(iv.) The state of adaptation of the observer's eye is dependent on his state of health, on a con dition of greater or less fatigue, or Circle of position ni ////fie on the inclina e,, ,,,y„ head Circle tion of the (,?ccleofdedinataon: in consequence of, ?
Dition being added and the every application, not so as A whole grape.
The path of a ray from the wave-surface AoBo to A or B is determined by the con dition that the optical distance, µ ds, is a minimum; and, as AB is by supposition a wave-surface, this optical distance is the same for both points.
61° tory organs of those creatures in the con-;...« dition of projecting appendages serving =?.?