"4. Heat is employed in the deoxidation of carbonic acid or other combinations of oxygen, and is evolved in combustion. While in the latent condition, heat may be kept without loss for an unlimited period of time or transported from equator to pole. By the various applications of these two general principles, all the different methods of equalizing temperature are determined. "I would have you remember also that these processes for transporting heat and modifying temperature are not confined to the regular changes of days and seasons and the permanent differences of zones, but apply to every possible difference of temperature. One minute the sun shines out in full splendor; the next, a cloud hides his face and cuts off his fervent beams; the methods employed to soften the heat of the one minute and the chill of the next are the same which equalize the temperature of the seasons. Evaporation carries off the heat from the seething tropics, evaporation carries off the excess of heat from the bodies of animals and men. The same methods are equally efficient upon the grandest and upon the smallest scale. "In this connection let me give one or two illustrations of the delicacy with which general principles adapt themselves to the minutest circumstances. When the earth is wet, it is fitting that evaporation should go on rapidly and remove the excess of water, but when the ground is drier, it is fitting that evaporation should be checked and the remaining moisture spared. This result is secured not merely by the lack of moisture at the surface, but also by the decreased capacity of the earth for absorbing heat. A dark color absorbs heat more readily than a lighter color, and the earth becomes, as a general rule, darker when wet; and lighter when dry. Moist earth, therefore, receives heat more readily than dry earth, and the excessive moisture is the more rapidly carried off by evaporation. "Another more interesting illustration is presented by the odor of flowers. In its place I told you that watery vapor hinders the radiation of heat from the earth. Dark heat is absorbed by it. The same is true of other gases, and also of the odors of fragrant substances. A bed of flowers fills the air around with odors. By these odors much of the heat radiated by the earth is stopped. By this means the air around the blooming flowers is warmed. The invisible fragrance raises the temperature and secures for the blooming plants a more genial atmosphere. The Lord provides for the flowers when most of all they need to be cherished by a congenial warmth.