PREFACE 



In connection with the system of meteorological observations estab- 

 lished b}' the Smithsonian Institution about 1850, a collection of 

 meteorological tables was compiled by Dr. Arnold GuyoT, at the 

 request of Secretary Henry, and published in 1852 as a volume of the 

 . Miscellaneous Collections. 



Five years later, in 1857, a second edition was published after 

 careful revision by the author, and the various series of tables were 

 so enlarged as to extend the work from 212 to over 600 pages. 



In 1859 a third edition was published, with further amendments. 

 Although designed primarily for the meteorological observers report- 

 ing to the Smithsonian Institution, the tables obtained a much wider 

 circulation, and were extensively used by meteorologists and physicists 

 in Europe and in the United States. 



After twenty-five years of valuable service, the work was again 

 revised by the author; and the fourth edition, containing over 700 

 pages, was published in 1884. Before finishing the last few tables. 

 Dr. GuYOT died, and the completion of the work was intrusted to his 

 assistant, Prof. Wm. Libeey, Jr., who executed the dlities of final editor. 

 In a few years the demand for the tables exhausted the edition, 

 and thereupon it appeared desirable to recast entirely the work. After 

 very careful consideration, I decided to publish the new tables in 

 three parts: Meteorological Tables, Geographical Tables, and 

 Physical Tables, each representative of the latest knowledge in its 

 field, and independent of the others; but the three forming a homo- 

 geneous series. 



Although thus historically related to Dr. Guy of s Tables, the present 

 work is so substantially changed with respect to material, arrange- 

 ment, and presentation that it is not a fifth edition of the older tables, 

 but essentially a new publication. 



