A huge camera or sky projector: any ideas?

[alex ph]

In the middle of nowhere, beside a highway, there is such a huge device. Its "lens" is pointed to the sky, but is possibly moving on a rail. If it is intended to be a huge camera, I wonder what kind of shots it may take in the polluted city atmosphere. If it is a projector device, what kind of light show it may serve for by the side of a highway? It is situated behind a fence, so I could not inspect it closer than that.

#1


#2


#3


#4 That looks more like a sensor than a projector filter, right?


#5 And it looks stripped off from behind. Missing parts?


Do you have an idea of what it is and what it serves for?

[visualopsins]

Solar furnace collector? Missing hot water tank behind sensor...

[alex ph]

With a beam focused as narrow as that?

[jamaeolus]

Vintage solar observer system? Maybe a pinhole camera.. Looks like a ground glass plate in the middle of the drum. Anybody know enough French to read the sign?

[dickb]

[alex ph]

Jamaeolus, this is what comes first to mind when looking at the construction and its orientation: kind of astronomic camera pointed to the sun or the moon. What is unusual for the ground glass if it is the one, it has further inside divisions in the center, the circular and the square ones. And its silver surface looks more like a reflective screen or a split prism than a mat ground glass.

As for the insigns, I did not give any precision or comment in my initial post just because they do not explain anything about the object. As Dickb points out, this is a delimited space where the new Olympic village is going to be constructed. There are several large tents or temporary hangars freshly installed behind the fence. But the thing does not seem to belong to them. It's visibly older (already in decay, as you see) and even marked with red-white warning ribbon as a dangerous construction.

Its location does not give more further hints. Astronomic equipment, if placed in the city, is usually installed on the top of the hills, to avoid light and atmospheric pollutions. This one is placed in a plane and just beside a polluting highway. When I say of the middle of nowhere I mean a kind of industrial zone which does not let suppose any scientific or entertainment function. Inhabited parts of Saint Denis are separated here with around 2kms of waste plots with some sparse technical buildings on them, crossed by a highway. So, I presume for local inhabitants it is pretty "nowhere".

If one think of a huge projector, there is a large stadium at a distance of 1km or even less, the Stade de France. I suppose the whole construction site is conceived as a large annex to the Olympic recycling of the stadium. But the stadium is located strictly to the east of the object and its "lens", as I see the construction, cannot be turned at 90 degrees. Looking at the map, the lens points north-east, more or less the direction of Basilica of Saint Denis. But the distance to the Basilica is around 2kms which, I presume, is a bit too far even for a powerful projector.

So, both the construction and the location of the object give pretty contradictory indicators of what it could serve for in its glory times. And it certainly awakes a desire to put the hand on its optics, even if it would be pretty problematic to adapt it to Sony Nex!

[jamaeolus]

Thanks for your help. It just looks vintage 1930s or so to me. The "objective" doesn't look like a lens in the modern sense. Fantastic mystery you have presented us with. It clearly has elevation controls, does it also have azimuth adjustments? It looks like it but it is not obvious.

[jamaeolus]

Can I post a copy of your image to another forum I am active on? It is chock full of technical and scientific oriented folk (ars technica). Someone on there may recognize the thing.

[jamaeolus]

If it is a solar observatory there is no need for the hilltop approach as there is more than enough light. Also, Where is it in relation to the prime meridian?

[visualopsins]

adjustable movement above and below horizon, the altitude/elevation. unclear how adjustable is the azmuth. both adjustments are necessary to track sky object. pointed at another on a mountain peak?

The missing parts...something attached to the rear of the "lens", something in front of, and something behind the "sensor".

The front of the lens looks like a horn loudspeaker or microphone.

[jamaeolus]

So they wanted to yell at the clouds;)

[visualopsins]

[stevemark]

[jamaeolus]

I also thought the "objective' looked like a horn/speaker I could make no plausible device where you would want a speaker that you could control elevation that also included an imaging screen behind it. I discounted that thought on that basis.

[alex ph]

Thank you, fellows, for your input! The discussion gets more and more intriguing. So you think it might be a sonic camera, and not an optic one. But regarding this option I have the same counter-intuition as Jamaeolus: if the direction of the moving light beam towards the "sensor" would give a distorted image, the same installation concerning the sound wave has even less sense if any at all.

Still, the lens does not look very much like a ususal lens, I agree. Here is a 100% crop from one of the shots I took, to exam it better. You may see or guess four or five smaller holes in it. And a short metal bar overlapping the outer edge of the "lens". Could all that be a kind of "tap" to protect the optics?



Otherwise, the standing out detail marked with red-white "attention" ribbon, does not it look like a part of radio of electricity antenna? If yes, may the whole device be a weather forecast or thunder-lightning-atmospheric measurement instrument?

As for azimuth adjustments, it seems to me the answer is positive: there is a chance that originally the bowed rail could move left-right in the range of approx 30 degrees or so.

Just in case, here is the crop of the "sensor" part of the device


Jamaeolus, please, share the post. Maybe sci-tech folks help to resolve the mystery. Here is its more or less precise location on the map, just in case. The "lens" points long the highway Anatole France, direction north-east.

[pdccameras]

This is a thermal boiler of some sort, as has already been pointed out. My French to English translation skills are pretty poor, so here is the original French description: decouverte de la chaudier a ventouse et focus de la thermatique de l'insertion. Please see this youtube video https://www.youtube.com/watch?v=mK0AvPwt7QE at about 1:29 into the video. It is part of the ZAC Plaine Saulnier development in St. Denis, a suburb of Paris about 9.4KM north of the city center.

Happy New Year!

Paul

[alex ph]

Cheers, Paul, what a find! How have you managed to find this info?

I am reading now about the construction of chadière à ventouse. The English translation is boiler with sealed chamber or room sealed boiler. And it's a pretty simple "suction" technology to evacuate the smoke from a heater or boiler installed inside the building. It normally requires a pipe fixed to the outer wall within another, larger pipe that sucks air from exterior to push the smoke outside. One of the key parameters of such installation, explaining why the pipe should be fixed well to the wall, is its hermetic isolation, to provide constant circulation and evacuation of the smoke.

Much in this description contradicts the construction we see. The rail which garantees vertical (and probably some horizontal) movements of the pipe and the presence of the "sensor" look unusual in this context. The same concerns some additional electric equipment installed on the side of the rail. I wonder if the guy explaining the destination of the thing to the mayor of Paris and to the whole group of officials could be wrong.

Happy New year to you too, with more optical experiences and resolved mysteries!

[stevemark]

[pdccameras]

Well, it appears that the mystery continues.......

[alex ph]

As it usually happens in such short presentation videos, the guide's comment is heavily edited. There is certainly some other words or even phrases in between his "un des vestiges de passé" (the vestige of the past) and "recherche et développement". I don't suppose the journalists who made the video added by their own initiative the famous "chaudière à ventouse" that Paul so well grasped from the video subtitle. The insign arrives just in the moment the object appears on the screen and must refer to what the guy said. So, I guessed that might be his error of attribution, not really mine.

[Blazer0ne]

...

[visualopsins]

Lost in Space

[Gerald]

At first, I thought it was a French version of the Batman signal projector.

[alex ph]

[Blazer0ne]

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