THE ALPINE SWIFT. 
45 
And amidst the flasliing and feathery foam 
The stormy ])etrel finds a home, — 
A home, if such a place ma,y be 
For her who lives on the wide, wide sea." 
The Alpine swift may also be instanced as a bird gifted with extra- 
ordinary faculties both of speed and endurance. She lives upon the 
wing ; from dawn to sunset she is constantly traversing the " fields of 
air," and her daily flight must comprehend several hundreds of miles. 
Most birds seem to fly with equal facility at all elevations, whatever 
may be the differences of the atmospheric pressure, and the degree of 
strength required. Near the summit of Chimborazo, Humboldt saw a 
condor hoverino^ above him at an incalculable height. Ao-ainst the 
profound azure of the heavens he seemed but a speck of black; yet to 
all appearance he moved with as much ease as he could have done in 
the lower regions. We must admit, however, that this is not always 
the case. Aeronauts have let pigeons loose at great elevations, and 
have observed that their flight was much more laboured and irregular 
than it is when near the ground. 
Sometimes the bird hovers tranquilly ; anon, he darts forward like 
