36 REPORT OF THE SECRETARY. 



could be gathered from all the accessible published data, the records 

 of the Land Office, and other sources. The facts presented at once 

 to the eye by this map are in striking accordance, as we have before 

 mentioned, with the deductions from the meteorological materials 

 which have been collected at this Institution, and serve to place in a 

 clear point of view the connexion of climate with the natural produc- 

 tions of different parts of the earth. The plan has. however, since 

 been enlarged, and Dr. Cooper now proposes, with the aid of the 

 Institution, to construct a map which shall give in detail the distribu- 

 tion of the several kinds of trees and shrubs found in different por- 

 tions of the country; and, in view of this, he has prepared an article, 

 which has been published and widely distributed by the Institution, 

 containing a list of the localities of the most important and useful 

 trees and shrubs, as far as known, and asking additional information. 

 The chief difficulty in carrying out the plan has been the want of 

 definite knowledge as to the locality of different plants: for example. 

 a plant is mentioned as occurring in Virginia, but this statement is 

 not sufficiently precise, since this State occupies a large surface, 

 on a small portion of which only the plant may be found. Facts are 

 also required as to the abundance of trees in a given locality. 



The collection of the material for a map of this kind, in connexion 

 with a work on the forest trees of America, still in progress by Dr. 

 Asa Gray, of Cambridge, is a very important matter both in a politi- 

 cal and an economical point of view, and the work might be materially 

 aided, without much expense to the government, by appending a few 

 additional queries to the questions propounded by the marshals who 

 collect the statistics of the census. The outline map. which has al- 

 ready been prepared at the expense of the Institution, has excited 

 much interest, and the proposition to enlarge the plan of the work 

 has been received with commendation. 



As an interesting object in regard to physical geography, and 

 intimately connected with meterology and various branches of natural 

 history, a commencement has been made, in connexion with the Coast 

 Survey, in collecting materials for the construction of a hypso- 

 metrical map of the United States. 



No part of the surface of the earth, of equal dimensions, has been 

 so extensively traversed by lines of explorations for canals, railways, 

 and river improvements, as the United States. The materials, how- 

 ever, which are afforded by these, for constructing a map of the ele- 



