2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



Analysis of weather records appears to show that each of the various 

 solar periodicities above referred to influences both temperature and 

 precipitation to a significant degree. At least five (perhaps six) other 

 periodicities in weather elements, closely associated in length with 

 the original seven, are also significant. Inasmuch as all of these 12 

 or 13 periodicities are very nearly aliquot parts of 23 years, it follows 

 that their combined efifect produces in the weather a large number of 

 features more or less pronounced during a period of 23 years. Suc- 

 ceeding intervals of 23 years tend to bring repetitions of these features. 

 For some of these periodicities, however, 46 years appears to be the 

 critical interval. Hence there is a somewhat closer correspondence 

 at some times and some stations between weather features 46 years 

 apart. Owing to certain modifying influences in the sun itself, to 

 which reference will be made below, and to the complexity of the 

 terrestrial agencies through which the solar influences act, these 

 repetitions of weather features are subject to moderate displacements 

 in time, and to modifications in amplitude. Actual reversals of phase, 

 as will be shown, sometimes occur after 23-year intervals. Never- 

 theless, special weather features remain recognizable in many in- 

 stances by comparison of successive 23-year curves. 



Based on these grounds it becomes possible to make forecasts of 

 weather conditions for years in advance which appear to be sig- 

 nificantly more representative than normal values. The modifying 

 factors referred to above detract as yet greatly from the accuracy of 

 such forecasts, but further study may lead to greater perfection. 

 The following paper gives the evidences for these statements. 



The evidence to be presented being extensive and complex, and 

 certain parts of it — as, for instance, the studies of periodicities in the 

 temperature of Berlin — being apt to prove tiresome to some and con- 

 troversial to others, it is suggested that high spots of the demonstra- 

 tion may be picked out as follows : 



1. Turn to captions 3 and 4, pages 6 and 10, and note the results 

 expressed by figures 4, 6, 7, and 8. 



2. Turn to captions 14-Ba, 14-Bb, and 15, pages 35, 38 and 53, and 

 note the results expressed by figures 15, 16, 17, 19, and 2^. 



3. Turn to captions 17 to 25, pages 56 to 75, and note at least a 

 part of the results expressed in figures 24 to 37, inclusive. 



4. Finally, with these results in mind, read the Summary, pages 88 

 and 89. 



In this way it is hoped that the reader will obtain briefly such a 

 view of the more remarkable parts of the investigation as will arouse 

 his curiosity to pursue the entire course of the demonstration. 



