Suddenly the storm broke. The rain fell as if something had given way overhead. The wind tore across the stubble of roofs and spires; and through the wind, the rain, and the rolling clouds shot a weird, yellow-green sunlight. I had never seen a storm like it. Nor had the night-hawks. They seemed to be terrified, and left the sky immediately. One of them, alighting on the roof across the street, and creeping into the lee of a chimney, huddled there in sight of me until the wind was spent and a natural sunlight flooded the world of roofs and domes and spires. Then they were all awing once more, hawking for supper. Along with the hawking they got in a great deal of play, doing their tumbling and cloud-coasting over the roofs just as they do above the fields. Mounting by easy stages of half a dozen rapid strokes, catching flies by the way, and crying _peent-peent_, the acrobat climbs until I look a mere lump on the roof; then ceasing his whimpering _peent_, he turns on bowed wings and falls--shoots roofward with fearful speed. The chimneys! Quick! Quick he is. Just short of the roofs the taut wings flash a reverse, there is a lightning swoop, a startling hollow wind-sound, and the rushing bird is beating skyward again, hawking deliberately as before, and uttering again his peevish nasal cry. This single note, the only call he has besides a few squeaks, is far from a song; farther still is the empty-barrel-bung-hole sound made by the air in the rushing wings as the bird swoops in his fall. The night-hawk, alias "bull-bat," does not sing. What a name bull-bat would be for a singing bird! But a "voice" was never intended for the creature. Voice, beak, legs, head--everything but wings and maw was sacrificed for a mouth. What a mouth! The bird can almost swallow himself. Such a cleft in the head could never mean a song; it could never be utilized for anything but a fly-trap. We have use for fly-traps. We need some birds just to sit around, look pretty, and warble. We will pay them for it in cherries or in whatever they ask. But there is also a great need for birds that kill insects. And first among these are the night-hawks. They seem to have been designed for this sole purpose. Their end is to kill insects. They are more like machines than any other birds I know. The enormous mouth feeds an enormous stomach, and this, like a fire-box, makes the power that works the enormous wings. From a single maw have been taken eighteen hundred winged ants, to say nothing of the smaller fry that could not be identified and counted. But if he never caught an ant, never one of the fifth-story mosquitos that live and bite till Christmas, how greatly still my sky would need him! His flight is song enough. His cry and eery thunder are the very voice of the summer twilight to me. And as I watch him coasting in the evening dusk, that twilight often falls--over the roofs, as it used to fall for me over the fields and the quiet hollow woods.