THE VELOCITIES OF MIGRATORY BIRDS. 247 



above a cliff to save wing power ; or — a comical instance — 

 Sparrows sheltering from wind or rain in the narrow, dry, 

 vertical area a yard or so from the corner of an ivied lee wall, 

 while intellectual mankind below is getting wet through ! 



If we examine a diagram of the atmospheric currents of the 

 earth, we see that there are regular tides between the Equator 

 and the Poles. A migrant must of necessity either fly with or 

 against these currents — we can ignore "beam winds" for the 

 present — on its annual journeys. To travel head to wind is, as 

 we see, wasteful and even dangerous, and from what we know of 

 the habits of birds in relation to winds and short flights, we are 

 led to expect that they are intelligent enough to take advantage 

 of air currents for long flights. A critic of my earlier paper was 

 led to view the migrant as " boarding " the rim of a cyclone as 

 one might board a moving roadway, and dropping off when that 

 part of the atmosphere came above its destination, or as near 

 that spot as possible. This was rather a flippant way of inter- 

 preting my views, but after all I cannot see any very great 

 objection to it, except that certain people are justly suspicious 

 of scientific views that are not couched in some form of scientific 

 argot. 



Migrants certainly possess the sense of direction to a high 

 degree, and this aspect of the study is a most important one. I 

 would draw attention to an unusually interesting paper by Dr. 0. 

 Viguier on " Le Sens de l'Orientation et ses organes chez les 

 Animaux et chez l'Homme," in the ' Revue Philosophique ' of 

 1882 (xiv. pp. 1-36). So far as I know, this piece of work, even 

 to-day and to a greater extent thirty years ago of prime interest to 

 the ornithologist, has not been even mentioned in any British 

 book or paper. Yet, on the other hand, Gatke's work received a 

 nattering welcome, although his book contained a number of 

 palpable errors. Many of these were combated by Mr. F. B. 

 Whitlock and others, but the personality of the man and the 

 ornithological richness of his island have ensured him a wide 

 circle of sympathetic readers for his fascinating book.* 



The experiments made with flying machines demonstrate 

 that winds directly influence the speed of aeroplanes moving in 



* All cautious students of Gatke's book should read also Whitlock's 

 1 Migration of Birds ; a Consideration of Herr Gatke's Views ' (1897, 8vo). 



