Sir, do you know how they were used to fill balloons, and how they now do...

Sir, do you know how they were used to fill balloons, and how they now do it?"
"No," said Alverstoke. "I've no doubt, however, that I soon shall."
He was right. From then on Felix, who had acquired a tattered copy of the History and Practice of Aerostation, maintained a flow of conversation, largely informative, but interspersed with eager questions.