LEONARDO DA VINCI
The relative infertility of Bacon's thought is shown by the fact
that he founded no school and left no trace of discipleship. The
entire century after his death shows no single European name that
need claim the attention of the historian of science. In the
latter part of the fifteenth century, however, there is evidence
of a renaissance of science no less than of art. The German
Muller became famous under the latinized named of Regio Montanus
(1437-1472), although his actual scientific attainments would
appear to have been important only in comparison with the utter
ignorance of his contemporaries. The most distinguished worker of
the new era was the famous Italian Leonardo da Vinci--a man who
has been called b 10510p1523k y Hamerton the most universal genius that ever
lived. Leonardo's position in the history of art is known to
every one. With that, of course, we have no present concern; but
it is worth our while to inquire at some length as to the famous
painter's accomplishments as a scientist.
From a passage in the works of Leonardo, first brought to light
by Venturi,[1] it would seem that the great painter anticipated
Copernicus in determining the movement of the earth. He made
mathematical calculations to prove this, and appears to have
reached the definite conclusion that the earth does move--or what
amounts to the same thing, that the sun does not move. Muntz is
authority for the statement that in one of his writings he
declares, "Il sole non si mouve"--the sun does not move.[2]
Among his inventions is a dynamometer for determining the
traction power of machines and animals, and his experiments with
steam have led some of his enthusiastic partisans to claim for
him priority to Watt in the invention of the steam-engine. In
these experiments, however, Leonardo seems to have advanced
little beyond Hero of Alexandria and his steam toy. Hero's
steam-engine did nothing but rotate itself by virtue of escaping
jets of steam forced from the bent tubes, while Leonardo's
"steam-engine" "drove a ball weighing one talent over a distance
of six stadia." In a manuscript now in the library of the
Institut de France, Da Vinci describes this engine minutely. The
action of this machine was due to the sudden conversion of small
quantities of water into steam ("smoke," as he called it) by
coming suddenly in contact with a heated surface in a proper
receptacle, the rapidly formed steam acting as a propulsive force
after the manner of an explosive. It is really a steam-gun,
rather than a steam-engine, and it is not unlikely that the study
of the action of gunpowder may have suggested it to Leonardo.
It is believed that Leonardo is the true discoverer of the
camera-obscura, although the Neapolitan philosopher, Giambattista
Porta, who was not born until some twenty years after the death
of Leonardo, is usually credited with first describing this
device. There is little doubt, however, that Da Vinci understood
the principle of this mechanism, for he describes how such a
camera can be made by cutting a small, round hole through the
shutter of a darkened room, the reversed image of objects outside
being shown on the opposite wall.
Like other philosophers in all ages, he had observed a great
number of facts which he was unable to explain correctly. But
such accumulations of scientific observations are always
interesting, as showing how many centuries of observation
frequently precede correct explanation. He observed many facts
about sounds, among others that blows struck upon a bell produced
sympathetic sounds in a bell of the same kind; and that striking
the string of a lute produced vibration in corresponding strings
of lutes strung to the same pitch. He knew, also, that sounds
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
investigations of Leonardo, it must be admitted that his work in
science remained almost as infertile as that of his great
precursor, Bacon. The really stimulative work of this generation
was done by a man of affairs, who knew little of theoretical
science except in one line, but who pursued that one practical
line until he achieved a wonderful result. This man was
Christopher Columbus. It is not necessary here to tell the trite
story of his accomplishment. Suffice it that his practical
demonstration of the rotundity of the earth is regarded by most
modern writers as marking an epoch in history. With the year of
his voyage the epoch of the Middle Ages is usually regarded as
coming to an end. It must not be supposed that any very sudden
change came over the aspect of scholarship of the time, but the
preliminaries of great things had been achieved, and when
alive who was to bring forward the first great vitalizing thought
in the field of pure science that the Western world had
originated for more than a thousand years. This man bore the name
of Kopernik, or in its familiar Anglicized form, Copernicus. His
life work and that of his disciples will claim our attention in
the succeeding chapter.
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