... Since daybreak a great wind has raged from the east, and even as I write you, my best of friends, it whines past the mess-tent. This, together with low clouds, had kept aircraft inactive—a state of things in which we had revelled for nearly a week, owing to rain and mist.

However, towards late afternoon the clouds were blown from the trench region, and artillery machines snatched a few hours' work from the fag-end of daylight. The wind was too strong for offensive patrols or long reconnaissance, so that we of Umpty Squadron did not expect a call to flight.

But the powers that control our outgoings and incomings thought otherwise. In view of the morrow's operations they wanted urgently a plan of some new defences on which the Hun had been busy during the spell of dud weather. They selected Umpty Squadron for the job, probably because the Sopwith would be likely to complete it more quickly than any other type, under the adverse conditions and the time-limit set by the sinking sun. The Squadron Commander detailed two buses—ours and another.

As it was late, we had little leisure for preparation; the cameras were brought in a hurry from the photographic lorry, examined hastily by the observers who were to use them, and fitted into the conical recesses through the fuselage floor. We rose from the aerodrome within fifteen minutes of the deliverance of flying orders.

Because of doubtful light the photographs were to be taken from the comparatively low altitude of 7000 feet. We were able, therefore, to complete our climb while on the way to Albert, after meeting the second machine at 2000 feet.

All went well until we reached the neighbourhood of Albert, but there we ran into a thick ridge of cloud and became separated. We dropped below into the clear air, and hovered about in a search for the companion bus. Five minutes brought no sign of its whereabouts, so we continued alone towards the trenches. Three minutes later, when about one mile west of PoziÈres, we sighted, some 900 yards to north of us, a solitary machine that looked like a Sopwith, though one could not be certain at such a range. If it was indeed our second bus, its pilot, who was new to France, must have misjudged his bearings, for it nosed across to the German air country and merged into the nothingness, miles away from our objective. What became of the lost craft is a mystery which may be cleared up to-morrow, or more probably in a month's time by communication from the German Prisoners' Bureau, or maybe never. Thus far we have heard nothing, so a forced landing on British ground is unlikely. For the rest, the pilot and observer may be killed, wounded, injured, or prisoners. All we know is that they flew into the Ewigkeit and are "missing."

For these many weeks PoziÈres has been but a name and a waste brick pile; yet the site of the powdered village cannot be mistaken from the air, for, slightly to the east, two huge mine-craters sentinel it, left and right. From here to Le Sars, which straddles the road four miles beyond, was our photographic objective. We were to cover either side of the road twice, so I had arranged to use half the number of plates during each there-and-back journey.

The R.F.C. camera used by us is so simple as to be called foolproof. Eighteen plates are stacked in a changing-box over the shutter. You slide the loading handle forward and backward, and the first plate falls into position. Arrived over the spot to be spied upon, you take careful sight and pull a string—and the camera has reproduced whatever is 9000 feet below it. Again you operate the loading handle; the exposed plate is pushed into an empty changing-box underneath an extension, and plate the second falls into readiness for exposure, while the indicator shows 2. And so on until the changing-box for bare plates is emptied and the changing-box for used ones is filled. Whatever skill attaches to the taking of aerial snapshots is in judging when the machine is flying dead level and above the exact objective, and in repeating the process after a properly timed interval.A.-A. guns by the dozen hit out immediately we crossed the lines, for we were their one target. No other craft were in sight, except a lone B.E., which was drifted by the wind as it spotted for artillery from the British side of the trenches. Scores of black puffs, attended by cavernous coughs, did their best to put the wind up us. They succeeded to a certain extent, though not enough to hinder the work on hand.

Everything was in Archie's favour. We were at 7000 feet—an easy height for A.-A. sighting—we were silhouetted against a cover of high clouds, our ground speed was only some thirty miles an hour against the raging wind, and we dared not dodge the bursts, however close, as area photography from anything but an even line of flight is useless. Yet, though the bursts kept us on edge, we were not touched by so much as a splinter. In this we were lucky under the conditions. The luck could scarcely have held had the job lasted much longer than a quarter of an hour—which is a consoling thought when one is safe back and writing to a dear friend in England, not?Northward, along the left-hand side of the road, was my first subject; and a damned unpleasant subject it was—a dirty-soiled, shell-scarred wilderness. I looked overboard to make certain of the map square, withdrew back into the office, pulled the shutter-string, and loaded the next plate for exposure.

"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.

Scores of staccato war-whoops reminded us that the Boche gunners wanted our scalp. I don't know how V. felt about it, but I well know that I was in a state of acute fear. Half-way to PoziÈres I abandoned checking the ground by the map, and judged the final photographs by counting the seconds between each—"one, two, three, four (wouff! wouff! wouff! wouff!)"; pull the string, press forward the loading-handle, bring it back; "one, two, three, four (wouff! wouff! wouff! wouff!)," et-cetera. Just as the final plate-number showed on the indicator a mighty report from underneath startled us, and the machine was pressed upward, left wing down.

This was terrifying enough but not harmful, for not one of the fragments from the near burst touched us, strange to say. The pilot righted the bus, and I made the last exposure, without, I am afraid, caring what patch of earth was shuttered on to the plate.

Nose down and engine full out, we hared over the trenches. Archie's hate followed for some distance, but to no purpose; and at last we were at liberty to fly home, at peace with the wind and the world. We landed less than three-quarters of an hour after we had left the aerodrome in a hurry.

"Good boys," said the Squadron Commander; "now see that lightning is used in developing your prints."

The camera was rushed to the photographic lorry, the plates were unloaded in the dark hut, the negatives were developed. Half an hour later I received the first proofs, and, with them, some degree of disappointment. Those covering the first outward and return journey between PoziÈres and Le Sars were good, as were the next three, at the beginning of the second journey. Then came a confused blur of superimposed ground-patterns, and at the last five results blank as the brain of a flapper. A jamb in the upper changing-box had led to five exposures on the one plate.

As you know, mon amie, I am a fool. But I do not like to be reminded of the self-evident fact. The photographic officer said I must have made some silly mistake with the loading handle, and he remarked sadly that the camera was supposed to be foolproof. I said he must have made some silly mistake when inspecting the camera before it left his workshop, and I remarked viciously that the camera was foolproof against a careless operator, but by no means foolproof against the careless expert. There we left the subject and the spoiled plates, as the evening was too far advanced for the trip to be repeated. As the photoman has a pleasant job at wing headquarters, whereas I am but an observer—that is to say, an R.F.C. doormat—the blame was laid on me as a matter of course. However, the information supplied by the successful exposures pleased the staff people at whose instigation the deed was done, and this was all that really mattered.

I have already told you that our main work in umpty squadron is long reconnaissance for G.H.Q. and offensive patrol. Special photographic stunts such as happened to-day are rare, thank the Lord. But our cameras often prepare the way for a bombing expedition. An observer returns from a reconnaissance flight with snapshots of a railhead, a busy factory, or an army headquarters. Prints are sent to the "I" people, who, at their leisure, map out in detail the point of interest. No fear of doubtful reports from the glossed surface of geometrical reproduction, for the camera, our most trusted spy, cannot distort the truth. Next a complete plan of the chosen objective, with its surroundings, is given to a bombing squadron; and finally, the pilots concerned, well primed with knowledge of exactly where to align their bomb-sights, fly off to destroy.

For the corps and army squadrons of the R.F.C. photography has a prominent place in the daily round. To them falls the duty of providing survey-maps of the complete system of enemy defences. Their all-seeing lenses penetrate through camouflage to new trenches and emplacements, while exposing fake fortifications. The broken or unbroken German line is fully revealed, even to such details as the barbed wire in front and the approaches in rear.

For clues to battery positions and the like, the gun country behind the frontier of the trenches is likewise searched by camera. One day a certain square on the artillery map seems lifeless. The following afternoon an overhead snapshot reveals a new clump of trees or a curious mark not to be found on earlier photographs. On the third day the mark has disappeared, or the trees are clustered in a slightly different shape. But meanwhile an exact position has been pin-pointed, so that certain heavy guns busy themselves with concentrated fire. By the fourth day the new gun-pits, or whatever it was that the Hun tried to smuggle into place unnoticed, have been demolished and is replaced by a wide rash of shell-holes.

Wonderful indeed is the record of war as preserved by prints in the archives of our photographic section. For example, we were shown last week a pair of striking snapshots taken above Martinpuich, before and after bombardment. The Before one pictured a neat little village in compact perspective of squares, rectangles, and triangles. The Aftermath pictured a tangled heap of sprawling chaos, as little like a village as is the usual popular novel like literature.

Of all the Flying Corps photographs of war, perhaps the most striking is that taken before Ypres of the first Hun gas attack. A B.E2.C., well behind the German lines, caught sight of a strange snowball of a cloud rolling across open ground, in the wake of an east wind. It flew to investigate, and the pilot photographed the phenomenon from the rear. This reproduction of a tenuous mass blown along the discoloured earth will show coming generations how the Boche introduced to the black art of warfare its most devilish form of frightfulness.

I would send you a few aerial photographs, as you suggest, if the private possession of them were not strictly verboten. Possibly you will have an opportunity of seeing all you want later, for if the authorities concerned are wise they will form a public collection of a few thousand representative snapshots, to show the worlds of to-day, to-morrow, and the day after what the camera did in the great war. Such a permanent record would be of great value to the military historian; and on a rainy afternoon, when the more vapid of the revues were not offering matinÉes, they might even be of interest to the average Londoner.

I can tell you little of the technical branch of this new science, which has influenced so largely the changing war of the past two years, and which will play an even greater part in the decisive war of the next two. All I know is that hundreds of photos are taken every day over enemy country, that ninety per cent of them are successful, and that the trained mechanics sometimes produce finished prints twenty minutes after we have given them our plates.

Moreover, I am not anxious to discuss the subject further, for it is 10 P.M., and at 5 A.M., unless my good angel sends bad weather, I shall be starting for an offensive patrol over Mossy-Face. Also you don't deserve even this much, as I have received no correspondence, books, or pork-pies from you for over a week. In ten minutes' time I shall be employed on the nightly slaughter of the spiders, earwigs, and moths that plague my tent.

Good night.

France, September, 1916