Manual controls - The Geochron has three simple control knobs. Two are located at the base of the unit and used primarily for the initial setting. One knob moves the map horizontally to set the time and day of the week and is also used to determine time of sunrise, sunset and the number of daylight hours at any location at a time other than current. The other knob sets the date indicator and light pattern. A third knob controls the minute dial located at the Geochron's upper right hand corner.

The Geochron map is reproduced in part from Chronoflexpositives of the U.S. Naval Oceanographic Chart #1262.

Legal time zone information is based on data from the U.S. Department of Defense Mapping, Time Zone Chart #76.

Delineation of the timezones and designs of the time scale are original with Geochron.

Recessed Mounting: The Geochron can also be recessed into the wall with special flush mounting brackets are supplied with the Boardroom model but must be ordered separately for other models. The recess opening required is 33 5/8" x 21 3/8" x4" for all models.

Installation instructions are supplied with each unit.

A switch at the base turns the lights on or off without disturbing the timing mechanism.