"There's no line there," replied Kenneth. "The only line shown on the map is the one running through the village almost due east; it turns to the north-east after cutting the German lines. It must be a good three or four miles from here. That sound went right across our front, from south to north, and couldn't have been more than half a mile away."
"Well, it's stopped now. We needn't bother about it. Quite certainly it wasn't made by the guns, and that's the only riddle we're called on to solve. I'm fed up with this, Ken."
"So am I. The idea of a whole day here is sickening. Still, it can't be helped."
They sat down again, each thinking his own thoughts.
Suddenly there was a momentary flash, instantly followed by a terrific roar.
"The gun!" exclaimed Kenneth, springing up.
"And jolly close, too," said Harry, looking across the fields. "Which side of us?"
"I don't know. We must wait for the next. This is getting exciting."
Within a minute or two they saw the flash again, lighting up the sky behind a low ridge on their left front. The noise of the discharge reverberated and died away.
"Come on!" whispered Kenneth.