It had been a hard and exciting day and now, after a steaming hot supper, they were scattered about the old mill in comfort and utter relaxation. Some were smoking, others chatting, some mending their clothes, which in these days of strenuous work were often in need of repair, while one or two by the light of candles were writing letters to the folks at home. Billy, seated on a stool, was strumming a banjo which had been his solace many a time while he was stationed on the Mexican border and which now was doing duty in France. "Hit 'er up, Billy," said Bart, lazily. "We don't mind being miserable if it gives you any comfort." "Quit your knocking," grinned Billy. "You know you're just dying to hear it. What do you fellows want--the Moonlight Sonata or something else simple like that?" "That's too high class for this bunch," said Tom. "Though there's plenty of moonlight outside," he added, as he looked out the window. "I've had all the outside I want for one day," said Frank. "I'd just as soon stay where I am." He was penning a letter to his mother, telling her of many things that had happened, and stating that, so far, he had not had a chance to learn anything about his grandfather's estate. "Well, I'm waiting," said Billy. "What does the gang want? Jazz band music? That's about your style." "No, give us something that sounds like home," said Tom. "Some of those southern melodies." "Yes," urged Bart. "You're a dabster at that, Billy." "All right," said Billy, cheerfully. "Anything to oblige." He picked the strings for a moment and then began to sing softly-- "Swing low, sweet chariot Gwine for to ca'y me home Swing low, sweet chario--ot Gwine for to ca'y me home." _Bang!_ There was a tremendous explosion close to the mill. The air was filled with a deafening din. The boys jumped to their feet. "That hit mighty close!" cried Frank. "What do you suppose it was?" came from Tom. "A shell?" "We're too far away from the German lines for that," replied Bart. "More likely it's a bomb from an airship," said Frank. "Let's take a squint outside and see." They rushed out and their first glance was toward the sky. But there was nothing visible there, nor could they hear the whirring of motors that was the invariable accompaniment of air raids. But when they searched around the mill they were more successful, for the bright moonlight revealed a freshly dug hole in the ground that formed a veritable crater. "It was a bomb all right," pronounced Frank. "And from the size of the hole it made it was a lallapalooza. It's lucky it didn't hit the mill." "I guess some Hun aviator was flying back to his own lines and dropped this as a sort of visiting card," said Billy. "Oh, well, what's a little bit of bomb between friends? Come on back, fellows." "Yes, come along in and listen to Caruso," chaffed Tom. Once inside, Billy again picked up his banjo and began to croon.