CHAPTER V 

 THE NON-LIVING WORLD 



HAVING now made some acquaintance with the laws 

 which regulate the stability and movements of bodies, 

 and with the various forces which may energise in them, 

 we may next proceed to survey the actual world about 

 us. We have to study the nature, structure and 

 properties of the parts which actually compose it, and 

 the various ways in which, as a whole, it is modified by 

 the physical forces which act upon it, making abstrac- 

 tion, however, of the phenomena of life. We assume 

 that the student knows the earth to be globular, with a 

 north and south pole equidistant from the equator ; also 

 that its surface is described by means of imaginary 

 circles, parallel with the equator, marking degrees of 

 latitude, and by others which, at right angles with the 

 former, pass through the poles and serve to indicate 

 degrees of longitude. The world is everywhere sur- 

 rounded by an aeriform mass, the atmosphere, while the 

 greater part of its surface is covered, more or less deeply, 

 by water. Its solid mass is, as every one knows, composed 

 of a variety of matters, such as different kinds of earth, 

 some being clay, some sand, &c., with many stones 

 scattered through and over its soil, while large tracts 

 are composed of rocks. These rocks may be sandstones, 

 slate, granite, limestone or chalk, &c., and the rocks 

 may contain metals, metallic ores or crystals. The 



