COMPARISON OF ARCTIC AND ANTARCTIC DISTURBANCES. 265 



a maximum at about 20h. 45m. to 21h., the second especially powerful at Dyrafjord, being most developed 

 between 22h. 30m. and 24h. There is also a somewhat vague reference to a "more lengthy perturbation" 

 as covering the time of the two polar storms, and to the possibility of " cyclo-median " perturbations being 

 felt in lower latitudes. 



At the time of the first "polar elementary" storm the most prominent feature at Kew was a bay on the 

 D curve. The element fell 4' - 2 between 20h. 36m. and 20h. -iGm., and then rose gradually to about its 

 original value at about 21h. 45m., the rate of recovery slackening after 21h. 10m. H rose about 7y 

 between 20h. 45m. and 20h. 57m., having been falling slowly for some time previously. 



At the time of the second " polar elementary " storm the most prominent feature at Kew was a bay on 

 the H curve, the value of the element rising and falling about 14y between 23h. 8m. and 23h. 48m. In D 

 there was a rise of about l'-5 between 23h. Om. and 23h. 15m., followed by an equal fall and a further 

 small rise. After midnight on the 26th one would ordinarily describe the curves as very quiet. The 

 conditions at Kew appear fairly representative of the European non-polar stations. 



The Antarctic curves were unmistakably disturbed after 19h. on the 26th until the sheet was removed 

 at 23h. 31m. The disturbance commenced apparently with a very rapid rise in D, the value increasing 

 141' in 6 minutes from 18h. 59m. to 19h. 5m. After some small rapid oscillations D continued to rise 

 until 19h. 15m., the total rise since 18h. 59m. being 158'. This was followed by a fall of 196' between 

 19h. 15m. and 19h. 53m., and a second rise of 224' between 19h. 53m. and 20h. 55m., the trace then going 

 off the sheet on the positive side for a few minutes. 



H commenced to fall at 18h. 59m., when D began to rise, and fell 79y in about 9 minutes, shortly 

 thereafter getting beyond the limits of registration on the negative side. The largest change shown in H 

 was between 20h. 27m. and 21h. 53m., when the element rose 160y in several steps interrupted by minor 

 oscillations. 



The V trace during this time showed numerous oscillations, including the following ( + denotes a rise, 

 - a fall) : 



From 



After 21h. 45m. there were further considerable movements in the Antarctic, the most notable being on 

 two occasions when the traces from the three elements show deep bays, occurring synchronously or very 

 nearly so. On the first occasion, lasting from about 21h. 55m. to 22h. 30m., 



D fell 136' and rose 130', 

 H 89y 69y, 



V 120y 112y. 



The turning-points (minima) occurred within a few minutes of one another. 



On the second occasion the oscillation was apparently not quite completed when the paper was changed. 

 So far as recorded, it lasted from about 22h. 56m. to 23h. 31m. During it 



D rose 33' and fell 39', 

 H 52y 66y, 

 V 23y 37y. 



The second movement is comparatively small, and is mentioned chiefly because the three elements 

 appear approximately in phase and the time synchronises with that of BIKKELAND'S second " polar 

 elementary " storm. 



2 M 



