d the limits of
this book to give an adequate statement of the results of this imposing
scientific movement. The ancient sciences were greatly extended--new
ones were brought into existence. The Indian method of arithmetic was
introduced, a beautiful invention, which expresses all numbers by ten
characters, giving them an absolute value, and a value by position,
and furnishing simple rules for the easy performance of all kinds
of calculations. Algebra, or universal arithmetic--the method of
calculating indeterminate quantities, or investigating the relations
that subsist among quantities of all kinds, whether arithmetical or
geometrical--was developed from the germ that Diophantus had left.
Mohammed Ben Musa furnished the solution of quadratic equations,
Omar Ben Ibra him that of cubic equations. The Saracens also gave to
trigonometry its modern form, substituting sines for chords, which had
been previously used; they elevated it into a separate science.
Musa, above mentioned, was the author of a "Treatise on Spherical
Trigonometry." Al-Baghadadi left one on land-surveying, so excellent,
that by some it has been declared to be a copy of Euclid's lost work on
that subject.

ARABIAN ASTRONOMY. In astronomy, they not only made catalogues, but
maps of the stars visible in their skies, giving to those of the larger
magnitudes the Arabic names they still bear on our celestial globes.
They ascertained, as we have seen, the size of the earth by the
measurement of a degree on her surface, determined the obliquity of
the ecliptic, published corrected tables of the sun and moon fixed
the length of the year, verified the precession of the equinoxes. The
treatise of Albategnius on "The Science of the Stars" is spoken of by
Laplace with respect; he also draws attention to an important fragment
of Ibn-Junis, the astronomer of Hakem, the Khalif of Egypt, A.D. 1000,
as containing a long series of observations from the time of Almansor,
of eclipses, equinoxes, solstices, conjunctions of planets, occultations
of stars--observations which have cast much light on the great
variations of the system of the world. The Arabian astronomers also
devoted themselves to the construction and perfection of astronomical
instruments, to the measurement of time by clocks of various kinds, by
clepsydras and sun-dials. They were the first to introduce, for this
purpose, the use of the pendulum.

In the experimental sciences, they originated chemistry; th