118 Jo] in BacJiman. 



some opportunities, by witnessing the migration of 

 birds, in three very distinct portions of America 



That instinct is truly mysterious, which, at partic- 

 ular seasons of the year, teaches birds to take wing 

 and leave their native haunts, pursuing their onwar<l 

 course, sometimes across arms of the sea, over moun- 

 tains and forests, into far distant countries. It is 

 e(|ually surprising, that many of them, beginning 

 their migrations in summer, should thus anticipate 

 the cold ; while others return from Southern climes, 

 before the snows of the North have disappeared, and 

 whilst winter still "lingers in the lap of spring." * * 



Whatever difficulties there may be in accounting 

 for that mysterious principle called instinct, whicli 

 induces birds, at certain seasons, to change their 

 abode, and, after an interval of six months, to return 

 to the neighborhood where, the year before, they 

 reared their young ; the fact of these migrations is 

 nncontrovertible, and the reasons why they take 

 place are becoming more and more apparent. Those 

 birds that migrate, are from the very structure of 

 their bodies, admirably adapted to rapid and con- 

 tinued flight. Their feathers are so light, that they 

 float in the atmosphere for many hours with very 

 little artificial support. The tubes of these feathers 

 are hollow ; the bones are specifically lighter than 

 those of quadrupeds ; the bones, also, are hollow, 

 and instead of marrow, are filled with air. They 

 are furnished with lungs of an unusually large size 

 adhering to the ribs, and provided with aerial cells, 

 insinuating themselves into the abdomen. These, 

 added to great length and strength of wing, enable 

 them with ease and rapidity, to navigate the air — to 

 elevate themselves above the clouds, and pass from 

 one country and climate to another. * * From 

 a variety of accurate experiments, which have been 

 made at different periods, it appears that the 



