37O PTOLEMY AND LATER GEOGRAPHERS. [CHAP. XVI.
gave way before the belief in its sphericity, the arguments for
which were formally stated by Aristotle. Further advances were
made at a later period by means of the measurement of the
circumference of the earth, and the computation of the size of
the habitable world, by Eratosthenes; and the commencement
of a system of parallels and meridians was made by that man of
science and Hipparchus. It was reserved for Ptolemy after the
lapse of several centuries to complete this, and at the same time
the new and scientific system of projection which he invented
laid the foundation on which a great part of modern cartography
is based.