detail modern mechanical inventions, an example which
was to be followed by L'Encyclopédie. As for conceiving
history as an exact study or science, that is nowhere appar-
ent. In general it may be said that his historical accounts of
the sciences are never very complete and always contain gaps.

To begin with his treatment of astronomy, his historical
account is rather brief. Passing over very hurriedly the
contributions of the Greeks, he makes the dubious state-
ment that Pythagoras "was the first among the Europeans
who taught that the earth and planets turn around the sun
which stands immovable in the center; that the diurnal
motion of the sun and fixed stars was not real but apparent,
arising from the earth's motion around its own axis". It is
usually held that Pythagoras considered the earth the center
of the universe, allowing the sun, moon and planets to build
circular paths around it. It was Aristarchus who set forth
the heliocentric theory; but Chambers considers it sufficient
to mention his name only. Of Ptolemy Chambers merely
remarks that he was "the great Alexandrian astronomer".
He does make note of an interesting fact concerning the
Ptolemaic system which seems to indicate that Ptolemy as
late as 1728 had not entirely lost his influence. For the
"principal assertions of the Ptolemaic system . . . are still
adhered to in some Universities where free philosophizing
is excluded". ⁷

The history of astronomy during the middle ages is not
treated at all. Neither the astronomical and trigonometric
tables of Al-Khwarismi, ⁸ nor the Sphaera Mundi of John
Sacrobosco find a place in Chambers. The Sphaera Mundi
was not only a useful book in the thirteenth century but for
many centuries thereafter it was the classic textbook in