142 GRAY LADY AND THE BIRDS 
light, and get to Grandma’s for breakfast, when they’d 
written on a picture postal, with tea-cups and a cat on 
it, that she might expect them for supper.” 
When the laugh at Tommy’s comparison had sub- 
sided, Gray Lady said, “Your idea is by no means a 
foolish one, and it may be that a boy like you, who 
watches and thinks, will some day piece the facts to- 
gether that will finally settle the question.” 
How do Birds find their Way ? 
“How do the birds find their way over the hundreds 
or thousands of miles between the winter and summer 
homes? Sight is probably the chief guide of those who 
fly by day, and it is known that these day travellers 
seldom make the long single flights that are so common 
with the birds that journey at night. Sight, undoubtedly, 
also guides them, to a large extent, in the night journeys, 
when the moon is bright. Migrating birds fly high, so 
that one can hardly hear their faint twittering. But 
if the sky is obscured and the clouds hang low, the flocks 
keep nearer to the earth, and their calls are more dis- 
tinctly heard; while on very dark nights, the vibration 
of their wings can be heard close overhead. 
“ Notwithstanding this, something besides sight guides 
these travellers in the upper air. (Here is a route 
for you to trace on the map.) In Alaska, a few years 
ago, members of the Biological Survey on the Harriman 
expedition went by steamer from the island of Unalaska 
to Bogoslof Island, a distance of about sixty miles. A 
dense fog had shut out every object beyond a hundred 
