[edby]

Rowbotham Chapter XIV:

Send a young girl, with short garments, from C on towards D; on advancing a hundred yards or more (according to the depth of the limbs exposed) the bottom of the frock or longest garment will seem to touch the ground; and on arriving at H, the vanishing point of the lines C, D, and E, H, the limbs will have disappeared, and the upper part of the body would continue visible, but gradually shortening until the line A, B, came in contact with E, H, at the angle of one minute. http://www.sacred-texts.com/earth/za/za32.htm

Is there any evidence for such an effect? Photographic evidence suggests not



Moreover, a theoretical reason is that, if the ground is perfectly flat, and if light travels in straight lines, light will follow a line drawn from the ankle parallel to the ground to a point above the level of the ground where the observer is positioned. So the observer will see the ankle.

This requires only one assumption, namely that light travels in a straight line across the earth.

[BillO]

This requires only one assumption, namely that light travels in a straight line across the earth.

You need to be careful here.  Light does not generally travel in straight lines across the earth due to changes in air density and temperature.  These effects are most pronounced near the surface and they change throughout the day as the surface temperature changes and either warms the air or gets cooled by the air.  The net effect is that light can either be refracted up or down depending on conditions.  Indeed, those conditions can change along the line of sight such that light is forced to follow a complex path.

So, while I agree with you, it would take proof of fairly extraordinary conditions, to wit where there is a net zero temperature, and hence air density, change over the entire line of sight, to produce any worthwhile photographic evidence to either support a flat earth of a spherical earth.

The fact that Rowbotham uses such experimentaly unrealizable arguments is enough to dismiss him as a quack.

[edby]

This requires only one assumption, namely that light travels in a straight line across the earth.

You need to be careful here.  Light does not generally travel in straight lines across the earth due to changes in air density and temperature.  These effects are most pronounced near the surface and they change throughout the day as the surface temperature changes and either warms the air or gets cooled by the air.  The net effect is that light can either be refracted up or down depending on conditions.  Indeed, those conditions can change along the line of sight such that light is forced to follow a complex path.

So, while I agree with you, it would take proof of fairly extraordinary conditions, to wit where there is a net zero temperature, and hence air density, change over the entire line of sight, to produce any worthwhile photographic evidence to either support a flat earth of a spherical earth.

The fact that Rowbotham uses such experimentaly unrealizable arguments is enough to dismiss him as a quack.

I agree, but the claim was that the ankles will always be visible on a flat earth, so long as light travels in straight lines.

Now FET may dispute that light travels in straight lines, but that is nothing to do with perspective. Moreover perspective collapses entirely if light is bendy.

[BillO]

Got it, and I agree.

[HorstFue]

Now FET may dispute that light travels in straight lines, but that is nothing to do with perspective. Moreover perspective collapses entirely if light is bendy.

I don't think, perspective, which is a mathematical projection from real world to an image plane, may not be possible with "curved rays". BTW. Mr Rowbotham denies any refraction and curvature of Earth, and that's the reason, why he had come up with this abstruse "law of perspective".
These effects similar to the "ship sinking behind the horizon" seem not so rare, so he had to find alternate way to explain it.

I agree, but the claim was that the ankles will always be visible on a flat earth, so long as light travels in straight lines.

These 'ankles' may be visible until you reach observers eye resolution. But this is not perspective.
Alone defining a 'distance' to an imaginary point, the vanishing point, is utter nonsense.
Defining this distance by hight of the observer and eye resolution, turns around the projection. The distance, where objects 'vanish' due to resolution, is given by the object size and eye resolution.
Do you think, you get better eye resolution and see the same object farther away, if you climb a ladder or so?
(assuming in both cases there's no obstruction between you and the object)
Why is eye resolution so "surface affine"? Does it make any difference, if the observed object is close to the ground or higher up? Where would e.g. a hat, on the head of the girl, same size as here ankles, 'vanish' from view?

[Mykrox47-9]

 How can someone who dropped out of school at the age of 9 write such seemingly intelligent arguments? Didn't Samuel Rowbotham run away from a lecture in Blackburn? Is this the same Samule Rowbotham who proposed the Bedford Level experiment? And wasn't that ruled in favor of Globe Earth? And the lantern at Eddystone on Plymouth Hoe? If the forerunner of the Zetetic Society was deemed a charlatan, what does that say about the validity of this group?

[AATW]

Is there any evidence for such an effect? Photographic evidence suggests not

I've never seen any. Like a lot of Rowbotham's claims his evidence is basically "this is what I saw" or "it is widely observed" although I've never seen photographic evidence of the effect. You may get some effect in certain conditions with refraction if there's some mirage effect which may hide the lower part of an object but otherwise it's just an attempt by Rowbotham to explain things like the sinking ship effect in another way other than the earth being the shape it really is.

[BigGuyWhoKills]

How can someone who dropped out of school at the age of 9 write such seemingly intelligent arguments?

Money.  In those days, money meant you had free time.  It often also meant you likely had access to a library.  People with money would pass time by reading.  This was about as good an education as one could get from any school short of a few serious universities.

Poor people were working in the fields and stressing over how they would put food on the table.  This left them very little time to think about the nature of the universe.  If you look at the great thinkers and inventors of times long past, they were usually wealthy.

And he may sound slightly more intelligent than he was because of the nature of the English vernacular at the time.  This should not be considered an indication of intelligence.

[Mykrox47-9]

 Then, there were the questions that followed. He was a conman. When put on the spot about ships disappearing over the horizon, he ran away. And he was not a great thinker. Just a good BS'er. You said it yourself, not many regular folks with the education to know better.

  He took advantage of people's ignorance. Check the Wiki about his life. This is who FE'rs revere. Maybe in another 100 years, they might actually be close to a working map.

[BigGuyWhoKills]

Then, there were the questions that followed. He was a conman. When put on the spot about ships disappearing over the horizon, he ran away. And he was not a great thinker. Just a good BS'er. You said it yourself, not many regular folks with the education to know better.

  He took advantage of people's ignorance. Check the Wiki about his life. This is who FE'rs revere. Maybe in another 100 years, they might actually be close to a working map.

They don't revere him, but it IS a little odd that they quote his work like it is a peer reviewed industry white paper or a proper thesis.  He definitely IS a con man, as is evidenced by his legal dispute with Wallace.  What he did with the Bedford level experiment would today qualify as mail fraud.

He uses "ad populum" a lot (https://en.wikipedia.org/wiki/Argumentum_ad_populum).  In his eclipse page (http://www.sacred-texts.com/earth/za/za29.htm), he says things like

Code: [Select]

It is a well known fact, that if the sun is allowed to shine strongly upon a common coal, coke, wood, or charcoal fire, the combustion is greatly diminished; and often the fire is extinguished.It boggles my mind that he thinks adding energy to a fire will put it out prematurely (implying this is without consuming all the fuel).

What is more egregious, is he continues his line of reasoning after this and similar logical fallacies, claiming that he just proved something!  To someone that doesn't have a good sense of rigor, they may buy into that.  That, right there, is one of the worst parts of the internet.  Something that is patently wrong, if it has enough confirmation bias for you, can be passed off as true.

It is also odd that FE'ers have practically nothing modern to cite, and literally nothing that is properly peer reviewed.

[Mykrox47-9]

 To be clear, I am not a scientist. But I was a Fire Control Technician on a destroyer. I've been half way around the world.I watched ships go over the horizon using binoculars so big, I had to hold them with both hands. And I mean watched. The whole time. It's fascinating.

 It never ceases to amaze me when FE'rs talk about this. I've seen the Milky Way at sea. It's spooky cool. Really puts the scale in perspective. I think the die hard believers are frightened by the prosect of an infinite distance above their heads. A reverse acrophobia if you will. I know what I've seen and I trust that.

 

[Westprog]

  I know what I've seen and I trust that.

It's a fundamental principle of FET to deny the evidence of one's eyes, while at the same time maintaining the opposite.