IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more. Thiscut and folded tan paper model ...

A pyramidal prism/angular cube reflector is always used to reflect a beam of light into the prism, regardless of the direction of the beam. Corner prisms are widely used where accurate alignment is ...

During a recent house sale, a 4½-inch-high heavy glass pyramid was for sale. The item was inexpensive, but no one knew what it was used for. It was almost too heavy to lift, so it wouldn't be a ...