Many other examples might be given, but the above will be sufficient for our purpose. Records of this nature were discredited in former times; but more modern researches have long since placed their reality beyond all question. The fall of stones from the sky is no longer regarded as a mere legendary tale, but as one of the well-assured operations of nature. Meteoric stones and irons have been classified according to the ingredients of their composition. Those in which iron is found in considerable amount are termed siderites, those containing an admixture of iron and stone, siderolites, and those consisting almost entirely of stone are known as aerolites. The siderite which fell in Shropshire on April 20, 1876, forms only the seventh recorded instance where a mass of meteoric iron has been actually seen to fall. _Fireballs._—The table on p. 268 gives the dates, heights, &c. of fifteen fireballs observed during the last quarter of a century. Fireballs are sometimes detonating, though more often silent. The fireball of Nov. 23, 1877, gave a sound like salvoes of artillery, and doors and windows were shaken violently. At Chester the noise of its explosion was compared to loud but distant thunder. Lieut.-Col. Tupman says that “thunder, to be loud, must be within five miles; hence it appears that the violence of the explosion must have been at least a hundred times greater than a peal of thunder, the intensity of sound-waves diminishing as the square of the distance.” “The explosion of a 13-inch bomb-shell, consisting of some 200 lb. of iron, would not have produced a sound of one hundredth part of the intensity of the meteor-explosion.” This fireball must therefore have been an object of considerable mass before its dissolution; and it is fortunate that such bodies are usually destroyed by the effects of combustion before they reach the Earth’s surface. These phenomena exhibit many varieties of appearance.