διόπτρ-α,ἡ,
A. optical instrumentfor measuring angles, altitudes, etc., Euc. Phaen. p.10M. , Plb. 10.46.1 , Attal. ap. Hipparch. 1.10.24 , Gem. 1.4 , Ptol. Alm. 5.14 , etc.; ἡ τῶν δ. θεωρία
Gem. 5.11
.
2. aperturesightin a torsion-engine, Ph. Bel. 64.9 , 76.48 .
II. plate of talcfor glazing windows, Str. 12.2.10 .
III.
= διαστολεύς , Aët. 16.89 , Paul.Aeg. 6.73 .
IV. σημεῖον ἐν θυτικῇ,
Hsch.