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ROMAN PORTABLE SUNDIAL

The instrument consists of two discs and a combined gnomon and hour scale. The stem of this last part passes through the central holes of the two disks and allowing them to be turned relative to one another. On the back of it are engraved the latitudes of 30 provinces of the Roman Empire, given in degrees. The instrument dates probably to 250 A.D. an it kept at the collection museum of the history of science in Oxford.