" LIGHT AS A FEATHER." 399 



The lightness of feathers has become proverbial. 

 No structure of human fabrication can be com- 

 pared to them. The entire plumage of an owl 

 frequently does not exceed one ounce and-a-half. 

 The very largest feathers are extremely light. It 

 is said that the largest feathers of a golden eagle 

 do not exceed one drachm and five grains in 

 weight, seven of them weighing not quite so much 

 as a five-shilling piece. Yet, if we attempt to do 

 violence to this light object, we shall find that it 

 is fully as remarkable for its stiffness and strength 

 as it is for its lightness. How manifestly both 

 these properties are required in structures forming 

 a part of the apparatus of flight ! Feathers, how- 

 ever, differ greatly in different birds, in their 

 compactness, &c. ; and this difference is rendered 

 necessary by the different habits of birds. Some 

 are ever on the wing; these must have the feathers 

 best suited for that, some are ever on the ground, 

 or only fly occasionally; the feathers of these birds 

 are looser and less resisting than those of the for- 

 mer. We have a remarkable contrast in the 

 compactness of feathers, if we place the quill- 

 feather of a swallow's wing by the side of the 

 gaily-adorned feather of a peacock's tail. 



