Yes; provided the wind be unattended with clouds, for these accumulations of moisture not only prevent the free radiation of the earth towards the upper regions, but themselves radiate towards the earth; under these circumstances much less dew is formed than on fine clear nights, when the radiation of the earth passes without obstacle through the atmosphere to the distant regions of space, whence it receives no caloric in exchange. The dew continues to be deposited during the night, and is generally most abundant towards morning, when the contrast between the temperature of the earth and that of the air is greatest. After sunrise the equilibrium of temperature between these two bodies is gradually restored by the solar rays passing freely through the atmosphere to the earth; and later in the morning the temperature of the earth gains the ascendency, and gives out caloric to the air by contact, in the same manner as it receives it from the air during the night. --Can you tell me, now, why a bottle of wine taken fresh from the cellar (in summer particularly), will soon be covered with dew; and even the glasses into which the wine is poured will be moistened with a similar vapour? EMILY. The bottle being colder than the surrounding air, must absorb caloric from it; the moisture therefore which that air contained becomes visible, and forms the dew which is deposited on the bottle. MRS. B. Very well, Emily. Now, Caroline, can you inform me why, in a warm room, or close carriage, the contrary effect takes place; that is to say, that the inside of the windows is covered with vapour? CAROLINE. I have heard that it proceeds from the breath of those within the room or the carriage; and I suppose it is occasioned by the windows which, being colder than the breath, deprive it of part of its caloric, and by this means convert it into watery vapour. MRS. B. You have both explained it extremely well. Bodies attract dew in proportion as they are good radiators of caloric, as it is this quality which reduces their temperature below that of the atmosphere; hence we find that little or no dew is deposited on rocks, sand, water; while grass and living vegetables, to which it is so highly beneficial, attract it in abundance--another remarkable instance of the wise and bountiful dispensations of Providence. EMILY. And we may again observe it in the abundance of dew in summer, and in hot climates, when its cooling effects are so much required; but I do not understand what natural cause increases the dew in hot weather? MRS. B.