The engineer saw them also, and a wave of ashy grey passed over his sallow olive features.
"Madre!" he gasped. "They will blow us all up."
He realized that the danger was greatest from his compatriots. Without the least compunction the Valderian airmen would sacrifice the luckless engineer if by so doing they would involve the fugitives in the destruction of the engine.
"Tell that fellow to get back upon the foot-plate," ordered Dacres, at the same time picking up the rifle. "Keep a bright look out ahead, Henri. We'll stop their little game."
The young Frenchman was now entirely carried away by the excitement of the wild ride. What little fear he had at the commencement of the adventure had completely left him. Although he lacked the cool, calculating manner of his Anglo-Saxon companion, and manifested all the vivacity of the Gaul, he was not deficient in courage.
There could be no doubt as to the intentions of the two aeroplanes. Flying low—less than three hundred feet from the ground—they followed the line of rails. In front and slightly the pilot in each was a light automatic gun. The airman-gunner, however, was busy not with this weapon but with a number of cylindrical objects that Dacres recognized as bombs. The idea of the airman was to overtake the fugitive engine and drop a charge of high explosive on or immediately in front of it. This manoeuvre must be frustrated at all costs.
Setting the sliding bar of the back-sight to a hundred yards, the Englishman waited. He realized that he was at a disadvantage owing to the jarring and swinging of the engine, but the targets were fairly large ones and moving at less than ten miles an hour more than the object of their pursuit.
Soon the whirr of the aerial propeller of the leading biplane was audible above the rush of the wind and the rattle of the locomotive. The bomb-thrower poised one of his missiles.
"Idiot!" muttered Dacres. "He'd make a better show of it with that automatic gun—well, here goes."
Gently pressing the trigger, the Englishman let fly. The bullet passed close enough to the pilot to make him duck, but without cutting any of the wire stays and struts it zipped through the upper plane and whistled away into space.