“That was our school-house.  Now it is an office for the Prussians.  They have a battalion or more of infantry camped in the field across from the building.  They are a guard to keep us afraid.  Sometimes one will see three or four regiments camped further along on that field, either regiments going to the front or coming back for rest.  Now, from that building you turn and go in that direction”—–­Papa Prim made a motion with his crooked forefinger—–­“and so you come to four sheds that are easily missed in the night, for they are camouflaged so as not to attract the eye of French flyers in the day time.  From here it will be the first shed that you come to that is more likely to be open at night.  In each shed are two airplanes.  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.  “And are there anti-aircraft guns in the camp?” Tom asked.

“In the troop camp, so I have heard, but I have not seen them,” answered Papa Prim.

Removing his steel helmet and taking it in his left hand, Dick bent over, seizing Papa Prim’s hand.

“Good-bye for a little while, monsieur,” he said earnestly.  “We go away with hearts full of gratitude to your own fine, loyal heart.  May you prosper and be happy, with your children safely returned from Germany.  May all good things in life be with you.  Our thanks will always be with you, and our thoughts often of you, monsieur.”

Tom Reade took leave of Papa Prim in equally hearty and grateful words.

The two Americans watched the slim, bent old figure plodding homeward.  After looking the ground over critically, they stole forward on their way.