latitudes differing by 10°; so that two consecutive verticals are inclined in every case at an angle of 10°.
If, as in fig. 78, the shape of the earth is drawn in accordance with Newton's views, the figure shews at once that the arcs a a1, a1 a2, etc., each of which corresponds to 10° of latitude, steadily increase as we pass from a point a on the equator to the pole b. If the opposite hypothesis be
adopted, which will be illustrated by the same figure if we now regard a as the pole and b as a point on the equator, then the successive arcs decrease as we pass from equator to pole. A comparison of the measurements made by Eratosthenes in Egypt (chapter ii., § 36) with some made in Europe (chapter viii., § 159) seemed to indicate that a degree of the meridian near the equator was longer than one in higher latitudes; and a similar conclusion was indicated by a comparison of different portions of an extensive
