A Slide Rule was a gadget used back in the 50’s and was basically an old fashioned calculator which you slide the rulers around to work out complex equations. The Slide Rule clock is basically a modern version of the slide rule that is now used to tell the time.

Greg Blonder was the creator of this device (he holds over 70 patents). The device is powered by LEGO Mindstorms programmable bricks and is constructed of foamcore.

The base of the clock was constructed from standard LEGOs, encasing two mindstorm servo motors. At the corners of the base are four switches, used to support the “slider”. By pressing the corners of the slider its possible to set the hours and minutes.

Each scale measures 2″ X 18″. The clock is DC powered and time can be set by tapping the sides of the rulers to move up and down the hours and minutes.

A modern,sliding clock: [via]