"What's that?" exclaimed Arthur, suddenly.
Overhead a strange noise filled the air; a shrieking, whining, whistling sound. It rose, as it came nearer, to a wild whistle, like the blast of a factory signal, releasing the workers at the end of the day's work. The two scouts stared at one another; then, without knowing why, they turned to look at the busy scene to the east. Suddenly, before their eyes, there was a flash; a puff of white smoke rising in the ghostly radiance of the arc lamps, and, after a distinct pause, a dull crash. Then, as the smoke cleared, and they still stood awe stricken, they saw that the bursting shell had torn a great hole in the ground. They saw men running; others were crawling, dragging themselves painfully along. And others still lay very quiet.
For just a moment there was a scene of wild confusion. But then order was restored, and a knot of men ran to the two guns that were uninjured and ready. Paul dived down at once. Quickly he told what had happened, then raced up again. Another whistling overhead, and then a terrific explosion. The two guns lay overturned, ruined.
CHAPTER X
PRISONERS OF WAR
For five minutes the two scouts, appalled, horrified, stood as if glued to the floor, staring at the scene of destruction. The guns in Fort Boncelles had the range now. Nothing more than Paul's hurried message, "Your shell landed beyond the guns," had been necessary. Now shell after shell was dropped in the midst of the battery that had been wiped out before it could fire even a single shot. There was a deadly, terrifying accuracy about the whole proceeding. Miles away the Belgian gunners, safe in their concrete and steel turrets, were producing this waste and destruction—not by fighting, it seemed to Paul and Arthur, but by a blackboard exercise. That was all it really was.
"You see, they know just where their gun is, and they can adjust it to fire a certain distance. They can take a map, and fire a shell at any given spot, just by mathematics. They know the angle they must use, and they know just how far, and how fast that shell will go. It won't always go quite true, of course; that was why the first shell didn't strike just the right spot."
"But why is that, if everything is so exact? I shouldn't think they'd ever make a miss."
"Oh, there are lots of reasons. For one, after a gun has been fired a few times the inside is affected. The rifling is worn in places, and that gives a slightly different spin to the shell. It doesn't take much of a change in conditions to alter the course of a shell a good deal. And the weather counts, too. Sometimes there is more air resistance; on a day when it is damp and foggy, with low lying clouds, for instance. So, though they have the range exactly, they may have to alter what they call the formula a little."