Apochrometer

An Apochrometer is a common mechanical device used in New Age aerial navigation. It is used to provide easily readable and adjustable speed-time estimates.

Workings

The Apochrometer has a main display of digits. Each base has a button that increments that digit; ie. units, tens, hundreds, thousands etc (most devices will display at least six figures). On one side is a dial for setting speed that determines rate of change per minute. The other side typically has a three-position switch for increment / stop / decrement. Once this switch is engaged either up or down, the digits will increment/decrement at the rate chosen.

Updating of the dial allows real-time adjustment of the estimate.