63 



manner at great heights above, the atmosphere in these elevated 

 regions being supposed to have returned to a state of calm. 



It seems hardly likely, however, that any birds would set out 

 to cross a wide sea under such conditions, and the appearance 

 of migratory flocks during a lull on 24th, when the wind had 

 considerably abated, points more to the fact that these individuals 

 had been merely awaiting a favourable opportunity to continue 

 their journey at some locality near at hand. Some light is 

 thrown on the theory that these migrating birds had only become 

 aware of the weather they were to encounter from indications 

 present aif the earth's surface, from the fact that many of them 

 were Hooded Crows, a species which only under most exceptional 

 circumstances migrates at a height of more than a few feet above 

 the surface of the land. They, in any case, would not have felt 

 the first indications at a great altitude. The assertion, however, 

 that the Hooded Crows had become aware of the approaching 

 storm at a distance of 1,200 miles from the area in which signs of 

 the disturbance were then becoming evident, i.e., in the Hebrides, 

 depends entirely on our acceptance of Herr Gatke's statements 

 as to the rate at which this species migrates, and also as to the 

 direction from which the flocks are derived. The position of 

 their starting-point, i.e., 600 east of Heligoland, being purely 

 theoretical. Had they been coming from Scandinavia, as seems 

 more probable than from due east, then there might have been at 

 their point of departure local indications of the approaching 

 change some time before they became apparent in Heligoland. 

 So far from the first indications of changes in the weather 

 becoming first perceptible at very great altitudes, where the 

 air is very thin, it seems far more reasonable to suppose that 

 near the surface of the earth where the influence of the large 

 masses of land and water, coupled with the greater effect of the 

 sun's rays on the denser atmosphere, is the region where all 

 changes of the weather have their origin and become first 

 apparent. At any rate the appearance of light fleecy clouds 

 travelHng at a great height in the opposite direction to the wind 

 prevaiUng at the surface of the earth, followed by others, at a 

 lower level and eventually culminating in rain, is hardly sufficient 

 evidence that the converse is the case. 



