206 REPORT~1880. 



St. Petersburg, tlie otlier small disturbances at all the places being tlie 

 same. 



Again, on the 13th, there is a magnetic storm, lasting from G.20 p.m. 

 until 8 p.m., which takes place absolutely at the same time at all tlie 

 stations, and for which the curves for places near together absolutely fit 

 one another. 



At St. Petei'sburg tliis storm was more violent than at the otlicr 

 stations, and was preceded by a violent storm, iu which the needle de- 

 viated first to the cast and then to the west, between 4.20 and 6 p.m. 

 This preceding storm was only slightly felt at the other stations, and 

 rather more at Vienna than at Kew or Stonyhurst. 



About 2.30 a.m. on the 14th, there is a sudden disturbance of the 

 needle to the westward, which is stronger at Kew and Stonyhurst than at 

 Vienna or at St. Petcvsburg. 



The nest considerable disturbance was on the 15th, beginning at 

 9.20 p.m. and ending at midnight, followed by lesser disturbances arising 

 from a distinct cause which lasted until 4 a.m. on the 16th. 



This disturbance from 9.20 p.m. to midnight produced similar deflec- 

 tions at Kew and Stonylmrst, and also at Coimbra and Lisbon, first rapidly 

 to the east until 9.50 and then to the west ; but tiie range was not so great 

 at these latter places. At St. Petersburg the deflections of the needle 

 were in the opposite direction to those at Kew and Stonyhurst, and the 

 opjjosite deflections occurred at the same time ; and this remark applies to 

 all the oscillations of the declination needle up to midnight. The dis- 

 turbance westward was also much greater than the simultaneous eastward 

 disturbance at Kew. 



The disturbances between midnight and 4 a.m. take place at the same 

 time at all the stations, and are precisely similar in character and in 

 direction at St. Petersburg, at Vienna, and at Kew. They are also equal 

 in amount, so that the curves almost fit one another. Here, then, we have 

 a cause producing opposite disturbances at Kew and at St. Petersbin-g 

 for more than two hours, followed by probably some other cause of dis- 

 turbance producing identical effects at all the stations for a period of four 

 hours. 



At Vienna from 9.20 to midnight the disturbances were simultaneously 

 in the same direction as, but were very weak in comparison with, those 

 at St. Petei'sburg, so that this magnetic storm was very little felt at 

 Vienna. 



On reveri5ing the Kew curve for this disturbance and comparing it 

 with St. Petersburg, it is seen that the successive maxima and minima 

 are absolutely simultaneous, so that the deflections opposite ways at the 

 two places are seen to be due to the same cause ; and the Vienna curve is 

 very nearly coincident with the mean curve obtained by superposing the 

 Kew and St. Peterslmrg curves. 



Plate VII., fig. 2, represents the St» Petersburg, Kew, Vienna, and 

 Coimbi-a declination curves for March 15th-lGth. 



The beginning of this disturbance was accompanied by a sudden and 

 large increase of the horizontal force until 9.50 p.m., and then by a dimi- 

 nution until 10.45 p.m., followed by slight oscillations of the needle until 

 midnio-ht, which are simultaneous with the oscillations of the St. Peters- 

 burg declination needle. 



The vertical force gradually diminishes from 9.20 to 10.30 p.m. 



Nothing can show move clearly than this the direct relation between 



