M ACNKTIC DISTURBANCES AND AURORA. 



L97 



An especially brilliant aurora suddenly appeared 

 ;i few minnl.es after 4.0 p.m., in the shape of a 

 curtain, or segment of an arc, extending from 

 \V. 20 N. to N.E. magnetic (8 N. of E. to 

 17 W. of S. true). There was more movement, 

 both vertical and horizontal, than has yet been 

 observed. The vertical movement of the whole 

 display en masse was fairly rapid from S. towards 

 the zenith, and the horizontal motion of the huge 

 shafts of light at one time too rapid for the eye to 

 follow . . . Altitude at first was about 10 at the 

 extremities E. and W., and 20" in the centre, 

 but this gradually rose to 50" and 60" in the 

 centre. The brightest display was at about 4.10 to 

 4.15 p.m. ; had almost entirely disappeared at 4.25 

 p.m. . . . During this special display a bright auroral 

 glow showed up above the hills almost at right 

 angles to the curtain. The display originated quite 

 suddenly in the direction of Mount Discovery (i.e. 

 nearly S.W.) and flashed across the sky towards 

 Observation Hill (nearly S.E.) in a few seconds. 



4.0 p.m. Auroral display in E. 



1903. 



There was a prominent movement in V, con- 

 sisting of an increase of about 240y, comincnring 

 about 3.30 and culminating about 4.15 p.m. 

 Din-ing the next 40 minutes there was a 

 of about 170y. The increase in V was m<>-,i 

 rapid from 4.5 to 4.15 p.m. (i.r. when the an 

 was brightest), the rise during the 10 minnte~ 

 being about 125y. 



The most notable change in I) consisted of //''/ 

 very rapid oscillations between 4.0 and 4.20 p.m. 

 During the first, which occupied about 9 minutes, 

 1) increased 60' and returned to its original 

 value. During the second oscillation, which 

 followed immediately on the first, D increased 

 118' and then diminished fully 130'. The H 

 trace was off the sheet, in the direction of force 

 increasing, most of the time from 3.30 to 5.0 p.m. 

 But some very rapid oscillations came on the 

 sheet about 4.5 to 4.15 p.m. 



July 27, 



a.m. Aurora just above hills from S. to 

 S.W. magnetic (approx. N.N.W. to N.N.E. true), 

 altitude about 5". 



21, 1903. 



A disturbance of the special type (though not 

 very typical) was in progress. From 3.32 to 

 3.44 p.m. V fell about 5y and then rose about 

 87y in the course of the next 31 minutes. 

 Between 4.15 and 4.55 p.m. V fell about 50y. 

 Between 3.32 and 4.15 p.m. the D magnet 

 executed a to-and-fro movement, first diminishing 

 nearly 60', arid then returning to about its 

 original value. The absolutely lowest value 

 occurred about 3.57 p.m. H showed an increase of 

 about 40y, followed by a decrease ; the maximum, 

 which was off the sheet, occurred apparently 

 about 4.10 p.m. In the case of both D and H 

 there were minor oscillations, which somewhat 

 obscured the phenomena near the turning-points. 

 1903. 



V, which had diminished about 80y since 

 10.20 p.m. on the 26th, commenced to rise about 

 11.50 p.m., and during the next 45 minutes 

 increased about 180y. It then diminished rapidly 

 for a few minutes, and then more slowly until 

 nearly 2.0 a.m. on the 27th. H went lieyond the 

 limit of registration, in the direction of force 

 diminishing, about 11.50 p.m. on the 2Gth, and 

 continued so until 0.40 a.m. on the 27th. D went 

 through a number of irregular oscillations, the 

 extreme range between 11.45 p.m. on the 26th 

 and 0.35 a.m. on the 27th exceeding 60'. 



