| Just beneath the surface of receptacles are spherical cavities called conceptacles where gametes are produced. |
| Menelaus's work formed the basis for Ptolemy's numerical solutions of spherical astronomy problems in the Almagest. |
| To eliminate the residual aberration in the spherical lens, we need to increase the refractive index of the glass. |
| He also considered curves of double curvature on the sphere and the quadrature of parts of a spherical surface. |
| In the introduction he pointed out that a plane was a special case of a spherical surface, that is a sphere with infinite radius. |
| Adding an aplanatic meniscus lens to an achromatic lens can increase relative aperture without introducing additional spherical aberration. |
