Este Cylinder Sun Dial

Roman cylinder sun dial from Este in Italy. Whether the 2 gnomons were the same or different lengths can not be determined as one is broken off. Of course such a sun dial would only give an approximate rather than an exact idea of the hour of the day, or 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, I reproduced one in bone (like the original) and one in boxwood.


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