The ice had melted there to such an extent that only a thin glaze covered the surface. Through this transparent covering Frank Sheldon caught sight of what seemed to be the outline of a door covered with gravel that only partially concealed it. He thought he saw something too that faintly resembled an iron ring.

"A trap door!" he muttered under his breath, jubilant in the thought that he had perhaps fallen upon a clue to the mystery that had so long perplexed him.

He took out his knife and began to dig down toward the ring, when a low whistle from the opening to the alley warned him to be on the alert. Instantly the light was extinguished and the next moment Bart was at his side.

"Better let up, Frank," he whispered. "There's a big commotion down the street and a crowd is beginning to gather. I think it's a fire."

As he spoke, a fire engine clanged down the street and an increasingly red light made itself apparent in the sky.

"Too bad," grumbled Frank, as he put his flashlight back into his pocket "I think I was just on the verge of finding out something that would put us on the track of those fellows who seemed to vanish into thin air."

"Hard luck," murmured Bart, sympathetically, "but well have to give it up for the present."

Frank hesitated, but the increasing glare that made the alley visible and the sound of footsteps of people hurrying to the fire showed him that his friend was right, and he reluctantly desisted.

"To-morrow's a new day," said Bart consolingly, as the comrades stole out of the alley and mingled with the groups of pa.s.sers-by.

"If Tom and Billy can tear themselves away from the girls, we'll bring them with us the first chance we get and try to clear up the whole mystery," observed Frank.

But this proved more difficult than they expected, and many days were to pa.s.s before their discovery could be followed up. There was a sudden tightening of the military regulations, which the boys attributed in part at least to the revelations that had followed the examination of their prisoners. A rigorous system of drill and training was put in force and the Army Boys' hours of liberty were greatly curtailed in consequence. They were kept more closely to their barracks, and their visits to the town except in the line of duty became few and far between.

The day following Frank's discovery that company of the old Thirty-seventh to which the boys belonged was sent on a long hike in full marching equipment, and when they returned after several hours they were, as Tom expressed it, "dog-tired." Nor were they pleased to find that in the interval their quarters had been changed and they had been a.s.signed to another part of the barracks.

It was with sighs of relief that they eased their heavy packs from their shoulders and dropped them thumping to the floor.

"Gosh!" exclaimed Billy, "I don't mind carrying a pack that weighs sixty pounds or even eighty; but after a time this pack of mine gets to weigh about two tons, and that seems just a little bit too much."

"You told a whole bookful that time," said Tom ruefully. "It is surprising how those packs keep getting heavier all the time.

Another half mile, and I think the straps would have been through my shoulders altogether."

"Well, there's no use worrying about what might have happened,"

laughed Frank, "seeing that we've arrived safe and sound. While we're in barracks we'll be able to get three square meals a day, and that appeals to me more, even, than getting rid of the old pack."

Frank had hardly finished speaking when an officer approached and called: "Attention!" Then followed roll call, and the boys, together with a number of their comrades, were a.s.signed to a barracks next but one to that in which they had stopped. This, of course, necessitated shouldering the heavy packs once more, but by this time the boys had come to expect things like this, so took it all as a matter of course, and soon found themselves in the quarters that were to be theirs until the order came once more to march.

The barracks was furnished with rows of army cots, and the boys dropped their packs at the heads of those a.s.signed to them. Then began the task of unpacking, and by the time that was completed it was almost time for mess.

"It's lucky we got our mess kits out before mess call blew,"

commented Tom. "It would be an awful thing to get caught without them around meal time."

"Not much danger of that," said Billy, with a mischievous twinkle in his eye. "We've been in the army quite some time now, Tom, and yet I can't call to mind a single time when you weren't Johnny on the spot when the bugle blew for eats."

"Say, don't you two fellows go to starting an argument along those lines," interrupted Bart. "When it comes to being chow hounds, I think we're all tarred with the same brush. None of us has ever got a call from the mess sergeant for not being on time."

"Well, perhaps you're right," admitted Tom laughingly. "And when you get right down to it, the whole of this man's army seems to be about the same way, so that leaves nothing for us to argue about."

Mess kits in hand, they all trooped down to the kitchen and took their places on the line that already was of sizable length. They wound slowly past the cooks, and in course of time the four friends were served and fell to on a savory plate of substantial food.

For a short time conversation ceased, the boys giving their whole- hearted attention to the entertainment that Uncle Sam had provided. The food disappeared with astonishing rapidity, and when the last of it was gone Billy exclaimed:

"Fellows, we can kick all we want to over army life, but I never had such an appet.i.te in civilian life, and never felt half as good as I do right this minute."

"All right, then, since you like it," grinned Frank, "to-morrow I'll let you carry my pack as well as your own, and then you'll feel just twice as good as you do now."

"No, thanks," declined Billy. "I don't want to feel any better than I do now. If I felt any better, I'd go to the medical officer to find out what was wrong with me."

"If you ate much more, you'd have a quartermaster officer coming around to find out what was the matter with you," countered Tom.

"The trouble with you is, that you don't understand my motives,"

complained Billy. "Personally, I dislike food, and, if I had my way, would make a canary bird look like a heavy eater. But I feel that it's my duty to eat a lot so that I can keep up my strength and continue to be a terror to all Germans. Uncle Sam expects this of me, and I refuse to disappoint him."

"Oh, well, if that's your motive, it's all right," said Tom, with mock gravity. "But seeing you in action, it looked to me as though you really enjoyed your grub. I hope you'll excuse my mistake."

"Oh, that's all right, please don't mention it," said Billy, with a magnanimous wave of his hand. "I've known others to make the same mistake, but, believe me or not, they don't always accept my statements as you do, when I explain the true state of affairs to them."

"Some people are hard to convince, I suppose," replied Tom, "but I guess I'm one of the easy ones."

"It's easier for both of you to talk than to wash mess gear apparently," said Frank, "What do you say to canning some of that brilliant repartee so that we can get these things out of the way and have time for a little something else before taps blow?"

"Suits me," acquiesced Billy. "But it surely does make me feel bad to have people think I really like to eat, and I can't seem to rest easy until I set them right. But now, let's get these things cleaned up in a little less than no time."

It did not take long for the boys to get their mess kits cleaned and out of the way, and then they found themselves with a couple of hours to spend exactly as they pleased.

"Might as well wander over toward the canteen and see what's doing," suggested Frank, and as none of the others had anything better to propose, they acted accordingly.

At the canteen all was life, bustle and activity, one line always going in to purchase tobacco, candy, and such other little comforts as were on sale, and another coming out in possession of these valued commodities. It was hard to realize that all these men were tried and seasoned fighters, ready to "go and get the Hun at the drop of a hat."

"What's doing in the way of a camp entertainment to-night?" asked Frank of one burly doughboy, who was contentedly munching a huge piece of cake.

"I understand there's going to be a movie show," replied the latter. "They generally have pretty good reels too, so I'd advise you not to miss it."

"Much obliged," said Frank. "Guess we might as well take it in, fellows, what do you say?" turning to his companions.

"Sure thing," they a.s.sented, and accordingly made their way to a brightly lighted tent, toward which many others were going. They arrived there only a short time before the show was to start, and having secured good seats, settled down to enjoy it.

The scene of the picture was in the West, when it was still "wild and woolly," and depicted many encounters between settlers and Indians. These fights were the subject of much criticism by the expert audience, who did not hesitate to shout words of advice at critical situations.

"Gosh!" growled one doughboy, in deep disgust, "just one machine gun would have cleaned up that bunch of redskins in less time than it takes a Hun to say _'kamerad'_"

"Yes, or a few good hand grenades would have done their business for them, too," said another. "It's too bad the old timers didn't have a few of those modern playthings along. It would have made things a whole lot easier for them."

"What would have been the matter with a few tankfuls of poison gas?" suggested Bart. "Seems to me that would have made them curl up and quit pretty quick."

There were other suggestions of the same nature, and when the picture finally came to a close there was a general impression that such warfare was mild indeed compared to that of the present day.

"I don't know how you fellows feel," remarked Frank, as they filed out of the tent and started for their barracks, "but I feel tired enough to crawl into my little two by four and get a real night's sleep."

"I'm with you," declared Tom. "I felt all right before, but that picture seems to have made me tired, because now it's all I can do to stay awake."