are greater than formerly; whence he argues a change of
latitudes. Now, however, Stadius, taking just the contrary view, proves by
observations that the latitudes have decreased. For he says: "The latitude
of Rome in Ptolemy's _Geographia_ is 41 degrees 2/3: and that you may not
suppose any error of reckoning to have crept in on the part of Ptolemy, on
the day of the Aequinox in the city of Rome, the ninth part of the gnomon
of the sun-dial is lacking in shadow, as Pliny relates and Vitruvius
witnesseth in his ninth book." But the observation of moderns (according to
Erasmus Rheinholdus) gives the same in our time as 41 degrees with a sixth:
so that you are in doubt as to half of one degree in {214} the centre of
the world, whether you show it to have decreased by the earth's obliquity
of motion. One may see then how from inexact observations men rashly
conceive new and contradictory opinions and imagine absurd motions of the
mechanism of the earth. For since Ptolemy only received certain latitudes
from Hipparchus, and did not in very many places make the observations
himself; it is likely that he himself, knowing the position of the places,
formed his estimate of the latitude of cities from probable conjecture
only, and then placed it in the maps. Thus one may see, in the case of our
own Britain, that the latitudes of cities are wrong by two or three
degrees, as experience teaches. Wherefore all the less should we from those
mistakes infer a new motion, or let the noble magnetick nature of the earth
be debased for an opinion so lightly conceived. Moreover, those mistakes
crept the more readily into geography, from the fact that the magnetick
virtue was utterly unknown to those geographers. Besides, observations of
latitudes cannot be made sufficiently exactly, except by experts, using
also finer instruments, and taking into account the refraction of the
lights.

* * * * *

CHAP. III.

On the magnetick diurnal revolution of the Earth's
globe, as a probable assertion against the time-honoured
_opinion of a Primum Mobile_.

Among the ancients Heraclides of Pontus and Ecphantus, afterwards the
Pythagoreans, as Nicetas of Syracuse and Aristarchus of Samos, and some
others (as it seems), used to think that the earth moves, and that the
stars set by the interposition of the earth and rose by her retirement. In
fact they set the earth moving and make her revolve around her axis from
west to