d across
at one another from either bank of the Somme through summer haze over
the green spaces of the islands edged with the silver of its tranquil
flow in the moonlight or its glare in the sunlight.

Not the least of the calculations in this activity was to screen every
detail from aerial observation. New hangars had risen at the edge of
level fields, whence the swift fighting machines of an aircraft
concentration in keeping with the concentration of guns and all other
material rose to reconnaissance, or to lie in wait as a falcon to pounce
upon an invading German plane. Thus the sky was policed by flight
against prying aerial eyes. If one German plane could descend to an
altitude of a thousand feet, its photographs would reveal the location
of a hundred batteries to German gunners and show the plan of
concentration clearly enough to leave no doubt of the line of attack;
but the anti-aircraft guns, plentiful now as other British material,
would have caught it going, if not coming, provided it escaped being
jockeyed to death by half a dozen British planes with their machine guns
rattling.

To "camouflet" became a new English verb British planes tested out a
battery's visibility from the air. Landscape painters were called in to
assist in the deceit. One was set to "camouflet" the automobile van for
the pigeons which, carried in baskets on the men's backs in charges,
were released as another means of sending word of the progress of an
attack obscured in the shell-smoke. This conscientious artist
"camoufleted" the pigeon-van so successfully that the pigeons could not
find their way home.

Night was the hour of movement. At night the planes, if they went forth,
saw only a vague and shadowy earth. The sausage balloons, German and
Allied, those monitors of the sky, a line of opaque, weird question
marks against the blue, stared across at each other out of range of the
enemy's guns, "spotting" the fall of shells for their own side from
their suspended basket observation posts from early morning until they
were drawn in by their gasoline engines with the coming of dusk. Clumsy
and helpless they seemed; but in common with the rest of the army they
had learned to reach their dugouts swiftly at the first sign of shell
fire, and descended then with a ridiculous alacrity which suggested the
possession of the animal intelligence of self-preservation. Occasionally
one broke loose and, buffeted like an umbrella down the street by