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.t 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. 1, p. 267 (‘* Aeronautics ”’). 
¢ ‘‘ Registering Balloon Ascents at Gloucester,” June 23, 1909, 
by W. Marriott (Meteorological Society’s Papers). 
{¢ Published by the Meteorological Society. 
