128 On the Importance of Geological hiformatioti, 6fC. 



If plants yield to the deleterious influence of those principles 

 which are injurious to other organized bodies, it is because — as 

 in the case of the young geranium — they cannot appropriate 

 those" salutary principles, upon which their existence depends, 

 and which enables them to exercise their natural functions, one 

 of which is, to reject that which is injurious to them. We speak 

 now of the circulation of plants, and not of mechanical applica- 

 tion of poison to their parts. Oil of turpentine apphed several 

 days to the bark of many trees, and especially the linden tree, 

 will soften, and eventually destroy the part ; but the experiments 

 tried with the balsamina, or lady-slipper, the palma christi, the 

 cabbage, and tobacco plant, whose roots were liberally supplied 

 with spirits of turpentine, prove that it did not affect them 

 through their circulation. Dr. Harlan's attention to this subject, 

 will be properly appreciated by those engaged in the study of 

 the physiology of plants. Editor. 



ON THE VALUE OF GEOLOGICAL INFORMATION TO ENGINEERS, AND 

 ON THE INEQUALITIES OF THE EARTH'S SURFACE, AND THEIR TRUE 

 LEVELS ABOVE TIDE WATER. 



The very gratifying encouragement which this work has receiv- 

 ed from so many distinguished officers of the government, resident 

 at Washington, has induced the Editor to suggest through these 

 pages, that this unexpected patronage, which, on account of the 

 advancement of science, is so honourable to all the parties con- 

 cerned, may receive the most beneficial direction, and our know- 

 ledge of the geology of this continent, and of physical geography, 

 be greatly increased, if the gentlemen connected with the mili- 

 tary branch of the U. S. government, would direct some physical 

 reconnoisanccs to be accurately made ; in our present ignorance 

 of whicli, we are not able to describe faithfully, the degree of 

 inequality of the surface of this continent, nor ascertain the 

 natural connexion between mountain ranges, and table lands, 

 that are locally distinct from each other. The trigonometrical 

 surveys that have been performed in Great Britain, and the 

 maps which have been executed by order of the board of ord- 

 nance, upon a scale of an inch to a mile, arc valuable monuments, 

 as well of the intelligence of that government, as of the cultiva- 



