1) Astronomical instrument 2) Measuring instrument
Found on
https://www.crosswordclues.com/clue/dioptra
A dioptra (διόπτρα) is a classical astronomical and surveying instrument, dating from the 3rd century BCE. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles. ==Use== Greek astronomers used the dioptra to measure the position...
Found on
http://en.wikipedia.org/wiki/Dioptra
• (n.) An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc.
Found on
http://thinkexist.com/dictionary/meaning/dioptra/
(from the article `Heron of Alexandria`) ...to those in the Metrica. However, the first three are certainly not by Heron in their present form, and the sixth consists largely of extracts ...
Found on
http://www.britannica.com/eb/a-z/d/52
A Greek surveying tool used for leveling or ancestor of the modern water level
Found on
http://www.encyclo.co.uk/visitor-contributions.php
No exact match found.
