Note: previous posts on this topic are *here* and *here*.

Motion flows. That is, there is always motion independent of us. We can also make standard motions that are effectively independent of us. They are called *clocks*. They can be used as standards of comparison to measure other motions.

Clocks are needed for synchronous measurement of motion. They can also be used for asynchronous measurement of motion, but simpler devices can be used for that, too. For example, a circular clock provides a standard angular motion to compare synchronously with another motion. The marked angles or circumferential lengths could be used for asynchronous measurement. So could protractors and rigid rods.

Clocks can have various units of measure. A *population clock* estimates current population growth (or its decline). Mechanical clocks use an escapement to count periods of standard motion. A *water clock* measures the flow of water in units of volume. An *hourglass* measures the flow of sand. A clock can be made from any regular motion that can be associated with or marked in units.

Thus clocks, or “flowkeeping devices,” are independent, standard movements to compare with other motions, either synchronously or asynchronously.

From common experience we know there are three dimensions of motion. These three dimensions of motion can be measured synchronously or asynchronously. Synchronous measurements measure time; asynchronous measurements measure space.

For every motion one can associate six measurements: three synchronous measurements and three asynchronous measurements. That is, there are three dimensions of time and three dimensions of space.

To associate motion with position or location one must sum or integrate motions. One takes an arbitrary starting point, an origin, and integrates motion in different dimensions to construct a coordinate system for positions. Asynchronous integration leads to spatial coordinates. Synchronous integration leads to temporal coordinates.