96 PHYSICAL GEOGRAPHY. 



PHYSICAL GEOGRAPHY. 



Earth's Rotatory and Orbicular Motions and Zones Latitude, Longitude, and 

 Ellipticity Division into Land and Water Elevation of Surface Highlands 

 and Lowlands Islands Springs and Rivers The Ocean, Tides, Currents, &c. 

 Changes on the Earth's Surface Climate or Temperature. 



OF THE EARTH'S ROTATORY AND ORBICULAR MOTIONS AND ZONES. 



THE earth is, as has been already observed, a pla- 

 netary body, of a spherical shape ; and forms one of a 

 system of bodies called the Solar System. 



The Solar System comprises seven Primary, and 

 eighteen Secondary Planets, together with the four Aster- 

 oids. The primary planets revolve round the Sun, as 

 their centre of motion, in the following order ; Mercury, 

 Venus, the Earth, Mars, Jupiter, Saturn, and Georgium 

 Sidus. The Asteroids also revolve round the Sun; 

 they are situated between the orbits of Mars and 

 Jupiter, and are named Vesta, Juno, Ceres, and Pallas. 

 Of the Secondary Planets or Moons, the Earth has one, 

 Jupiter four, Saturn seven, and Georgium Sidus sir, all of 

 which revolve round their Primaries, and accompany 

 them in their orbits round the Sun. 



The Earth is situated at the distance of about 93 

 millions of miles from the Sun, and its motion, as well as 

 that of the other planets, is two-fold, orbicular and rota- 

 tory. By its rotatory motion, or its revolution on its 

 axis, is produced the succession of day and night, while 

 its orbicular motion, combined with a deviation of its 

 axis from a perpendicular to its orbit (which devia- 

 tion is always uniform) produces the various seasons 

 of the year, at once so necessary and delightful. 



From the nature of the orbicular motion of the 

 earth, it follows that some parts of its surface will 

 receive a greater degree of heat than other parts, which 

 circumstance has induced Geographers to divide it into 

 Zones, so that there are considered to \jejive zones one 

 Torrid, two Frigid and two Temperate : they receiving 

 their names from their localities as it regards the Sun, 

 and the degree of heat experienced. The zone which 

 includes that part of the earth in which the Sun in the 



