WINDS OF THE GLOBE. 



SERIES C. VELOCITY TABLES AND DEFLECTING FORCES, 



VELOCITY TABLES. 



These tables, and the accompanying Plates 13 and 25, are designed to elucidate 

 the last of the series of questions proposed at the outset of this discussion, and to 

 show the effect of combining the element of force or velocity, with that of time, 

 in computing the mean direction of the wind. The question itself is a highly 

 important one, for since the real point that we wish to arrive at is the mean 

 direction and amount of the actual motion, or transfer, of the air that passes over 

 any given place, it is obvious that if there is a difference in the velocity of winds 

 from the different points of the compass, or over different sections of country, such 

 as to materially affect the results that would be obtained if it were always and 

 everywhere the same, all the computations in the foregoing pages must require 

 correction, if they be not rendered in great measure worthless; for (where not 

 expressly stated to the contrary) they were all made on the assumption that the 

 velocity was uniform ; or, which is the same thing, without any reference to the 

 velocity. And, not. only so, but nearly all the observations that have ever been 

 taken, both by land and sea, must be thrown aside (for in very few of them has 

 the velocity of the wind been attempted to be recorded), and the whole work of 

 observation must be commenced anew. 



This question can be determined only by observation and experiment. We can 

 know nothing about it a priori. Difference of velocity may produce a very great 

 effect, upon the mean direction, or very little, or none all. The solution of this 

 question must therefore be viewed as vital to the search for the law^ of atmospheric 

 circulation. 



The accompanying tables, collected from Series B of this work, are designed to 

 give a synoptical view of the elements on which a determination may be based, as 

 derived from observations taken mainly in the United States by the observers that 

 reported to the Smithsonian Institution, in the years 1854, 1855, 1856 and 1857. 

 The laborious work required to obtain the results here presented, was performed, 

 under the direction of the author, by his brother, Robert A. Coffin, A.M., ot 

 Conway, Massachusetts, and other assistants, the cost being defrayed by the 



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