66 THE CONICAL GROWTH OF TREES. 



more extended area. Now, up to a certain period in the life of 

 the tree, the increase of leaf surface in the atmosphere keeps 

 pace with the gradually increasing surface of the cones, and this 

 produces that uniformity of breadth which characterizes the 

 wood-rings formed each season ; but, when the main stem and 

 branches of the tree approach the maximum of their development, 

 owing to the diminished vital activity of the leaves, less woody 

 matter is formed, which still continues to be spread over a con- 

 stantly increasing extent of conical surface ; hence the thickness 

 of the woody strata gradually diminishes as the tree draws 

 nearer to the limit of its life. 



It is thus that, in the course of centuries, solid and enduring 

 vegetable monuments are reared ; trees which outlive the succes- 

 sive generations of man broad at the base and tapering to the 

 extremities. Nature builds on the conical principle to ensure 

 their stability ; and the dark and sombre forests of oak, pine, and 

 fir, which clothe the sides of mountains, whose summits rise 

 above the snow-line, are constructed on the same architectural 

 principles as the mountains themselves ; for the avalanche loos- 

 ening from its mountain heights, and coming down with an 

 accelerated rush into the subjacent valleys, and the leaf falling 

 from the tree, are both detached from cones. Such is the beauty, 

 simplicity, and grandeur of the works of Nature ! 



Reader, startle not at the boldness of this language. It is 

 strictly true. Great and little are but relative terms, distinc- 

 tions made by finite and imperfect minds. Sir John Herschel 

 in his admirable " Preliminary Discourse on the Study of Natu- 

 ral Philosophy," says, page 173 : " The student who makes any 

 progress in the study of natural philosophy will encounter num- 

 berless cases in which this transfer of ideas from one extreme of 

 magnitude to the other is called for. He will find, for instance, 

 the phenomena of the propagation of winds referred to the same 

 laws which regulate the propagation of motion through the 

 smallest masses of air; those of lightning assimilated to the 

 mere communication of an electric spark, and those of earth- 

 quakes to the vibrations of a stretched wire. In short, he must 

 lay his account to finding the distinctions of great and little 

 altogether annihilated in nature." 



