Comparative Extent _of one of the TWO TEMPERATE_ ZONES _Fig. 4._ ONE _of the ARCTIC_ ZONES _Fig. 5._ _Comparative Extent of the WHOLE LAND on our GLOBE_ ] [Illustration: _N^o. XIII._ ] [Illustration: _N^o. XIV._ _Square contents_ of the Two TEMPERATE ZONES. _Square contents of the_ WHOLE TORRID ZONE. _Square contents of the Two_ ARCTIC ZONES. The whole surface _of the five GREAT CONTINENTS on our_ GLOBE _Compared to one of the two_ TEMPERATE ZONES. ] § 34. The Earth’s surface is not throughout equally illumined or heated by the Sun; because the Sun’s rays strike some portions of the Earth more perpendicular than others. Our Earth, therefore, is divided into _Climates_ or _Zones_, which you will understand better from Plate XII. You will see from it that the Sun’s rays are perpendicular to the central part of the Earth’s surface; but that toward the extremities of the Earth’s Diameter these rays strike us more and more _obliquely_. The greatest heat, therefore, must be felt by the people living between the two circles EF and IK. The circle GH, which is exposed to the perpendicular rays, is termed the _Equator_; and the two circles EF and IK, _which are at equal distance from the Equator, are called Tropic Circles_. The whole surface included by these two circles is called the _torrid Zone_. The space between either of the circles CD and EF, or IK and LM, is called a _temperate Zone_; because the Sun’s rays striking these portions neither perpendicular nor very obliquely, their inhabitants suffer neither great heat nor cold. In one of these Zones are situated the United States of America and the greater portion of Europe. Beyond them, toward the extremities of the Diameter AB, are the two _icy_ or _arctic_ zones. The Sun’s rays strike them very obliquely; which is the cause of their being almost continually covered with ice or snow. The two circles, CD and LM, are called _Polar_ circles; and the two extremities, A and B, of the Earth’s Diameter, situated in those regions, are called _the Poles_. A is called the _North-Pole_ and B the _South-Pole_ of the Earth. § 35. The different zones of which we have just spoken, are not equal to one another. Plate XIII, will show their relative extent. Fig. I represents the surface of the Earth divided proportionally into its three zones: the _torrid_, the _temperate_ and the _arctic_. The inner circle represents both the arctic zones; the yellow ring b, which surrounds it, represents the united extent of the two temperate zones; and the outmost red ring, the whole of the two _torrid zones_. Fig. II represents separately the whole torrid zone;—Fig. III one of the temperate zones;—Fig. IV one of the arctic zones; and Fig. V the whole extent of land on our globe.