1SS EIGHTH ANNUAL REPORT OF 



to be expended under the direction of the Navy Department for meteor- 

 ological purposes ; and Professor Espy, engaged under the act making 

 this appropriation, has been directed to co-operate with the Institution, 

 in promotion of the common object. Besides the aid which we have 

 received from Professor Espy's knowledge of this subject, the general 

 sysi&m has been benefited in the use of instruments purchased by the 

 surplus of the appropriation, after paying the salary of the director and 

 other expenses. 



During the last year, Professor Espy has been engaged in a series of 

 interesting experiments on the variations of temperature produced by 

 a sudden change in the density of atmospheric air. The results 

 obtained are important additions to science, and directly applicable 

 to meteorology. The experiments were made in one of the rooms of 

 the Smithsonian Institution, and with articles of apparatus belonging 

 to the collection which constituted the liberal donation of Dr. Hare. 

 An account of these investigations will be given in a report to the 

 Secretary of the Navy. 



It was mentioned in the last report that the Regents of the Univer- 

 sity of the State of New York, in 1849, made a liberal appropriation of 

 funds for the reorganization of the meteorological system of observa- 

 tions established in 1825 ; and that Dr. T. Romeyn Beck and the Hon. 

 Gideon Hawley, to whom the enterprise was entrusted, had adopted 

 the forms and ihe instruments prepared under the direction of the 

 Smithsonian Institution. Another appropriation has been made, for 

 1850 ; and the system has been carried, during the past year, into suc- 

 cessful operation by Professor Guyot, late of Neufchatel, in Switzerland. 

 This gentleman, who has established a wide reputation as a meteoro- 

 logical observer by his labors in his own country, was recommended 

 to Dr. Beck and Mr. Hawley by this Institution, and employed by 

 them to superintend the fitting up of the instruments in their places, to 

 instruct the observers in the minute details of their duty, and to deter- 

 mine the topographical character and elevation above the sea of each 

 station. 



The whole number of stations which have been established in the 

 State of New York is thirty-eight, including those which have been 

 furnished with instruments by the Smithsonian Institution, and the Adi- 

 rondack station by the liberality of Archibald Mclntyre, esq-, of Albany. 

 This number gives one station to twelve hundred and sevent} r square 

 miles, or about one in each square of thirty-five and a.half miles on a 

 side. These stations are at very different heights above the level of 

 the sea. They were selected in conference with Dr. Beck, Professor 

 Guyot, and myself. The State is naturally divided into the following 

 topographical regions, namely : 



1. The southern or maritime region. 



2. The eastern, or region of the Highlands and Catskill mountains, 

 with the valleys of the Hudson and Mohawk rivers. 



3. The northern, or region of the Adirondack mountains, isolated by 

 the deep valleys of the Mohawk, Lake Chomplain, the St. Lawrence, 

 and Lake Ontario. 



4. The western, or region of the western plateau, with the small 

 lakes and sources of the rivers. 



