INTRODUCTION. xiii 



When we come to look at the ground closely, we 

 soon learn that it rests upon masses of rocks and 

 stone. Some of these stones are very hard; others 

 are very beautiful, such as the rosy granites, the varie- 

 gated marbles, and the blue slates. These, we see, are 

 capital building-materials. Other stones are not so 

 beautiful, and make good foundation-stones for our 

 houses; others are soft, like soapstone; others split 

 into thin slabs suitable for flagstones ; others can be 

 heated, and will melt, giving iron, copper, and other 

 metals. In still other stones, gold and silver are found. 

 Some stones will burn, some with a bright flame, 

 others with much smoke ; and we call these stones 

 coals. All of these various stones form, with many 

 others, the crust or outside of the earth ; and they are 

 often of great value. At the same time, we must 

 observe here a distinction. The places where these 

 granites, slates, soapstones, marbles, and other stones 

 are blasted, cut, or dug out of the ground, are called 

 quarries. The deep places where the ore-stones and 

 crude metals are obtained are mines. These mines 

 and quarries give us these valuable stones and metals, 

 and so give us wealth. The work of getting them, or, 

 as it is called, of winning them, is the art of mining 

 and the art of quarrying. While we intend to study 

 the ground, these lines of work would only lead us 

 far astray. We are to study the top, or the immedi- 

 ate surface, of the ground ; and the art of gathering 

 wealth from this thin skin or outside of the ground, 

 we call agriculture. We are to begin by studying the 



