Kent, in King Lear (Act II. Sc. 2), speaks of rogues who—
“Turn their halcyon beaks
With every gale and vary of their masters.”
And, after Shakespeare, Marlowe, in his Jew of Malta, says,—
“But how now stands the wind?
Into what corner peers my halcyon’s bill?”
For brightness and beauty of plumage, the kingfisher has no equal amongst our British birds, and so straight and rapid withal is its line of flight, that when the sunlight falls upon its bright blue back, it seems as if an azure bolt from a crossbow had been suddenly shot across our path.
It is difficult to calculate or limit the speed which can be produced by the effort of a wing’s vibration. We may, nevertheless, ascertain with tolerable accuracy the rate of a bird’s flight, as follows:—If we note the number of seconds which are occupied by a bird in passing between two fixed points in its line of flight, and measure the distance between these points, we resolve the question to a simple “rule-of-three” sum; inasmuch as, knowing the number of yards flown in a certain number of seconds, we can ascertain the distance traversed in 3,600 seconds, or an hour, and thus obtain the rate of speed per hour; supposing, of course, the speed to be uniform. In this way the flight of the common Swallow (Hirundo rustica) has been computed at ninety miles,—
“As swift as swallow flies.”
Titus Andronicus, Act iv. Sc. 2;