Help with Auguste Piccard translation


One claim that still circulates every now and then is that the explorer Auguste Piccard said the earth was flat due to this language in a Popular Mechanic article:

"Through the portholes, the observers saw the earth through copper-colored, then bluish haze. It seemed a flat disk with upturned edge." This was at an altitude of approximately 50,000 feet.

Now, Piccard wrote about the globe in his book Earth, Sea, and Sky, so he clearly could not have thought he was witnessing a flat earth from his balloon, and the translation in the comments section of this interview YouTube video seem to indicate the believed he'd be able to see the curvature with a ruler at that altitude (
), but I have another question for the group.

If you continue to listen to that interview, the French subtitles seem to say the following, which I'm sure is a very poor transcription:
  • Interviewer: est ce qu'un pareil l'altitude terrestre diminue deja assez sensible ces depots d'instruments? (does such a terrestrial altitude already decrease quite significantly these deposits of instruments?)
  • Piccard: ampere impots mille la du poids de 3000 mais nous avons denc un demi pour cent de perte. c'est dire sur 100 kilos on perde un demi kilo de poids. avec un balance dynamometrique alors on pourrait parfaitement constate et quelle temperature avait voulu a cette altitude. (ampere taxes thousand the weight of 3000 but we have lost half a percent. that is to say on 100 kilos we lose half a kilo of weight. with a dynamometer then we could perfectly see and what temperature had wanted at this altitude.)

Clearly, the translation suffers, but I think the general point is that Piccard was saying at the altitude of 50,000 feet, you lose half a percent of weight, which somehow affects the measurements of the equipment. I believe this is an indirect reference to gravity, since by my calculation, an object at 50,000 feet should have a "g" of approximately 9.7599 m/s², which is about 99.5% of 9.8 m/s². So my question is, is there anyone who speaks French that can give a better transcription and translation of this portion of the interview? This would be helpful to refute those who like to use Auguste Piccard as a Flat Earth champion.

It seemed a flat disk with upturned edge."
the surface is very far down, and the horizon is still nearly at eye level
the description of his impression makes perfect sense

at 50,000 ft, you can see 300 miles in each direction, with only 10 miles of drop, that you can't really discern because that's only ~4⁰ down from eye level

Earth is so huge that it's approximately flat at many scales
Earth is so huge that it's approximately flat at many scales
my link above has a "horizon" graphic of what Piccard would have seen*, but i have no idea if it's accurate so didnt add it to thread. maybe you can take a look at it.

*i'm also wondering if he would have seen all that in a 3 inch window. He seems to say he would have if he had a ruler. would you see the edges of that graphic from 300 miles away? i'm guessing yes?
my link above has a "horizon" graphic of what Piccard would have seen*,

It's without refraction, and a 65⁰ field of view. Whether Piccard could have achieved that would depend on how close he could get to the outside of his 8cm porthole (and still see the ruler?), he'd need to be at 7.3 cm (2 7/8") or closer. The gondola itself was 0.35cm thick.

It definitely looked like he was above something round, it just looked more like a bowl than a sphere to him, I guess?
It's without refraction, and a 65⁰ field of view.

"" says: "This is the curvature of the Earth should look like at the altitude of Auguste Piccard’s first flight." ( Source of the picture is:

The angle 65° in the View∠-box is the diagonal FOV. To get the horizontal FOV with option "AspectcRatio off" you must divide this value by 1.2018502. So the horizontal FOV is about 54.1°. (See the conversation:

To be precise you must also select "Show Left-Right Drop". Then the correct curve Piccard could see at 54.1° horizontal FOV is between the two little triangles.

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the porthole is round?
The angle α in my formula (1) doesn't depend on how (in what position) the observer sees the angular segment of the horizon, or how much else he can see. The only thing is that he can see the segment so that the chord's angular size is α (see

The calculator uses photographic terms. Bislin explains the connections here:


So in the View∠-box is the angle θ = diagonal FOV. From this you get the horizontal FOV α with the formula above. But the formula refers to r = w/h = aspect ratio of viewing frame (=width/height). The horizontal FOV is the same as the angle α in formula (1). But now to get the correct horizontal FOV you must use the correct aspect ratio of the viewing frame.

I checked that my coefficients k for different ratios r give the same relation for θ and α as the above formula.

"The angles don't scale linearly" said Mick referring the lengths on the screen. That is true, but somehow the calculator seems to take care of that. Giving the angles of horizontal FOV and Left-Right Drop I can calculate the ratio in which the chord (red line segment) and the sagitta should be seen on the screen. When I measured these lengths on the screen, the ratio was quite the same as the calculated value. So this is not a concern.

If you are not dealing with cameras and photographs and just interested how the horizon looks at some horizontal FOV, it might be a little frustrating. (Why can't I just put the horizontal FOV direct in the calculator?)

Maybe the easiest way is select AspectRatio off (this is practically same as ratio 3:2) and then put into View∠-box the value 1.2018502*(the desired horizontal FOV). To get the most correct horizon curve picture you must select "Show Left-Right Drop". Then the correct curve at that horizontal FOV is between the two little triangles.

In these calculations is no reference to the window or some else opening through which you see the horizon segment. Only thing that matters is that you can see the whole segment and its chord's angular size equals your desired horizontal FOV.

Long comment to your short question "the porthole is round?" If I understood it right and my explanation is right, the short answer could be "It doesn't matter."
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I think I've mentioned this before somewhere, but Picard's balloon ascent was made from Augsburg in Bavaria (mis-spelled as 'Augsberg' in the Popular Science article). From there the Swiss Alps would have been visible in the distance to the south, and the Austrian Alps to the south-east. It would not be a good location for observing the curvature of the earth, and in some directions a 'flat disk with upturned edge' may not have been a bad description.
In the radio interview on YT the French subtitles seem garbled in places; for example 'avez vous vu' [have you seen] comes out as 'avez voulu' [have wanted], and 'degres' [degrees] comes out as 'de tri', which I think is meaningless!
Also worth stressing that Piccard didn't actually say this, they are the words of the writer of the article.

The writer of the article seems to have gathered his information from some of Piccard's interviews, which he then reports. He places direct citations in quotes (like "blue air"), but that famous phrase is not in quotes. It's likely the writer's interpretation of Piccard's words and not a quote. a flat disk with upturned edge"&f=false

Actually, this doesn't matter. Piccard might very well describe his feelings with those words. So, when looking from a height, can it feel like you are above/inside a flat plate (or bowl)?

Marcel Minnaert writes on page 159 of his classic book "The nature of LIGHT & COLOUR in the open air" (Dover Publications Inc. 1954, translation H.M.Kremer-Priest revision K.E.Brian Jay):

113. The Concave Earth

This is the counterpart of the visual impression made by the vault of the sky. When the air is clear the earth surveyed from a balloon appears to curve upwards, so that we seem to be floating above a huge concave plate. The horizontal plane through our eye appears to us invariably as a flat plane; other horizontal planes in the distance, above or below it, seem to curve towards this fixed plane.

When the balloon is sailing a few miles above banks of clouds these too seem curved, their convex side being turned towards the earth and the concave side turned upwards. Should we happen to be between two layers of clouds, one above us and one below, we feel as if we are floating between two enormous watch-glasses. Similar observations can be made from an aeroplane.

Maybe this observation is a sensory-psychological phenomenon like the "moon illusion" (the Moon appears larger on the horizon than high in the sky).

Also PhD David Rosen talks about a similar experience in the Quora

That is what the earth looks like on top of a tall tower or mountain.

I lived in a high rise in Brooklyn near a top floor. Every morinng I woke up, and looked out from my window. And there it was! An inverted bowl with a rim that was the horizon. I never wrote a book about it because I am sure many other people have seen such a thing. You would have to live in a dense jungle not to see the inverted bowl sometimes.

It is a matter of parallax. The explanation is just simple geometry.

Your brain takes the image on your retina and puts in a correction determined by the angle of your head relative to the rest of the body. You judge distances and height at large distances mainly by the angle you turn your head.

Now imagine standing up on top of a huge tower looking down at the earth, your best friend besides you. Imagine someone looking at you while you scan the horizon.

You look down at the ground, You see the cars as little images. Your friend notices that your head, relative to the rest of your body, is pointed straight down. Your brain doesn’t store the information of the direction of your head. Instead, your brain remembers that the ground is straight down from your head. Using the cars as a scale reference, you deduce that the ground is hundreds of feet below you.

Now you look at the horizon. Your friend sees your head pointed orthogonal to your body. However, your brain doesn’t store information that way. Instead, your brain interprets the horizon as a distant line level with your eyes.

So if the horizon is level with your eyes and the ground is hundreds of feet below you, what does that mean for the rest of the scenary?

Right. Your brain will interpret the scenery as a huge bowl.

Basically, most visual effects can be explained in terms of how your brain interprets geometric information from the retina. The image of your retina is an image. What your brain believes is an interpretation based on geometry.

Of course, there is no indication in Auguste Piccard's books and writings that he considered the Earth to be flat. I don't know if the "Concave Earth Society" has already managed to declare Piccard their own man.
I lived in a high rise in Brooklyn near a top floor. Every morinng I woke up, and looked out from my window. And there it was! An inverted bowl with a rim that was the horizon. I never wrote a book about it because I am sure many other people have seen such a thing. You would have to live in a dense jungle not to see the inverted bowl sometimes.
When looking at a wide expanse of near 180°, the "fisheye lens" effect is apparent. In a place with tall buildings such as a city view, if you look left, the building to your left looks vertical, and the same is seen when you look right, because you are looking at a small portion of the scene. But if you draw the whole scene, the rules of perspective work in both the horizontal and vertical directions, and if you carefully line up the diagonal angles in each spot according to your straight-on view for each segment, you'll draw the fish-eye, thus demonstrating to yourself that our eyes can only judge a limited area at a time.

You can see the same effect by sitting relatively close to the corner of a small building, where if you must turn your head to see all the parts, your drawing will "bulge in the middle". Thus when you are at a height, you are "in a bowl", optically, as the sky appears larger in the middle and smaller at a distance. Similarly when you're in a low spot looking up, the hill in front of you will look much steeper than it would from a distance. We see the effect when taken with a fisheye camera lens, but don't realize that our own senses can do the same thing.