A Rare Angus McNab Retinoscope

c.1910, English or Scottish, in lacquered brass with ivory handle, cylindrical mirror to determine astigmatism, reverse of mirror with five degree divisions, in velvet and silk-lined Moroccan leather case;  Note: Produces a band of light on illuminated area of fundus instead of image of lamp. By means of milled wheels the mirror is allowed to rotate and the band of light on the fundus can be made to lie in the axis of the astigmatism when this is present.