It was an artificial leg, so cleverly and so artfully designed that it could hardly be told from a real one. Dr. Schmidt handed it to Larry. “Feel it,” he said, beaming, “it’s made of plastic and titanium. It doesn’t weigh very much.”

Larry hefted the incredibly real contraption. To the touch, it felt as if it were made of human flesh. Its lightness was due to its being made of titanium, a metal as strong as steel, but much lighter. Its upper portion carried a web strap-and-belt arrangement for attaching, to the thigh.

Larry peered into the hollow leg, Dr. Schmidt handed him a flashlight. There was a complex arrangement of levers and racks and Larry could see them move as he flexed the leg at the knee and at the foot.

“This is wonderful,” he breathed staring at it admiringly.

“Show him the brain, Doctor," Joanne interrupted, “That will really startle him!”

(Cybernetic Brain from 'The Cybernetic Brain')

Dr. Schmidt reached in the wooden box and brought out a metal chassis similar to a small radio. Mounted on it were several tubes, coils and transformers. It was not very impressive. He set it on his desk.

“Larry,” he said, now grave, “if this will do what I think it will, it will be the greatest invention of the time. It is an auxiliary brain!”

“ — and we fit this little electronic brain and amplifier in the hollow of the leg, connect its output to certain servo-motors and relays within the leg. Into the input of the brain we connect nerve-endings from your thigh! The power supply comes from built-in batteries and electric capacitor-accumulators. In the bottom of the foot-portion of the leg is mounted a pressure sensitive device which will help control the leg — which will tell the brain and your body, when you are, dividing the weight between the real leg and the artificial one.”

“Am I to understand,” Larry asked incredulously, “that you’re actually going to connect my nervous system to a mechanical amplifier?”

"[Dr. Clydestone] will bring out the desired nerve endings from the end of the stump. He’ll connect them through platinum wires to little cable connectors... to seven nerve-endings protruding from his flesh, terminating, in ordinary electrical connections!"

But it was not the leg itself which was the real impressive agent; rather it was the electronic brain and the servo-mechanisms servicing it. Servomechanisms were simply electric or hydraulic motors whose motion was precisely controlled from a distance by electronic means.

The leg was to function, in a way, as a servo-mechanism operated by Larry’s brain, through the mediation of the electronic brain in the leg. It might be said that the artificial leg was a robot. Larry laughed at the thought. He was going to be actually made up of part-man, part-robot when the leg was finally fitted to him. But it was better by far than using the crude prosthetic devices ordinarily employed.