The bases of modern science / by J.W.N. Sullivan.

  • Sullivan, J. W. N. (John William Navin), 1886-1937.
Date:
[1939]
Catalogue details

Licence: In copyright

Credit: The bases of modern science / by J.W.N. Sullivan. Source: Wellcome Collection.

    41/260 (page 31)
    always numerically the same. For if the earth, for instance, moves, a space of our air, which relatively and in respect of the earth always remains the same, will at one time be one part of the absolute space into which the air passes ; at another time it will be another part of the same, and so, absolutely under¬ stood, it will be perpetually mutable. “ Place is a part of space which a body takes up, and is, according to the space, either absolute or relative. . . . “ Absolute motion is the translation of a body from one place into another ; and relative motion, the translation from one relative place into another. Thus in a ship under sail, the relative place of a body is that part of the ship which the body possesses ; or that part of its cavity which the body fills, and which therefore moves together with the ship : and relative rest is the continuance of the body in the same part of the ship, or its cavity. But real, absolute rest is the continuance of the body in the same part of that immovable space in which the ship itself, its cavity and all that it contains, is moved. Wherefore, if the earth is really at rest, the body, which relatively rests in the ship, will really and absolutely move with the same velocity which the ship has on the earth. But if the earth also moves, the true and absolute motion of the body will arise, partly from the true motion of the earth in immovable space ; partly from the relative motion of the ship on the earth ; and if the body moves also relatively in the ship, its true motion will arise, partly from the true motion of the earth in immovable space, and