SEVENTH ANNUAL MEETING 



87 



The next step is simply to determine from a weather map the 

 particular tract of the cyclone in which Davenport lies and to 

 record the simultaneously existing weather conditions. By ob- 

 taining a sufficient number of observations it is possible to 

 ascertain the average weather conditions when Davenport is 

 situated in any given area of the cyclone. 



The present study is based upon an examination of the 



CONSTANCY SCALE 



CI »J4J<?« 9'° 



CI i J4 S . 



t i i T i i i 



N 



A 



18 



"K 



10 



if 



24 



I 



12\ 



^23 



80- 



Figure 12. 



s 



Wind Direction 



morning and evening weather maps for a period of about 

 twenty years. A total of 4508 observations have been secured. 

 These are distributed unequally among the 25 tracts of the hy- 

 pothetical cyclonic area as seen in Fig. 10. The maximum num- 

 ber of observations, namely 521, occurs in tract 15 ; in this posi- 

 tion Davenport lies about 550 miles southwest of the center of 

 the low. The fewest observations, 17 in number, are found in 



