NO. 17.] ATMOSPHERIC PRESSURE. 399 



The numbers in the baric wind-roses for the individual months run rather 

 irregularly. It is only when we come to the weighted and smoothed numbers 

 for the seasons that we observe something of a general rule. The winter 

 summer and autumn show minima at about ENE and at W, and maxima 

 at N and S. This is also the rule for the Dark Season and for the Sunny 

 Season. The spring months have minima at NNW (and at S), and maxima 

 at E and WSW. The two equinoctial months differ from each other. March 

 has minima at NNW and at SSE, maxima at ENE and at WSW, while 

 September has its minimum at SW, and maximum at NNW. It is difficult 

 to draw conclusions from the baric wind-roses as to the position and move- 

 ment of the barometrical minima and maxima in the polar sea. The frequency 

 of the minima of pressure with the winds from W and NE seems to indicate 

 that the tracks of the barometric depressions lie both North and South of 

 the position of the Fram. This question I shall discuss later on from other 

 points of view. 



WIND ROSES FOR THE CHANGE OF PRESSURE. 



From the Tables of observation, the number of those cases have been 

 taken out in which the wind-direction has been accompanied by a rise or 

 fall of the barometer. The change of pressure is reckoned from the fore- 

 going to the following observation. The numbers for the intermediate points 

 of the compass have been equally distributed over the neighbouring 16 points. 

 The resulting figures were divided, for each wind-direction, by their sum, so 

 that the figures given in the following Table represent the percentage of cases 

 with rising (+) and decreasing ( ) pressure, their sum being 100. The 

 maxima are printed in larger type. 



