PACE AND LAST 113 



tion changed no more than 500 feet up. Sometimes 

 directly opposite currents were met with at different 

 heights in the same ascent, and three or four streams 

 of air were encountered moving in different direc- 

 tions.* But we have other more recent observations 

 at our disposal. During the last few years the upper 

 atmosphere has been investigated with a thorough- 

 ness never before attempted. Unfortunately most 

 of the papers written on the subject deal more with 

 the question of temperature than with wind direction. 

 Often, too, they are concerned with altitudes to 

 which no bird could possibly attain. But when we 

 have made these deductions there still remains in 

 the papers published by the Meteorological Society 

 much that is of the greatest interest to the orni- 

 thologist. I single out the records of a few striking 

 observations. 



On June 23rd, 1909, kite ascents at Glossop 

 brought out the fact that while the surface-wind 

 was south, there was at an altitude of 2,460 feet a 

 south-by -west current, f A great deal is to be learnt 

 from Mr. Cave's Pilot Balloon Observations in Bar- 

 bados, Dec. 6-11, 1909. { Mr. Cave found that on 

 Dec. 8th, at an elevation of some 4,400 feet, the air- 

 current formed an angle of 60° with the wind below. 

 On Dec. 10th, at 6.10 a.m., at a height of 5,500 feet, 

 there was a change in the direction of the wind 

 amounting to 50°. When, therefore, the migrant 

 bird may appear to have the wind on his shoulder 



* See Encyclopedia Britannica, Vol. i, p. 267 (" Aeronautics "). 



f " Registering Balloon Ascents at Gloucester," June 23, 1909, 

 by W. Marriott (Meteorological Society's Papers). 



% Published by the Meteorological Society. 



