502 



TME MECHANICAL FUNCTIONS. 



encounter the resistance and impulse of the air. It 

 is here that strength is wanted, and it is here that 

 strength has been bestowed. 



On examining the assemblage of these laminated 

 filaments still more minutely, we find that they 

 appear to adhere to one another. As we cannot 

 perceive that they are united by any glutinous 

 matter, it is evident that their connexion must be 

 eifected by some mechanism invisible to the unas- 

 sisted eye. By the aid of the microscope the 

 mystery is unravelled, and we discover the presence 

 of a number of minute fibrils, arranged along the 

 margin of the laminae, and fitted to catch upon and 

 clasp one another, whenever the laminae are brought 

 within a certain distance. The fibrils of a feather 

 from the wing of a goose are represented magnified 

 at a, a, b, b, Fig. 226, as they arise from the two 



sides of the edges of each lamina. They are ex- 

 ceedingly numerous, above a thousand being con- 

 tained in the space of an inch ; and they are of 

 two kinds, each kind having a different form and 

 curvature. Those marked a, a, which arise from 

 the side next to the extremity of the feather, are 

 branched or tufted, and bend downwards ; while 



