The peculiar structure and form of the skull afford a perfect shelter for
the brain--an organ so delicate that, if unprotected, an ordinary blow
would destroy it. Its oval or egg shape adapts it to resist pressure. The
smaller and stronger end is in front, where the danger is greatest.
Projections before and behind shield the less protected parts. The hard
plates are not easy to penetrate. [Footnote: Instances have been known
where bullets, striking against the skull, have glanced off, been
flattened, or even split into halves. In the Peninsular Campaign, the
author saw a man who had been struck in the forehead by a bullet which,
instead of penetrating the brain, had followed the skull around to the
back of the head, and there passed out.] The spongy packing deadens every
blow. [Footnote: An experiment resembling the familiar one of the balls in
Natural Philosophy ("Steele's Popular Physics," Fig. 6, p. 26),
beautifully illustrates this point. Several balls of ivory are suspended
by cords, as in Fig. 5. If A be raised and then let fall, it will transmit
the force to B, and that to C, and so on until F is reached, which will
fly off with the impulse. If now a ball of spongy bone be substituted for
an ivory one anywhere in the line, the force will be checked, and the last
ball will not stir.] The separate pieces with their curious joinings
disperse any jar which one may receive, and also prevent fractures from
spreading.

FIG. 5.

[Illustration]

The frequent openings in this strong bone box afford safe avenues for the
passage of numerous nerves and vessels which communicate between the brain
and the rest of the body.