Related to Rotating Binocular Lamp
Description:

In his description of the Rotating Binocular Lamp, Charles Sherrington notes that 'The speed of rotation of the cylindrical screen [surrounding the lamp] was recorded by marking the completion of each revolution of its spindle by an electro-magnetic signal writing on a travelling blackened surface. On the same surface the time was recorded by a writing clock marking fifths of seconds.' (C.S. Sherrington, 'On Binocular Flicker and the Correlations of Activity of 'Corresponding' Retinal Points', Journal of Psychology 1 (1) (1904), p.29)