Concave Lenses are used in the treatment of myopia or shortsight.
3) the terms by which these parts are designated: The skin does not form eyelids; but the epidermis passes over the eye, forming a transparent disk, concave like the glass of a watch, behind which the eye moves.
The arches bear on the convex outer side the delicate arborescent gills, and on the concave inner side develop a membranous septum with vermicular perforations, a special sifting or filtering contrivance through which the water absorbed by the mouth has to pass before reaching the respiratory organs of the branchial apparatus.
He refers to Maurolycus' work with concave specula.
Rayleigh points out that this clinging of the sound to the surface of a concave wall does not depend on the exactness of the spherical form.