Note u — BOOK IV.

Besides those particular Motions which the Eye receives from the Oblique Muscles, and I may add its Libration also in some Measure, some Anatomists ascribe another no less considerable Use to them; namely, to lengthen and shorten the Eye (by squeezing and compressing it) to make it correspond to the Distances of all Objects, according as they are nigh or far off. Thus the ingenious Dr. Keil; The Aqueous Humour being the thinnest and most liquid, easily changeth its Figure, when either the Ligamentum Ciliate contracts, or both the Oblique Muscles squeeze the middle of the Ball of the Eye, to render it Oblong when Objects are too near us. Keil’s Anat. Chap. 4. Sect. 4. See Note (y).