86 MIGRATION. 



If ever I saw any thing like actual migration, it 

 was last Michaelmas -day.* I was travelling, and 



* The subject of migration appears to have been a very 

 favourite one with our author, occupying the greater part of 

 many of his subsequent letters, and evidently often the subject 

 of his private thoughts. He sometimes seems puzzled with 

 regard to the possibility of many of the migrating species being 

 able to undergo the fatigue of long or continued journeys ; and 

 often wishes almost to believe, though contrary to his better 

 judgment, that some of these enter into a regular torpidity. 

 We find torpidity occurring among animals, fishes, the amphibise, 

 and reptiles, and among insects ; but we have never found any 

 authenticated instance of this provision taking place among 

 birds. Theirframes are adapted to a more extensive locomotive 

 power ; and the change 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 occasionally 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 an 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. 



