in Geography and Astronomy, a division of the terraqueous globe with respect to the different degrees of heat found in the different parts thereof. The zones are denominated torrid, frigid, and temperate. The torrid zone is a band, surrounding the terraqueous globe, and terminated by the two tropics. Its breadth is $46^\circ 58'$. The equator, running through the middle of it, divides it into two equal parts, each containing $23^\circ 26'$. The ancients imagined the torrid zone uninhabitable. The temperate zones are contained between the tropics and the polar circles. The breadth of each is $43^\circ 2'$. The frigid zones are segments of the surface of the earth, terminated, one by the antarctic, and the other by the arctic circle. The breadth of each is $46^\circ 58'$.