Sphere
in astronomy, a term formerly applied to any one of the concentric and eccentric revolving transparent shells in which the heavenly bodies were supposed to be fixed, and by which they were carried so as to produce their apparent motions. The word now signifies the vault of heaven, which to the eye seems the concave side of a hollow sphere, and on which the imaginary circles marking the positions of the equator, the ecliptic, etc., are supposed to be drawn. It is that po portion of limitless space which the eye is powerful enough to penetrate, and appears a hol hollow sphere because the capacity of the eye for distant vision is equal in every direction.
SPHEX its radius. It is also equivalent to twothirds of the volume of its circumscribing cylinder. The following formula gives the value of the volume of any sphere, whose radius is r and diameter is d: v= pr. Spheres are to one another as the cubes of their diameters. In logic, the extension of a general. conception; the individuals and species comprised in any general conception.
The doctrine of the sphere is the application of geometrical principles to geography and astronomy. An oblique sphere, or spherical projection, is the projection made on the plane of the horizon of any place not on the equator or at the poles.
SPHERICAL TRIGONOMETRY. See TRIGONOMETRY.