revolutions
of his carriage wheel. He concluded that it is 24,480 Italian miles
round the globe. The last attempt of the kind had been that of the
Khalif Almaimon seven hundred years previously on the shore of the Red
Sea, and with nearly the same result. The mathematical sciences were
undergoing rapid advancement. Rhaeticus had published his trigonometrical
tables; Cardan, Tartaglia, Scipio Ferreo, and Stefel were greatly
improving algebra.

[Sidenote: Copernicus, the works of.] The first formal assertion of the
heliocentric theory was made in a timid manner, strikingly illustrative
of the expected opposition. It was by Copernicus, a Prussian, speaking
of the revolutions of the heavenly bodies; the year was about 1536. In
his preface, addressed to Pope Paul III., whether written by himself,
or, as some have affirmed, for him by Andreas Osiander, he complains of
the imperfections of the existing system, states that he has sought
among ancient writers for a better way, and so had learned the
heliocentric doctrine. "Then I too began to meditate on the motion of
the earth, and, though it appeared an absurd opinion, yet since I knew
that in previous times others had been allowed the privilege of feigning
what circles they chose in order to explain the phenomena, I conceived
that I might take the liberty of trying whether, on the supposition of
the earth's motion, it was possible to find better explanations than the
ancient ones of the revolutions of the celestial orbs."

"Having, then, assumed the motions of the earth, which are hereafter
explained, by laborious and long observation I at length found that, if
the motions of the other planets be compared with the revolution of the
earth, not only their phenomena follow from the suppositions, but also
that the several orbs and the whole system are so connected in order and
magnitude that no one point can be transposed without disturbing the
rest, and introducing confusion into the whole universe."

[Sidenote: Introduction of his system.] The apologetic air with which he
thus introduces his doctrine is again remarked in his statement that he
had kept his book for thirty-six years, and only now published it at the
entreaty of Cardinal Schomberg. The cardinal had begged of him a
manuscript copy. "Though I know that the thoughts of a philosopher do
not depend on the judgment of the many, his study being to seek out
truth in all things as far as is permitted by God to human rea