THE EARTH. 



THE EARTH. 



LOCKE somewhere observes, with his usual felicity of illustration, that the 

 " mind, like the eye, while it makes us see and perceive all other things, can 

 never turn its view with advantage upon itself." We encounter something 

 similar to this in our researches through the universe ; for of all the objects 

 which compose it, one of the most difficult with which to obtain a complete 

 and accurate knowledge is the planet which we inhabit. The cause of this 

 is our proximity to it, and intimate connexion with it. We are confined upon 

 its surface, from which we cannot separate ourselves. We cannot obtain a 

 bird's-eye view of it, nor at any one time behold more than an insignificant 

 portion of its surface. We have the same difficulty in obtaining an acquaint- 

 ance with it that a microscopic animalcule would have in acquiring a perfect 

 knowledge of the form and dimensions of ,a terrestrial globe twelve inches in 

 diameter, on the surface of which it creeps. 



Still, by a variety of indirect methods supplied by the ingenuity of scientific 

 research, we have been enabled to ascertain its form, and dimensions, and 

 physical constitution, with a considerable degree of accuracy. 



FORM OF THE EARTH. 



The first impression produced upon the eye of an observer, who has not 

 carried his inquiries further, is, that the surface of the earth is a flat plane, in- 

 terrupted only by the inequalities of the land. A little careful observation, 

 however, upon the many phenomena which are easily accessible to every 

 observer, will correct this erroneous impression. 



1. It is well known that if a voyage were made upon the earth, continually 

 preserving one and the same direction, or doing so as nearly as circumstances 

 will permit, we should at length arrive at the place Horn which we departed. 

 If the earth were an indefinite plane, this could not happen. It is evident, 

 then, that whatever be the exact form of the earth, it is a body which is on 





