that's it ; 



44 



upon the occurrence of a lunar 

 eclipse, it forms a circular shade. 

 The roundness of the sun and 

 moon, and of the planetary 

 bodies generally, supports the 

 inference that all the heavenly 

 bodies possess the same shape. 

 Navigators have repeatedly sailed 

 round the globe. The roundness 

 of the earth causes the horizon 

 which bounds our view to be 

 circular, and to be of less extent 

 than would occur if the earth 

 possessed a flat surface. A 

 person in a balloon, 3, sees a 



228. 



larger extent of country, than 

 another standing upou a hill, 4 ; 

 an aeronaut in a balloon might 

 see the masts and hull of a ship, 

 5, coming from sea, before a 

 spectator from a Mil could see 

 more than the topmasts, and 

 while a person walking on the 

 level earth, 6, could perceive no 

 part of the vessel whatever. For 

 convenience in referring to por- 

 tions of the heavens and earth, 

 the names of east, west, north, 

 and south have been given to 

 four opposite points, or direc- 

 tions. If we turn our faces 

 towards the rising sun, we look 

 towards the east, 7, the west will 

 be behind us, the south on our 

 right, 8, and the north on our 

 left, 9. For more accurate 



reference to the positions of 

 heavenly bodies, and to divisions 



229. 



of the earth, celestial and terres- 

 trial maps have been adopted, 

 with which, by the aid of imagi- 

 nary lines, parallels, squares, etc., 

 exact references may be made, 

 upon a small scale, to orbs in the 

 great expanse of the heavens, 

 and to the various divisions of 

 the earth. Geography chiefly 

 requires the use of terrestrial 

 maps, which are- usually repre- 

 sented in two divisions, the 

 western hemisphere (or half 

 sphere), 225, and the eastern hemi- 

 sphere, 226. A map describes the 

 land ; a chart the coast, the islands, 

 rocks, divisions, and currents, 

 and depths of the sea. The use 

 of maps necessitates the employ- 

 ment of lines, angles, figures, and 

 geographical terms. A right line, 

 10, or straight line, is the shortest 

 that can be 10 



drawn be- — 



tween two m 



points, objects, or places. A 



