GEOGRAPHY. 3 



rotation of an ellipse about its minor axis. Nevertheless, the difference 

 between the greatest and least diameters of the earth, ott the oblatcness, 

 amounts only to about ^Ij of the former (the equatorial), or to about twenty- 

 six statute miles. The following table expresses the dimensions of the earth, 

 as given in English statute miles : 



Radius at the equator, . . . 3962.6. 



Radius at the pole, . . - . 3949.6. 



Mean radius, or at 45° latitude, 3956.1. 



Mean length of a degree, . . 69.05. 



The fourth part of a meridian, 6214.2. 



The length of an English geographical mile is equal to about 2025 yards. 



As the statute mile is 1760 vards, the ratio between the two is as 1 : 1.16, 



The Grermans count fifteen geographical miles to the degree. Consequently 



one German geographical mile is equal to four English ditto ; and one 



German geographical mile equals 4.6 English statute or ordinary miles. 



The squares of these values expressing square miles will then be to each 



other as 1 to 21.16. Unless otherwise stated, future measurements will be 



expressed in English geographical miles. The reduction to statute miles 



can, however, be readily made by multiplying by 1.15. We add a comparison 



of some French and English measures for the sake of convenience in 



reduction : 



French foot — 1.065.765 English feet. 

 '• metre = 39.370.091 " yards. 

 " toise= 6.394.592 '• feet. 

 Coming now to the subject of Physical Geography^ we shall present a 

 condensed description of the surfoce of the earth, introducing as many of 

 such accessories to Physical Geography, as the distribution of plants and 

 animals, aerial and oceanic currents, (fee, as may be necessary for the proper 

 elucidation of the plates. 



The entire surface of the earth includes about 148,160,000 geographical 

 square miles, of which about one fourth belongs to the land, and the remainder 

 to the sea. The world of waters which thus covers the greater part of the 

 earth, may be divided into five principal bodies or oceans : the Arctic, the 

 Antarctic, the Atlantic, the Pacific, and the Indian. 



The Arctic Ocean extends from the arctic circle towards the north pole : 

 the Antarctic^ from the antarctic circle to the south pole. The two are for 

 the most part continualh^ frozen, and consequently inaccessible. 



The Pacific Ocean is bounded to the west by Asia and New Holland, to 

 the east by the Americas ; to the south it is continuous with the Antarctic 

 Ocean, communicating to the north with the Arctic Ocean, through Behring's 

 Straits. Its area amounts to about 44,800,000 square miles, or nearly one 

 third of the entire surface of the earth. The southern part of the Pacific 

 Ocean is sometimes called the South Sea. 



The Atlantic Ocean is bounded to the west by the Americas, to the east by 

 Europe and Africa; it is continuous to the north with the Arctic Ocean, to 

 the south-west with the Pacific, and to the south-east with the Indian. 



The Indian Ocean lies between the Atlantic and Pacific Oceans, 



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