Dew
2 of the 7 encyclopedias on this shelf carry an entry for Dew. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a quiet deposit of atmospheric water on the surface of the earth. The process of dew making may be seen quite frequently on the surface of a water pitcher. A pitcher of iced water, placed on the table on a hot summer day, is apt to gather moisture from the air. Dew making is closely connected with the theory of saturation. Hot air holds more moisture than cold air. If air has all the water it can hold, it is said to be saturated. If saturated air be cooled it deposits the water it cannot retain. The point of coolness at which air is unable to retain all its moisture is called the dew point. If the heated air around the ice pitcher be saturated, and the pitcher cools the adjacent air below what is called the dew point, the moisture which the air can no longer hold settles on the surface of the pitcher. During the summer season the earth cools off after nightfall, and then begins to absorb heat from the layer of saturated air lying next to it. If there be no wind to carry away the cooled air, it precipitates the water which it can no longer hold, and globules collect, not only on the surface of the earth, but especially on blades of grass or other vegetation, which cool much more rapidly than the earth itself. To understand the cooling of the earth, it must be kept in mind that the heat is radiated into space, not absorbed by the atmosphere. Clouds hovering over the earth's surface act like a blanket to catch this radiated heat and throw it back to the earth's surface again. For this reason dew forms chiefly on clear nights. The philosophy of dew making rests on the fact that the earth readily absorbs heat from the atmosphere, but gives it off into space, not into the adjacent air. See Frost; Rain ; Snow
Collier's New Encyclopedia (1921)
a deposition atmosphere on the surface of the earth of water from the in the form of minute globules. During the day the earth heat, but after sunset its supply of both absorbs and emits warmth is cut off, while it still continues to radiate heat into the surrounding space good radiators, lose after sunset the heat . Grass, flowers, and foliage being which has previously been absorbed by them, without hout receiving any in return, and their temperature consequently falls considerably below that of the atmosphere. here. From the substances the particles of vapor in the proximity of these cold adjoining air are condensed and deposited on their surfaces in the form of dew, or of hoar-frost where the temperature of the earth is below 32°. When the sky is clouded the heat abstracted from the earth's surface by radiation is restored by the clouds, which, being good radiators, send back an amount of heat equal to what they receive; and a balance of temperature being thus maintained between the earth and the surrounding atmosphere, no dew is formed. Horizontal surfaces, and those which are exposed to a wide expanse of sky, receive a greater supply of dew than sheltered or oblique surfaces, where circumstances diminish the amount of radiation. The radiation from the earth's surface is one of these happy provisions for the necessities of living beings with which nature everywhere abounds. The heavy dews which fall in tropical regions are in the highest degree beneficial to vegetation, which, but for this supply of moisture, would, in countries where scarcely any rain falls for months, be soon scorched and withered. In cold climates the earth, being cold and sufficiently moist, requires little dew; accordingly the clouds, which are so common in damp and chilly regions, prevent the radiation of heat; the surface is thus preserved warm, and the deposition of dew is, in a great measure, prevented.