REPORT OF TIIE SECRETARY. 35 



One of the most important operations with which the Institution 

 has been connected during the past year is the construction of a map 

 to represent at one view the arable and forest land of the United States. 

 This work has been intrusted to Dr. J. G-. Cooper, a young naturalist, 

 who has paid particular attention to botany, has been engaged in 

 government explorations in the western part of the United States, and 

 has critically examined all the authorities to be found on the subject. 

 The facts presented at once to the eye by this map are in striking 

 accordance 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 productions 

 of different parts of the earth. 



No appropriation has been made for the last two years for the pur- 

 chase and distribution of instruments other than rain-gages and ther- 

 mometers. The attempt to furnish barometers to important stations 

 at a distance has not been successful. In the majority of cases they 

 have been broken before they arrived at their place of destination, and 

 we find from experience that this instrument cannot be safely trans- 

 ported, except by hand or by water. 



Magnetic Observatory. — From the date of the last report the declina- 

 tion needle of the magnetic observatory, established at the expense of 

 the Coast Survey and the Smithsonian fund, was in continued opera- 

 tion until October, 1858, when the introduction of a large iron pipe 

 for the supply of the grounds with the Potomac water made a new 

 adjustment of the apparatus necessary, and interrupted the continuity 

 of the record. Up to that time the remaining instruments had not 

 been received from London, though they were ordered by Professor 

 Bache before the erection of the building, several years ago. The 

 delay, we have since learned, was occasioned by death in the family of 

 the inventor, who had kindly undertaken to superintend their construc- 

 tion, and especially to make the adjustments for the compensation for- 

 changes of temperature. The instruments have at length been re- 

 ceived, and will be put in operation early in the- spring of the present 

 year. They were completed and forwarded under the direction of 

 Mr. Charles Brooke, the author of this ingeaious and truly valuable 

 mode of automatic registration. 



The importance of putting this observatory in full operation will be- 

 manifest by a reference to a communication in the appendix to this, 

 report from General Sabine to the Secretary, in which it is stated that 

 it is in contemplation to establish similar observatories at Pekin, the 



