P R K FACE. xiii 



For the better illustration of Ur. Woeikof's discussion, three plates have been 

 reproduced from the important paper by Alexander Buchan, in the Transactions 

 of the Royal Society of Edinburgh/ and for which acknowledgment is here made. 

 These plates exhibit by isobaric lines the mean pressure of the atmosphere over 

 the earth for the year, and for January and July. 



This work is given to the world with confidence that it will be an acceptable 



contribution to science, worthy of the Smithsonian Institution, and a permanent 



memorial of one who cheerfully devoted to its preparation much of the enerc'ies 



of a long life. 



JOSEPH HENRY, 



Secretary S. I. 

 Washington, November, ]875. 



' The mean pressure of the atmosphere, and the prevailing winds over the globe for the months 

 and for the year, Part 11., by Alexander Buchan, M A., Secretary of the Scottish Meteorological 

 Society. — Trans, of the Royal Soc. of Edinb., vol. xxv. 1869. 



