My advice for creating a Flat Earth presentation is to do the following:
1. Show that the Flat Earth is a model under development, and that there are many interesting ideas.
2. Bring up the Earth Not a Globe Experiments, its repetitions, and hammer home how the results are not easily explained away with "refraction" as alleged by Rowbotham's opponents.
The "refraction" argument introduces increasingly absurd coincidences. See my post here:
Unfortunately, most of his experiments have been invalidated due to the proximity of his telescope to the surface of the river, where the effects of refraction are strongest.
Incorrect. Such an argument is supposing that there is a refraction effect that makes a Round Earth look like a Flat Earth.
This was explained to you in other threads. If you are going to claim that Rowbotham experienced atmospheric refraction effects where light passed through some warm air and a mirage was created then you are going to have to explain the coincidences that this argument creates.
It is quite the coincidence that a a chance atmospheric effect occurred at the time Rowbotham did the experiment.
If theorized a permanent one; it quite a coincidence and quite curious that there is this permanent gradient of warm air or pressure above the Bedford Canal at all times that makes the Round Earth look flat.
It is quite the coincidence that this effect, whether you theorize it to be chance or "permanent," is an effect that projects the body to the exact height it needed to be if the earth were flat, and no more or no less, according to Round Earth curvature and according to the the distance looked across in the particular experiment.
It is quite the coincidence that this effect projected the target and the land around it into the air and produced a solid picture rather than a wavy mess like most mirages produce.
Quite the coincidence that this perfect Flat Earth effect occurred on the numerous times Rowbotham performed the experiment. Quite the coincidence that Lady Blount and others experienced it too.
That is a bad argument. You are arguing for increasingly absurd coincidences. Any honest person should feel embarrassed to maintain that all of these coincidences happened.
The Earth Not a Globe experiments are not "invalidated." You are just a Coincidence Theorist.