But Captain Mignot evidently had his own ideas of military smartness, and these lads were all clean-shaven. They trooped in from their game, under that little cloud of shrapnel smoke that still hung in the sky, for all the world a crowd of overheated and self-conscious schoolboys receiving an unexpected visit from the master of the school.
The path ended at the battery. In the centre of the guns was a raised platform of wood, and a small shelter house for the observer or officer on duty. There were five guns in pits round this focal point and forming a circle. And on the platform in the centre was a curious instrument on a tripod.
"The telemeter," explained Captain Mignot; "for obtaining the altitude of the enemy's aëroplane."
Once again we all scanned the sky anxiously, but uselessly.
"I don't care to have any one hurt," I said; "but if a plane is coming
I wish it would come now. Or a Zeppelin."
The captain's serious face lighted in a smile.
"A Zeppelin!" he said. "We would with pleasure wait all the night for a Zeppelin!"
He glanced round at the guns. Every gunner was in his place. We were to have a drill.
"We will suppose," he said, "that a German aëroplane is approaching. To fire correctly we must first know its altitude. So we discover that with this." He placed his hand on the telemeter. "There are, you observe, two apertures, one for each eye. In one the aëroplane is seen right side up. In the other the image is inverted, upside down. Now! By this screw the images are made to approach, until one is superimposed exactly over the other. Immediately on the lighted dial beneath is shown the altitude, in metres."
I put my eyes to the openings, and tried to imagine an aëroplane overhead, manoeuvring to drop a bomb or a dart on me while I calculated its altitude. I could not do it.