"But where does the force come from?" I ventured to ask.
Mein Herr turned quickly round, to look at the new speaker. Then he took off his spectacles, and polished them, and looked at me again, in evident bewilderment. I could see he was thinkingas Indeed I was alsothat we must have met before.
"They use the force of gravity," he said. "It is a force known also in your country, I believe?"
"But that would need a railway going down-hill," the Earl remarked. "You ca'n't have all your railways going down-hill?"
"They all do," said Mein Herr.
"Not from both ends?"
"From both ends."
"Then I give it up!" said the Earl.
"Can you explain the process?" said Lady Muriel. "Without using that language, that I ca'n't speak fluently?"
"Easily," said Mein Herr. "Each railway is in a long tunnel, perfectly straight: so of course the middle of it is nearer the centre of the globe than the two ends: so every train
