BIRDS. 
25 
BIRDS.— I. 
1. On the day next appointed, William and Arthur 
went to Mr. Johnson’s house, and found that gentle- 
man quite ready to receive them. 
2 . Leading the boys to a room in which he had a 
number of stuffed birds, he said: “ I call these my 
feathered friends. Birds, you know, are the only 
creatures that have feathers for a covering, though 
that is not the only guide we have in placing them 
in their class. We distinguish them from other 
animals by their general shape, which so well fits 
them for flight through the air, by their horny 
beaks, and by their wings. There are other points, 
not so easily noticed, in which birds agree, as I shall 
presently explain. 
3. “ Unless you trace very carefully the bones in a 
bird’s leg, you may make the mistake of thinking 
that the foot is that part which rests on the ground, 
or grasps the branches of trees. The fact is, a bird 
walks entirely on its toes, and the bones belonging 
to the foot extend up to the first joint, which is 
about half way between the ground and the bird’s 
body. Above that joint you may trace the two 
portions of the leg. You will find that the thigh is 
very short, so that the knee is high up near the 
body and mostly hidden in the feathers. 
4. “ Like Mammals, Birds have a four- chambered 
heart, red warm blood, and lungs for breathing. 
