he would be apt to learn the cause of the odor, so like burnt powder, if he followed it up.
The others heard Rob give a half suppressed shout, as though he had made a sudden and startling discovery.
"Oh! what is it?" cried Tubby, straining to keep his horse from trying to start up the ascent again.
"Across the river, over there under the arch of the bridge, don't you see that little curl of blue-white rising?" exclaimed Rob. "Watch it and you'll find that it is creeping along over the ground. Come, we've got to get up out of this in a hurry! Turn your horses, and let them help to drag you up! Quick, everybody; not a second to lose, I tell you!"
Tubby no longer tried to hold his horse back; on the contrary, he even urged the animal to climb the grade in frantic haste. He did not know what it all meant, but Rob acted as though there must be some terrible danger threatening them; and Tubby was no fool.
With cries and shouts they urged the animals to ascend. Several times a horse would slip, and come near falling headlong backward; then it was the one who held the reins found it necessary to encourage the struggling beast with word and act, so that the horse might regain his footing.
Tubby, chancing to glimpse Rob's face about the time they drew near the top was horrified to see how very white it seemed. Then more than ever did he realize that it must be something dreadful that had threatened them.
"Rob, tell us what it was all about?" Tubby managed to gasp, when, having reached the road again, they were hurrying back as rapidly as they could go, the horses helping to drag them along.
"Just this," Rob told him briefly. "They've fixed a mine there under the bridge, so as to blow it up; and we've had the narrowest escape of our lives!"
CHAPTER VI.
GETTING NEAR THE WAR ZONE
"Hold on to your horses, everybody!" called out Merritt, as he looked back toward the bridge from which they had now managed to press quite a little distance.
Merritt somehow did not seem to be very much astonished at what Rob had said. It might be he himself had entertained suspicions along those same lines.
They had heard that the determined Belgians were engaged in throwing all the obstacles possible in the way of an advance in force on the part of the invaders. If only cavalry were to be dealt with, the defenders of the soil had faith in their ability to take care of all that could be sent against them; but it was known to be a fact that the artillery arm was what the Germans meant to depend on more than anything else in this war for conquest.
If bridges and culverts were destroyed in every direction before the enemy could take possession of the roads, it would be next to impossible to move the great siege guns until some sort of strong temporary structure had been built in place of the stone and steel fabrics that were blown up.
And so, for days, there had been reports drifting in to Antwerp that certain bridges had been marked for destruction. Those who sallied forth in armored cars to speed over the country, and play havoc with their Maxim guns, found it necessary to revise their map of the district every night so as to conform to the new changes that had been wrought.
It was hardly ten seconds after Merritt told them to keep a firm grip on the bridles of their horses that the boys on looking back saw the bridge suddenly rear itself in the air. Then came a terrifying boom that made the very ground under their feet quiver; and, in a moment later, in place of the fine bridge lay a horrible gap, from which smoke and dust was arising in sickening clouds.
Tubby was as white as a sheet. The others could hear the big sigh with which he drew in a gulp of air.
"I want to say right here," he started to remark solemnly, "that I'm thankful I've got such a cracking good nose for queer odors. Think what might have happened to us if I hadn't begun to sniff around, and made Rob take notice. All that pile of stuff would have buried us out of sight. And the horses knew, sure they did. That explains why they acted so funny all the while. But isn't it a shame to see how they had to smash that splendid bridge!"
"Don't forget that this is war, Tubby," Merritt told him, "and to hinder the enemy from coming up, anything is allowable."
"But that's going to block our going on, I take it," ventured Tubby, watching Anthony, who showed evidences of having been considerably excited by the explosion, though Tubby could not tell whether it was fear that influenced the man, or an overmastering desire to join the army, and engage in some of this obstructive work himself.
"Oh! that doesn't follow," Rob assured him. "I noticed that the river was shallow just now; and I imagined I could see the old ford that used to answer before this bridge was ever thought of. We can get across without swimming. You forded the Rio Grande once upon a time, Tubby, and such a little bug stream as this shouldn't phase you a bit."
"Oh! count on me going wherever the rest of you lead," retorted Tubby, with a blustering air, as though he did not want anyone to think him at all timid.
"We might as well go back now," remarked Rob, "and see about getting over. If the mine has been exploded, there shouldn't be any danger; I want to try that ford."
It was found that though the bridge was wrecked pretty badly, the greatest damage was to the span, and not so much to the anchorages or piers. In time another arch could be built – should peace ever come to this distracted land – when men would be able to once more "beat their swords into ploughshares," and start to rebuilding what had been destroyed.
"Follow after me," Rob told them, as he started to urge his horse across where he could see the old ford had been.
Little of the material from the wrecked bridge had been thrown to any distance, so the ford was not blocked. The horses still displayed more or less restlessness, as though they could not understand that, with such a smell of choking gases in the air, the danger was all over. The three boys, however, had had considerable experience in handling balky animals, and knew just how to urge them on.
Once on the other side, they started up the bank. As they arrived at the road, having crossed the abyss, they saw a crowd of men hurrying toward the spot. They were partly Belgian soldiers, it turned out, along with some civilians, possibly men versed in explosives or strategy to be employed to delay the advance of the German artillery.
Of course, they were very much excited at meeting the boys. The khaki uniforms seemed to soften their anger to some extent, but one who appeared to be in authority started to scold them for walking so blindly into a trap.
Through the guide Rob hastened to explain how it came they had not suspected the truth. Then as questions began to follow, he also told who and what they were, even mentioning something concerning their self-imposed mission into the danger zone of the fighting.
When the precious passport, written out by the good burgomaster, was shown, it had an additional soothing effect. The man in charge of the squad of destruction smiled and nodded as he perused the document, written in French.
"He say burgomaster his uncle!" explained Antonio, after the other had handed the paper back, and made some remark.
"Well, now, that's what I call fine. Tell him we're glad we got out from under that bridge in time," said Rob, "and also that we think he made a clean sweep of the job."
This seemed to please the Belgian officer, for he insisted on shaking hands all around. Feeling that they were now free to proceed, the scouts resumed their journey along the road that led to Brussels; probably, wholly in the hands of the invaders further on toward the capital, since rumor had it that immense numbers of German troops were daily being moved toward Ghent.
"All of which only goes to show how necessary it is to be constantly on the watch while you're in a country that's fighting for its life," Merritt remarked to his companions as they lost sight of the ruined bridge.
"If only we had eyes in the back of our heads, we might get along a heap better, I think," grumbled Tubby, as his horse awkwardly stumbled over some small object, and gave him a shock.
"It was a close call, all right," acknowledged Merritt, "and has sobered our guide a whole lot, I notice. He listens to every far-off boom now, as though something might be drawing him. But