Measurement by motion

Traditional expressions and units are often associated with motions. For example, English farmers used the distance and area of land that their animals could plow for units of measure:

A furlong was the length of a plowed furrow, i.e. furrow-long. An acre was the area that could normally be plowed by an ox in a single day. An oxgate was the area an ox would plow over a whole year, equal to 15 acres. A virgate was the area two oxen could plow over a year, 30 acres. A carucate was the area eight oxen could plow over a year, 120 acres.

Nowadays there are a variety of idioms that express measures, for example:

Distance: a stone’s throw away, as far as the eye can see, room to swing a cat, within hailing distance, within striking distance, within spitting distance, within walking distance.

Duration: before you can say Jack Robinson, before you can snap your fingers, in the blink of an eye, once in a blue moon.

Measurement in science and engineering requires standard units, which are calibrated with standard procedures, which are used in standard methods of measurement. For example, the meter is the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second. The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. See for example the National Institute of Standards and Technology.

Motion is the basis of measurement. So it is appropriate to begin with motion and reference space and time to motion.