"_Wouff!_ _Ouff!_ _Ouff!_" barked Archie, many times and loud. An instinct to swerve assaulted the pilot, but after a slight deviation he controlled his impulse and held the bus above the roadside. He had a difficult task to maintain a level course. Whereas we wanted to make east-north-east, the wind was due east, so that it cut across and drifted us in a transverse direction. To keep straight it was necessary to steer crooked--that is to say, head three-quarters into the wind to counteract the drift, the line of flight thus forming an angle of about 12° with the longitudinal axis of the aeroplane. "_Wouff!_ _ouff!_" Archibald continued, as I counted in seconds the interval to the scene of the next snapshot, which, as assurance that the whole ground would be covered, was to overlap slightly the first. A quick glance below, another tug at the string, and plate the second was etched with information. The third, fourth, and fifth followed; and finally, to our great relief, we reach Le Sars. Here the pilot was able to dodge for a few seconds while we turned to retrace the course, this time along the southern edge of the road. He side-slipped the bus, pulled it around in an Immelmann turn, and then felt the rudder-controls until we were in the required direction. The interval between successive exposures was now shorter, as the east wind brought our ground speed to 120 miles an hour, even with the engine throttled back. There was scarcely time to sight the objective before the photograph must be taken and the next plate loaded into place. Within two minutes we were again over Pozières. V. took us across the lines, so as to deceive the Archie merchants into a belief that we were going home. We then climbed a little, turned sharply, and began to repeat our outward trip to north of the road. Evidently Archie had allowed his leg to be pulled by the feint, and for two minutes he only molested the machine with a few wild shots. But soon he recovered his old form, so that when we had reached Le Sars the bus was again wreathed by black puffs. We vertical-turned across the road and headed for the trenches once more, with the last few plates waiting for exposure. Archie now seemed to treat the deliberation of the solitary machine's movements as a challenge to his ability, and he determined to make us pay for our seeming contempt. An ugly barrage of A.-A. shell-bursts separated us from friendly air, the discs of black smoke expanding as they hung in little clusters. Into this barrier of hate we went unwillingly, like children sent to church as a duty.