METEOROLOGY. 429 



needle, the rapidity of tlie oscillations, or the persistency of the more 

 moderate disturbances, but also they were found to follow at consid- 

 erably different intervals after the commencement of the observed 

 solar outbursts. {Nature, 1881, xxiv, p. 4G6.) 



Prof. W. G. Adams, in a study as to the origin and nature of magnetic 

 disturbances, chose the month of March, 1879, for a comparison of the 

 photographic records of magnetic disturbances, and records for the 

 whole month were sent from Lisbon, Coimbra, Stonyhurst, Vienna, St. 

 Petersburg, and Bombay in the northern hemisphere, and from Mel- 

 bourne and Mauritius in the southern hemisphere. He finds that an 

 inductive action equivalent to a change of i^osition of the north magnetic 

 pole towards the geographical pole would account for the changes re- 

 corded at these places. 



In attempting to explain the disturbance of March 15 by currents 

 of electricity or discharges of str.tical electricity in the air above the 

 needles, we must imagine that at first there is a strong current from 

 the southwest over St. Petersburg, from the west over Vienna, and 

 from the northwest over Kew and Lisbon 5 that at Mauritius this cur- 

 rent is from the north, and at Bombay from the south. Thus we must 

 inuigine that a current of electricity passes down from the northwest 

 to the southeast, going on towards the east over Vienna, and towards 

 the northeast over St. Petersburg. This must be kept up verj^ much 

 along the same line throughout the first part of the disturbance, and 

 then the current must be altered in strength in the same manner at all 

 stations. 



The study of the great storm of August 11 points rather to solar ac- 

 tion as the cause of this disturbance. In the storm of March 12 these 

 magnetic changes are so large as to be quite comparable with the earth's 

 total force, so that any cause which is shown to be incompetent from 

 the nature of things to produce the one can hardly be held to account 

 for the other. {Nature, 1881, xxiv, p. 492.) 



W. Ellis has compared with the Greenwich records lithographed 

 copies of the photographic traces made at Zi-ka-wei (lat. 31° K,, long. 

 122° east) of the declination and horizontal force magnets, extending 

 from August 11 to 14, and from August 17 to 20, 1880. Some particu- 

 lars of the comparison are as follows (Greenwich time is used through- 

 out) : 



A general exami nation of the two sets of curves shows that the 

 disturbances were usually greater in magnitude at Greenwich than at 

 Zi-ka-wei. Comparing the curves in detail, it is found on August 11, 

 at 10.20 A. M., after a quiet period, the declination and horizontal force 

 magnets at Greenwich both made a sudden start, which was the com- 

 mencement of a magnetic disturbance lasting until midnight. An ap- 

 parently equal horizontal force is shown on the Zi-ka-wei curves, oc- 

 curring in declination at 10.12 A. m., and in a horizontal force at 

 10.20 a. m. (as nearly as the small scale on which the curves are drawn 



