METEOROLOGY. 54SJ 



are entirely discordant. (3) The characteristic features of this storm are 

 as follows : 



Character of disturbances. 



(4) The magnitude of the perturbation for each element, especially the 

 intensity, and for each day, shows a diurnal period closely coinciding 

 with normal daily variations. (5) It is probable that the sun is to be 

 considered as the principal agent of the periodic and non-periodic vari- 

 ations of the elements of terrestrial magnetism. However, it must be 

 conceded that this conclusion would require that we assign to the sun 

 a magnetization per unit of mass about 13,000 times that of a unit of the 

 earth's mass, and that at times of great perturbations this varies to and 

 fro by thirty times its own amount ; but our present knowledge only 

 justifies our attributing to a unit of mass in the sun a magnetic power 

 2,000 times that of a unit of the earth, even supposing the sun to be a 

 fully saturated steel magnet. Therefore, it appears not likely that the 

 sun alone is the cause of the normal and abnormal variations. It will be 

 more intelligible to adopt with De La Rive the view that the earth is a 

 Le^ den jar, whose inner covering is the surface of the ground, and whose 

 outer surface is the highly attenuated upper strata of air, and that dis- 

 charges from pole to equator in the atmosphere and also from pole 

 to pole within the eartn continually take place. The ordinary charges 

 cause the normal deviations of the magnet, the abnormal cause the per- 

 turbations. We have, then, only to assume that the daily position of 

 the sun has an influence upon the direction and force of this discharge, 

 and that the abnormal stronger discharge is caused by special occur- 

 rences on the sun. In this way the cause is made present on the earth, 

 and the sun comes in only as the medium releasing it and setting it into 

 activity. Observations on, earth currents have been instituted in Pav- 

 losk that will perhaps be further explanatory of this matter. (Z. 0» 

 G. M., xvii, p. 14.) 



Prof. H. Wild has investigated the so-called magnetic weather of Jan- 

 uary 30-February 1, 1881, by means of the records of magnetographs, 

 at eleven places in America, Europe, India, China, and Australia. He 

 finds that the perturbations began everywhere simultaneously, so far 

 as the time scales enabled the moments to be determined. A perfect 

 similarity in the declination curves existed throughout Southern Eu- 

 rope, but the curves for Pavlosk, Zikawei, Bombay, show no similarity, 

 while for Melbourne and Toronto, the declination curves generally show 

 almost opposite variations. A very similar statement as to the opposite 

 character of the variations in Europe and America would hold good for 

 the curves of horizontal and vertical intensity and the dip of the needle. 



