HISTORY OF THE WORK. xxi 



in which I showed that observations clearly indicated, and, indeed, all but demon- 

 strated, the existence of a system of winds about the south pole, and extending 

 from 25° to 30° from it, analogous to that which had been proved to exist about 

 the north pole. Although the visits of explorers to this inhospitable region had 

 been limited to periods of a few days each — too short a time for any well-defined 

 results — yet the observations disclosed the remarkable fact that while in the con- 

 tiguous zone further north, and between it and the trade-winds, the mean direction 

 of the wind was always from some point between N. and N. W., with most 

 wonderful uniformity, far more so than in the northern hemisphere, owing 

 undoubtedly to the less amount of land to obstruct its passage, yet out of fifteen 

 visits by explorers to as many diff'erent points in this southern polar zone, in none 

 was the wind from any point in the N. W. quarter, a series of coincidences without 

 a parallel, if merely accidental, and no such system exists. 



[Next, in this monograph, occur the author's remarks on the influence of differ- 

 ence of velocity in modifying the mean direction of the wind, which have been 

 placed on pages 637-639, in the introduction to the Velocity Tables. Though a 

 longer time would be desirable, the discussion is limited to observations for a 

 period of four years, owing to the great labor and expense of making the com- 

 putations.] 



" The discussion of the remaining point named as belonging to the investigation, 

 viz., the connection between the direction of the wind and the rise or fall of the 

 barometer, may not be prepared for appearance in my new work, though it is not 

 inferior in point of interest and practical value to either of the others. It was 

 commenced in its present form about the same time as that of the mean direction 

 of the wind (1836-8), and, like that, nearly simultaneously in Europe and in this 

 country, neither party having any knowledge of what the other was doing. In- 

 quiries had been previously instituted as to the direction of the wind which 

 usually attended a maximum or a minimum pressure of the atmosphere, and 

 statements liad been published in England, and in this country also (I), that the 

 former was N. E. and the latter S. W. ; but the far more important question was, 

 " What change takes place in the barometer during the continuance of different 

 winds'?" And it was to this point that the new investigation was chiefly directed. 

 The statements just quoted may be true, but the inference drawn by some there- 

 from, that winds from the former point tended specially to raise the barometer, and 

 those from the latter to depress it, was not well founded. It was as though the 

 astronomer should conclude that the difference between the mean and true motions 

 of a planet is greatest about midway between the apsides of its orbit, because 

 the equation of the centre is greatest there. If winds from the west, northwest, 

 and north tend to raise the barometer, and those from the east, southeast, and 

 south tend to depress it, and if the wind is prone to shift its direction in the order 

 just named, it is obvious tliat when it reaches the N. E. point, the barometer must 

 show the accumulated effects of all tlie winds through the preceding 180 degrees, 

 and so of course stand high, although the N. E. wind itself were neutral in its 

 influence. To study tlie question properly, we need either self-registering instru- 

 ments (both barometer and wind-vane), or very frequent observations ; and conse- 



