An *odologe* (o′∙do∙loje) a constant-rate length-measuring device symmacronized with a common waypoint. It is a new coinage from the Greek *odo*(s), way/path + (horo)*loge*, clock. In short, it is a clock that shows length instead of time.

The simplest odologe takes time from a clock and multiplies it by a conversion speed to produce a length. This is commonly done in relativity with *c*, the speed of light: *ct* equals time multiplied by the speed of light, resulting in a length. A device which output such a length would be an odologe.

Given a starting point the Moon could be considered an odologe that travels at the rate of 3,683 kilometers per hour, since that is its speed around the Earth. The Earth itself could be considered an odologe that travels at its orbital rate of 107,000 km/h. Another odologe is the distance of the Pioneer 10 spacecraft from the Earth and Sun, which is tracked *here*.

A circular analog clock is also an odologe of the angle made by each hand, as below:

Each minute is represented by 1/60 of a 360° circle, or 6° of arc. Each hour is represented by 1/12 of a circle, or 30° of arc.

There are 24*60 = 1440 minutes in a day, which equates to 360 = 1440/4 degrees, so the apparent mean speed of the Sun along the ecliptic is one degree every four minutes. The Sun provides an approximate angular odologe.

A standard clock with hands “travels” at the rate of one revolution per hour or minute. A standard odologe “travels” as the rate of one revolution per meter. A standard odologe speed could be 1 m/s (3.6 kph).

A kind of virtual odologe comes from using the typical speed for a vehicle in a metropolitan area to convert travel time into travel distance. So, for example, one might estimate that a traveler has progressed 20 kilometers since they have been gone a half hour and the typical speed is 40 km/h.

Another virtual odologe is an app that displays an odometer that increases at a constant rate, as illustrated below.