Douglas, GAWAIN

or GAVIN, 1474-1522. Scottish poet; Bp. of Dunkeld 1515; son of Archibald, fifth Earl of Angus. Palace but under certain circumstances the two are not combined, but produce a double image of the object. This is readily shown by holding up the two forefingers vertically in front of the eyes and ab. a foot from each other. If now the eyes be focused so that the nearer finger be seen distinctly as single, the further finger will be seen double; and similarly, if the further finger be focused, the nearer one will appear double. The phenomenon is partially explained by the existence in the ret inæ of so-called identical points, i.e. , points in each retina corresponding to points in the other upon which, if rays of light from an object fall, the object is perceived as one, while if the rays fall on non-corresponding or disparate points, the object is seen as two. The rays are brought to identical points on the ret inæ by means of the mechanism of accommodation of the eye. See VISION.