slow movement completed." Thus, according to these observations of Dominicus Maria, the North pole is at a higher elevation, and the latitudes of places 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 Æquinox 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_.