“It would be something to say we had done it,” Pudge hastened to remark, showing the trend of his thoughts.

“Yes, we might as well take a look in, and see what the Germans are doing there,” Frank announced. “After which, with a swing around, we can set sail for the fighting line, pass over to ground which the British are holding, and then start for the coast at Dunkirk, and so complete the roundabout cruise.”

The seaplane passenger was staring at his native city through his glasses, muttering to himself in French. They could easily give a guess that these were far from blessings he was calling down on the heads of the Germans, who held on to everything they ran across so obstinately.

They were again made a target for numerous guns, but as Frank had risen to a somewhat higher level, they did not believe there was any chance of a stray missile doing any damage.

So they passed over Lille, and left the sorely stricken city behind them. M. Le Grande twisted himself halfway around, the better to see the last of the place where his heart lay.

It was just at this minute that Frank was heard to utter a cry, and manifest considerable consternation.

“What’s happened?” cried Billy, as quick as a flash; Pudge turned pale and glued his eyes on Frank’s face, which was to him a barometer.

“There’s a slackening up in the feed as though the pipe might be clogged!” exclaimed Frank, in considerable apprehension. “Billy, take a look and see about the amount of petrol we’ve got in the tank!”

Billy knew how to go about this; indeed, it was a part of his regular business.

He had hardly started to carry out Frank’s instructions before he shouted: