[The relation of the motion velocity of the real image to the velocity of illusory image in diplopia studied by the clock method].

From a perspective of 34 years' experience of using the clock method to examine ophthalmo-plegia, the author assesses the utility of this method and discusses the ensuing principles. He gives a thorough analysis of the principle which states that if the real image traverses a circular (or semi-circular) path then the apparent image moves in the same time along an elliptic (or semi-elliptic) path. According to his calculations the velocity of the apparent image is greater than the velocity of the real image and proportional to the magnitude of the disparation.