Horizon
the visual circle of the firmament. The term "sensible," "visible," or "physical" horizon is often used, though not quite accurately, for a plane supposed to be extended from the observer's eye at right angles to a vertical line at the place and extending to the celestial vault. The horizon convensheaths inserted one into another, the innermost resting upon the vascular membrane covering the bony core. The tip is very dense, and the layers of which it is composed are scarcely distinguishable. This kind of horn appears to consist of coagulated albumen; and there is a regular connection between horns, nails, claws, hoofs, scales, hair, feathers, the principal ones used for manufacturing purposes; the horns of bulls and cows being preferred to those of buland even skin. The horns of oxen are locks, which are thin and of a coarse texture. The horns of goats and sheep are whiter and more transparent than those of any other animals.
In horn manufacture, the first process necessary is to remove the core which is forming bone ash, a substance valuable in making cupels for assaying purposes.
They are also used in other ways-for making glue, stiffening for cloth dresses, and for manure. The solid tip of the horn, after being sawn off, is used for making knife handles, umbrella handles, etc. After being divided into thin laminæ, the remainder of the horn is used for various purposes. Hoofs and horn cuttings are used for making prussiate of potash and prussian blue; and the clippings of the combmaker are used as manure. An artificial horn is made from the gelatine obtained from bones ient for astronomical purposes, and by muriatic acid, and converting it into called the astronomical, or rational horizon, is different from this. The spectator's eye is supposed to be, not at the surface, but at the center of the earth, with the planet transparent enough not to impede vision. In geology the term a horny substance by tanning.