Earths, a term applied in geology to certain loosely aggregated siliceous and aluminous materials, the detritus of pre-existing rocks. In chemistry the term earth is given to certain metallic oxides, such as the 'alkaline earths' lime, baryta, and strontia; also to alumina and a series known as the 'rare earths'. The earths were regarded as simple bodies until Sir H. Davy proved them to be compounds of oxygen with metals.
Earth-shine, in astronomy, a name given to the faint light visible on the part of the moon not directly illuminated by the sun, due to the illumination of that portion by the sunlight which the earth reflects on her. It is most conspicuous when the illuminated part of the disc is small, as soon after new moon. This phenomenon is popularly described as 'the old moon in the new moon's arms'.
Earth-tongue. See Geoglossum.
Earthworks (in fortification) are military works formed chiefly of earth and designed either as permanent or temporary defences. They are cheaper, more easily repaired, and expose their defenders to less risk from broken stone than stone-works. See Entrenchments.
Earthworm, the name applied to segmented worms (Annelids) that burrow in the soil, and belong to the ord. Oligochæta, a subdivision of the bristle-worms (Chætopoda). They have a long, cylindrical body, divided by transverse furrows into numerous rings. The mouth is destitute of jaws, and they have no eyes, tentacles, or other head appendages. They are hermaphrodite. The commonest British forms are chiefly species of Lumbricus and Allolobophora. They feed on earth and various kinds of animal and vegetable matter, and move by the contractions of successive parts of the body aided by a double row of bristles. They are of great service to the agriculturist by loosening the soil and increasing its depth. This is chiefly the result of their mode of nourishment, since they deposit the soil they have swallowed, after digestion, in heaps called worm castings which bring up rich fine soil to the surface, gradually covering the upper layer sometimes to the extent of several inches.
Ear-trumpet, an artificial instrument for aiding the collection of the vibrations or waves of sound, and carrying them in an intensified form to the internal parts of the ear. They are generally made of tin, vulcanite, or gutta-percha, and are of various forms. A small kind known as ear-cornets or acoustic auricles, attached to the ear by a spring, is sometimes used in slight cases of deafness.
Earwig (Forficŭla), a common orthopterous insect whose name is derived from its supposed habit of insinuating itself into the ears of persons. This is practically impossible, yet the notion is widely spread, as appears from the names given to the earwig in different languages, as in Fr. perceoreille (pierce-ear), in Ger. ohrenhöhler (ear-borer). Much damage is sustained by gardeners from the depredations of these insects among fruit and tender vegetables, which constitute their proper food. The earwig is about three-quarters of an inch in length, having the wings folded under very short and truncate elytra or wing-cases, and the extremity of the abdomen armed with a horny forceps.
Easement, in law, a right or privilege which one proprietor may have to use the land of another in connection with the needs of his own land, as the use of a way, a water-course, &c. The right to an easement may be acquired either
by grant or by uninterrupted enjoyment for a period of years.