[Illustration: _At Work in the Plaster Pit._] Men brick-makers nowadays bake their bricks in ovens called kilns, which are heated with fire. Eve and Petro let their brick bake, too, and the fire they used was the same one the Egyptians used in the days of Pharaoh--a fire that had never in all that time gone out, but had glowed steadily century after century, baking many bricks for folk and birds. Of course you know what fire that is, for you see it yourself every day that the sun shines. Every now and again Eve and Petro and all the rest of the swallow colony left off their brick-building and went on a hunting trip. They hunted high in the air and they hunted low over the meadow. They hunted afar off along the stream and they hunted near by in the barnyard. And all the game they caught they captured on the wing, and they ate it fresh at a gulp without pausing in their flight. As they sailed and swirled, they were good to watch, for a swallow's strong long wings bear him right gracefully. Why did they stop for the hunting flight? Perhaps they were hungry. Perhaps their mouths were tired of being hods for clay they could not eat. Perhaps the fresh plaster on the walls of their homes needed time to dry a bit before more was added. Be that as it may, they made the minutes count even while they rested from their building work. For they used this time getting their meals; and whenever they were doing that, they were working for the owner of the barn, paying their rent for the house-lot on the wall by catching grass insects over the meadow, and mosquitoes and horseflies and house-flies by the hundreds, and many another pest, too. [Illustration: _The Hunting Flight._] Ah, yes, there may be some reason for the belief that swallows bring good luck to men. I once heard of a farmer who said he didn't dare disturb these birds because of a superstition that, if he did, his cows wouldn't give so much milk. Well, maybe they wouldn't if all the flies a colony of swallows could catch were alive to pester his herd; for the happier and more comfortable these animals are, the healthier they are and the more milk they give. The hunting flights of Eve and Petro and their comrades lasted about fifteen minutes each time they took a recess from their building. After two days the nest was big enough, so that there was room for both swallows to build at once; and after that, Petro didn't have to fly around with his mouth full of plaster waiting for Eve to go if he chanced to come before she was through. They always chatted a bit and then went on with their work, placing their plaster carefully and bunting it smooth on the inside, modeling with clay a house as well suited to their needs as is the concrete mansion a human architect makes suited to the needs of man.