MIGRATING BIRDS. 



and out early in the morning : at first there was 

 a vast fog, but, by the time that I was got seven 

 or eight miles from home towards the coast, the 



though contrary to his better judgment, that some of these 

 enter into a regular torpidity. We find torpidity occurring 

 among animals, fishes, the amphibiae, and reptiles, and 

 among insects ; but we have never found any authenticated 

 instance of this provision taking place among birds. Their 

 frames are adapted to a more extensive locomotive power ; 

 and the changes to climates more congenial to their con- 

 stitutions, preventing the necessity of any actual change 

 in the system, is supplied to those animals deprived of the 

 power for extensive migration, by a temporary suspension 

 of the most of the faculties, which, in other circumstances, 

 would be entirely destroyed. Birds, it is true, are occa- 

 sionally found in holes, particularly our summer birds of 

 passage, in what has been called a torpid state, and have 

 revived upon being placed in a warmer temperature ; but 

 this, I consider, has always been a suspended animation, 

 where all the functions were entirely bound up as in death, 

 and which, by the continuance of a short period, would 

 have caused death itself not torpidity, where various 

 functions and 'secretions, capable for a time of sustaining the 

 frame, are still going on. 



The possibility of performing long journeys, as we must 

 believe some species are obliged to do before arriving 

 at their destination, at first appears nearly incredible ; but 

 when brought to a matter of plain calculation, the difficulty 

 is much diminished. The flight of birds may be estimated 

 at from 50 to 150 miles a'n hour ; and if we take a medium 

 of this as a rate for the migrating species, we shall have 

 little difficulty in reconciling the possibility of their flights. 

 This, however, can only be applied to such species as, in 

 their migrations, have to cross some vast extent of ocean, 

 without a resting place. Many that visit this country, 

 particularly those from Africa, merely skirt the coast, 

 crossing at the narrowest parts, and again progressively 

 advancing, until they reach their final quarters ; and 

 during this time having their supply of suitable food daily 

 augmented. 



The causes influencing the migration of birds appear 

 more difficult to solve, than the possibility of the execution 

 of it. They seem to be influenced by an innate law, 



