SCIENTIFIC KNOWLEDGE AMONG THE ROMANS.
[Sidenote: Wonders of modern science.]
[Sidenote: Every great age distinguished for something never afterwards
equaled.]
It would be absurd to claim for the ancients any great attainments in
science, such as they made in the field of letters or the realm of art.
It is in science, especially when applied to practical life, that the
moderns show their great superiority to the most enlightened nations of
antiquity. In this great department, modern genius shines with the
lustre of the sun. It is this which most strikingly attests the advance
of society, which makes their advance a most incontestible fact. It is
this which has distinguished and elevated the races of Europe more
triumphantly than what has resulted from the combined energies of Greeks
and Romans in all other departments combined. With the magnificent
discoveries and inventions of the last three hundred years in almost
every department of science,--especially in physics, in the
explorations of distant seas and continents, in the analysis of chemical
compounds, in the explanation of the phenomena of the heavens, in the
wonders of steam and electricity, in mechanical appliance to abridge
human labor or destroy human life, in astronomical researches, in the
miracles which inventive genius has wrought,--seen in our ships, our
manufactories, our wondrous instruments, our printing-presses, of our
observatories, our fortifications, our laboratories, our mills, our
machines to cultivate the earth, to make our clothes, to build our
houses, to multiply our means of offense and defense, to make weak
children do the work of Titans, to measure our time with the accuracy of
the orbit of the planets, to use the sun itself in perpetuating our
likenesses to distant generations, to cause a needle to guide the
mariner with assurance on the darkest night, to propel a heavy ship
against the wind and tide without oars or sails, to make carriages
ascend mountains without horses at the rate of thirty miles an hour, to
convey intelligence with the speed of lightning from continent to
continent, under oceans that ancient navigators never dared to cross;
these and other wonders attest an ingenuity and audacity of intellect
which would have overwhelmed with amazement the most adventurous of
Greeks and the most potent of Romans. The achievements of modern science
settle forever the question as to the advance of society and the
superiority of modern times over those of the most favored nations of
antiquity. But the great discoveries and inventions to which we owe this
marked superiority are either accidental or the result of generations of
experiment, assisted by an immense array of ascertained facts from which
safe inductions can be made. It is not, probably, the superiority of the
Teutonic races over the Greeks and Romans to which we may ascribe the
wonderful advance of modern society, but the particular direction which
genius was made to take. Had the Greeks given the energy of their minds
to mechanical forces as they did to artistic creations, they might have
made wonderful inventions. But it was so ordered by Providence. Nor was
the world in that stage of development when this particular direction of
intellect would have been favored. There were some things which the
Greeks and Romans exhausted, some fields of labor and thought in which
they never have been, and, perhaps, never will be, surpassed; and some
future age may direct its energies into channels which are as unknown to
us as clocks and steam-engines were to the Greeks. This is the age of
mechanism and of science, and mechanism and science sweep every thing
before them, and will probably be carried to their utmost capacity and
development. Then the human mind may seek some new department, some new
scope for energies, and a new age of wonders may arise,--perhaps after
the present dominant races shall have become intoxicated with the
greatness of their triumphs and have shared the fate of the old
monarchies of the East. But I would not speculate on the destinies of
the European nations, whether they are to make indefinite advances,
until they occupy and rule the whole world, or are destined to be
succeeded by nations as yet undeveloped,--savages, as their fathers
were when Rome was in the fullness of material wealth and grandeur. We
know nothing of the future. We only know that all nations are in the
hands of God, who setteth up and pulleth down according to his infinite
wisdom.
I have shown that in the field of artistic excellence, in literary
composition, in the arts of government and legislation, and even in the
realm of philosophical speculations, the ancients were our
schoolmasters, and that among them were some men of most marvelous
genius, who have had no superiors among us.
[Sidenote: The ancients deficient in the application of science.]
But we do not see the exhibition of genius in what we call science, at
least in its application to practical life. It would be difficult to
show any department of science which the ancients carried to any degree
of perfection. Nevertheless, there were departments in which they made
noble attempts, and in which they showed considerable genius, even if
they were unsuccessful in great practical results.
[Sidenote: Labors of the ancients in astronomy.]
Astronomy was one of these. So far as mathematical genius is concerned,
so far as astronomy taxed the reasoning powers, such men as
Eratosthenes, Aristarchus, Hipparchus, and Ptolemy were great lights, of
whom humanity may be proud; and, had they been assisted by our modern
accidental inventions, they might have earned a fame scarcely eclipsed
by that of Kepler and Newton. The Ionic philosophers added but little to
the realm of true philosophy, but they were pioneers of thought, and
giants in their native powers. The old astronomers did as little as they
to place science on a true foundation, but they showed great ingenuity,
and discovered some great truths which no succeeding age has repudiated.
They determined the circumference of the earth by a method identical
with that which would be employed by modern astronomers. They
ascertained the position of the stars by right ascension and
declination. They knew the obliquity of the ecliptic, and determined the
place of the sun's apogee as well as its mean motion. Their calculations
on the eccentricity of the moon prove that they had a rectilinear
trigonometry and tables of chords. They had an approximate knowledge of
parallax. [Footnote: Delambre, _Hist. d'Astr. Anc._, tom. 1, p.
184.] They could calculate eclipses of the moon, and use them for the
correction of their lunar tables. They understood spherical
trigonometry, and determined the motions of the sun and moon, involving
an accurate definition of the year, and a method of predicting eclipses.
They ascertained that the earth was a sphere, and reduced the phenomena
of the heavenly bodies to uniform movements of circular orbits.
[Footnote: Lewis, _Hist. of Astron._, p. 209.] We have settled, by
physical geography, the exact form of the earth, but the ancients
arrived at their knowledge by astronomical reasoning. "The reduction of
the motions of the sun, moon, and five planets to circular orbits, as
was done by Hipparchus, implies deep concentrated thought and scientific
abstraction. The theory of eccentrics and epicycles accomplished the end
of explaining all the known phenomena. The resolution of the apparent
motions of the heavenly bodies into an assemblage of circular motions,
was a great triumph of genius, [Footnote: Whewell, _Hist. Induc.
Science_, v. i. p. 181.] and was equivalent to the most recent and
improved processes by which modern astronomers deal with such motions."
But I will not here enumerate the few discoveries which were made by the
Alexandrian school. I only wish to show that there are a few names among
the ancients which are inscribed on the roll of great astronomers,
limited as were the triumphs of the science itself. But, until the time
of Aristarchus, most of the speculations were crude and useless. Nothing
can be more puerile than the notions of the ancients respecting the
nature and motions of the heavenly bodies.
[Sidenote: Astronomy born in Chaldea.]
Astronomy was probably born in Chaldea as early as the time of Abraham.
The glories of the firmament were impressed upon the minds of the rude
primitive races with an intensity which we do not feel with all the
triumphs of modern science. The Chaldean shepherds, as they watched
their flocks by night, noted the movements of the planets, and gave
names to the more brilliant constellations. Before religious rituals
were established, before great superstitions arose, before poetry was
sung, before musical instruments were invented, before artists
sculptured marble or melted bronze, before coins were stamped, before
temples arose, before diseases were healed by the arts of medicine,
before commerce was known, before heroes were born, those oriental
shepherds counted the hours of anxiety by the position of certain
constellations. Astronomy is, therefore, the oldest of the ancient
sciences, although it remained imperfect for more than four thousand
years. The old Assyrians, Egyptians, and Greeks made but few discoveries
which are valued by modern astronomers, but they laid the foundation of
the science, and ever regarded it as one of the noblest subjects which
could stimulate the faculties of man. It was invested with all that was
religious and poetical.
[Sidenote: Discoveries made by oriental nations.]
The spacious level and unclouded horizon of Chaldea afforded peculiar
facilities of observation; and its pastoral and contemplative
inhabitants, uncontaminated by the vices and superstitions of subsequent
ages, active-minded and fresh, discovered, after a long observation of
eclipses--some say extending over nineteen centuries--the cycle of two
hundred and twenty-three lunations, which brings back the eclipses in
the same order. Having once established their cycle, they laid the
foundation for the most sublime of all the sciences. Callisthenes
transmitted from Babylon to Aristotle a collection of observations of
all the eclipses that preceded the conquests of Alexander, together with
the definite knowledge which the Chaldeans had collected about the
motions of the heavenly bodies. It was rude and simple, and amounted to
little beyond the fact that there were spherical revolutions about an
inclined axis, and that the poles pointed always to particular stars.
The Egyptians also recorded their observations, from which it would
appear that they observed eclipses at least one thousand six hundred
years before the commencement of our era. Nor is this improbable, if the
speculations of modern philosophers respecting the age of the world are
entitled to respect. The Egyptians discovered, by the rising of Sirius,
that the year consists of three hundred and sixty-five and one quarter
days, and this was their sacred year, in distinction from the civil,
which consisted of three hundred and sixty-five days. They also had
observed the courses of the planets, and could explain the phenomena of
the stations and retrogradations, and it is even asserted that they
regarded Mercury and Venus as satellites of the sun. Some have
maintained that the obelisks which they erected served the purpose of
gnomons, for determining the obliquity of the ecliptic, the altitude of
the pole, and the length of the tropical year. It is thought that even
the Pyramids, by the position of their sides toward the cardinal points,
attest their acquaintance with a meridional line. The Chinese boast of
having noticed and recorded a series of eclipses extending over a period
of three thousand eight hundred and fifty-eight years, and it is
probable that they anticipated the Greeks two thousand years in the
discovery of the Metonic cycle, or the cycle of nineteen years, at the
end of which time the new moons fall on the same days of the year. They
determined the obliquity of the ecliptic, one thousand one hundred years
before our era, to be 23 degrees 54' 3-15". The Indians, at a remote
antiquity, represented celestial phenomena with considerable exactness,
and constructed tables by which the longitude of the sun and moon are
determined. Bailly thinks that astronomy was cultivated in Siam three
thousand one hundred and two years before Christ, which hardly yields in
accuracy to that which modern science has built on the theory of
universal gravitation. The Greeks divided the heavens into
constellations fourteen centuries before Christ. Thales, born 640 B.C.,
taught the rotundity of the earth, and that the moon shines with
reflected light. He also predicted eclipses. Anaximander, born 610 B.C.,
invented the gnomon, and constructed geographical charts.
[Sidenote: The early Greek investigators.]
But the Greeks, after all, were the only people of antiquity who
elevated astronomy to the dignity of a science. They however confessed
that they derived their earliest knowledge from the Babylonian and
Egyptian priests, while the priests of Thebes asserted that they were
the originators of exact astronomical observations. [Footnote: Diod., i.
50.] Diodorus asserts that the Chaldeans used the Temple of Belus, in
the centre of Babylon, for their survey of the heavens. [Footnote:
Diod., ii. 9.] But whether the Babylonians or the Egyptians were the
earliest astronomers, it is of little consequence, although the pedants
make it a grave matter of investigation. All we know is, that astronomy
was cultivated by both Babylonians and Egyptians, and that they made but
very limited attainments. The early Greek philosophers, who visited
Egypt and the East in search of knowledge, found very little to reward
their curiosity or industry; not much beyond preposterous claims to a
high antiquity, and an esoteric wisdom which has not yet been revealed.
They approximated to the truth in reference to the solar year, by
observing the equinoxes and solstices, and the heliacal rising of
particular stars. Plato and Eudoxus spent thirteen years in Heliopolis
for the purpose of extracting the scientific knowledge of the priests,
but they learned but little beyond the fact that the solar year was a
trifle beyond three hundred and sixty-five days. No great names have
come down to us from the priests of Babylon or Egypt. No one gained an
individual reputation. The Chaldean and Egyptian priests may have
furnished the raw material of observation to the Greeks, but the latter
alone possessed the scientific genius by which indigested facts were
converted into a symmetrical system. The East never gave valuable
knowledge to the West. It gave only superstition. Instead of astronomy,
it gave astrology; instead of science, it gave magic and incantations
and dreams--poison which perverted the intellect. [Footnote: Sir G. G.
Lewis, _Hist. of Anc. Astron._, p. 293.] They connected their
astronomy with divination from the stars, and made their antiquity reach
back to two hundred and seventy thousand years. There were soothsayers
in the time of Daniel, and magicians, exorcists, and interpreters of
signs. [Footnote: Dan. i. 4, 17, 20.] They were not men of scientific
research, seeking truth. It was power they sought, by perverting the
intellect of the people. The astrology of the East was founded on the
principle that a star or constellation presided over the birth of an
individual, and either portended his fate, or shed a good or bad
influence upon his future life. The star which looked upon a child at
the hour of his birth, was called the horoscopus, and the peculiar
influence of each planet was determined by professors of the genethliac
art. The superstitions of Egypt and Chaldea unfortunately spread both
among the Greeks and Romans, and these were about all that the western
nations learned from the boastful priests of occult science. Whatever
was known of real value among the ancients, is due to the earnest
inquiries of the Greeks.
[Sidenote: Researches of the Greeks.]
And yet their researches were very unsatisfactory until the time of
Hipparchus. The primitive knowledge, until Thales, was almost nothing.
The Homeric poems regarded the earth as a circular plain, bounded by the
heaven, which was a solid vault or hemisphere, with its concavity turned
downwards. And this absurdity was believed until the time of Herodotus,
five centuries after; nor was it exploded fully in the time of
Aristotle. The sun, moon, and stars, were supposed to move upon, or
with, the inner surface of the heavenly hemisphere, and the ocean was
thought to gird the earth around as a great belt, into which the
heavenly bodies sunk at their setting. [Footnote: _Il_., vii. 422;
_Od_., iii. i. xix. 433.] Homer believed that the sun arose out of
the ocean, ascending the heaven, and again plunging into the ocean,
passing under the earth, and producing darkness. [Footnote: _Il_.
viii. 485.] The Greeks even personified the sun as a divine charioteer
driving his fiery steeds over the steep of heaven, until he bathed them
at evening in the western waves. Apollo became the god of the sun, as
Diana was the goddess of the moon. But the early Greek inquirers did not
attempt to explain how the sun found his way from the west back again to
the east. They merely took note of the diurnal course, the alternation
of day and night, the number of the seasons, and their regular
successions. They found the points of the compass by determining the
recurrence of the equinoxes and solstices; but they had no conception of
the ecliptic--of that great circle in the heaven, formed by the sun's
annual course, and of its obliquity when compared with the equator. Like
the Egyptians and Babylonians, they ascertained the length of the year
to be three hundred and sixty-five days; but perfect accuracy was
wanting for want of scientific instruments, and of recorded observations
of the heavenly bodies. The Greeks had not even a common chronological
era for the designation of years. Thus Herodotus informs us that the
Trojan War preceded his time by eight hundred years: [Footnote:
_Il_, ii. 53.] he merely states the interval between the event in
question and his own time; he had certain data for distant periods. Thus
the Greeks reckoned dates from the Trojan War, and the Romans from the
building of their city. And they divided the year into twelve months,
and introduced the intercalary circle of eight years, although the
Romans disused it afterwards until the calendar was reformed by Julius
Caesar. Thus there was no scientific astronomical knowledge worth
mentioning among the primitive Greeks.
Immense research and learning have been expended by modern critics, to
show the state of scientific astronomy among the Greeks. I am equally
amazed at the amount of research, and its comparative worthlessness,
for what addition to science can be made by an enumeration of the
puerilities and errors of the Greeks, and how wasted and pedantic the
learning which ransacks all antiquity to prove that the Greeks adopted
this or that absurdity. [Transcriber's Note: Lengthy footnote relocated
to chapter end.]
[Sidenote: Thales.]
[Sidenote: Anaximander and Anaximenes.]
But to return. The earliest historic name associated with astronomy in
Greece was Thales, the founder of the Ionic school of philosophers, born
639 B.C. He is reported to have predicted an eclipse of the sun, to have
made a visit to Egypt, to have fixed the year at three hundred and
sixty-five days, and to have determined the course of the sun from
solstice to solstice. He attributed an eclipse of the moon to the
interposition of the earth between the sun and moon; and an eclipse of
the sun to the interposition of the moon between the sun and earth.
[Footnote: Sir G. G. Lewis, _Hist. of Astron._, p. 81.] He also
determined the ratio of the sun's diameter to its apparent orbit. As he
first solved the problem of inscribing a right-angled triangle in a
circle, [Footnote: Diog. Laert, i. 24.] he is the founder of geometrical
science in Greece. He left, however, nothing to writing, hence all
accounts of him are confused. It is to be doubted whether in fact he
made the discoveries attributed to him. His speculations, which science
rejects, such as that water is the principle of all things, are
irrelevant to a description of the progress of astronomy. That he was a
great light, no one questions, considering the ignorance with which he
was surrounded. Anaximander, who followed him in philosophy, held to
puerile doctrines concerning the motions and nature of the stars, which
it is useless to repeat. His addition to science, if he made any, was in
treating the magnitudes and distances of the planets. He attempted to
delineate the celestial sphere, and to measure time by a sun-dial.
Anaximenes of Miletus taught, like his predecessors, crude notions of
the sun and stars, and speculated on the nature of the moon, but did
nothing to advance his science on true grounds, except the construction
of sun-dials. The same may be said of Heraclitus, Xenophanes,
Parmenides, Anaxagoras. They were great men, but they gave to the world
mere speculations, some of which are very puerile. They all held to the
idea that the heavenly bodies revolved around the earth, and that the
earth was a plain. But they explained eclipses, and supposed that the
moon derived its light from the sun. Some of them knew the difference
between the planets and the fixed stars. Anaxagoras scouted the notion
that the sun was a god, and supposed it to be a mass of ignited stone,
for which he was called an atheist.
[Sidenote: Socrates.]
[Sidenote: Pythagoras.]
Socrates, who belonged to another school, avoided all barren
speculations concerning the universe, and confined himself to human
actions and interests. He looked even upon geometry in a very practical
way, so far as it could be made serviceable to land measuring. As for
the stars and planets, he supposed it was impossible to arrive at a true
knowledge of them, and regarded speculations upon them as useless. The
Greek astronomers, however barren were their general theories, still
laid the foundation of science. Pythagoras, born 580 B.C., taught the
obliquity of the ecliptic, probably learned in Egypt, and the identity
of the morning and evening stars. It is supposed that he maintained that
the sun was the centre of the universe, and that the earth revolved
around it. But this he did not demonstrate, and his whole system was
unscientific, assuming certain arbitrary principles, from which he
reasoned deductively. "He assumed that fire is more worthy than earth;
that the more worthy place must be given to the more worthy; that the
extremity is more worthy than the intermediate parts; and hence, as the
centre is an extremity, the place of fire is at the centre of the
universe, and that therefore the earth and other heavenly bodies move
round the fiery centre." But this was no heliocentric system, since the
sun moved like the earth, in a circle around the central fire. This was
merely the work of the imagination, utterly unscientific, though bold
and original. Nor did this hypothesis gain credit, since it was the
fixed opinion of philosophers, that the earth was the centre of the
universe, around which the sun and moon and planets revolved. But the
Pythagoreans were the first to teach that the motions of the sun, moon,
and planets, are circular and equable. Their idea that they emitted a
sound, and were combined into a harmonious symphony, was exceedingly
crude, however beautiful. "The music of the spheres" belongs to poetry,
as well as the speculations of Plato.
[Sidenote: Eudoxus.]
Eudoxus, who was born 406 B.C., may be considered the founder of
scientific astronomical knowledge among the Greeks. He is reputed to
have visited Egypt with Plato, and to have resided thirteen years in
Heliopolis, in constant study of the stars, communing with the Egyptian
priests. His contribution to the science was a descriptive map of the
heavens, which was used as a manual of sidereal astronomy to the sixth
century of our era. He distributed the stars into constellations, with
recognized names, and gave a sort of geographical description of their
position and limits, although the constellations had been named before
his time. He stated the periodic times of the five planets visible to
the naked eye, but only approximated to the true periods.
The error of only one hundred and ninety days in the periodic time of
Saturn, shows that there had been, for a long time, close observations.
Aristotle, whose comprehensive intellect, like that of Bacon, took in
all forms of knowledge, condensed all that was known in his day in a
treatise concerning the heavens. [Footnote: Delambre, _Hist. de
l'Astron. Anc._, tom. i. p. 301.] He regarded astronomy as more
intimately connected with mathematical science than any other branch of
philosophy. But even he did not soar far beyond the philosophers of his
day, since he held to the immobility of the earth--the grand error of
the ancients. Some few speculators in science, like Heraclitus of Pontus
and Hicetas, conceived a motion of the earth itself upon its axis, so as
to account for the apparent motion of the sun, but they also thought it
was in the centre of the universe.
[Sidenote: Meton.]
The introduction of the gnomon and dial into Greece advanced
astronomical knowledge, since they were used to determine the equinoxes
and solstices, as well as parts of the day. Meton set up a sun-dial at
Athens in the year 433 B.C., but the length of the hour varied with the
time of the year, since the Greeks divided the day into twelve equal
parts. Dials were common at Rome in the time of Plautus, 224 B.C.;
[Footnote: Ap. Gell., _N. A._, iii. 3.] but there was a difficulty
of using them, since they failed at night and in cloudy weather, and
could not be relied on. Hence the introduction of water-clocks instead.
[Sidenote: Aristarchus.]
Aristarchus is said to have combated (280 B.C.) the geocentric theory so
generally received by philosophers, and to have promulgated the
hypothesis "that the fixed stars and the sun are immovable; that the
earth is carried round the sun in the circumference of a circle of which
the sun is the centre; and that the sphere of the fixed stars having the
same centre as the sun, is of such magnitude that the orbit of the earth
is to the distance of the fixed stars, as the centre of the sphere of
the fixed stars is to its surface." [Footnote: Lewis, p. 190.] This
speculation, resting on the authority of Archimedes, was ridiculed by
him; but if it were advanced, it shows a great advance in astronomical
science, and considering the age, was one of the boldest speculations of
antiquity. Aristarchus also, according to Plutarch, [Footnote: Plut.,
_Plac. Phil._, ii. 24.] explained the apparent annual motion of the
sun in the ecliptic, by supposing the orbit of the earth to be inclined
to its axis. There is no evidence that this great astronomer supported
his heliocentric theory with any geometrical proof, although Plutarch
maintains that he demonstrated it. [Footnote: _Quaest. Plat._, viii.
1.] This theory gave great offense, especially to the Stoics, and
Cleanthes, the head of the school at that time, maintained that the
author of such an impious doctrine should be punished. Aristarchus has
left a treatise "On the Magnitudes and Distances of the Sun and Moon,"
and his methods to measure the apparent diameters of the sun and moon,
are considered sound by modern astronomers, [Footnote: Lewis, p. 193.]
but inexact owing to defective instruments. He estimated the diameter of
the sun at the seven hundred and twentieth part of the circumference of
the circle, which it describes in its diurnal revolution, which is not
far from the truth; but in this treatise he does not allude to his
heliocentric theory.
[Sidenote: Archimedes.]
[Sidenote: Eratosthenes.]
Archimedes, born 287 B.C., is stated to have measured the distance of
the sun, moon, and planets, and he constructed an orrery in which he
exhibited their motions. But it was not in the Grecian colony of
Syracuse, but of Alexandria, that the greatest light was shed on
astronomical science. Here Aristarchus resided, and also Eratosthenes,
who lived between the years 276 and 196 B.C. He was a native of Athens,
but was invited by Ptolemy Euergetes to Alexandria, and placed at the
head of the library. His great achievement was the determination of the
circumference of the earth. This was done by measuring on the ground the
distance between Syene, a city exactly under the tropic, and Alexandria
situated on the same meridian. The distance was found to be five
thousand stadia. The meridional distance of the sun from the zenith of
Alexandria, he estimated to be 7 degrees 12', or a fiftieth part of the
circumference of the meridian. Hence the circumference of the earth was
fixed at two hundred and fifty thousand stadia, not far from the truth.
The circumference being known, the diameter of the earth was easily
determined. The moderns have added nothing to this method. He also
calculated the diameter of the sun to be twenty-seven times greater than
of the earth, and the distance of the sun from the earth to be eight
hundred and four million stadia, and that of the moon seven hundred and
eighty thousand stadia--a very close approximation to the truth.
[Sidenote: Hipparchus.]
[Sidenote: Greatness of Hipparchus.]
Astronomical science received a great impulse from the school of
Alexandria, and Eratosthenes had worthy successors in Aristarchus,
Aristyllus, Apollonius. But the great light of this school was
Hipparchus, whose lifetime extended from 190 to 120 years B.C. He laid
the foundation of astronomy upon a scientific basis. "He determined,"
says Delambre, "the position of the stars by right ascensions and
declinations; he was acquainted with the obliquity of the ecliptic. He
determined the inequality of the sun, and the place of its apogee, as
well as its mean motion; the mean motion of the moon, of its nodes and
apogee; the equation of the moon's centre, and the inclination of its
orbit; he likewise detected a second inequality, of which he could not,
for want of proper observations, discover the period and the law. His
commentary on Aratus shows that he had expounded, and given a
geometrical demonstration of, the methods necessary to find out the
right and oblique ascensions of the points of the ecliptic and of the
stars, the east point and the culminating point of the ecliptic, and the
angle of the east, which is now called the nonagesimal degree. He could
calculate eclipses of the moon, and use them for the correction of his
lunar tables, and he had an approximate knowledge of parallax."
[Footnote: Delambre, _Hist. de l'Astron. Anc._, tom. i. p. 184.]
His determination of the motions of the sun and moon, and method of
predicting eclipses, evince great mathematical genius. But he combined,
with this determination, a theory of epicycles and eccentrics, which
modern astronomy discards. It was, however, a great thing to conceive of
the earth as a solid sphere, and reduce the phenomena of the heavenly
bodies to uniform motions in of circular orbits. "That Hipparchus should
have succeeded in the first great steps of the resolution of the
heavenly bodies into circular motions is a circumstance," says Whewell,
"which gives him one of the most distinguished places in the roll of
great astronomers." [Footnote: _Hist. Ind. Science_, vol. i. p.
181.] But he even did more than this. He discovered that apparent motion
of the fixed stars round the axis of the ecliptic, which is called the
Precession of the Equinoxes, one of the greatest discoveries in
astronomy. He maintained that the precession was not greater than fifty-
nine seconds, and not less than thirty-six seconds. Hipparchus framed a
catalogue of the stars, and determined their places with reference to
the ecliptic, by their latitudes and longitudes. Altogether, he seems to
have been one of the greatest geniuses of antiquity, and his works imply
a prodigious amount of calculation.
[Sidenote: Posidonius.]
[Sidenote: The Roman Calendar.]
Astronomy made no progress for three hundred years, although it was
expounded by improved methods. Posidonius constructed an orrery, which
exhibited the diurnal motions of the sun, moon, and five planets.
Posidonius calculated the circumference of the earth to be two hundred
and forty thousand stadia by a different method from Eratosthenes. The
barrenness of discovery, from Hipparchus to Ptolemy, in spite of the
patronage of the Ptolemies, was owing to the want of instruments for the
accurate measure of time, like our clocks, to the imperfection of
astronomical tables, and to the want of telescopes. Hence the great
Greek astronomers were unable to realize their theories. Their theories
were magnificent, and evinced great power of mathematical combination;
but what could they do without that wondrous instrument by which the
human eye indefinitely multiplies its power?--by which objects are
distinctly seen, which, without it, would be invisible? Moreover, the
ancients had no accurate almanacs, since the care of the calendar
belonged to the priests rather than to the astronomers, who tampered
with the computation of time for temporary and personal objects. The
calendars of different communities differed. Hence Julius Caesar rendered
a great service to science by the reform of the Roman calendar, which
was exclusively under the control of the college of pontiffs. The Roman
year consisted of three hundred and fifty-five days, and, in the time of
Caesar, the calendar was in great confusion, being ninety days in
advance, so that January was an autumn month. He inserted the regular
intercalary month of twenty-three days, and two additional ones of
sixty-seven days. These, together of ninety days, were added to three
hundred and sixty-five days, making a year of transition of four hundred
and forty-five days, by which January was brought back to the first
month in the year after the winter solstice. And to prevent the
repetition of the error, he directed that in future the year should
consist of three hundred and sixty-five and one quarter days, which he
effected by adding one day to the months of April, June, September, and
November, and two days to the months of January, Sextilis, and December,
making an addition of ten days to the old year of three hundred and
fifty-five. And he provided for a uniform intercalation of one day in
every fourth year, which accounted for the remaining quarter of a day.
[Footnote: Suet., _Caesar_, 49; Plut., _Caesar_, 59.]
"Ille moras solis, quibus in sua signa rediret,
Traditur exactis disposuisse notis.
Is decies senos tercentum et quinque diebus
Junxit; et pleno tempora quarta die.
Hic anni modus est. In lustrum accedere debet
Quae consummatur partibus, una dies."
[Footnote: Ovid, _Fast._, iii.]
[Sidenote: Caesar's labors.]
Caesar was a student of astronomy, and always found time for its
contemplation. He is said even to have written a treatise on the motion
of the stars. He was assisted in his reform of the calendar by
Sosigines, an Alexandrian astronomer. He took it out of the hands of the
priests, and made it a matter of pure civil regulation. The year was
defined by the sun, and not, as before, by the moon.
Thus the Romans were the first to bring the scientific knowledge of the
Greeks into practical use; but while they measured the year with a great
approximation to accuracy, they still used sun-dials and water-clocks to
measure diurnal time. And even these were not constructed as they should
have been. The hours on the sun-dial were all made equal, instead of
varying with the length of the day, so that the hour varied with the
length of the day. The illuminated interval was divided into twelve
equal parts, so that, if the sun rose at five A.M. and set at eight
P.M., each hour was equal to eighty minutes. And this rude method of
measurement of diurnal time remained in use till the sixth century. But
clocks, with wheels and weights, were not invented till the twelfth
century.
The earlier Greek astronomers did not attempt to fix the order of the
planets; but when geometry was applied to celestial movements, the
difference between the three superior planets and the two inferior was
perceived, and the sun was placed in the midst between them, so that the
seven movable heavenly bodies were made to succeed one another in the
following order: 1. Saturn; 2. Jupiter; 3. Mars; 4. The Sun; 5. Venus;
6. Mercury; 7. The Moon. Archimedes adopted this order, which was
followed by the leading philosophers. [Footnote: Lewis, p. 247.]
[Sidenote: Ptolemy and his system.]
The last great light among the ancients in astronomical science was
Ptolemy, who lived from 100 to 170 A.D. in Alexandria. He was acquainted
with the writings of all the previous astronomers, but accepted
Hipparchus as his guide. He held that the heaven is spherical and
revolves upon its axis; that the earth is a sphere, and is situated
within the celestial sphere, and nearly at its centre; that it is a mere
point in reference to the distance and magnitude of the fixed stars, and
that it has no motion. He adopted the views of the ancient astronomers,
who placed Saturn, Jupiter, and Mars next under the sphere of the fixed
stars, then the sun above Venus and Mercury, and lastly the moon next to
the earth. But he differed from Aristotle, who conceived that the earth
revolves in an orbit round the centre of the planetary system, and turns
upon its axis--two ideas in common with the doctrines which Copernicus
afterward unfolded. But even he did not conceive the heliocentric theory
that the sun is the centre of the universe. Archimedes and Hipparchus
both rejected this theory.
In regard to the practical value of the speculations of the ancient
astronomers, it may be said that, had they possessed clocks and
telescopes, their scientific methods would have sufficed for all
practical purposes. The greatness of modern discoveries lies in the
great stretch of the reasoning powers, and the magnificent field they
afford for sublime contemplation. "But," as Sir G. Cornwall Lewis
remarks, "modern astronomy is a science of pure curiosity, and is
directed exclusively to the extension of knowledge in a field which
human interests can never enter. The periodic time of Uranus, the nature
of Saturn's ring, and the occupation of Jupiter's satellites, are as far
removed from the concerns of mankind as the heliacal rising of Sirius,
or the northern position of the Great Bear." This may seem to be a
utilitarian view with which those philosophers, who have cultivated
science for its own sake, finding in the same a sufficient reward, as in
truth and virtue, can have no sympathy.
[Sidenote: Result of ancient investigations.]
The upshot of the scientific attainments of the ancients, in the
magnificent realm of the heavenly bodies, would seem to be that they
laid the foundation of all the definite knowledge which is useful to
mankind; while in the field of abstract calculation they evinced
reasoning and mathematical powers which have never been surpassed.
Eratosthenes, Archimedes, and Hipparchus were geniuses worthy to be
placed by the side of Kepler, Newton, and La Place. And all ages will
reverence their efforts and their memory. It is truly surprising that,
with their imperfect instruments, and the absence of definite data, they
reached a height so sublime and grand. They explained the doctrine of
the sphere and the apparent motions of the planets, but they had no
instruments capable of measuring angular distances. The ingenious
epicycles of Ptolemy prepared the way for the elliptic orbits and laws
of Kepler, which, in turn, conducted Newton to the discovery of the laws
of gravitation--the grandest scientific discovery in the annals of our
race.
[Sidenote: Geometry.]
[Sidenote: Ancient Greek geometers.]
[Sidenote: Euclid.]
[Sidenote: Archimedes.]
Closely connected with astronomical science was geometry, which was
first taught in Egypt,--the nurse and cradle of ancient wisdom. It arose
from the necessity of adjusting the landmarks, disturbed by the
inundations of the Nile. Thales introduced the science to the Greeks. He
applied a circle to the measurement of angles. Anaximander invented the
sphere, the gnomon, and geographical charts, which required considerable
geometrical knowledge. Anaxagoras employed himself in prison in
attempting to square the circle. Pythagoras discovered the important
theorem that in a right-angled triangle the squares on the sides
containing the right angle are together equal to the square on the
opposite side of it. He also discovered that of all figures having the
same boundary, the circle among plane figures and the sphere among
solids, are the most capacious. The theory of the regular solids was
taught in his school, and his disciple, Archytas, was the author of a
solution of the problem of two mean proportionals. Democritus of Abdera
treated of the contact of circles and spheres, and of irrational lines
and solids. Hippocrates treated of the duplication of the cube, and
wrote elements of geometry, and knew that the area of a circle was equal
to a triangle whose base is equal to its circumference, and altitude
equal to its radius. The disciples of Plato invented conic sections, and
discovered the geometrical loci. They also attempted to resolve the
problems of the trisection of an angle and the duplication of a cube. To
Leon is ascribed that part of the solution of a problem, called its
_determination_, which treats of the cases in which the problem is
possible, and of those in which it cannot be resolved. Euclid has almost
given his name to the science of geometry. He was born B.C. 323, and
belonged to the Platonic sect, which ever attached great importance to
mathematics. His "Elements" are still in use, as nearly perfect as any
human production can be. They consist of thirteen books,--the first four
on plane geometry; the fifth is on the theory of proportion, and applies
to magnitude in general; the seventh, eighth, and ninth are on
arithmetic; the tenth on the arithmetical characteristics of the
division of a straight line; the eleventh and twelfth on the elements of
solid geometry; the thirteenth on the regular solids. These "Elements"
soon became the universal study of geometers throughout the civilized
world. They were translated into the Arabic, and through the Arabians
were made known to mediaeval Europe. There can be no doubt that this
work is one of the highest triumphs of human genius, and has been valued
more than any single monument of antiquity. It is still a text-book, in
various English translations, in all our schools. Euclid also wrote
various other works, showing great mathematical talent. But, perhaps, a
greater even than Euclid was Archimedes, born 287 B.C., who wrote on the
sphere and cylinder, which terminate in the discovery that the solidity
and surface of a sphere are respectively two thirds of the solidity and
surface of the circumscribing cylinder. He also wrote on conoids and
spheroids. "The properties of the spiral, and the quadrature of the
parabola were added to ancient geometry by Archimedes, the last being a
great step in the progress of the science, since it was the first
curvilineal space legitimately squared." Modern mathematicians may not
have the patience to go through his investigations, since the
conclusions he arrived at may now be reached by shorter methods, but the
great conclusions of the old geometers were only reached by prodigious
mathematical power. Archimedes is popularly better known as the inventor
of engines of war, and various ingenious machines, than as a
mathematician, great as were his attainments. His theory of the lever
was the foundation of statics, till the discovery of the composition of
forces in the time of Newton, and no essential addition was made to the
principles of the equilibrium of fluids and floating bodies till the
time of Stevin in 1608. He detected the mixture of silver in a crown of
gold which his patron, Hiero of Syracuse, ordered to be made, and he
invented a water-screw for pumping water out of the hold of a great ship
he built. He used also a combination of pulleys, and he constructed an
orrery to represent the movement of the heavenly bodies. He had an
extraordinary inventive genius for discovering new provinces of inquiry,
and new points of view for old and familiar objects. Like Newton, he had
a habit of abstraction from outward things, and would forget to take his
meals. He was killed by Roman soldiers when Syracuse was taken, and the
Sicilians so soon forgot his greatness that in the time of Cicero they
did not know where his tomb was. [Footnote: See article in Smith's
_Dictionary_, by Prof. Darkin, of Oxford.]
[Sidenote: Eratosthenes.]
Eratosthenes was another of the famous geometers of antiquity, and did
much to improve geometrical analysis. He was also a philosopher and
geographer. He gave a solution of the problem of the duplication of the
cube, and applied his geometrical knowledge to the measurement of the
magnitude of the earth--one of the first who brought mathematical
methods to the aid of astronomy, which, in our day, is almost
exclusively the province of the mathematician.
[Sidenote: Apollonius of Perga.]
Apollonius of Perga, probably about forty years younger than Archimedes,
and his equal in mathematical genius, was the most fertile and profound
writer among the ancients who treated of geometry. He was called the
Great Geometer. His most important work is a treatise on conic sections,
regarded with unbounded admiration by contemporaries, and, in some
respects, unsurpassed by any thing produced by modern mathematicians.
He, however, made use of the labors of his predecessors, so that it is
difficult to tell how far he is original. But all men of science must
necessarily be indebted to those who have preceded them. Even Homer, in
the field of poetry, made use of the bards who had sung for a thousand
years before him. In the realms of philosophy the great men of all ages
have built up new systems on the foundations which others have
established. If Plato or Aristotle had been contemporaries with Thales,
would they have matured so wonderful a system of dialectics? and if
Thales had been contemporaneous with Plato, he might have added to his
sublime science even more than Aristotle. So of the great mathematicians
of antiquity; they were all wonderful men, and worthy to be classed with
the Newtons and Keplers of our times. Considering their means, and the
state of science, they made as _great_, though not as _fortunate_
discoveries--discoveries which show patience, genius, and power
of calculation. Apollonius was one of these--one of the master
intellects of antiquity, like Euclid and Archimedes--one of the master
intellects of all ages, like Newton himself. I might mention the
subjects of his various works, but they would not be understood except
by those familiar with mathematics. [Footnote: See Bayle's _Dict_.;
Bossuet, _Essai sur L'Hist. Gen. des Math_.; Simson's _Sectiones
Conicae_.]
[Sidenote: Cultivation of geometry by the Greeks.]
Other famous geometers could also be mentioned, but such men as Euclid,
Archimedes, and Apollonius are enough to show that geometry was
cultivated to a great extent by the philosophers of antiquity. It
progressively advanced, like philosophy itself, from the time of Thales,
until it had reached the perfection of which it was capable, when it
became merged into astronomical science. It was cultivated more
particularly by the disciples of Plato, who placed over his school this
inscription, "Let no one ignorant of geometry enter here." He believed
that the laws by which the universe is governed are in accordance with
the doctrines of mathematics. The same opinion was shared by Pythagoras,
the great founder of the science, whose great formula was, that number
is the essence or first principle of all things. No thinkers ever
surpassed the Greeks in originality and profundity, and mathematics,
being highly prized by them, were carried to the greatest perfection
their method would allow. They did not understand algebra, by the
application of which to geometry modern mathematicians have climbed to
greater heights than the ancients. But then it is all the more
remarkable that, without the aid of algebraic analysis, they were able
to solve such difficult problems as occupied the minds of Archimedes and
Apollonius. No positive science can boast of such rapid development as
geometry for two or three hundred years before Christ, and never was the
intellect of man more severely tasked than by the ancient
mathematicians.
[Sidenote: Empirical sciences.]
No empirical science can be carried to perfection by any one nation or
in any particular epoch. It can only expand with the progressive
developments of the human race itself. Nevertheless, in that science
which for three thousand years has been held in the greatest honor, and
which is one of the three great liberal professions of our modern times,
the ancients, especially the Greeks, made considerable advance. The
science of medicine, having in view the amelioration of human misery,
and the prolongation of life itself, was very early cultivated. It was,
indeed, in old times, another word for _physics_,--the science of
nature,--and the _physician_ was the observer and expounder of
physics. The physician was supposed to be acquainted with the secrets of
nature--that is, the knowledge of drugs, of poisons, of antidotes to
them, and the way to administer them. He was also supposed to know the
process of preserving the body after death. Thus Joseph commanded his
physician to embalm the body of his father seventeen hundred years
before the birth of Christ, and the process of embalming was probably
known to the Egyptians beyond the period when history begins. Helen, of
Trojan fame, put into wine a drug that "frees man from grief and anger
and causes oblivion of all ills." [Footnote: _Odyssey_, b. iv.]
Solomon was a great botanist, with which the science of medicine is
indissolubly connected. The "Ayur Veda," written nine hundred years
before Hippocrates was born, sums up the knowledge of previous periods
relating to obstetric surgery, to general pathology, to the treatment of
insanity, to infantile diseases, to toxicology, to personal hygiene, and
to diseases of the generative functions. [Footnote: Wise, _On the
Hindu System of Medicine_, p. 12.] The origin of Hindu medicine is
lost in remote antiquity.
[Sidenote: Hippocrates.]
Thus Hippocrates, the father of European medicine, must have derived his
knowledge, not merely from his own observations, but from the writings
of men unknown to us, and systems practiced for an indefinite period.
The real founders of Greek medicine are fabled characters, like Hercules
and Aesculapius--that is, benefactors whose names have not descended to
us. They are mythical personages, like Hermes and Chiron. One thousand
two hundred years before Christ temples were erected to Aesculapius in
Greece, the priests of which were really physicians, and the temples
themselves were hospitals. In them were practiced rites apparently
mysterious, but which modern science calls by the names of mesmerism,
hydropathy, mineral springs, and other essential elements of empirical
science. And these temples were also medical schools. That of Cos gave
birth to Hippocrates, and it was there that his writings were commenced.
Pythagoras--for those old Grecian philosophers were the fathers of all
wisdom and knowledge, in mathematics and empirical sciences, as well as
philosophy itself--studied medicine in the schools of Egypt, Phoenicia,
Chaldea, and India, and came in conflict with sacerdotal power, which
has ever been antagonistic to new ideas in science. He traveled from
town to town as a teacher or lecturer, establishing communities in which
medicine as well as numbers was taught.
The greatest name in medical science, in ancient or in modern times,--
the man who did the most to advance it; the greatest medical genius of
whom we have record,--is Hippocrates, born on the island of Cos B.C.
460, of the great Aesculapian family, and was instructed by his father.
We know scarcely more of his life than we do of Homer himself, although
he lived in the period of the highest splendor of Athens. And his
writings, like those of Homer, are thought by some to be the work of
different men. They were translated into Arabic, and were no slight
means of giving an impulse to the Saracenic schools of the Middle Ages
in that science in which the Saracens especially excelled. The
Hippocratic collection consists of more than sixty works, which were
held in the highest estimation by the ancient physicians. Hippocrates
introduced a new era in medicine, which, before his time, had been
monopolized by the priests. He carried out a system of severe induction
from the observation of facts, and is as truly the creator of the
inductive method as Bacon himself. He abhorred theories which could not
be established by facts. He was always open to conviction, and candidly
confessed his mistakes. He was conscientious in the practice of his
profession, and valued the success of his art more than silver and gold.
The Athenians revered him for his benevolence as well as genius. The
great principle of his practice was trust in nature. Hence he was
accused of allowing his patients to die; but this principle has many
advocates among scientific men in our day, and some suppose the whole
philosophy of homeopathy rests on the primal principle which Hippocrates
advanced. He had great skill in diagnosis, by which medical genius is
most severely tested. His practice was cautious and timid in contrast
with that of his contemporaries. He is the author of the celebrated
maxim, "Life is short and art is long." He divides the causes of disease
into two principal classes,--the one comprehending the influence of
seasons, climates, and other external forces; the other from the effects
of food and exercise. To the influence of climate he attributes the
conformation of the body and the disposition of the mind. He also
attributes all sorts of disorders to a vicious system of diet. For more
than twenty centuries his pathology was the foundation of all the
medical sects. He was well acquainted with the medicinal properties of
drugs, and was the first to assign three periods to the course of a
malady. He knew, of course, but little of surgery, although he was in
the habit of bleeding, and often employed his knife. He was also
acquainted with cupping, and used violent purgatives. He was not aware
of the importance of the pulse, and confounded the veins with the
arteries. He wrote in the Ionic dialect, and some of his works have gone
through three hundred editions, so highly have they been valued. His
authority passed away, like that of Aristotle, on the revival of
European science. Yet who have been greater ornaments and lights than
these distinguished Greeks?
[Sidenote: Galen.]
The school of Alexandria produced eminent physicians, as well as
mathematicians, after the glory of Greece had departed. So highly was it
esteemed that Galen went there to study five hundred years after its
foundation. It was distinguished for inquiries into scientific anatomy
and physiology, for which Aristotle had prepared the way. He was the
Humboldt of his day, and gave great attention to physics. In eight books
he developed the general principles of natural science known to the
Greeks. On the basis of the Aristotelian researches, the Alexandrian
physicians carried out extensive inquiries in physiology. Herophilus
discovered the fundamental principles of neurology, and advanced the
anatomy of the brain and spinal cord.
[Sidenote: Medical science among the Romans.]
Although the Romans had but little sympathy for science or philosophy,
being essentially political and warlike in their turn of mind, yet when
they had conquered the world, and had turned their attention to arts,
medicine received great attention. The first physicians were Greek
slaves. Of these was Asclepiades, who enjoyed the friendship of Cicero.
It is from him that the popular medical theories as to the "pores" have
descended. He was the inventor of the shower-bath. Celsus wrote a work
on medicine which takes almost equal rank with the Hippocratic writings.
Medical science at Rome culminated in Galen, as it did at Athens in
Hippocrates. He was patronized by Marcus Aurelius, and availed himself
of all the knowledge of preceding naturalists and physicians. He was
born at Pergamus about the year A.D. 165, where he learned, under able
masters, anatomy, pathology, and therapeutics. He finished his studies
at Alexandria, and came to Rome at the invitation of the emperor. Like
his patron, he was one of the brightest ornaments of the heathen world,
and one of the most learned and accomplished men of any age.
"_Medicorum dissertissimus atque doctissimus_." [Footnote: St.
Jerome, _Comment. in Aoms_, c. 5, vol. vi.] He left five hundred
treatises, most of them relating to some branch of medical science,
which give him the merit of being one of the most voluminous of authors.
His celebrity is founded chiefly on his anatomical and physiological
works. He was familiar with practical anatomy, deriving his knowledge
from dissection. His observations about health are practical and useful.
He lays great stress on gymnastic exercises, and recommends the
pleasures of the chase, the cold bath in hot weather, hot baths to old
people, the use of wine, three meals a day, and pork as the best of
animal food. The great principles of his practice were that disease is
to be overcome by that which is contrary to the disease itself, and that
nature is to be preserved by that which has relation with nature. As
disease cannot be overcome so long as its cause exists, that, if
possible, was first to be removed, and the strength of the patient is to
be considered before the treatment is proceeded with. His "Commentaries
on Hippocrates" served as a treasure of medical criticism, from which
succeeding annotators borrowed. No one ever set before the medical
profession a higher standard than Galen, and few have more nearly
approached it. He did not attach himself to any particular school, but
studied the doctrines of each--an eclectic in the fullest sense.
[Footnote: See Leclerc, _Hist. de la Medicine_; Hartt Shoengel,
_Geschichte der Arzneykunde_. W. A. Greenhill, M.D., of Oxford, has
a very learned article in Smith's _Dictionary_.] The works of Galen
constituted the last production of ancient Roman medicine, and from his
day the decline in medical science was rapid, until it was revived among
the Arabs.
The physical sciences, it must be confessed, were not carried by the
ancients to any such length as geometry and astronomy. In physical
geography they were particularly deficient. Yet even this branch of
knowledge can boast of some eminent names. When men sailed timidly on
the coasts, and dared not explore distant seas, the true position of
countries could not be ascertained with the definiteness that it is at
present. But geography was not utterly neglected, nor was natural
history.
[Sidenote: Physical geography.]
Herodotus gives us most valuable information respecting the manners and
customs of oriental and barbarous nations, and Pliny has written a
natural history, in thirty-seven books, which is compiled from upwards
of two thousand volumes, and refers to twenty thousand matters of
importance. He was born A.D. 23, and was fifty-three when the eruption
of Vesuvius took place which caused his death. Pliny cannot be called a
scientific genius, in the sense understood by modern savants; nor was he
an original observer. His materials are drawn up second hand, like a
modern encyclopedia. Nor did he evince great judgment in his selection.
He had a great love of the marvelous, and is often unintelligible. But
his work is a wonderful monument of human industry. It treats of every
thing in the natural world--of the heavenly bodies, of the elements, of
thunder and lightning, of the winds and seasons, of the changes and
phenomena of the earth, of countries and nations, seas and rivers, of
men, animals, birds, fishes, and plants, of minerals and medicines and
precious stones, of commerce and the fine arts. He is full of errors;
but his work is among the most valuable productions of antiquity. Buffon
pronounced his natural history to contain an infinity of knowledge in
every department of human occupation, conveyed in a dress ornate and
brilliant. It is a literary rather than a scientific monument, and as
such it is wonderful--a compilation from one hundred and sixty volumes
of notes. In strict scientific value, it is inferior to the works of
modern research; but there are few minds, even in these times, who have
directed inquiries to such a variety of subjects.
[Sidenote: Strabo.]
[Sidenote: Construction of maps.]
[Sidenote: Ptolemy.]
Geographical knowledge was advanced by Strabo, who lived in the Augustan
era; but researches were chiefly confined to the Roman empire. Strabo
was, like Herodotus, a great traveler, and much of his geographical
information is the result of his own observations. It is probable he is
much indebted to Eratosthenes, who preceded him by three centuries, and
who was the first systematic writer on geography. The authorities of
Strabo are chiefly Greek, but his work is defective, from the imperfect
notions which the ancients had of astronomy; so that the determination
of the earth's figure by the measure of latitude and longitude, the
essential foundations of geographical description, was unknown. The
enormous strides, which all forms of physical science have made since
the discovery of America, throw all ancient descriptions and
investigations into the shade, and Strabo appears at as great
disadvantage as Pliny or Ptolemy; yet the work of Strabo, considering
his means, and the imperfect knowledge of the earth's surface, and
astronomical science, was really a great achievement of industry. He
treats of the form and magnitude of the earth, and devotes eight books
to Europe, six to Asia, and one to Africa. His great authorities are
Eratosthenes, Polybius, Aristotle, Antiochus of Syracuse, Posidonius,
Theopompus, Artemidorus Ephorus, Herodotus, Anaximenes, Thucydides, and
Aristo, chiefly historians and philosophers. Whatever may be said of the
accuracy of the great geographer of antiquity, it cannot be denied that
he was a man of immense research and learning. His work in seventeen
books is one of the most valuable which have come down from antiquity,
both from the discussions which run through it, and the curious facts
which can be found nowhere else. It is scarcely fair to estimate the
genius of Strabo by the correctness and extent of his geographical
knowledge. All men are lost in science, and science is progressive. The
great scientific lights of our day may be insignificant, compared with
those who are to arise, if profundity and accuracy of knowledge is the
test. It is the genius of the ancients, their grasp and power of mind,
their original labors which we are to consider. Anaxagoras was one of
the greatest philosophical geniuses of all ages; but, as philosophy is a
science, and is progressive, his knowledge could not be compared with
that of Aristotle. Again, who doubts the original genius and grasp of
Aristotle, but what was he, in accuracy of knowledge and true method, in
comparison with the savants of the nineteenth century; yet, it would be
difficult to show that Aristotle was inferior to Bacon or Cuvier, or
Stuart Mill. If, however, we would compare the geographical knowledge of
the ancients with that of the moderns, we confess to the immeasurable
inferiority of the ancients in this branch. When Eratosthenes began his
labors, it was known that the surface of the earth was spherical. He
established parallels of latitude and longitude, and attempted the
difficult undertaking of measuring the circumference of the globe by the
actual measurement of a segment of one of its great circles. Posidonius
determined the arc of a meridian between Rhodes and Alexandria to be a
forty-eighth part of the whole circumference--an enormous calculation,
yet a remarkable one in the infancy of astronomical science. Hipparchus
introduced into geography a great improvement, namely, the relative
situation of places, by the same process that he determined the
positions of the heavenly bodies. He also pointed out how longitude
might be determined by observing the eclipses of the sun and moon. This
led to the construction of maps; but none have reached us except those
which were used to illustrate the geography of Ptolemy. Hipparchus was
born B.C. 276, the first who raised geography to the rank of a science.
He starved himself to death, being tired of life, like Eratosthenes,
more properly an astronomer, and the most distinguished among the
ancients, born about 160 B.C., although none of his writings have
reached us. The improvements he pointed out were applied by Ptolemy
himself, an astronomer who flourished about the year 160 at Alexandria.
His work was a presentation of geographical knowledge known in his day,
so far as geography is the science of determining the position of places
on the earth's surface. The description of places belongs to Strabo. His
work was accepted as the textbook of the science till the fifteenth
century, for in his day the Roman empire had been well surveyed. He
maintained that the earth is _spherical_, and introduced the terms
_longitude_ and _latitude_, which Eratosthenes had established,
and computed the earth to be one hundred and eighty thousand
stadia in circumference, and a degree five hundred stadia in length,
or sixty-two and a half Roman miles. His estimates of the length
of a degree of latitude were nearly correct; but he made great errors in
the degrees of longitude, making the length of the world from east to
west too great, which led to the belief in the practicability of a
western passage to India. He also assigned too great length to the
Mediterranean, arising from the difficulty of finding the longitude with
accuracy. But it was impossible, with the scientific knowledge of his
day, to avoid errors, and we are surprised that he made so few.
* * * * *
REFERENCES.--An exceedingly learned work has recently been issued in
London, by Parker and Son, on the Astronomy of the Ancients, by Sir
George Cornwall Lewis, though rather ostentatious in his parade of
authorities, and minute on points which are not of much consequence.
Delambre's History of Ancient Astronomy has long been a classic, but
richer in materials for a history than a history itself. There is a
valuable essay in the Encyclopedia Britannica, which refers to a list of
authors, among which are Biccoli, Weilder, Bailly, Playfair, La Lande.
Lewis makes much reference to Macrobius, Vitruvius, Diogenes Laertius,
Plutarch, and Suidas, among the ancients, and to Ideler, Unters. uber
die Art. Beob. der Alten.
Whewell's History of the Inductive Sciences may also be consulted with
profit. Leclerc, Hist, de Med.; Spengel, Gesch. der Arzneykunde.
Strabo's Geography is the most valuable of Antiquity. See also Polybius.
[Relocated Footnote: The style of modern historical criticism may thus
be exemplified, like the discussions of the Germans, whether the Arx on
the Capitoline Hill occupied the northeastern or southwestern corner,
which take up nearly one half of the learned article in Smith's
Dictionary, on the Capitoline. "Thales supposed the earth to float on
the water, like a plank of wood": [Greek: oi d hudatos keisthai touton
gar archaiotaton pareilaephamen ton logon hon phasin eipein thalae ton
Milaesion]. Aristot., _De Coel_., ii. 13: "_Quoe sequitur Thaletis
ineptq sententia est. Ait enim terrarum orbem aqua sustineri._" Seneca,
_Nat. Quoest_., iii. 13. This notion is mentioned in _Schol. Iliad_,
xiii. 125. This doctrine Thales brought from Egypt. See Plut., _Pac_.,
in. 10; Galen, c. 21. But this maybe doubted. Callimach., _Frag_., 94;
Hygin, _Poet. Astr_., ii. 2; Martin, _Timee de Platon_., tom. ii. p.
109, thinks it questionable whether Thales saw Egypt. Diog. Laert.,
viii. 60. Compare, however, Sturz, _Thales_, p. 80; Proclus, _in Tim_.,
i. p. 40; _Schol. Aristophanes, Nub_., ii. 31; Varro, ii. vi. 10. See
also, _Ideler Chron_., vol. i. p. 300. But Brandis sheds light upon the
point, though his suggestions conflict with Origen, _Phil_., p. 11; also
with Aristotle, _De Coel_., ii. 13.
This style of expending learning on nothing, meets with great favor with
the pedants, who attach no value to history unless one half of the page
is filled with erudite foot-notes which few can verify, and which prove
nothing, or nothing of any consequence.]