They are kept here for the purpose of sending up at night when French planes pass over to bomb railways or perhaps to bomb German towns.

When our own French airmen come then these airplanes shoot up into the sky and give battle.

But the Huns have lost twelve planes here in half that number of months," Papa Prim added proudly, "and only lately have enough new ones arrived from Germany to make up the eight required for this station." "Where do the airmen sleep ?" Dick interjected.
"In the camp with the troops; in the hangars there are no sleeping places." "And the hangars are at some distance from the troop camp ?" Tom asked.
"The troop camp begins over that way," Papa Prim continued, pointing, "for, as you will understand, there must be ground on which the airplanes may run before they rise.

So there is some distance.
I came near forgetting to tell you that, behind the hangars, are four tents in which the hangar guard sleeps." "And how many sentries at a time walk post around the hangars ?" Dick inquired.
"I do not know," confessed Papa Prim, "but I do not believe there are more than three or four sentries on duty at a time.

Of course, there are other sentries on post at the camp." "And airships leaving fly directly over the camp ?" Tom wanted to know.
"You have said truly," replied Papa Prim.