254 Miss Baxter and Miss Rintoul on the [Ibis, 



Seventhly. In an interesting article in ^Nature/ 26 July, 

 1917, by W. H. Dines, he shows the etfect o£ wind on the 

 drift of an aeroplane. He states : " The pilot, therefore, if 

 the earth is hidden from him by a sheet of clouds, is abso- 

 lutely and entirely ignorant of the strength and direction of 

 the wind in which he is flying ; it is just the same to him 

 if it be a dead calm or if it be blowing at the rate of a hundred 

 miles an hour from the east or from the west ; he is, indeed, 

 as unconscious of the motion which he is sharing with the 

 air as he is of his daily revolution at a ratein these latitudes 

 of some 600 miles an hour round the axis of the earth. But 

 the effect upon the drift of his machine may be very con- 

 siderable, and as he does not know what it is he cannot 



allow for it Thus Glasgow lies very close to a point 



400 miles due north of Plymouth, and an aeroplane leaving 

 Plymouth and flying due north at 80 miles an hour would 

 find herself close to Glasgow in five hours' time. Should, 

 however, a strong west wind be blowing of which the pilot 

 did not know, and also clouds so that he could not see the 

 earth, he would, if steering by compass, find himself in five 

 hours^ time over the North Sea, and quite possibly much 

 nearer to the Danish than to the English coast. In the pre- 

 sent state of our knowledge he could obtain information at 

 starting of the general direction and strength of the wind, 

 but not in such detail that he could hit oft' Glasgow within 

 100 or 200 miles." Easterly winds with low clouds, haze 

 or fog is exactly the type of weather in which big rushes 

 of birds occur on our coasts, and we think it a fair deduc- 

 tion that they, like the aeroplane pilot, have been drifted 

 from their direct route. 



Eighthly. In an autumn such as this (1917), in which per- 

 sistent westerly winds prevail, not only do the large move- 

 ments of passage migrants through Scotland not occur, but 

 the numbers of winter visitors are enormously below the 

 average, Fieldfares, Redwings, Bramblings, &c., being con- 

 spicuous by their absence. Dr. Eagle Clarke kindly informs 

 us that in 1887, when similar weather conditions prevailed, 

 winter visitors were equally scarce. 



