[ J 99 ] 



They never pafs, however, at this time, from point to point, but 

 only tumble in the air, merely for their diversion. 



It feems, therefore, that birds are by no means calculated for 

 flights acrofs oceans, for which they have no previous practice : 

 and they are, in fact, always fo fatigued, that, when they meet 

 a (hip at fea, they forget all apprehenfions, and deliver themfelves 

 up to the failors. 



Let us now confider another objection to the migration of the 

 fwallow, which Monf de BufFon fuppofes may crofs the Atlantic 

 to the Line in eight days z ; and this is not only from the want of 

 reft, but of food, during the paflage. 



A fwallow, indeed, feeds on the wing ; but where is it to find 

 any infects, whilff. it is flying over a wide expanfe of fea ? This 

 bird, therefore, if it ever attempted fo adventurous a paflage, 

 v would foon feel a want of food, and return again to land, where 

 it had met with a conftant fupply from minute to minute. 



I am aware it may be here objected, that the fwallow leaves us 

 on the approach of winter, when foon no flying infects can be 

 procured : but I fhall hereafter endeavour to fhew, mat feme fpe- 

 cies of thefe birds are then torpid, and, confequently, can want no 

 fuch food. 



Another objection remains to the hypothefis o Emigration, which 

 is, that birds, when flying from point to point, endeavour always 

 to have the wind againfr them % as is periodically experienced by 

 the London bird-catchers in March and October, when they lay 

 their nets for ringing birds b . 



z Difcours fur la nature des oifeaux, p. 32. 



a Kalm, in his voyage to America, makes the fame observation, with 

 regard to flying fifh ; and Valentine fays, that if the wind does not con- 

 tinue to blow againfl the bird of paradife, it immediately drops to the 

 "round. 



Thefe birds, as it mould feem, are then in motion ; becauie, at thofe 

 - fcafons, the ground is plowed either for the winter or lent corn. 



' ' 4 Let 



