52 



harder to bend out of their plane, which is the 

 direction in which they have to encounter the 

 impulse and pressure of the air, and in which 

 their strength is wanted and put to the trial, 



This is one peculiarity in the structure of a 

 feather; a second is still more extraordinary. 

 Whoever examines a feather, cannot help taking 

 notice, that the threads or laminae of which we 

 have been speaking, in their natural state unite; 

 that their union is something more than the mere 

 apposition of loose surfaces; that they are not 

 separated without some degree of force; that, 

 nevertheless, there is no glutinous cohesion 

 between them ; that, therefore, by some mecha- 

 nical means or other, they catch or clasp among 

 themselves, thereby giving to the beard or vane 

 its closeness and compactness of texture. Nor 

 is this all : when two lamina?, which have been 

 separated by accident or force, are brought to- 

 gether again, they immediately re-clasp: the 

 connexion, whatever it was, is perfectly reco- 

 vered, and the beard of the feather becomes as 

 smooth and firm as if nothing had happened to 

 it. Draw your finger down the feather, which 

 is against the grain, and you break, probably, 

 the junction of some of the contiguous threads: 



