“THE explanations of this morning account for the formation of clouds. A continual evaporation takes place on the surface of the damp earth as well as on the surface of the different sheets of water, lakes, ponds, marshes, streams, and above all the sea. The vapors formed rise into the air and remain invisible as long as the heat is sufficient. But since heat diminishes as the height increases, there comes a time when the vapors can no longer be kept in complete solution, and they condense into a mass of visible vapor, into a fog or cloud.

“When, after a chill encountered in the upper strata of the atmosphere, the cloud-mist reaches a certain degree of condensation, little drops of water form and fall in rain. At first very small, they increase in volume on the way by the union of other similar little drops. Their size on reaching us is proportioned to the height from which they fell, but never exceeds the limits suitable to the part rain is intended to play. If too large, the rain-drops would fall heavily on the plants they are to water, and would lay them flat on the ground, dead. And what would happen if the condensation of vapor, instead of taking place gradually, should be sudden? There would no longer descend from heaven rain-drops, but heavy columns of water, which, in their fall, would strip the trees of their branches, crush the harvests, and make the roofs of our houses fall in. But, far from taking this devastating form, rain falls in drops as if passed through a sieve placed by design in its passage to divide it and weaken the shock. On rare occasions, it is true, rain does reach us under so strange a disguise as to strike the ignorant with terror. Who would not be frightened when it rains blood or sulphur?”

“What do you say, Uncle?” interrupted Emile; “rains blood or sulphur? For my part, I should be dreadfully afraid.”

“I too,” said Claire.

“Is that true?” Jules asked, in his turn.

“True. You know well I only tell you true stories. There are rains of blood and sulphur, at least in appearance. It is proved that showers have been seen of which the drops left on the walls, roads, leaves of the trees, and clothes of passers-by, are red spots like blood. At other times, with the rain, there has fallen from the sky a fine dust, of a beautiful yellow, resembling sulphur. Did it really rain blood, sulphur? No. This so-called rain of blood or sulphur, causing foolish alarms, is ordinary rain stained with various sorts of dust raised from the ground by the wind. In the spring when, in mountainous countries, immense forests of fir-trees are in blossom, every breath of wind carries clouds of a fine yellow dust contained in the............