alternations -with ease, provided he be near enougli ; the wings 

 are never extended to their full length, the elbow-joint being 

 always more or less bent, and the hand or pinion always 

 inclined backwards." 



Of a feather's lightness, we may form some idea, when we 

 find that the largest qtiill of a golden eagle weighs only sixty- 

 five grains, and that seven such quiUs barely turn the beam 

 against a copper penny. The feathers of a common fowl, 

 weighing more than two poraids, weigh only two onnces ; and 

 the whole of an owl's plnmage weighs but one ounce and a 

 half. " Meant, as they are," says Bishop Stanley, " some for 

 covering and some for strength, we shall find them, on exami- 

 nation, very differently put together. The bight downy part, 

 when examined through a microscope, will be found to bear 

 little resemblance to the flat part, or blade of the qufll. If it 

 were not so, a bird would scarcely be able to fly at all; for 

 when the flat of the wing was pressed down, the air would 

 pass through it, yielding little or no resistance. The fibres of 

 the downy parts have, we see, little connection with each 

 other ; they have short and loose side shoots, just sufficient to 

 meet them together when pressed close to the skin; whereas 

 the side shoots of the quill-feather hook and grapple with one 

 another, so as to make one firm and united surface. It is 

 clear, that if water could soak into the soft feathery covering 

 of a bird, every shower of rain would be the death of thou- 

 sands ; inasmuch as it would increase their weight considerably, 

 and at the same time, by destroying the fine elastic nature of 

 the feathers, entirely disable them from flying, and they must 

 remain in a helpless state upon the ground, either to perish 

 through hunger or become the prey to men or animals, who 

 would catch them without trouble." 



The air bones in young birds are described as being filled with 

 marrow, which becomes gradually absorbed, to make room for 

 the admission of air. This gradual expansion of the air-cells 

 and absorption of the marrow can nowhere be observed so 

 well as in young tame geese, when killed in different periods of 

 the autumn and winter. The limits to the air-cells may be 

 clearly seen without, from the transparency of the bony walls. 

 From week to week the marrow disappears, and the air-vessels 

 increase in size, till, towards the close of the season, they 

 become transparent. 



" To give some idea of the duration and continuity of 

 motion in birds," says an English naturalist, " and likewise 



