Sonorous Bodies. Those bodies which are capable of being put into a state of vibration, so as to emit sounds.
Specific Gravity. The relative weight of bodies of different species, when the same bulk of each is taken. Water has been chosen as the standard for comparison. If we say that the specific gravity of a body is 6, we mean, that its weight is six times as great as that of a portion of water, exactly equal to it in bulk.
Spectrum. That appearance of differently coloured rays, which is produced by the refraction of the solar ray, by means of a prism, is called the prismatic spectrum; it exhibits most distinctly, and beautifully, all the colours seen in the rainbow.
Sphere. A globe, or ball.
Spheroid. Spherical; a body approaching nearly to a sphere in its figure. The earth, is denominated an oblate spheroid; it not being an exact sphere, but flattened at the poles, so as to cause the polar diameter to be upwards of thirty miles less than the equatorial. Oblate, is the reverse of oblong, and means shorter in one direction, than in another.
Spring Tides. Those tides which occur at the time of new, or of full moon. The tides then rise to a greater height than at any other period.
Square. A figure having four sides of equal length, and its angles all right angles.
In numbers; the product of a number multiplied into itself; thus, the square of 3 is 9, and the square of 8 is 64.
Star. The fixed stars are so called, because they retain their relative situations; while the planets, by revolving in their orbits, appear to wander amongst the fixed stars.
Subtend. This term is applied to the measurement of an angle; when the lines by which it is bounded recede but little from each other, they are said to subtend; that is, to be contained under, a small angle.