A History of Science, vol 2 | Page 7

the Arabs, far from destroying the western
literature, were its chief preservers. Partly at least because of their
regard for the records of the creative work of earlier generations of
alien peoples, the Arabs were enabled to outstrip their contemporaries.
For it cannot be in doubt that, during that long stretch of time when the

western world was ignoring science altogether or at most contenting
itself with the casual reading of Aristotle and Pliny, the Arabs had the
unique distinction of attempting original investigations in science. To
them were due all important progressive steps which were made in any
scientific field whatever for about a thousand years after the time of
Ptolemy and Galen. The progress made even by the Arabs during this
long period seems meagre enough, yet it has some significant features.
These will now demand our attention.

II. MEDIAEVAL SCIENCE AMONG THE ARABIANS
The successors of Mohammed showed themselves curiously receptive
of the ideas of the western people whom they conquered. They came in
contact with the Greeks in western Asia and in Egypt, and, as has been
said, became their virtual successors in carrying forward the torch of
learning. It must not be inferred, however, that the Arabian scholars, as
a class, were comparable to their predecessors in creative genius. On
the contrary, they retained much of the conservative oriental spirit.
They were under the spell of tradition, and, in the main, what they
accepted from the Greeks they regarded as almost final in its teaching.
There were, however, a few notable exceptions among their men of
science, and to these must be ascribed several discoveries of some
importance.
The chief subjects that excited the interest and exercised the ingenuity
of the Arabian scholars were astronomy, mathematics, and medicine.
The practical phases of all these subjects were given particular attention.
Thus it is well known that our so-called Arabian numerals date from
this period. The revolutionary effect of these characters, as applied to
practical mathematics, can hardly be overestimated; but it is generally
considered, and in fact was admitted by the Arabs themselves, that
these numerals were really borrowed from the Hindoos, with whom the
Arabs came in contact on the east. Certain of the Hindoo alphabets,
notably that of the Battaks of Sumatra, give us clews to the originals of
the numerals. It does not seem certain, however, that the Hindoos
employed these characters according to the decimal system, which is
the prime element of their importance. Knowledge is not forthcoming
as to just when or by whom such application was made. If this was an
Arabic innovation, it was perhaps the most important one with which

that nation is to be credited. Another mathematical improvement was
the introduction into trigonometry of the sine--the half-chord of the
double arc--instead of the chord of the arc itself which the Greek
astronomers had employed. This improvement was due to the famous
Albategnius, whose work in other fields we shall examine in a moment.
Another evidence of practicality was shown in the Arabian method of
attempting to advance upon Eratosthenes' measurement of the earth.
Instead of trusting to the measurement of angles, the Arabs decided to
measure directly a degree of the earth's surface--or rather two degrees.
Selecting a level plain in Mesopotamia for the experiment, one party of
the surveyors progressed northward, another party southward, from a
given point to the distance of one degree of arc, as determined by
astronomical observations. The result found was fifty-six miles for the
northern degree, and fifty-six and two-third miles for the southern.
Unfortunately, we do not know the precise length of the mile in
question, and therefore cannot be assured as to the accuracy of the
measurement. It is interesting to note, however, that the two degrees
were found of unequal lengths, suggesting that the earth is not a perfect
sphere--a suggestion the validity of which was not to be put to the test
of conclusive measurements until about the close of the eighteenth
century. The Arab measurement was made in the time of Caliph
Abdallah al-Mamun, the son of the famous Harun-al-Rashid. Both
father and son were famous for their interest in science.
Harun-al-Rashid was, it will be recalled, the friend of Charlemagne. It
is said that he sent that ruler, as a token of friendship, a marvellous
clock which let fall a metal ball to mark the hours. This mechanism,
which is alleged to have excited great wonder in the West, furnishes yet
another instance of Arabian practicality.
Perhaps the greatest of the Arabian astronomers was Mohammed ben
Jabir Albategnius, or El-batani, who was born at Batan, in
Mesopotamia, about the year 850 A.D., and died in 929. Albategnius
was a student of the Ptolemaic astronomy, but he was also a practical
observer. He made the important discovery