Cited by C.S. Sherrington, 'On Reciprocal Action in the Retina as studied by means of some Rotating Discs', Journal of Physiology 21 (1) (1897), pp. 33-54.
Description:

'Fick [note: 'Arch. f. Anat. u. Physiol. 1863.'] has shown that a more intense light sensation developes more speedily than does a less intense.' (35)

Cited by O.F.F. Grünbaum, 'On Intermittent Stimulation of the Retina (Part II)', Journal of Physiology 22 (6) (1898), pp. 433-450
Description:

'The absolute accuracy of the Talbot-Plateau law was questioned by Fick [note: 'Reichert's Archiv, p. 739. 1863.'] in 1863, who adopted the same method of investigation as Plateau [note: 'Pogg. Annalen, XXXV. p. 457. 1835.'] had devised some years earlier.' (438)

 

'Fick [note: 'loc. cit.'] found that the luminosities of the rotating disc measured in this manner did not agree absolutely with that determined by the angle of black upon the disc.

[includes table of data from Fick]

All except the last disc were found to produce a sensation of greater luminosity than would have been expected from calculation of their angular brightness.' (439)

Cited by O.F.F. Grünbaum, 'On Intermittent Stimulation of the Retina (Part I)', Journal of Physiology 21 (4-5) (1897), pp. 396-402.
Description:

'Fick found that under certain conditions 170 alternations might be necessary to produce fusion; this was the case when parallel lines were drawn on a drum which was rotated around an axis parallel to the lines: if, however, the observations were made through a slit no flicker was seen above 40 per second.

...

Fick suggested that movement of the eyes might be the explanation of the observations; wheni the speed of translation was small the eyes followed the sectors and thus flicker was not destroyed until high speeds were attained; the use of a window partially prevented this.' (396)