According to Mr. Locke, is "the measure of duration." "We acquire our notions of time," says Dr. Robison, "by our faculty of memory, in observing the succession of events. Time is conceived by us as unbounded, continuous, homogeneous, unchangeable in the order of its parts, and divisible without end. The boundaries between successive portions of time may be called instants, and minute portions of it may be called moments. Time is conceived as a proper quantity, made up of, and measured by, its own parts. In our actual measurements we employ some event, which we imagine always to require an equal time for its accomplishment; and this time is employed as a unit of time or duration, in the same manner as we employ a foot-rule as a unit of extension. As often as this event is accomplished during some observed operation, so often do we imagine that the time of the operation contains this unit. It is thus that we affirm that the time of a heavy body falling 144 feet is thrice as great as the time of falling 16 feet; because a pendulum, 39 1/2 inches long, makes three vibrations in the first case, and one in the last" There is an analogy," says our learned author, "between the affections of space and time, so obvious, that in most languages the same words are used to express the affections of both.
Hence it is that time may be represented by lines, and measured by motion; for uniform motion is the simplest succession of events that can be conceived." This further analogy also occurs between time and space, namely, that as in space all things are placed in the order of situation, so in time all events occur in the order of succession. (See Elements of Mechanical Philosophy, by John Robison, LL.D)., Vol. I.) Like place, time may also be distinguished into absolute and relative. Absolute time is time considered in itself, without any relation to bodies or their motions. Relative, or apparent time, is the sensible measure of any duration by means of motion. Time is also astronomical, or civil. Astronomical time is that of which the computation and measure depend solely on the motion of the heavenly bodies. Civil time is astronomical time modified, and accommodated to the purposes of civil life.