640 WINDS OF THE GLOBE. 



Column III is the laborious product obtained by computini,^ tlie resultants from 

 the number of miles travelled by the winds from eacli point of the compass for 

 each season. As, for example, Red River Settlement, page 148, " Number of 

 miles, Spring, North, 383, N. E. 38," etc. It therefore represents time multiplied 

 by velocity. 



The remaining columns IV, V, VI and VII, are taken from the sub-tables. (See, 

 for instance, foot-note 2 on page 148.) Column IV containing the average ve- 

 locity of all winds in miles per hour, though derived from the same sourcg as the 

 " INIean Velocity" for the separate points of the compass, is, of course, not the 

 arithmetical average of the latter, but was separately computed. The numbers in 

 column V show tlie velocity in miles per hour in the mean direction, on the sup- 

 position that the winds from every point of the compass move with the average 

 velocity given in column IV These figures are obtained by multiplying the num- 

 bers in column IV by the ratios in column II. Column VI exhibits the true 

 velocity in the mean direction, giving to tlie winds from the several points of the 

 compass each their own average velocity. The results are the product of the miles 

 per hour in column IV midtiplied' by the corresponding ratios in column III. 

 Column VII represents the excess of the velocities ill column VI over those in 

 column V, as expressed by the use of the plus sign, the minus sign being 

 employed when the figures in column V are the greater. The " Mean Resultants" 

 for the groups of stations in columns II and III were obtained mechanically by 

 the use of a drafting instrument, and are given to the nearest whole degree, the 

 fractions of a degree having been excluded after the computations were made. 



A DRAFT OF THESE RESULTS is found in Plate 25, where the figures in column II 

 are drawn as arrows, flying with the v/ind, the length of the shaft (without the 

 barb) being proportioned to the ratios; those in column III are similarly noted, 

 the barb being omitted, and the greater length of the shaft conforming to the 

 increase in the ratios over those in column II. The average velocities given in 

 column IV are found in the vertical series in the middle of the plate, a scale of 

 miles being attached at the left. The vertical series at the extreme right-hand of 

 the plate contains delineations of the results in the remaining columns ; column V 

 being shown in a dotted line, column VI in a continuous line ; and the intervening 

 space, which is in most cases filled with tlie sign-f, representing column VII. In 

 the individual stations at the lower part of the page, the velocities were, in some 

 cases, so great as to need changes in the scale employed, which is, therefore, 

 recorded in the margin. 



An inspection of the tallies and plate shows clearly that, as a general thing, the 

 difference in the relocitij of the icinds from different points of the conqxiss affects the 

 resultant but stightli/ either in direction or amount. In the United States, north 

 of 32° N. latitude, the resultant had by noting the actual velocities (i. e., the dotted 

 arrow) is found inclined more to the right hand, that is, it represents a direction 

 more northerly than the unbroken arrow that represents the effect when the velocity 

 is disregarded. The annual resultants in the former case averaging S. 89° + AV. 

 with a ratio of .261, and in the latter S. 80° + W. .227. The divergence of these 



