NTRODUCTION. 



Meteorology and Terrestrial Magnetism. 



1 he gigantic store of meteorological obser^'ations that in the course 

 of years have been collected from thousands of stations all over the world, 

 has laid the foundation of our knowledge of the climatic conditions of the 

 earth. This store has also formed valuable material in the study of the 

 laws for the mutual connections of meteorological phenomena; and the 

 theories resulting 'from this study have contributed many useful and in- 

 structive suggestions towards our imderstanding of the physical conditions 

 of our atmosphere. But even.* meteorologist who has been occupied for 

 a number of years in issuing daily weather-forecasts, must have found 

 that the reliability- of the forecasts has not kept pace with the times: we 

 stand now about where we stood twenty-five years ago. It is true that 

 at the central meteorological offices we have been able graduallv to 

 acquire a practical understanding of the way in which certain more marked 

 states of weather will in most cases be to some extent determinative of 

 the atmospheric conditions for the coming 24 hours, over a more or less 

 extensive area around the central station in question; but this under- 

 standing will often be of a purely personal and local nature, and cannot 

 be distinctly converted into numerical values or graphic representations. 

 We have no certain signs of sudden or gradual changes in a state of the 

 weather, nor of the extent of these changes. 



The synoptic charts which are daily constructed at nearly all central 

 meteorological offices, often cause great and inexplicable disappointment. 

 The distribution of the atmospheric pressure, or of temperature, so fre- 

 quently proves to be quite different from what there seemed reason to 

 expect, after the telegraphic weather-reports of the previous day. We 

 are continually receiving the impression that there is an unknown factor, 



Vid.-S€lsk. Skrifter. I. M.-X. Kl. 190t. No. 2. 1 



