MOTIONS OF TEEES. 127 



We observe occasionally other motions which I have not 

 described, such as the uniform bending of the whole tree. 

 In a strong current of wind, tall and slender trees es- 

 pecially attract our attention by bending over uniform- 

 ly like a plume. This habit is often seen in the white 

 birch, a tree that in its usual assemblages takes a plume- 

 like form. When a whole grove of white birches is 

 seen thus bending over in one direction from the action 

 of a brisk wind, they seem like a procession of living 

 forms. In a storm we watch with peculiar interest the 

 bending forms of certain tall elms, such as we often see 

 in clearings, with their heads bowed down almost to the 

 ground by the force of the tempest. • It is only the waves 

 of the ocean and the tossing of its billows that can afford 

 us so vivid an impression of the sublimity of a tempest 

 as the violent swaying of a forest and the roaring of 

 the winds among the lofty tree-tops. 



The motions of an assemblage of trees cannot be ob- 

 served except from a stand that permits us to look down 

 upon the surface formed by their summits. We should 

 then perceive that pines and firs, with all the stiffness of 

 their branches, display a great deal of undulating motion. 

 These undulations or wavy movements' are particularly 

 graceful in a grove of hemlocks, when they are densely 

 assembled without being crowded. It is' remarkable that 

 one of the most graceful of trees belongs to a family 

 which are distinguished by their stiffness and formality. 

 The hemlock, unlike other firs and spruces, has a very 

 flexible spray, with leaves also slightly movable, which 

 are constantly sparkling when agitated by the wind. If 

 we look down from an opposite point, considerably ele-' 

 vated, upon a grove of hemlocks when they are exposed ' 

 to brisk currents of wind, they display a peculiar undulat- 

 ing movement of the branches and foliage, made more 

 apparent by the glitter of their leaves. 



