Turned wooden scioptric ball or "ox-eye". The ball, approx. 3 1/4 in. diameter, housed in 7 1/2 x 7 1/2 in. mount. Underside signed, "R.W. Lisle, 1978."

In 1636, a German mathematician described a wooden ball with a hole bored through it and a lens fitted at each end. It could be placed in the opening of the camera obscura, projecting a brighter, more detailed image. The scioptric ball was used for popular entertainment and as a sketching aid in mural painting.