2 BIRDS THROUGH AN OPERA-GLASS. 
down the scale. Others are only monotonous 
trills, always the same two notes, varying only in 
length and intensity, such as that of the chipping 
bird, who makes one’s ears fairly ache as he sits 
in the sun and trills to himself, like a complacent 
prima donna. Then there is always plenty of gos- 
siping going on, chippering and chattering that 
does not rise to the dignity of song, though it adds 
to the general jumble of sounds; but this should 
be ignored at first, and only the loud songs lis- 
tened for. When the trill and the elaborate song 
are once contrasted, other distinctions are easily 
made. The ear then catches the quality of songs. 
On the right the plaintive note of the meadow- 
lark is heard, while out of the grass at the left 
comes the rollicking song of the bobolink. 
Having begun sorting sounds, you naturally 
eroup sights, and so find yourself parceling out 
the birds by size and color. As the robin is a 
well-known bird, he serves as a convenient unit 
of measure —an ornithological foot. If you call 
anything from a humming-bird to a robin small, 
and from a robin to a crow large, you have a 
practical division line, of use in getting your 
bearings. And the moment you give heed to col- 
ors, the birds will no longer look alike. To sim- 
plify matters, the bluebird, the oriole with his 
orange and black coat, the scarlet tanager with 
his flaming plumage, and all the other bright birds 
can be classed together; while the sparrows, fly- 
