could be heard at a distance at sea by listening at one end of a
tube, the other end of which was placed in the water; and that
the same expedient worked successfully on land, the end of the
tube being placed against the ground.

The knowledge of this great number of unexplained facts is often
interpreted by the admirers of Da Vinci, as showing an almost
occult insight into science many centuries in advance of his
time. Such interpretations, however, are illusive. The
observation, for example, that a tube placed against the ground
enables one to hear movements on the earth at a distance, is not
in itself evidence of anything more than acute scientific
observation, as a similar method is in use among almost every
race of savages, notably the American Indians. On the other hand,
one is inclined to give credence to almost any story of the
breadth of knowledge of the man who came so near anticipating
Hutton, Lyell, and Darwin in his interpretation of the geological
records as he found them written on the rocks.

It is in this field of geology that Leonardo is entitled to the
greatest admiration by modern scientists. He had observed the
deposit of fossil shells in various strata of rocks, even on the
tops of mountains, and he rejected once for all the theory that
they had been deposited there by the Deluge. He rightly
interpreted their presence as evidence that they had once been
deposited at the bottom of the sea. This process he assumed bad
taken hundreds and thousands of centuries, thus tacitly rejecting
the biblical tradition as to the date of the creation.

Notwithstanding the obvious interest that attaches to the