It was not until the knowledge of anatomy had made considerable progress that the existence of this cavity was known. Highmore, in the early part of the seventeenth century, was the first anatomist to give a correct description of this cavity. I hope it will not be thought presumption in me to call attention briefly to the anatomical outlines of this cavity.
It should be remembered, in connection with diseases of the maxillary sinuses, that this cavity is of considerable size, with walls of different thickness. In youth the walls are thick and the cavity small. After attaining its maximum size in the adult it is again diminished in old age. It is larger in males than in females. But in adult life its size varies in different subjects, and the larger the cavity the thinner the walls. The roof is formed by the orbital plate, and the thickness of