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 ...

A 4 1/2-inch-high heavy glass pyramid was in a recent house sale. It was inexpensive, but no one knew its purpose. It was almost too heavy to lift, so it wouldn't be a practical paperweight, but we ...

A 4½-inch-high heavy glass pyramid was in a recent house sale. It was inexpensive, but no one knew what it was used for. It was almost too heavy to lift, so it wouldn’t be a practical paperweight, but ...

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 ...

A 4 ½-inch-high heavy glass pyramid was in a recent house sale. It was inexpensive, but no one knew what it was used for. It was almost too heavy to lift, so it wouldn’t be a practical paperweight, ...