Your FOV would be 1 inch
A FOV is measured in degrees or another angular measurement. It is not a linear measurement.
So saying it would be 1 inch is basically the same as saying you have no FOV.
What you see outside of that tube, is compressed images all a within that 1 inch diameter.
i.e. The light goes into the tube due to perspective.
Like this:
The line on the right is "visually compressed" to fit in the same angular region as that on the left. And then it gets compressed even smaller than that as it goes into your eye.
That "compression" is merely travelling upwards (and downwards) at an angle, such that it always subtends the same angle and thus has a smaller linear size.
That is simply light travelling in straight lines, with an angular FOV.
That is the blue line coming up to see.
There is no need to invoke nonsense like magical compression with linear FOVs, rather than just accepting reality, with angular FOV.
But regardless of if you want to invoke compression, or if you are just going to admit that light travels in a straight line and the blue line gets in; you CAN see things below the level of the tube.
And that means you can see a downwards gradient from a level tube.
With an angular measurement you simply use the angles directly, rather than pretending 1 length is actually a different length.
With a linear measurement and your nonsense compression, then if the tube is 6 inches, and is 1 inch, then at 6 inches you have your reference 1 inch, at 1 foot that 1 inch corresponds to a "compressed" 2 inches, i.e. a 2 inch object will be "visually compressed" to fit into the 1 inch at the end of the tube. At 2 feet, you compress 4 inches into that 1 inch, and so on. At 100 feet, your 1 inch will now fit 200 inches (with it "compressing" to 1 inch at the end of the tube). That means an object 99.5 inches below the tube will be seen. And that is more than 8 feet. So if you were standing 6 feet above flat, level ground on a hypothetical FE, you would see the ground through the tube. If instead of level, if it was sloping down such that over 100 feet sideways it dropped no more ~2.3 feet then you would still see the ground.
For a sharper gradient, you would need further. For example, if for every 20 feet it dropped 1 foot, and you were standing 6 feet above it, you would need 180 feet, as in those 180 feet, the ground would have dropped by 9 feet, and the "visual compression" would compress 15 feet into that 1 inch at the end of the tube, so you would just see the ground.
Again, the simple questions you have been asked shows that to be the case.
What magic stops the blue line? The answer is NOTHING! It will travel to the eye and you will see things below the tube.
Likewise, if you are standing on a level surface (or even with a small downwards gradient), you can stand far enough back from a tree to see the tree from top to bottom through a level tube. That means you can see the ground through a level tube, depending on the FOV and the gradient.
Try something better. I'm not quite getting what you're trying to say.
Stop playing dumb. It is incredibly simple. If you are standing far enough back from a tree and look at it through a level tube you can see the entire tree from top to bottom. This shows that light is coming from the base of the tree and up into the tube and reaching your eye. Exactly what you claim should never happen.
You tell me how it's possible to see the ground of that downward gradient (not the upward gradient after it) by using a level tube on that gradient.
You have already been told.
We have a FOV. We don't magically see in 1D like your diagram pretends.
Remember this diagram (the one you are yet to show a problem for it):
While it is for a tube, a similar principle applies unless you have a scope that gives no FOV (i.e. a FOV of 0)
Light can come up from below that magical line you appeal to.
As light comes up from below, this allows you to see things below eye level, including a downwards gradient, depending on the gradient and FOV.
It doesn't take a genius to realise this, and these questions you keep avoiding show it quite simply and your repeated avoidance shows you likely know you are wrong and are just refusing to admit it.
I ask any genuine person who is not bound by the global peer pressured adherence, to do this for themselves and show that I am correct or wrong.
And if they show you are wrong, you will thus dismiss them as "bound by the global peer pressured adherence" rather than just admit you are wrong.
Now here's the key. I have done it.
Yet you refuse to provide any evidence of that.
Now why would I say this if I haven't checked it out?
To continue propagating your pathetic lie that the RE and so much of science is wrong, and because you need to double down to refuse admitting you are wrong.
It definitely helps if there's truth in it
Glad you can admit it helps. As there is plenty of truth in it.
Teaching a person how to go about in life is one thing. Teaching a person that it's not ok to question stuff outside of the stories told.... is another.
Then you misunderstand entirely.
The point is so they understand how the RE works so they can see all the nonsense spouted by people like you.
For example, without education, they might foolishly think that a simple tube magically makes it so you can only ever see 1 inch of any distant object.
With a proper education which includes understanding, they will realise that light can come up at an angle from the bottom of the tube to the eye.
Likewise, without education, they might be caught off guard by all the nonsense that pretends Earth is a tiny ball, rather than realise that on this massive ball the horizon, when viewed from close to sea level will be so close to eye level it isn't funny.
Likewise, without education, they might foolishly think that you should be able to feel velocity and think that everything should be thrown off the spinning Earth, rather than realise that you don't feel velocity, instead you feel acceleration (or velocity relative to another object), and that the acceleration at the surface of Earth due to Earth's massive size is insignificant for most everyday activities.