16) “The experiment known as “Airy’s Failure” proved that the stars move relative to a stationary Earth and not the other way around. By first filling a telescope with water to slow down the speed of light inside, then calculating the tilt necessary to get the starlight directly down the tube, Airy failed to prove the heliocentric theory since the starlight was already coming in the correct angle with no change necessary, and instead proved the geocentric model correct.”

and

18) “The Michelson-Morley and Sagnac experiments attempted to measure the change in speed of light due to Earth’s assumed motion through space. After measuring in every possible different direction in various locations they failed to detect any significant change whatsoever, again proving the stationary geocentric model.”

These experiments did not test either the spherical or flat earth hypotheses, at all. At the time, of these experiments, one of the prevailing theories of the nature of light was that it required a medium through which it could travel and this was know as the aether. 

Both of these experiments were trying to determine the effects of the aether on the motion of light, by a theoretical process called aether drag. Airy’s experiment showed that there is no aether being dragged along by the Earth (and objects flying through space in general) and the Michelson-Morley experiment showed that the Earth isn’t flying through the stationary aether. 

In either case, the experiments don’t show that the Earth isn’t moving, but instead that there is no aether and the null results for both cases can be explained with special relativity. In fact, there is even a measurable amount of aberration in the location of stars that varies between +/- 20 arcseconds across the course of a year, depending on where the Earth is in its orbit, giving us evidence that the Earth is, in fact, moving. 

He also perpetrates a well know fallacy called false dichotomy. He says that an experiment failed to prove Hypothesis A, so it proves Hypothesis B. Not true – what about the possibility that the truth might be Hypothesis C, or D, or E….

Mr Dubay just didn’t understand what the experiments were testing. They really don’t have anything to do with proving the shape of the Earth.

http://the-uncredibles.tumblr.com/post/13259”81664/200-pensb-16-airys-failure-18

As Daimonie says: “I think we got sidetracked. Airy's failure - a term only used by flat earthers, as far as I can find - refers to an experiment that falsified a specific model and generally any aether model that included first-order drag. There is nothing in the experiment about relative motions and so forth. So, it's a false claim (also known as a lie).”

8.  “The Suez Canal connecting the Mediterranean with the Red Sea is 100 miles long without any locks making the water an uninterrupted continuation of the two seas. When constructed, the Earth’s supposed curvature was not taken into account, it was dug along a horizontal datum line 26 feet below sea-level, passing through several lakes from one sea to the other, with the datum line and water’s surface running perfectly parallel over the 100 miles.”

 So what? Of course this is exactly what we would expect from a (roughly) spherical Earth. For the whole length, the balance of gravitational and centrifugal forces are the same, so it is level to for all practical purposes.

“It's literally the instruction 'dig this deep'. Can you make an incision, 1 cm deep, in an apple?

You can? Well, therefore that apple is flat. Well done, that person.”

Thank you, Daimonie

For yet more information debunking Dubay read this, too.

 3) “The natural physics of water is to find and maintain its level. If Earth were a giant sphere tilted, wobbling and hurdling through infinite space then truly flat, consistently level surfaces would not exist here. But since Earth is in fact an extended flat plane, this fundamental physical property of fluids finding and remaining level is consistent with experience and common sense.”

Dubay claims that truly flat surfaces wouldn’t exist on a sphere. Not for the last time, Mr Dubay shows that he doesn’t understand why numbers and quantities matter when seeking the truth.

 Do the mathematics. Work out how large the curvature would be on a sea or large lake , given an Earth with a diameter of 7,900 miles.

Of course, we have been seeing the curvature for as long as we have been going to sea.

In the days of sail, sailors often noticed that they could see other ships further off if they climbed to the tops of their masts. This was an important factor in times of war or piracy.

One thing that Dubay doesn’t understand is that the difference between water being level, and its supposedly being flat. A level ocean, on the Earth’s surface, means that the surface is the same distance from the earth’s centre of gravity. It has run “downwards” (that is, inwards) as far as it can go!

And the Earth is not “wobbling and hurdling” – its slightly elliptical path around the sun is quite steady and not at all ‘wobbly’ – there is nothing to make it wobble, despite Dubay believes. Again, he simply doesn’t understand the ideas that he is criticising.

For those who understand geometry, the surface of the water is perpendicular to the centre of the earth at every point.

·         (Note: Not all water is actually flat. 

• Very small drops are slightly curved because of surface tension. On a small scale, surface tension is stronger than gravity. So we get this shape 
• The wind causes waves which roughen the surface very slightly.
•   Oceans aren’t completely level because of tides.