Este Cylinder Sun Dial

Roman cylinder sun dial from Este in Italy. The 2 gnomons are of different lengths probably for different seasons of the year, but might also have been meant to be used at different latitudes. But as Seneca (Apocolocyntosis 2.2) said "facilius inter philosophos quam inter horologia conveniet" (philosophers will more readily be in agreement than will clocks). The original is made of bone, but as I didn't have time to source material of the right size I decided to go for a boxwood version.

• A Roman cylinder dial: witness to a forgotten tradition. By Mario Arnaldi und Karlheinz Schaldach.
  Journal for the History of Astronomy, Jan 1, 1997