ENaG Chapter XIV: "Spherical Excess"

On reading through Earth Not a Globe, I've spotted a few misunderstandings and faulty assumptions. I plan to start up individual threads on some of these, so that they can be discussed and, hopefully, clarified.

I've decided to start with the section on spherical excess, found here.

Spherical excess is the theory behind the 'triangle with three 90 degree angles' thought experiment, which has been proposed on this forum before. This experiment is a bit impractical, due to the distances involved, but "...the excess of three spherical angles above two right angles..." has been observed and recorded on smaller scales already.

Rowbotham contends that this excess is due to collimation, which he mistakenly compares to refraction: "...the influence of refraction or "collimation" in their instruments...". Apparently, he did not know that collimation is "the accurate adjustment of the line of sight of a telescope". Even then, if there were an error present in the measurements being made, it would be either left or right, but always the same way, and always the same amount, which would mean that the angles would still be accurately measured, and any excess found would be real.

So, given that spherical excess has been accurately measured as long as 150 years ago, despite Rowbotham's assertions to the contrary, I would consider it a reasonable contribution to the evidence supporting a round earth.

What are your thoughts?

The real question for me is... how on Earth did you fight the boredom all the way through to chapter 14?

This is a vain attempt at twisting evidence against your claim into evidence for it. As a general principle, repeating the measurements several times is better, not worse, than making them just once or twice.

And the analysis of several sets of measurements is a lot more complicated than "many measurements... that's bad". Repeating the measurements under a variety of circumstances is exactly what a good scientist does. If he shows the complete set of results, and not only those that support his conclusions, he is giving other scientists a good sense of how solid the conclusions are.

Also, you have to take into account that repeating the experiment takes care of some kinds of experimental error, but not all kinds. A good scientist gives as much information as possible so any of his colleagues can find sources of error that he did not see.

What Rowbotham does is the total opposite. He does not give us the details or the results of the measurements he criticizes. He does not analyze the possible sources of error, either systematic or not. He does not give us even a hint of the circumstances or the design of the experiment. He just criticizes the fact that the scientists did their due diligence and repeated the experiment several times, hoping that his audience is ignorant.

I don't care whether the experiment Rowbotham describes was in fact done, or whether it was done right, or if the results indicated a curvature or no curvature. What I can tell you is that Rowbotham is no source at all for scientific data.

On reading through Earth Not a Globe, I've spotted a few misunderstandings and faulty assumptions. I plan to start up individual threads on some of these, so that they can be discussed and, hopefully, clarified.

I've decided to start with the section on spherical excess, found here.

Spherical excess is the theory behind the 'triangle with three 90 degree angles' thought experiment, which has been proposed on this forum before. This experiment is a bit impractical, due to the distances involved, but "...the excess of three spherical angles above two right angles..." has been observed and recorded on smaller scales already.

Rowbotham contends that this excess is due to collimation, which he mistakenly compares to refraction: "...the influence of refraction or "collimation" in their instruments...". Apparently, he did not know that collimation is "the accurate adjustment of the line of sight of a telescope". Even then, if there were an error present in the measurements being made, it would be either left or right, but always the same way, and always the same amount, which would mean that the angles would still be accurately measured, and any excess found would be real.

So, given that spherical excess has been accurately measured as long as 150 years ago, despite Rowbotham's assertions to the contrary, I would consider it a reasonable contribution to the evidence supporting a round earth.

What are your thoughts?

Your argument is based on semantics and the definition of a word.  The meaning of the word is clear from the context in which it is meant.  Please move on. 

If it is clear -and- being used improperly, is the definition still unimportant?

On reading through Earth Not a Globe, I've spotted a few misunderstandings and faulty assumptions. I plan to start up individual threads on some of these, so that they can be discussed and, hopefully, clarified.

I've decided to start with the section on spherical excess, found here.

Spherical excess is the theory behind the 'triangle with three 90 degree angles' thought experiment, which has been proposed on this forum before. This experiment is a bit impractical, due to the distances involved, but "...the excess of three spherical angles above two right angles..." has been observed and recorded on smaller scales already.

Rowbotham contends that this excess is due to collimation, which he mistakenly compares to refraction: "...the influence of refraction or "collimation" in their instruments...". Apparently, he did not know that collimation is "the accurate adjustment of the line of sight of a telescope". Even then, if there were an error present in the measurements being made, it would be either left or right, but always the same way, and always the same amount, which would mean that the angles would still be accurately measured, and any excess found would be real.

So, given that spherical excess has been accurately measured as long as 150 years ago, despite Rowbotham's assertions to the contrary, I would consider it a reasonable contribution to the evidence supporting a round earth.

What are your thoughts?

My thoughts are that you don't understand what scientific method is: If you find inconsistencies in one theory it does not contribute to the proof of another.

That is not his assertion. There is a general lack of evidence for triangles in excess of 180 degrees available, however it would seem that they have been measured and a long time ago. Triangles in excess of 180 degrees are a phenomenon derived from spherical geometry and not Euclidean.

My thoughts are that you don't understand what scientific method is: If you find inconsistencies in one theory it does not contribute to the proof of another.

In general what you are saying is right. Inconsistencies in one theory do not add credibility to another. However, this specific inconsistency, where the sum of the angles of a supposedly flat triangle add to more than 180 degrees, is evidence towards a non-flat Earth.

The quality of the measurement is impossible to assess, since Rowbotham did not give any references. We don't even know that the experiment was made. We also don't have information on the quality of topographic measurement equipment of the time. But if you combine the result of local curvature with the even greater evidence that the Earth's surface is not concave, you get evidence that the place where the measurement was made is actually convex.

This is a really small piece of evidence, and, I repeat, the quality is unknowable, but it is a tiny evidence towards the roundness of whatever place the measurement was made.

Quote from: Amalgafiend on May 15, 2013, 04:13:52 AM

My thoughts are that you don't understand what scientific method is: If you find inconsistencies in one theory it does not contribute to the proof of another.

In general what you are saying is right. Inconsistencies in one theory do not add credibility to another. However, this specific inconsistency, where the sum of the angles of a supposedly flat triangle add to more than 180 degrees, is evidence towards a non-flat Earth.

The quality of the measurement is impossible to assess, since Rowbotham did not give any references. We don't even know that the experiment was made. We also don't have information on the quality of topographic measurement equipment of the time. But if you combine the result of local curvature with the even greater evidence that the Earth's surface is not concave, you get evidence that the place where the measurement was made is actually convex.

This is a really small piece of evidence, and, I repeat, the quality is unknowable, but it is a tiny evidence towards the roundness of whatever place the measurement was made.

We can also assume that the measurement was of sufficient quality that Rowbotham needed to address, so it was non-trivial.

Quote from: Amalgafiend on May 15, 2013, 04:13:52 AM

My thoughts are that you don't understand what scientific method is: If you find inconsistencies in one theory it does not contribute to the proof of another.

In general what you are saying is right. Inconsistencies in one theory do not add credibility to another. However, this specific inconsistency, where the sum of the angles of a supposedly flat triangle add to more than 180 degrees, is evidence towards a non-flat Earth.

My point exactly.