AT WINTER QUARTERS. 



161 



with the immediately preceding portion. Prior to 8.10 a.m., L.T., the V trace was sloping gently down the 

 sheet, representing most probably a gradual rise in temperature, which can, however, only be inferred, as 

 the temperature trace got beyond the edge of the sheet at 2 a.m., L.T. But from 8.10 to 8.14, L.T., the 

 slope is slightly the other way. The measurements of the original gave an increase of about 1 mm. of 

 ordinate during this 4 minutes, answering to l'2y. Thus we have apparently a real oscillation in all 

 three elements, from approximately S.10 to 8.18 a.m., L.T. (9.3 to 9.11 p.m., G.M.T.), for the magnitude 

 of which I find : 



The time of commencing the second phase in the Antarctic is, if anything, before 9.7 p.m., G.M.T., whilst 

 the times of the commencement of the increase in H at Kew, Falmouth, and Colaba are all, if anything, later 

 than 9.6. Thus the evidence certainly points to the conclusion that it is the second phase in the Antarctic 

 which answers to the commencement seen elsewhere. If so, it is certainly remarkable that what seems to 

 a considerable extent a recovery from a sudden disturbance should exert an effect visible all over the world, 

 whilst the effect of the preceding disturbance is visible only in the Antarctic. 



66. Plate XXIV shows a disturbance corresponding to the second of those appearing in Plate XV. 

 In this instance the commencing movement was distinctly double at Falmouth and elsewhere, and in the 

 Antarctic this oscillatory character is even more clearly shown in the H and V traces. Taking the 

 H curve, we have first a sudden movement down the sheet (increase of H) commencing at 2.59 a.m., L.T., 

 on November 7 (3.52 p.m., G.M.T., on November 6) and lasting about 1 minutes. This is followed by a 

 reverse motion of more than double the amplitude, occupying about 10 minutes. The first movement, so 

 far as can be judged, is exactly synchronous with that at Falmouth, but the second movement somewhat 

 overlaps the corresponding Falmouth movement. The Falmouth trace is rounded at the top, but a slight 

 fall in H is visible before the corresponding turning-point appears in the Antarctic curve. The Antarctic 

 V trace shows a sudden rise synchronous with the first movement in H, followed by a larger fall. The 

 second turning-point occurs, however, about two minutes earlier than that in H, and so corresponds more 

 nearly to the summit of the Falmouth II curves. What happened to the Antarctic Declination is uncertain, 

 as the trace is invisible during the most rapid part of the H movement. The fact that the D trace is 

 invisible suggests that the movement was even larger than that in the H trace; so presumably a 

 to-and-fro movement of large amplitude occurred. 



When the D trace becomes visible it shows two small peaks in rapid succession. It is the second of these 

 that answers to the turning-point terminating the second movement in H. The first peak preceded this 

 by three minutes. 



The amplitudes of the first two movements in H and V are as follows : 



The H and V magnets had at this time their highest sensitiveness, so that the large size of the apparent 

 movements in these traces requires to be discounted when compared with that in other disturbances. The 

 D trace, however, had the same sensitiveness as usual. Thus the fact that so much of the D trace is lost 

 partly through going off the sheet, partly from being too faint to be visible is evidence that in the 

 Antarctic the storm was a very considerable one, including some very rapid changes of force. At Kew 



Y 



