Figure 3: Grey Walter Tortoise Elsie:
One of eight built, with phototube eye and two vacuum tube amplifiers
driving relays that controlled steering and drive motors. Elsie's
shell, removed for surgery, can be seen in the background. The tortoises
exhibited very lively behavior, for instance dancing near a lighted
recharging hutch until their battery ran low, then enter. Their
simple tropisms resemble bacterial "intelligence".