I s 79.] Observations of the Arctic Expedition, 1875-76. 35 



to that in March, is 3"25, but the ratio of the easterly excess in the 

 same months is 1*32; the mean actual values being — W 7 and — 38'1; 

 + 8-5 and +11-2. 



Among the peculiarities of the disturbances at Discovery Bay, are 

 two which exhibit their semi- American, semi-Asiatic character. 



At Pekin, Nertschinsk, and Discovery Bay the aggregate values of 

 the westerly deflections decidedly predominate, the contrary obtains 

 in America. In ^Nbrth America " the conical form (of the curves) 

 characterizes the easterly deflections. *** The same occurs at Discovery 

 Bay. but the double maximum — which is observed in the easterly 

 deflections at Pekin and Xertschinsk, and the westerly in 2s"orth 

 America — is common to both easterly and westerly deflections. 



Objections may possibly be raised to a comparison being made 

 between the observations of a few months with those of as many 

 years. The period of observation, however, includes one solstice and 

 the subsequent equinox ; it is, therefore, considered that according to 

 Mr. Broun's investigations in high latitudes, all the broad features of 

 the disturbances have been rendered prominent. 



Before concluding this analysis, the question of how far the 

 observed and assumed days of disturbance at Discovery Bay coincided 

 with those at Kew Observatory seems worthy of examination. 



The period embraced by these observations was one of great dis- 

 turbance, especially towards the end of February and the greater part 

 of March, the declinometers at both stations being for the most part 

 affected on the same days. At Kew Observatory, Mr. Whipple 

 noted 57 days of principal disturbance, while at Discovery Bay there 

 were 72. 



The two greatest disturbances or " magnetic storms," occurred on 

 the 19th February and the 25th March, and the time limits at the two 

 stations agree fairly in "absolute time,"f thus: the principal dis- 

 turbances — 



'Kew. Discovert/ Bay. 



I 19th February, r Commenced at 4 to 5 p.m. J Commenced at 4 p.m. 



1S75. \ Ended at 2 p.m. of 20th | Ended between 1 and 2 p.m. of 20th. 

 25th to 26th J Commenced at 11/45 a.m. [ About noon. 

 March, 1875. [Ended at 330 a.m. ; 26th I Indeterminate. 



The hours of disturbance at Floeberg Beach were about the same 

 (in February) as at Discovery Bay. 



During the second storm of the 25-26th March at Discovery Bay, 

 the magnet kept continuously to the westward of the normal from 

 the commencement to 10.20 p.m. (absolute), and at 6.50 p.m. (absolute) 

 it had deviated 4° 15' from the mean hourly position, whilst at Kew it 

 was often to the eastward as well as to the westward, 18' being the 



* See " Phil. Trans. Roy. Soc," 1863, page 2S2. 

 t Or mean time at Greenwich. 



D 2 



