If you want a definitive, permanent, accurate answer to the Earth being flat, get yourself:
A) a pinpoint laser that has very low dispersion.
B) Get about 500 yards of clear plastic tubing. Diameter does not matter. Find the middle. Insert a T-fitting with about a foot of turbing on it, and close off the end of the tube.
Pump it full of water and pinchoff/plug ends to keep it in.. trying to trickle the water in by gravity would take quite a long time.
C) Get some also-cheap tripods, five of them.
D) Get a cheap scope you can affix to the laser trained along a parallel axis to the laser.
1) Lay out plastic tubing. A straight line is preferable, but not mandatory, with about a five-foot-extra bump in the middle.
2) Erect two end tripods at one ends. Set up laser on one of them and turn it on, then point it at a target mounted on a tripod just past the furthest tripod used to hold up the water tube,about 490 yards from each other or so.
3) Erect third tripod about center distance between the others, and attach T-fitting part comfortably on the tripod somewhere near your laser line, on its target. Do not open the T fitting short piece of tube, which should be vertically oriented above the rest of the tubing.
4) Attach tubing to two ends tripods, with a target paper or such on it so you can see where the tubing is relative to the laser beam. You will need to get them close to what you regard as being level.
5) with tubing ends on both ends about three feet above laser mark, unplug both ends of the tubing. One end will be lower than the other. whatever level the water ends up at in both ends after it spills out of the lowest end is your level line. That is the line that indicates that both of those water lines are the same distance from the Earth's center of gravity. Adjust your laser so it hits your two end targets right at the water line.
Get tubing so that both ends are about two inches above the laser line.
6) The step after this one is the part where you find out if the Earth is flat or round, definitively. Remember, you have to have a pinpoint laser, not some huge fat scattergun low-buckPost too long. Click here to view the full text.