ADVERTISEMENT. 



At the commencement of the operations of the Smithsonian Institution a system 

 of meteorology was established, carried on by voluntary observers, which was 

 continued for more than twenty years until it was transferred to the Signal Service 

 of the United States Army in 1874 to be continued by means of the annual appro- 

 priations of Congress. This system included observations on the temperature, 

 pressure, aqueous precipitation, moisture of the air, and winds. 



The object now of the Smithsonian Institution is to render the results of these 

 observations accessible to meteorologists by their reduction, discussion, and publi- 

 cation; but to give greater value to this work it has been thought advisable to 

 incorporate in it all accessible and reliable meteorological observations that have 

 been made in the United States since the early settlement of this country. 



The first part of the general work, that on the aqueous precipitation, was pub- 

 lished in 1872, that which relates to the winds is now in the press, and the other 

 parts will follow in succession. 



The present memoir relating to the temperatures contains the results of all 

 observations to the end of the year 1870, from the following sources : — 



1st. The registers of the Smithsonian Institution, embracing upwards of 300 folio 

 volumes. 



2d. The joint publications of the Institution and of the Patent Office and Depart- 

 ment of Agriculture. 



3d. All the publications and unpublished records of the meteorological system 

 of the United States Army. 



4th. The records of the United States Lake Survey under the Engineer Depart- 

 ment of the United States Army. 



5th. The records of the United States Coast Survey, under the Treasury Depart- 

 ment. 



6th. The volumes compiled by Dr. F. B. Hough from observations made under 

 the direction of the Eegents of the University of the State of New York. 



7th. The records made in Pennsylvania under the direction of the Franklin 

 Institute of Philadelphia. 



8th. The transactions of. various societies and periodical publications. 



The first part of the work was the formation of an extended series of classified 

 tables derived from the foregoing sources, and the second the deduction from these 

 consolidated tables, of average temperatures. The first of these series, owing to 

 its great bulk, must for the present remain in manuscript. It can, however, be 



(V) 



