[JenBurdoo] What are we looking at?

[JenBurdoo]

What is the purpose of the devices in this photograph?

[Doriana]

Are the people soldiers? Relevant?
Are the devices there to protect the people?

[trebor]

Is photography relevant? Art? Is their location relevant?

[AlbatrossLover]

Is it relevant when the picture was taken? Is it black and white because of its age? Is it a modern picture that was deliberately made to look like that? Is part of the devices buried underground?

[Enjay]

Is there a relevant image or design on the front of the devices (the side facing away from us)? Are they providing some kind of camouflage?

It looks like the people can see their reflections in the devices, is that part of the function of the device?

[JenBurdoo]

Are the people soldiers? Relevant? Yes to both.
Are the devices there to protect the people? Yope.

Is photography relevant? No. Art? No. Is their location relevant? No, but...

Is it relevant when the picture was taken? Yes. Is it black and white because of its age? Yes. Is it a modern picture that was deliberately made to look like that? No. Is part of the devices buried underground? No.

Is there a relevant image or design on the front of the devices (the side facing away from us)? Possibly, assume yes. Are they providing some kind of camouflage? Yope.

It looks like the people can see their reflections in the devices Correct, is that part of the function of the device? No, but...

[trebor]

Were there other people (apart from the photographer, I’m assuming) around outside the frame of this picture? Other animals? Are the reflective properties of these devices relevant? Were they used to focus light?

[JenBurdoo]

Were there other people (apart from the photographer, I’m assuming) around outside the frame of this picture? Yes. Other animals? No. Are the reflective properties of these devices relevant? Yes. Were they used to focus light? No.

[Sundowner]

Are the men standing in manholes?
Do they observe the enemy?
Is the camouflage on the other side of the device mainly to cover the soldiers? or mainly to cover the device?
Does the mirror help the men to see when someone/something is approaching from behind? like an aircraft?
Would the men go down into the manhole and pull the device over them when an aircraft approaches?

[JenBurdoo]

Are the men standing in manholes? No.
Do they observe the enemy? Irr.
Is the camouflage on the other side of the device mainly to cover the soldiers? or mainly to cover the device? Both; explore.
Does the mirror help the men to see when someone/something is approaching from behind? like an aircraft? No, FA.
Would the men go down into the manhole and pull the device over them when an aircraft approaches? No.

[biograd]

Is there a FA that this device is used in battle? Is it rather used in some sort of training exercise? in other military functions beside combat (such as delivery of supplies, navigation, medical care, etc.)?

[JenBurdoo]

Is there a FA that this device is used in battle? No - it was intended for use in battle (though it probably wasn't, at least by the men depicted). Is it rather used in some sort of training exercise? The photo is actually from a training exercise, but the intention was to use the items in battle. in other military functions beside combat (such as delivery of supplies, navigation, medical care, etc.)? No.

[Sundowner]

Relevant that the mirror-like surface was not exactly vertical? Was it possible to adjust the angle? Was a specific angle necessary for the device to work?
Are the men looking at the mirror? are they looking through a hole in the device?
Does the mirror reflect something? the sun?
In a battle, would these devices be operated at the front line? behind the front line? secretly in the enemy's territory?
Relevant that it's three men? (or is one of them an instructor?)

[peter365]

Is the primary function of the devices to deceive the enemy? Make them miss with rifle or artillery fire? Is there an element of dazzle at play here?

[Mimino]

Is it a see-through mirror? Does it have the function to bring something that is flat on the ground before the eyes of the soldiers? a map?

[JenBurdoo]

Relevant that the mirror-like surface was not exactly vertical? Yes. Was it possible to adjust the angle? Yes. Was a specific angle necessary for the device to work? Possibly.
Are the men looking at the mirror? No. are they looking through a hole in the device? Possibly, but doubtful.
Does the mirror reflect something? Yes. the sun? No.
In a battle, would these devices be operated at the front line? This. behind the front line? secretly in the enemy's territory?
Relevant that it's three men? (or is one of them an instructor?) No to both, but instructors are present.

Is the primary function of the devices to deceive the enemy? This. Make them miss with rifle or artillery fire? Is there an element of dazzle at play here? As in "dazzle camouflage?" No.

Is it a see-through mirror? Possibly. (I haven't found more specific info about the technique beyond the photo and its caption.) Does it have the function to bring something that is flat on the ground before the eyes of the soldiers? No. a map? Maps are irrelevant.

[GalFisk]

Do the mirrors reflect the ground? Sky? Enemy? Muzzle flashes? WAG: are they tricking the enemy into thinking that their own gunfire is enemy gunfire?

[JenBurdoo]

Do the mirrors reflect the ground? This. Sky? Enemy? Muzzle flashes? WAG: are they tricking the enemy into thinking that their own gunfire is enemy gunfire? No to the rest.

[Sundowner]

Are there mirrors on both sides of the device?
Are the men cavalry? or military police? (guessing from their hats)
Were the devices ever used in combat? if so: WW I? WW II?
Would in combat situations these men have the primary task of observing? observing the enemy? other observations (weather, geography)? target identification and observation?

[JenBurdoo]

Are there mirrors on both sides of the device? Assuming that on the side we can see is a mirror, yes.
Are the men cavalry? or military police? (guessing from their hats) Infantry.
Were the devices ever used in combat? Unlikely, and certainly not by these men. if so: WW I? But if so, WWI. WW II?
Would in combat situations these men have the primary task of observing? observing the enemy? other observations (weather, geography)? target identification and observation? These are all possible, but they could be used in active fighting contexts as well.

[trebor]

Is there anything relevant in the ground? Perhaps another part of the apparatus?

Are the devices used for communication? Would an infantry person use it to communicate with someone behind them? In front of them? Are they used to confuse someone/something?

[Sundowner]

Are there mirrors on both sides of the device? Assuming that on the side we can see is a mirror, yes.
So, is there a mirror on the side we can see?
Is there a mirror on the other side?

Were the devices ever used in combat? Unlikely, and certainly not by these men.
Because these men were not combat soldiers? Were they testing the devices?
Did the devices work as expected?

[JenBurdoo]

So, is there a mirror on the side we can see? I'm not certain, but I think we can assume yes.
Is there a mirror on the other side? Definitely yes.

Because these men were not combat soldiers? Were they testing the devices? No to both.
Did the devices work as expected? Yes, but...

[Sundowner]

Was the function of the mirror on the enemy-facing side to mirror the ground to the enemy? so that it would appear to the enemy that there is just ground, no soldiers? So that the men behind the devices could do whatever their task is, invisible to the enemy?
Was the problem with the device that in order to see whether the angle is correct you have to look at it from the enemy side?

[JenBurdoo]

Was the function of the mirror on the enemy-facing side to mirror the ground to the enemy? so that it would appear to the enemy that there is just ground, no soldiers? So that the men behind the devices could do whatever their task is, invisible to the enemy? Yes to all!
Was the problem with the device that in order to see whether the angle is correct you have to look at it from the enemy side? No; there are instructors looking on from the "enemy" side to ensure the angle is correct. Here's the entire photo:

[GalFisk]

Were they unusable in combat? Too fragile? Hard to use correctly? Only effective when not reflecting sunlight onto the ground? Too expensive? Developed too late for the kind of warfare they were intended for? Too late before peace? Were they too effective, so they didn't want the enemy to capture any and get ideas of their own?

[JenBurdoo]

Were they unusable in combat? Yes. Too fragile? Hard to use correctly? This. Only effective when not reflecting sunlight onto the ground? Too expensive? Developed too late for the kind of warfare they were intended for? This, basically. Too late before peace? Were they too effective, so they didn't want the enemy to capture any and get ideas of their own?

Spoiler:

The device is a mirror, held away and angled towards the ground. The apparent reflection of the face is the rear, unpolished side, and the oddly shaped frame is probably camouflaged. The theory was that men crawling across flat, open ground towards enemy positions would reflect the ground immediately to their front, making any viewers think they saw empty ground.

The problem for these American troops training in 1917 is that while no-man's-land might be open ground, it was anything but flat. Such devices, however ingenious, would have been all too cumbersome in the actual trench warfare that the Americans hadn't actually observed yet. And it would be far more difficult to make it reflect, say, a shell crater...