Side view of the eyeball. Labels: a, the eyeball, and b,b, are the upper and lower sides. Now in order to prevent dust and other bodies from working their way between the ball and the lid, through passages at c,c, into the socket of the eye where they would excite great inconvenience and pain, we find the common skin of the eye lids d,d, after covering their edges turn in a little way between the lid and the ball, and then turn back and are reflected over the surface of the cornea; where, to prevent the obstruction of vision, it becomes perfectly transparent.

Side View of the Eyeball

Side view of the eyeball. Labels: a, the eyeball, and b,b, are the upper and lower sides. Now in order…

Sagittal section of the left orbital cavity.

Sagittal Section of Orbital Cavity

Sagittal section of the left orbital cavity.