49.—Velocity diagram in horizontal section of a cyclone 398 50.—Funnel-like cloud sometimes observed in a tornado 409 51.—Vertical section of the St. Louis, Mo., tornado of May 27, 1896 411 52.—Horizontal section of St. Louis tornado of May 27, 1896 412 53.—Vertical section of short tornado 414 54.—Vertical section of a tall tornado 415 55.—Vertical section of a hail tornado 417 56.—Universal anemograph 428 57.—Records of wind variation in horizontal and vertical direction 429 58.—Records of Wind speed obtained by Langley 433 INTRODUCTION INTRODUCTION FANCY AND FOLK-LORE Of silver wings he took a shining pair, Fringed with gold, unwearied, nimble, swift; With these he parts the winds, the clouds, the air, And over seas and earth himself doth lift. Thus clad he cuts the spheres and circles fair, And the pure skies with sacred feathers clift; On Lebanon at first his feet he set And shook his wings with rosy may-dews wet. TASSO, CANTO I, XIV. How beautiful! May we hope ever to journey thus, on wings actuated by human power? It is an old question, once dear to the philosopher and fool alike, but now important mainly to the fool. Or say more kindly it is the affair of untechnical inventors—the amateur, the rustic, the man of chimerical dreams. For the wise aëronaut now numbers that project among the roseate illusions of his youth.[1] Ovid relates a story, doubtless credible in his day, of a clever craftsman who with his son flew bravely aloft, the very first time they put on wings. Daedalus, a Greek architect, having fled from Athens for murder, went with his son Icarus to the island of Crete, where he built the celebrated labyrinth for Minos, the king. He offended that monarch and was cast into prison. In order to escape he made wings for himself and his son, with which they flew far over the sea. But Icarus, in his elation, soared too near the sun, ruined his wings, fell into the sea and was drowned. For proof of this we have the Icarian Sea, named after the unfortunate boy. Also we have Ovid’s charming poem: