MIGJIATION. 43 



hour; and SPALLANZANI found that of the swallow com- 

 pleted about 92 miles, while he conjectures that the rapidi- 

 ty of the swift is nearly three times greater. A falcon 

 which belonged to HENIIY the Fourth of France, escaped 

 from Fountainbleau, and in twenty-four hours afterwards 

 was found at Malta, a distance computed to be no less than 

 1350 miles ; a velocity nearly equal to 57 miles an hour, 

 supposing the falcon to have been on wing the whole time. 

 But as such birds never fly by night, and allowing the day 

 to be at the longest, his flight was perhaps equal to 75 miles 

 an hour. It is probable, however, says MONTAGU, that 

 he neither had so many hours of light in the twenty-four, 

 to perform his journey, nor that he was retaken the mo- 

 ment of his arrival. But if we even restrict the migratory 

 flight of birds to the rate of 50 miles an hour, how easily 

 can they perform their most extensive migrations ! And 

 we know, in the case of woodcocks, and perhaps all other 

 " migrating birds, that they in general take advantage of a 

 fair wind with which to perform their flights. This breeze 

 perhaps aids them at the rate of 30 or 40 miles an hour ; 

 nay, with three times greater rapidity, even in a moderate 

 breeze, if we are to give credit to the statement of aerial 

 navigators, who seem to consider the rate of the motion of 

 winds as in general stated too low. 



It has been already observed, that many species do not 

 perform their migrations at once, but reach the end of their 

 journey by short and easy stages. There is little exertion 

 required from such ; while those who execute their move- 

 ments at one flight, (if there be any that do so), may in a 

 very short time, perhaps a day, by the help of a favourable 

 breeze, reach the utmost limits of their journey. Many 

 birds, we know, can subsist a long time without food ; but 

 there appears to be no necessity for supposing any such ab- 



