CHAPTER IV.
THE BUILDING OF A BIRD It rained on Wednesday--a warm spring rain, swelling the rivers and ponds, and watering the newly planted garden; but discouraging the birds in their nest-building, and disappointing Nat and Dodo, who wished to have their lesson in the orchard.
"Come in here, children," said the Doctor.

"The wonder room, as Dodo calls it, is a good place for a talk about feathers and bones, and the rest of the things birds are built of.

I have sent for Rap, too, so that the trio may be complete." "Feathers and bones for building birds ?" said Nat.

"What a queer idea for a bird story." "Not a bird story exactly," answered the Doctor.

"But some things are true of all birds, and you must know them if you wish to understand the _reason why_ of any bird in particular." In a few minutes the three children were seated on the wide settle, with a cheery log fire, to make them forget the outside dampness.