Trouvelot.] 258 [March 16, 



I 



The Secretary read the following observations of Mr. L. 

 Trouvelot upon the tendency of trees to bend toward the 

 east. 



In the Scientific American of March 5th, 1870, is inserted a para- 

 graph headed " The Growth of Tree Trunks." It is there stated that 

 a French naturalist had been measuring the tree trunks in a forest, 

 and had found them all broader in the east-west than in the north- 

 south direction, while another arborist of Toulouse, similarly gauging 

 the trees, found the greatest swelling of their trunks towards the east- 

 southeast; the former attributing this want of symmetry to the 

 rotation of the earth, while the latter thinks that it is due to the 

 early action of the sun upon the sap. As this paragraph reminded 

 me of some observations which I made some five or six years ago, and 

 which bear closely upon the same subject, I will present them to the 

 Society, thinking they may have some value in a scientific as well as 

 in a practical point of view. While in the country, if we observe at- 

 tentively the tree tops, we will soon perceive that many species seem 

 affected by a steady wind, though there is not the least breeze to 

 be felt. Soon we notice that the branches of a great many trees 

 have a general tendency to obey an unknown force which bends their 

 extremities towards the east, or perhaps more correctly, in a direction 

 perpendicular to the magnetic meridian. This bending of small 

 branches cannot be observed so plainly upon all kinds of trees; some 

 species having it well marked in every instance, while other species 

 have it less visible, and even some others not at all noticeable. 

 Most prominent for this peculiarity is the cherry tree, sometimes 

 bending its branches towards the east, from head to foot. Next to 

 this come the maple, the button wood tree (Platanus), then the pear 

 tree, then the oak, etc. In the last named it is not always noticeable, 

 though if the tree is isolated from others it is very plain in every 

 instance. With the cherry tree it is so certain, that one could almost 

 invariably determine the cardinal points by looking at the direction 

 of its branches. At first I thought this might be due to the action of 

 the prevailing winds, but this hypothesis was somewhat shaken, when 

 I saw in many instances cherry trees sheltered entirely from the west 

 winds by high blocks of houses within a few feet of them, exhibiting 

 the same phenomenon. Whether this direction of the branches of 

 trees is to be attributed to the prevailing winds, or to the rotation of 

 the earth upon its axis, or to the heat or light of the sun, or again, 



