Here's a better experiment, one that actually uses scientific method rather than "A is true, therefore A must be true" logic.

Materials:

A high powered laser

A mirror

Perform at night (to ensure the laser doesn't get "lost" amidst all the sunlight).

Perform over the ocean (if possible), so as to provide a "flat" surface

1) Select an arbitrary altitude*

2) Shine a laser from a point above the north pole at *exactly* that altitude

3) Set up a receiver 3,000 miles distant, and once more at that altitude.

4) Shine the laser at the receiver "parallel" to the earth.

5) If the laser does not strike the receiver at precisely the same altitude (with tolerances for inaccuracies in measurement), then the earth is not flat.

6) If by some miracle the laser does strike the receiver within the range of tolerance, the world is then flat.

*Ideally the experiment would be run at 0ft, but as a rock might block the laser, higher altitudes might be needed to ensure that the laser does not get blocked by any object that may obstruct it's path.

Note: For a "proof" to have any real logical basis, it can make no arbitrary assumptions. Your "proof" assumes that all of it's statements are true, which is what is being contended. Prove that you can draw a **perfect** mathematical vector - using only current technology and not hypothetical measurements - between a series of structures, or your "proof" is nonsense.