Motion
Motion names 2 different subjects across the 6 encyclopedias on this shelf. Each is set out below.
Motion LAWS OF, three principles or axioms which were laid
Collier's New Encyclopedia (1921)
LAWS OF, three principles or axioms which were laid down by Sir Isaac Newton: (1) If a body be started in motion, and if no force act upon it, that body will continue in motion in the same direction, and with the same velocity. Of course this cannot be directly proved by observation, no one being able to start a body in a portion of the universe free from other bodies which will attract it, and if he could start it on in a vacant space, he could not watch its subsequent progress through infinite space and eternity. But the length of time during which tops will spin or finely mounted pendulums will go in the exhausted receiver of an air pump, can be accounted for in no other way than by supposing the truth of the first law of motion. (2) Change of motion is proportioned to the acting force, and takes place in the direction of the straight line in which the force acts. (3) To every action there is always an equal and contrary reaction; or, the mutual actions of any two bodies are always equal and oppositely directed in the same straight line.
Motion a movement. In art
Collier's New Encyclopedia (1921)
a movement. In art, the change of place or position which from certain attitudes a figure seems to be making. In law, an application made to a court of justice by the parties to an action or their counsel, to obtain some rule of order of court necessary to the progress of the action. In music: (1) The movement of a single part with reference to intervals taken by it. Conjunct motion takes place when the sounds move by single degrees of the scale, e. g., C, D, E, F; disjunct motion is when they move by skips, e. g., C, F, D, G. (2) The movement of two or more parts with relation to each other. Similar or direct motion is when parts move in the same direction either by single degrees or by skips; contrary motion is when parts move in opposite directions; oblique motion is when one part remains stationary while another moves. In watches and clocks, the train of wheels immediately concerned in the moving of the hands. Organic molecular motion, a kind of motion occurring in nearly all the internal processes in organic bodies. It must exist to produce absorption, secretion, etc.
What Has Changed in the Last Century
Newton's three laws, as Collier's set them out in 1921, are still taught in exactly that form and still govern every bridge, engine and rocket built since. What the entry does not mention is that Einstein had already redrawn their limits — special relativity in 1905 and general relativity in 1915 — so the laws are now understood as an excellent approximation that fails near the speed of light, in strong gravity, and at atomic scale, where quantum mechanics took over from the mid-1920s. One small vindication: Collier's argued the first law could never be watched directly, since no one could launch a body into empty space "and watch its subsequent progress". Voyager 1, launched in 1977 and coasting beyond the solar system with its engines silent, is about as close to that experiment as anyone will get.
Written for this edition, 2026.