"I've got a lot of old nests that fell down the chimney after a storm last winter that wet the glue and made them come unstuck," said Joe; "and I'll give you each one. If you look up the hole where the kitchen fireplace was, you can see the new nests quite plain; for the birds don't build them very near the top." "Be careful of loose stones!" called the Doctor; but in a flash four young heads had disappeared in the ruins of the great fireplace, where three pairs of trousers and a short brown linen skirt alone were visible. In a little while they had some milk and strawberries; and before they drove on Joe's father promised to take him up to Orchard Farm to see the birds in the Doctor's wonder room, as soon as haying should be over. To the children's astonishment they found it was half-past six o'clock; they had been at the farm an hour and a half, and could not stop again until they reached the wood lane where their uncle had promised to look for the Pewee's nest. "Stay here, little people, and ask all the questions you like of Olive," said the Doctor, when they had reached the lane; "for I shall be able to find the nest more easily if you do not frighten the birds by talking." "Pewee, pewee, pe-e-er!" cried a little voice. "There he is, crying 'peek-a-boo' again," said Dodo. "Please, Olive, won't you tell us the table for the Chimney Swift now?" "Certainly; and there is plenty of light yet if you wish to write it down." The Chimney Swift Length five and a half inches. Sooty brown. Sharply pointed tail-feathers. A Summer Citizen of eastern North America from Florida to the Fur Countries. An excellent neighbor--a friend of the farmer and his cattle. An officer in the guild of Sky Sweepers, who shoots through the air in the shape of a bow and arrow. "Come softly," said the Doctor, returning to the roadside; "I have found the Pewee's nest; it is quite new, and has no eggs in it as yet. This way--up along this ledge of rocks, and you can almost look into it." They moved quietly over the rocks until they reached a pepperidge tree, when the Doctor motioned them to stop and pointed to one of its branches which stretched over the rock. There was a flat nest with an evenly rounded edge, all covered with lichen scales outside. "It is just like a Hummingbird's nest," whispered Nat. "Only flatter, more like a saucer than a cup," said Rap. "Is it made of plant-down, too?" "No--of fine grasses, rootlets, and bits of bark," said the Doctor; "and in a few days it will hold three or four creamy-white eggs, prettily wreathed around one end with dark-brown spots." "Pewee, pewee, pe-e-er!" cried the nest owner very sadly. "We are going home, so you needn't worry, dear," said Dodo. "Good-night." CHAPTER XXII TWO WINGED MYSTERIES THE NIGHTHAWK