Before doing so, let us gather together the sum of what has been said about the aqueous vapor of the air. We have learned that, as every sheet of water on the face of the globe evaporates, the air is full of vapor; that this vapor is condensed into visible form, and appears as dew, mist, and cloud. We have learned further, that the vapor of which clouds are formed is resolved into rain and snow, and, in one or other of these forms, descends to the earth again. There is thus a circulation of water between the solid earth beneath and the air above. This circulation is as essential to the earth in making it a fit habitation for living things, as the circulation of blood is in keeping our bodies alive. It mixes and washes the air, clearing away impurities, such as those which rise from the chimneys of a town. It moistens and quickens the soil, which it renders capable of supporting vegetation. It supplies springs, brooks, and rivers. In short, it is the very mainspring of all the life of the globe. So important a part of the machinery of the world deserves our careful consideration. Let us next attend, therefore, to what becomes of the rain and the snow after they have been discharged from the air upon the surface of the earth. [To be continued.] SUNDAY READINGS. SELECTED BY REV. J. H. VINCENT, D.D. [_October 7._] “TENDENCIES TO ERROR.” By REV. WILLIAM FRASER, LL.D. “Let no one, upon a weak conceit of sobriety or an ill-applied moderation, think or maintain that a man can search too far, or be too well studied in the book of God’s word, or in the book of God’s works—divinity or philosophy—but rather let men endeavor an endless progress or proficiency in both; only let them beware that they apply both to charity and not to arrogance; to use, and not to ostentation; and again, that they do not mingle or confound these learnings together.”—_Bacon._ Many have lost their early faith in the Bible and are following its guidance with faltering footstep. Between them and hitherto accepted truths the sciences have been placing apparently insurmountable obstacles. The trustful simplicity with which they once read the sacred record has almost perished. Inferences by the man of science, conflicting with the interpretations of scripture by the theologian, have rudely shaken their most cherished convictions. They are not infidels, they are not skeptics, for doubt is distasteful to them, they long for more definite expositions and a firmer faith.