Max_Almond

1. Use a professional theodolite. Eye level is where the crosshair is:



2. Download and properly calibrate a theodolite app. Eye level is where the crosshair is:



3. Make your own theodolite using a spirit level. Eye level is level with the top of the spirit level, when you're sighting along it:



4. Use parallel lines to find the vanishing point (which is always at eye level):



5. Take a picture of some actual eyes, with the camera at eye height, and see where the horizon is:



6. Use a homemade water level. Eye level is where the surfaces of the water are aligned:


« Last Edit: May 22, 2018, 10:52:21 PM by Max_Almond »

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
1. Rowbotham discusses Theodolite Tangent here: http://www.sacred-texts.com/earth/za/za45.htm

6. Bobby personally performed this sort of water experiment himself and can tell you how sensitive and complex this seemingly simple experiment is. He decided to abandon it. Read his thread: https://forum.tfes.org/index.php?topic=9492.0
« Last Edit: May 22, 2018, 10:25:01 PM by Tom Bishop »

Max_Almond

1. Rowbotham discusses Theodolite Tangent here: http://www.sacred-texts.com/earth/za/za45.htm

6. Bobby personally performed this sort of water experiment himself and can tell you how sensitive and complex this seemingly simple experiment is. He decided to abandon it. Read his thread: https://forum.tfes.org/index.php?topic=9492.0

1. Rowbotham is only useful as an example of how to bamboozle simple folk with mindgames and twisted logic.

6. The water level equipment is more than accurate enough for purpose.
« Last Edit: May 22, 2018, 10:42:35 PM by Max_Almond »

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
1. Rowbotham discusses Theodolite Tangent here: http://www.sacred-texts.com/earth/za/za45.htm

6. Bobby personally performed this sort of water experiment himself and can tell you how sensitive and complex this seemingly simple experiment is. He decided to abandon it. Read his thread: https://forum.tfes.org/index.php?topic=9492.0

1. Rowbotham is only useful as an example of how to bamboozle simple folk with mindgames and twisted logic.

6. The water level equpiment is more than accurate enough for purpose.

Bobby's thread chronicles his journey and the issues faced. It is not a simple experiment.

Surveying is not easy. It is incredibly difficult and sensitive.

Surveying is always in error. Always. The device needs to be finely aligned, positioned, and calibrated. Even then, there is still inherent error.

http://whistleralley.com/surveying/theoerror/

Quote
As any surveyor should understand, all measurements are in error. We try to minimize error and calculate reasonable tolerances, but error will always be there. Not occasionally; not frequently; always. In the interest of more accurate measurements, we look for better instruments and better procedures.

The greater the distance you are trying to align your devices with, the greater the potential error. All devices need to be of superior calibration.

...

For the rest of your points, I see you give examples of a Theodolite app on a personal phone, which is not accurate. And another point which links to instructions for a user to build a theodolite himself; which is not a proof at all.
« Last Edit: May 22, 2018, 11:09:16 PM by Tom Bishop »

Max_Almond

But, like I say, "accurate enough".

We're not trying to split the atom here, Tom, or perform brain surgery - if that were the case I'd agree, a theodolite or a homemade water level isn't going to be precise enough, or the right tool for the job.

But when it comes to sufficiently measuring "eye level", they do just fine.

If you can show otherwise - I don't just mean "say otherwise" - then go ahead and do so.

But in the absence of that, all you're doing is blowing hot air.

Cheers. :)
« Last Edit: May 22, 2018, 10:42:48 PM by Max_Almond »

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
But, like I say, "accurate enough".

We're not trying to split the atom here, Tom, or perform brain surgery - if that were the case I'd agree, a theodolite or a homemade water level isn't going to be precise enough, or the right tool for the job.

But when it comes to sufficiently measuring "eye level", they do just fine.

If you can show otherwise - I don't just mean "say otherwise" - then go ahead and do so.

But in the absence of that, all you're doing is blowing hot air.

Cheers. :)

Read through Bobby's thread. He built and performed the experiment and posted pictures of his results, which were similar to the ones seen in your post, and at the end of it when he looked at the water levels of the water device in the post-analysis, the water was not perfectly level. One column was higher than the other, in contradiction to the usual assumption that water levels out.

These are not simple experiments. The devices need to be very finely calibrated, positioned and aligned. Bobby's thread is an example of this.

The tiniest error or uncertainty to the device will cause great error in the background.
« Last Edit: May 22, 2018, 11:32:03 PM by Tom Bishop »

Max_Almond

I'll just say one last time that they are accurate enough.

They don't have to be "perfectly precise" - just as, I'm sure, the floors in your house look pretty level despite being put there with instruments that weren't "100% accurate".

99% is good enough for purpose. Heck, it may be even higher than that.

To prove otherwise you would have to show that the degree of inaccuracy gives an incorrect result.

But repeating the same old tired argument shows nothing; proves nothing; and convinces no one.

They're six good methods. What are you afraid of? Be zetetic and try one. ;)

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
I'll just say one last time that they are accurate enough.

As was Bobby's statement leading up to the end. Towards the end of the thread someone posted a video and link to some maths for how small the horizon would actually dip on a Round Earth for the altitude and Bobby remarked that if he had seen the video he may not have even bothered with the experiment.

Your proofs are not well researched and there is no teardown to verify accuracy. At least Bobby was there and willing to verify the elements of the experiment in honesty; which is commendable.
« Last Edit: May 22, 2018, 11:27:51 PM by Tom Bishop »

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
I see that you yourself made a remark to Bobby on his latest experiment idea:

Be sure to calibrate it right: bloody difficult, I found.

Yet we are supposed to assume that all elements in the leveling devices and concepts in your examples are "good enough"?

You are making threads that we need to change our Wiki or theories because of it?
« Last Edit: May 22, 2018, 11:38:10 PM by Tom Bishop »

I see that you yourself made a remark to Bobby on his latest experiment idea:

Be sure to calibrate it right: bloody difficult, I found.

Yet we are supposed to assume that all elements in the leveling devices in your examples are "good enough"?
There is a large difference between trying to measure something with a phone and measuring it with tools that architects have been using for centuries.
Recommended reading: We Have No Idea by Jorge Cham and Daniel Whiteson

Turtle Town, a game made by my brothers and their friends, is now in private beta for the demo! Feedback so far has been mostly positive. Contact me if you would like to play.

Max_Almond

I see that you yourself made a remark to Bobby on his latest experiment idea:

Be sure to calibrate it right: bloody difficult, I found.

Yet we are supposed to assume that all elements in the leveling devices in your examples are "good enough"?

You are making threads that we need to change our Wiki or theories because of it?

I believe that's called "quote mining", Tom - as I'm sure you know, I later go on to say that the theodolite app is a perfectly adequate piece of kit for showing that the horizon falls below eye level as elevation increases:

Be sure to calibrate it right: bloody difficult, I found.

Best way seemed to be at sea level and set it to zero with the horizon there.

It may not give you perfectly accurate angles, but it will reflect perfectly that the angle you look down to the horizon at increases in tandem with your elevation.

Have you anything useful or relevant to add?
« Last Edit: May 22, 2018, 11:54:30 PM by Max_Almond »

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
I'll just say one last time that they are accurate enough.

As was Bobby's statement leading up to the end. Towards the end of the thread someone posted a video and link to some maths for how small the horizon would actually dip on a Round Earth for the altitude and Bobby remarked that if he had seen the video he may not have even bothered with the experiment.

Your proofs are not well researched and there is no teardown to verify accuracy. At least Bobby was there and willing to verify the elements of the experiment in honesty; which is commendable.

Hmm, not correct there Tom, I am sure Bobby will correct this, but,
He was referring to a video someone posted showing a mountain in transit with the horizon, and as the top of the further mountain in transit with the horizon was well below the hieght of the observer it was pretty conclusive of the horizon being below the eye line. I noticed you ran away at that point.

I would suggest if you are going to quote someone else, you actually get the context, and quote correctly.........

If you want to see the post, go to page 15 of  “the horizon is always at eye level” over on Flat earth debate.
Sorry, dont know how to link it. But i am pretty sure you can find it.......
« Last Edit: May 23, 2018, 12:56:38 AM by Tontogary »

Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
I'll just say one last time that they are accurate enough.

As was Bobby's statement leading up to the end. Towards the end of the thread someone posted a video and link to some maths for how small the horizon would actually dip on a Round Earth for the altitude and Bobby remarked that if he had seen the video he may not have even bothered with the experiment.

Your proofs are not well researched and there is no teardown to verify accuracy. At least Bobby was there and willing to verify the elements of the experiment in honesty; which is commendable.

Hmm, not correct there Tom, I am sure Bobby will correct this, but,
He was referring to a video someone posted showing a mountain in transit with the horizon, and as the top of the further mountain in transit with the horizon was well below the hieght of the observer it was pretty conclusive of the horizon being below the eye line. I noticed you ran away at that point.

I would suggest if you are going to quote someone else, you actually get the context, and quote correct.........

Here is the post in question. Bobby remarks to it "If I'd seen that video earlier, I might never have bothered with this topic."

I assumed it was because the video and text provided calculation showing that the expected RET horizon dip was very slight, and because Bobby had been expecting something much more pronounced, but Bobby can speak on that.

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
#7, actually measure the arc of the sky, horizon to horizon from an elevated platform!

Ok no pictures for this one, but...
A marine sextant (used to measure angles to an accuracy of 10.1 arc minute) measures angles up to 130 degrees.
Using an object (like the sun at noon) it is possible to measure from one horizon to the sun (or moon if high enough) or even a star or planet (if seen) and then to the obtuse angle across the sky to the opposite horizon.
Simple maths (adding the 2 together) gives you the arc of the sky, which if there is a dip of the horizon will be more than 180 degrees.

I have done this........

Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

*

Offline Bobby Shafto

  • *
  • Posts: 1390
  • https://www.youtube.com/channel/UCdv72TaxoaafQr8WD
    • View Profile
    • Bobby Shafto YouTube Channel
Here is the post in question. Bobby remarks to it "If I'd seen that video earlier, I might never have bothered with this topic."

I assumed it was because the video and text provided calculation showing that the expected RET horizon dip was very slight, and because Bobby had been expecting something much more pronounced, but Bobby can speak on that.

My meaning was that that answers the question of whether or not the horizon is always at eye-level. I wouldn't have bothered with the question had I seen that. Not that the dip is "slight." But that there's no question of dip.

I'm still glad I got into it because I think it's always interesting to check for yourself and verify what others report. And though it does take some care, you it's within reach of anyone to detect.

Max_Almond

I assumed it was because the video and text provided calculation showing that the expected RET horizon dip was very slight, and because Bobby had been expecting something much more pronounced, but Bobby can speak on that.

The text around that video very clearly shows that the poster felt it was a categorical denial of the 'horizon rises to eye level' lie.

I assumed the reason Bobby said what he said was because, had he seen the vid before, it would have saved the trouble, given that it shows what he was looking to show.
« Last Edit: May 23, 2018, 01:21:24 AM by Max_Almond »

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
Here is the post in question. Bobby remarks to it "If I'd seen that video earlier, I might never have bothered with this topic."

I assumed it was because the video and text provided calculation showing that the expected RET horizon dip was very slight, and because Bobby had been expecting something much more pronounced, but Bobby can speak on that.

My meaning was that that answers the question of whether or not the horizon is always at eye-level. I wouldn't have bothered with the question had I seen that. Not that the dip is "slight." But that there's no question of dip.

I'm still glad I got into it because I think it's always interesting to check for yourself and verify what others report. And though it does take some care, you it's within reach of anyone to detect.

Well, you were in error to quickly declare victory then. We can see that the matter was swarmed over in the comments section:

Quote
The error of your reasoning is that you assume that you see the real horizon. Well, you see the 'horizon', but only as the limit of visibility of the sea surface. But not every limit of visibility of the sea surface is the real horizon, the geometric one, the one that matters in this case. Imagine that you live on flat land, let us assume that it is. And imagine that on the day you did this observation the surface of the sea was visible only at a distance of about 45.8 km. Well, with such assumptions, the result of your observation is the same as the one you showed. Is 46 km low visibility? Well, this is more or less average visibility. Most often the visibility reaches about several dozen kilometers. Only in exceptional circumstances, visibility, low above the surface of the sea reaches, for example, 200-300 km.

Why is visibility not infinite? There are a lot of reasons. The two most important are lighting (brightness) and air. What is air? Well, the air is fog. Yes, the air is 'diluted fog', because it differs from the fog only by the degree of dilution. In the air, as in the fog, various fine particles, dust and humidity are always suspended.

That is why we, the inhabitants of the earth, can not see infinitely, even if the earth is flat. Because there is air, or 'diluted fog'. I hope you understand that on a foggy day you also see a border of the sea surface and that this border does not coincide with the geometric horizon. Well, it is similar in every other day. But on a foggy day it is obvious to you, while on a normal day, as we can see it is not. On a foggy day the limit of visibility of the sea surface reaches, for example, half a mile, whereas on an average day, for example, 35 miles. Because the difference between the first and the second day is only in the degree of dilution of the fog.

But there is no day that you can see at an infinite distance !

The horizon of the sphere is at a specific distance depending on the height above the surface of the sphere. But the horizon of a sufficiently large flat surface ('infinite flat surface') is infinite. However, in the real world the limit of visibility of the sea surface is not the same as the geometric horizon. Because in the real world, apart from geometry, there are also physical phenomena, i.e. air, that is, 'diluted fog', which limits visibility.

Therefore, such observations with the horizon are not good for inferring the shape of the earth. Because most often we can not know if a boundary of the sea surface we see is a geometric horizon, or is it only due to the physical limitation of visibility. You would have to pump air out of the surface of the earth and the sea, so as to have a vacuum and then you would have a chance to see at any distance (of course with the right surface lighting!). But in ordinary conditions, the visibility, eg of the surface of the sea, is limited to several dozen kilometers.

In short:

1. One issue is the geometric horizon, and the second one is the horizon resulting from the limitation of visibility.

2. the geometric horizon over the infinitely large flat surface is level and does not decrease.

3. in the real world there are physical phenomena that limit visibility (e.g. air as 'diluted fog') => you can not see infinitely far away, even on flat ground => 'horizon' (different from the geometric one) always lowers below the level, even on a flat land.

I looked at the video, and the distant horizon was not particularly the sharpest thing. You can see that the distant lands and the horizon was muddied and a bit blurred, lending credence to the above.
« Last Edit: May 23, 2018, 01:18:17 AM by Tom Bishop »

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
So then if we can NEVER see a horizon, (because it is not at eye level, ever) how do people successfully calculate their position using the sun and stars at sea?

If there is not a clear horizon then we cannot take the altitude of the sun or stars to make our calculations.

Now if you know how how we do it, i would love to know what i have been doing wrong for the last 33 years.
Maybe you will enlighten me?

Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

*

Offline Tom Bishop

  • Zetetic Council Member
  • **
  • Posts: 10637
  • Flat Earth Believer
    • View Profile
So then if we can NEVER see a horizon, (because it is not at eye level, ever) how do people successfully calculate their position using the sun and stars at sea?

If there is not a clear horizon then we cannot take the altitude of the sun or stars to make our calculations.

Now if you know how how we do it, i would love to know what i have been doing wrong for the last 33 years.
Maybe you will enlighten me?

At altitudes near sea level where the earth's horizon is sharp, it may be at eye level per Earth Not a Globe's explanation of finite perspective lines. This has not been disproven.

We know that from an international flight the horizon is just a foggy mess.

At various other altitudes and atmospheric conditions, the situation is less clear; but you may keep trying. I can see in that video that it is not the clearest day.
« Last Edit: May 23, 2018, 01:42:59 AM by Tom Bishop »

*

Offline Bobby Shafto

  • *
  • Posts: 1390
  • https://www.youtube.com/channel/UCdv72TaxoaafQr8WD
    • View Profile
    • Bobby Shafto YouTube Channel

At altitudes near sea level where the earth's horizon is sharp, it may be at eye level per Earth Not a Globe's explanation of finite perspective lines. This has not been disproven.

We know that from an international flight the horizon is just a foggy mess.

At various other altitudes and atmospheric conditions, the situation is less clear; but you may keep trying. I can see in that video that it is not the clearest day.
Well, here's some new information. Rowbotham's EnaG reasoning for the horizon coinciding with "eye level" is only for sea level range observations. And then only for periods when the horizon is subjectively "sharp." Else, the principle's applicability is less clear.

That's interesting, and I did not see that anywhere in the book, nor in any of the previous discussions about the "horizon is always at eye level" claim.

I can't dispute that for rises in elevation of say, oh, the height of the Grand Brighton, that one can't well disprove that the horizon is always at eye level. The angle change on a convex surface of the size claimed by a globe earth would be quite small and difficult to detect with crude precision. Where it would start to be detectable, though, you say the horizon (and situation) is less clear.

Okay. Thanks for explaining that.
« Last Edit: May 23, 2018, 02:50:26 AM by Bobby Shafto »