Portable horizontal sundial

Octagonal in shape, this small silver pocket sundial and recessed compass would have been carried in a protective case and would allow the owner to keep time while traveling and to set his clock or watch accordingly. The front plate of the dial is engraved with three-hour scales in Roman and Arabic numerals serving different latitudes. The hinged pointer or gnomon, which could be adjusted for the desired latitude (indicated by the bird’s beak on the pointer), would cast a shadow on the calibrated surface indicating the time. The reverse records the latitudes of 22 European cities and indicates the name of the maker: Ja[c]ques Lucas from La Rochelle who left France and settled in Amsterdam in about 1681 where he died in 1723. These small horizontal dials are known as Butterfield dials for an English instrument maker Michael Butterfield (1635–1724) who worked in Paris from circa 1778 on where he dominated the market with such small traveling sundials. However, the type was known before he manufactured them and was also made by others.