The morning was dull and cloudy, with a raw coldness in the air. To Bob one of the delights of an early start was to fly up into the rays of the morning sun. But to-day when, ten minutes later, they mounted toward the east, the cold, gray clouds seemed endlessly banked above them, and Bob picked up the speaking tube to say, doubtfully:
"Not much photography to-day, Benton. Did you expect it?"
"No," Benton replied. "We shan't be able to get within range for that unless they are all asleep."
At eight thousand feet an airplane is almost safe from rifle or machine-gun fire. But at this height no photographs of any value can be taken. To fly at four or five hundred feet over the enemy would be ideal for observing and photography, but would mean almost certain death to pilot and observer. So an unsatisfactory middle course of two to four thousand feet is usually adopted. Benton did not hesitate to fly low where he could gain valuable information, but he was usually prudent.
Bob's map was spread across his knees, and as they neared the German lines he scrutinized with his glasses the outskirts of the village they approached. Nothing new seemed to require closer attention here. Benton circled and flew behind the village, rising a hundred feet higher as black, white and yellow puffs of smoke appearing from below indicated enemy guns aimed at the tiny target the biplane offered. Suddenly Bob stiffened.
"Ah! Here we have it!" he cried exultantly. "A nice new line of concrete block-houses, Benton, right behind the village—their second line of defense. Fly a little lower, can't you?"
"No," called back the pilot with his usual calmness, "but we'll go a bit further north, so you can find out the extent of the line. Those gunners don't seem very clever yet, but they're getting closer."
Bob sketched for dear life while the machine floated and hovered. Below in a narrow strip of woodland beyond the village he could distinguish plainly the tiny bald spots that marked the hastily constructed fortifications.
"Good, we're losing them," remarked Benton, glancing down. "The clouds have hidden us, I think."
Below them a swirling fog bank sheltered the airplane a moment from the gunners, but it also began to cut off Bob's view, and Benton had to dodge and circle for openings in the misty curtain.