The Reason Why / A Careful Collection of Many Hundreds of Reasons for Things Which, Though Generally Believed, Are Imperfectly Understood

by Robert Kemp Philp

So perfect is the Almighty contrivance, that not only are the ribs made to protect the lungs, but, by their elasticity, and the contractions and dilations of the muscles which lie between them, they assist the lungs in their labours, and work with them in perfect harmony.

Fig. 55.—SECTION OF THE KNEE JOINT, SHOWING THE CELLULAR STRUCTURE OF BONE, BY WHICH LIGHTNESS AND STRENGTH ARE OBTAINED.

934. Why are the bones of the arms, legs, &c., made hollow?

Because lightness is thereby combined with strength. There is a provision by which, in the extremities of bones, where an enlarged surface is required, lightness is still combined with the necessary degree of strength.

The bones are made up of a cellular formation; and this generally occurs in parts which are much called into action, in the various movements of the body.

A. Lower part of the bone of the thigh.

B. Head of the bone of the leg.

C. The knee cap, showing its relation to the other bones, and the manner in which it is enclosed by the tendons seen at [Fig. 58].