XXVI 
INTRODUCTION. 
developed to such an extent that extraordinary rates of velocity and distances traversed have been recorded. 
Thus Mr. Charles Boner states, in his ‘ Forest Creatures,’ that the flight of the Eagle is sixty feet per 
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second, being at the rate of somewhat more than forty miles per hour ; and my friend Mr. White Cooper 
mentions. In his ‘ Zoological Notes and Anecdotes,’ that “ the flight of a Hawk is calculated at one hundred 
and fifty miles an hour ; and the anecdote of the Falcon belonging to Henry IV. of France, which flew, in 
one day, from Fontainebleau to Malta, a distance of thirteen hundred and fifty miles, is well authenticated.” 
Mr. Harting, in his interesting ‘ Ornithology of Shakespeare,’ mentions that the flight of the Common 
Swallow {Hirundo rustled) has been computed to be at the rate of ninety miles an hour. If this be a just 
computation, that of the Alpine Swift must he twice as great; but these are as nothing when compared with 
the velocity of the Frigate bird {Tachypetes aquilus), which, says Audubon, “is possessed of a power of 
flight I conceive superior to that of perhaps any other bird. However swiftly the Cayenne Tern, the smaller 
Gulls, or the Jager move on the wing, it seems a matter of mere sport to it to overtake any of them.” 
“ There are two facts observable in all birds of great and long-sustained powers of flight,” remarks the 
Duke of Argyll, in his admirable ‘Reign of Law.’ “The first is that they are always provided with wings 
which are rather long than broad, and sometimes extremely narrow in proportion to their length ; the 
second is that the wings are always sharply pointed at the ends. Let us look at the mechanical laws which 
absolutely require this structure for the purpose of powerful flight, and to meet which It has accordingly been 
devised and provided. One law appealed to in making wings rather long than broad is simply the law of 
leverage and a long wing is nothing hut a long lever. The mechanical principle or law, as is well 
known, is this — that a very small amount of motion (or motion through a very small space) at the short 
end of a lever, produces a great amount of motion (through a long space) at the opposite or longer end. 
This action requires, indeed, a very intense force to be applied at the shorter end ; but it applies that force 
with immense advantage for the purpose in view, because the motion which is transmitted to the end of a 
long wing is a motion acting at that point through a long space, and is therefore equivalent to a very heavy 
weight lifted through a short space at the end which is attached to the body of the bird. Now, this is 
precisely what is required for the purpose of flight.” The preceding extract is sufficient for my present 
purpose ; but my readers will find many other interesting remarks on the laws affecting and governing the 
flight of birds, in the work above mentioned, to which I would earnestly direct their attention. 
Birds, like other animals, are endowed with the usual senses ; but these vary in degree of perfection in 
accordance with the variety in their habits. That that of sight is very highly developed is amply testified in 
the Kestrel, whose eyes must be almost telescopic to enable it to see an inseet or a mouse on the ground 
from the nreat elevation at which it usually hovers ; the familiar Robin, who discovers the wriggling worm 
