The Collaborative International Dictionary
Periscopic spectacles
Periscopic \Per`i*scop"ic\, a. [Cf. F. p['e]riscopique.] Viewing all around, or on all sides.
Periscopic spectacles (Opt.), spectacles having concavo-convex or convexo-concave lenses with a considerable curvature corresponding to that of the eye, to increase the distinctness of objects viewed obliquely.