IT may be of interest to give a preliminary account of what I believe to be a new method of producing acoustic spectra. The method, which is to employ the striations on “variable-density” sound-film ...

Movement of a grating behind a fixed aperture can be detected by human subjects when the grating is well below the diffraction limit of the pupil and below acuity measured with stationary gratings.

DENTON 1 has suggested that a possible function of the pupil light reflex might be to provide apertures optimum for visual acuity at different light intensities. At low levels of luminance visual ...