Torsional Motions of the Eyeball *

OF the many attempts which have been made in the past to record motions of the eyeball, the most successful investigations have used the corneal reflex method (Lord and Wright, 1948), photographic recording ofthe motions of a beam of light reflected from a plane mirror worked on a contact lens (Ratliff and Riggs, 1950; Ditchburn and Ginsborg, 1953), or photographic recording of the motion of the image of a bright source reflected in a globule of mercury pipetted on to the cornea (Barlow, 1952). These experiments have recorded at most the motions of the eyeball producing side-to-side and up-and-down motion of the visual axis when performing various visual tasks. The motions described by previous authors may be summarized as follows: