Tropics

The term given to the two imaginary celestial and terrestrial circles parallel to and equidistant, each 23° 27 ’ from the Equator of the Heaven or the Earth. When the sun cro es the Equator (21w March) northward towards the Tropic of Cancer, its progre is continuous till reaching that parallel circle, when its course becomes retrograde, once more approaching and eventually recro ing the Equator (23rd Sep‘) southward to the opposite tropical boundary of Capricorn, and so on in succe ion. The regular recurrence of these motions causing the changes of seasons in the northern-, and southern Hemispheres. The Tropics form the boundaries of the hottest region on the Earth surface; all countries lying within those parallel circles having in turn (once each year) the sun in the Zenith, i. e: right overhead.