PREFACE. 



This work has been prepared by the joint agency of the late Professor Coffin 

 and the Smithsonian Institution, the former furnishing the general plan and 

 oversight of the work, and such parts of the labor as could not be satisfactorily 

 confided to others ; while the latter contributed the greater part of the material, 

 and defrayed the entire cost of making all the reductions and numerical computa- 

 tions, except what was done by Professor Coffin, or was found in other works. 

 The resultants at the academies in the State of New York, computed by Ur. 

 Pranklin B. Hough, and those at numerous places in Russia, computed by Mr. 

 Wesselowski, and some few others, have been made use of. 



This work may be considered an extension of Professor Coffin's former one on 

 the " Winds of the Northern Hemisphere," so as to embrace the entire surface of 

 the globe so far as it has been accessible to scientific observation. 



In the words of Professor Coffin, "the design is to show primarily — 



" 1st. The mean direction in which the lower currents of the atmosphere move 

 over all parts of the surface of the earth, including in the term '■loicer currents' 

 all that part of the atmosphere on which direct observations can be made, whether 

 by means of a vane or by the motions of the clouds. 



"2d. The ratio that the progressive motion bears to the total distance travelled. 



" 3d. The modifications that the mean current undergoes in the different seasons^ 

 of the year. 



"4th. The directions in which the forces^ act that produce these modifications. 



"5th. The amount of their intensities, reckoned on the same scale as that which 

 determines the mean annual direction. 



" 6th. To show, by separate solutions for the surface winds and those indicated by 

 the motion of the clouds, how the two differ, and how they differ according as we 

 do, or do not take into account the difference in the velocity of the different winds ; 

 the discussion of this latter question being confined chiefly to the observations 

 reported to the Smithsonian Institution from the year 1854 to 1857 inclusive. 



"The data used for elucidating these points consist of series of observations on 



' To avoid confusion the months of December, January and February are designated as winter in 

 the southern as well as the northern hemisphere, March, April, May as spring, etc. 

 ' Monsoon influences. 



(vii) 



