436 THE FARMER AT HOME. 



one contained by three right lines ; and a spherical triangle is one 

 contained by three arcs of great circles of the sphere. Triangles are 

 denominated, from their angles, right, obtuse, and acute. A right- 

 angled triangle is that which has one right angle ; an obtuse-angled 

 triangle is such as has one obtuse angle ; and an acute-angled triangle 

 is that which has all its angles acute. The triangle is the most im- 

 portant figure in geometry ; and its various lines bear the most inter- 

 esting relations to each other. 



TREES. Few objects can be more innocently pleasing and of 

 more importance in the economy of nature, and to man, than the 

 various vegetable productions of the earth. The large proportion 

 which its surface bears to its herbage and the immense extent of the 

 forests in comparison with that of meadows, pastures, prairies, or 

 plains, seem to indicate that trees and shrubs act an important part in 

 the economy of our globe. In countries uninhabited by man, the 

 influence of forests must be great on the climate, on the soil, and on 

 the number of wild animals, and on the herbaceous vegetables. In 

 civilized countries, to those influences must be added the relation in 

 which they stand to man. 



It appears highly probable, that the greater part of the surface of 

 our globe has been, at one time, covered with wood ; because among 

 other reasons, coal is found in nearly all countries in both hemispheres, 

 from the equator to the poles ; at all events, it is certain that this has 

 been the case with the greater part of the temperate regions of the 

 globe at no very distant period. The whole of the American conti- 

 nent was, until lately, we are led to presume, almost entirely covered 

 with trees and shrubs, and presented few naked surfaces, except those 

 of the prairies, alluvial deposits on the banks of its large rivers, and 

 on the tops of the highest mountains ; and what was so recently the 

 condition of America must, we have reason to suppose, once, at least, 

 have been that of every other part of the whole world. 



The influence which a predominance of forest must have in a 

 country uninhabited by man, must have extended to the animals, the 

 herbaceous vegetables, the soil, the waters, and the climate. To wild 

 animals of every kind, especially to those of the more ferocious tribes, 

 forests have, in all countries, furnished shelter, arid in a great meas- 

 ure, food ; birds, insects and reptiles are the more common inhabi- 

 tants. Herbaceous plants are, for the most part, destroyed by dense 

 forests ; but some kinds are encouraged by the thickness of the shade, 

 and the moist heat which prevails among the trunks and the branches 

 of trees. But the great influence of forest scenery in a wild state, is 

 on the soil ; and in this point of view, natural forests may be regarded 

 as a provision of nature for preparing the surface of the earth for the 

 cultivation of the chief productions which constitute the food of man, 

 and of domestic animals. It would be interesting to show how the 

 soil is furnished with the organized matter, so essential to the growth 



