Coffin's Winds of the Globe. 277 



Dr. Woeikof instances latitude 40° to 60° south as that part 

 of the earth where the winds have the greatest velocity, strong 

 westerly winds prevailing there the whole year: due to the 

 great difference in the pressure of the air at a small distance, or 

 in other words, the steep barometric gradient. As to this 

 topic, Professor Coffin left on record but a few general conclu- 

 sions, of which we would note onlv his determination of 65° as 

 the average angle made by the line of the wind's approach, 

 with one drawn to the point of maximum pressure. 



The velocity tables, elaborately prepared, mainly from data 

 m the United States, are designed to show the effect of com- 

 bining the element of velocity with that of time, in computing 

 the resultants. The question is one of vital importance, and 

 the magnitude of the task alone hinders its being solved in a 

 similar manner for all parts of the world. Five years of work- 

 ing time were spent on the reduction of the observations taken 

 at 418 places on the American continent, for a total period of 

 700 years. The results show that the effect of velocity is to 

 throw the resultant northerly far more frequently than south- 

 erly, and at a much greater angle; that it increases its magni- 

 tude far more frequently than it diminishes it, and by a greater 



In the United States, north of latitude 32°, the annual results 

 obtained by noting the actual velocities average S. 89° -f W., 

 with a ratio of -261 ; while those had by disregarding the un- 

 equal velocities are S. 80° + W., ratio '227. The divergence is 

 therefore about 9° in the yearly resultants, but greater in win- 

 ter, and less in summer. 



This general fact of a [northerly] divergence and excess of 

 ratio, holds true also for the few places computed, that are 

 situated within the limits of the Polar and Equatorial systems ; 

 yet, as the divergence seldom exceeds 15°, the great general 

 conclusions reached must be considered safe, although the 

 va "ftion in velocity be disregarded. 



The average velocity, so obtained, of all winds in the United 

 States, is seven miles an hour, being slightly i 



. For positions considered separately, the velocity of the wind 

 18 greater— 



J- On high isolated peaks, than at low stations, 

 . 2 - On the seashore, and especially on isolated islands, than 

 ^ the interior of continents, . 



». In level countries, than in countries surrounded by moun- 

 ts; and 



