It was different from any that he had ever seen, but its leading principle, of course, was familiar to him.

At first it surprised him to find that it was supplied with power by weak batteries, which the Germans had ruined.
"You couldn't send more than twenty miles with those batteries!" he said to himself.
But when Vladimir returned that was explained.

For he removed a picture that hung on the wall and disclosed a number of wires.
"I do not understand," he said.

"But my master and Ivan have told me that those wires that you see run down to a place far below the cellar, where there is a great engine that moves when petrol is put into it--" "Oh, I see, a dynamo run by a Diesel engine, probably!" said Fred, suddenly enlightened.

"That's a fine idea! They can develop power without steam! Costs a lot--but it's worth it, of course! I'll just try that out!" Quickly he connected up the wires, tried out his key, after replacing the parts that had been taken away, and in a moment got a powerful spark.
"That's great!" he said, to himself, ignoring old Vladimir, who watched him in fascinated wonder.