'pseudo-equinoctial' or seasonally inclining dials use the Chinese time system in which a day is made up of 12 double hours, each of which are named with characters that denote the traditional hours of the Chinese year. Each of the hour divisions is subdivided to show 30 minute and 15 minute intervals. The dial is set according to the geomantic compass and the traditional Chinese seasons, rather than latitude. Geomantic compasses - which often indicated South as opposed to North - are surrounded by rings with divisions indicating 24 traditional directions, with the names of 12 animals and 12 elements. The strut beneath the hour-plate is placed in the ratchet scale which is divided according to the traditional Chinese seasons. This changes the angle and inclination of the hour-plate, ensuring that the dial gives the correct time with the changing declination of the sun of different seasons.