GLOBES. A globe is a round or spherical body (see SPHERE), and in the singular number the word is often used to signify the earth, as in the phrase, "the terraqueous globe ;" but by "globes," or " the globes," we usually mean a pair of artificial globes used as a part of school-room apparatus. These globes are hollow spheres of card-board, coated with a composition of whiting, glue, and oil, upon which paper bearing certain delineations is laid. On one of the pair—the celestial globe—are represented the stars, so placed that, to an eye supposed to observe them from the center of the globe, their relative position and distance correspond to those actually observed; while on the terres trial globe, the distribution of land and water, the divisions and subdivisions of the former, together with a few of the anost important places, are laid down in the positions corresponding to those which they actually occupy on the surface of the earth.
The usual of manufacture is as follows: A ball of wood or iron is used as a matrix, and a layer of damped paper is carefully and closely placed upon this, without paste, and other layers are successively pasted over the first one; ordinary card-board is thus produced, but instead of being ilat, as usual, it forms a spherical shell. When sufficiently thick, this is cut into two hemispheres, the section being made in the line of the intended equator. The hemispheres are then taken off the matrix, and again glued together on an axis, and the whiting composition laid on, the outside of which is smoothed and finished to shape in a lathe. The workman has to lay on this composi tion so as to balance the globe, in order that it may rest at whatever point it is turned. The smooth surface is now marked with the lines of latitude and longitude, and is cov ered with the-paper on which the)required geographical or astronomical delineations are engraved. In order to adapt the plane surface of the paper to the curvature of the sphere, it is printed in pieces, small circles for the Arctic and Antarctic regions, and the rest in lens-shaped gores, varying from 20° to 30° of longitude, and meeting these circles which are pasted first. Great care is required in laying on these curved pieces, so that their edges shall meet exactly without overlapping. The surface is then colored, and
strongly varnished, and mounted in its frame anestand.
Globes of india-rubber and gutta-percha have also been made, others of thin paper, to be inflated and suspended in a schOol-room. Betts's paper globes fold up when not in use. Embossed globes show, in exaggerated relief, the elevations and depressions of the earth's surface. Compound globes, including the celestial and terrestrial, are made with an outer glass sphere for the celestial, and orrery mechanism to show the varying relative positions of the sun and moon, etc. As school-room apparatus, globes are used for the purpose of illustrating the form and motion of the earth, the position and apparent motion of the fixed stars, and for the mechanical solution of a number of problems in geography' and practical astronomy. For this purpose, each globe is sus pended in a brass ring of somewhat greater diameter, by means of two pins exactly opposite to each other—these pins forming the extremities of the axis round which it revolves, or the north and south poles. This brass circle is then let into a horiZontal ring of wood, supported on a stand, as represented in the article ARMILLARY SPHERE; in which the lines drawn on the surface of globes are also explained. The globes in con mon use in schools are 12 in. in diameter; those found in private libraries are more frequently 18 inches.
The problems to which the globes are applied are such as: To find when a star rises, sets, or comes to the meridian on a given day at a given place. The mode of solution will be found in any school-book on the subject. The answers obtained in this way to such questions are only very rough approximations, and are in themselves of little or no value. But the "use of the globes," as it is called, serves the purpose of making evident to the senses how many of the appearances connected with the motions of the earth and the heavenly bodies are caused, and enabling the nature of the problems connected with these appearances to be clearly conceived. It is only by trigonomet rical calculation that the accurate solutions can be obtained.