THE SMITHSONIAN INSTITUTION. 375 



change in the size of the bulb, and thus to derange the accuracy of the 

 scale. An accurate barometer is another instrument which cannot 

 readily be obtained, unless at too great a price for the means of ordinary 

 observers. The common weather glasses, sold under the name of 

 barometers, though they may be of use in indicating variations of atmo- 

 spheric pressure, and thus assist in furnishing data lor determining the 

 progress of aerial waves, are inapplicable to the precise and accurate 

 observations necessary to determine the minute changes of atmospheric 

 pressure, or to ascertain the height of places above the level of the 

 eea. 



Considerable pains have been taken during the past year to ascertain 

 the best form of a barometer, which could be procured at a reasonable 

 cost; and, after considerable inquiry and comparison of different instru- 

 ments, we have at length decided upon one, with an adjustable cistern 

 and enclosed in a brass case, which may be transported to a distance, 

 and will serve as well for a mountain barometer as for inchcating 

 meteorological changes. For the construction of these instruments, v^-e 

 have employed Mr. James Green, formerly of Baltimore, now of New 

 York; and in order that the instruments furnished by him to ourselves, 

 or sold to our observers, may be comparable with each other, we have 

 procured a standard barometer from London, with which each in- 

 strument, previously numbered, is accurately compared, and the record 

 carefully preserved. We have also decided upon the forms of rain 

 and snow guages and wind vanes, and have ordered a number of these 

 to be constructed by Benjamin Pike & Son, Broadway, New York. 



It is the policy of the Institution to do as much with its funds as possi- 

 ble, and to call in aid from every quarter whence it may be obtained. 

 With reference to the system of meteorology, I am happy to inform the 

 Board that we have received assistance from a number of sources from 

 which it could scarcely have been expected at the commencement of 

 the scheme. The last Congress appropriated two thousand dollars for 

 meteorology, to be expended under the direction of the Navy Depart- 

 ment. It was understood that Professor Espy was to be engaged in 

 tlie investigations to be made in accordance with this appropriation, 

 and, in order that his labors might co-operate with those of the Institu- 

 tion, the late Secretary of the Navy directed him to apply to me for 

 instructions. During the past year he has been engaged in directing 

 observations and making prejiaration for a series of experiments having 

 an important bearing on the explanation of meteorological phenomena. 

 It is understood that the remainder of this appropriation, after paying 

 the salary of Mr. Espy, will be expended in deh-aying incidental ex- 

 penses, such as printing, engraving, &c. 



The Regents of the University of the State of New York, in 1825, 

 organized a system of meteorology, which has continued ever since, and 

 which iias added many interesting facts to the stock of scientific know- 

 ledge. In order to extend the usefulness of tiiis system, the Regents of 

 the University have lately resolved to reorganize the whole, and to 

 pupply the observers with accurate and well compared instruments. 

 This work has been intrusted to Dr. T. Romeyn Beck and one of our 

 Regents, Gideon Hawlcy, esq., both of Albany. Tiiey have adopted 

 the same system and instruments as those of the Smithsonian Institution, 



