The Bulbdial Clock has no hands, just one pole in the center of the clock.  Towards the outer rim we find three light sources of varying heights which revolve around the pole casting shadows on the dial.  As you can see in the above image, the light sources are each attached to special rings, which rotate around the pole.  There’s the innermost ring that rotates once per minute, analogous to a “second hand”.  Then follows the middle ring, which completes a rotation once per hour and casts the “minute hand” shadow.  Ultimately, the outer ring rotates once every 12 hours, casting the “hour hand” shadow.

Kinda neat….