Shouldn't you know some proofs for a round Earth before you make a thread like this? I'm confused.
Maybe mention something about the Transit of Venus? Damn. I shouldn't be doing this for you.
Since you asked so nicely:
I. Horizon
A. Flat Horizon—An observer on the surface of a still ocean viewing sees the horizon as flat.
B. Rounded Horizon—An observer on the surface of a still ocean viewing at a great height sees the horizon as rounded. It appears to be highest directly ahead of the viewing angle and drops equally away to both sides at a constant predicted rate, regardless of the viewing angle.
C. The Higher, the Farther—An observer on a middle floor of a tall building watching a departing ship disappear over a clear horizon can climb to the top floor and again view the ship.
D. Tops First—An observer on a ship approaching a port with skyscrapers will first see the tops of the tallest buildings then the rest of the city’s skyline as the ship comes further into port.
II. Earth Based Astronomy
A. Apparent size of the Sun—Regardless of the season, the time of day, or viewing location, an observer views the Sun in the sky as same shape and size.
B. Sunrise and sunset—An observer sees the sun set and rise as a disk sliding over the horizon at a predicted time and angle.
C. Phases of the Moon—An observer sees the Moon go through predicted phases (with the illuminated face facing the Sun when both are visible in the sky).
D. Moonrise and Moonset—An observer sees the Moon rise and set at the predicted time and angle.
E. Shadows on the Moon—At the first quarter and third quarter of the lunar phases, an observer sees shadows of features of the moon pointing in opposite direction, but always away from the Sun.
F. Total Solar Eclipse—An observer sees a total solar eclipse at a predicted time and location.
G. Annular Solar Eclipse—An observer sees an annular solar eclipse at a predicted time and location.
H. Lunar Eclipse—An observer sees a total lunar eclipse at a predicted time and location.
I. Retrograde Motion of Mars—At the predicted times, an observer sees that Mars apparently reverses its motion in the sky.
J. Retrograde Motion of Jupiter—At the predicted times, an observer sees that Jupiter apparently reverses its motion in the sky.
K. Retrograde Motion of Saturn—At the predicted times, an observer sees that Saturn apparently reverses it motion in the sky.
L. Retrograde Motion of Uranus—At the predicted times, an observer sees that Uranus apparently reverse its motion in the sky.
M. Transit of Mercury—An observer sees Mercury transit the Sun at the predicted time and along the predicted path.
N. Phases of Mercury—An observer sees Mercury as predicted as a partially illuminated disk with the illuminated portion facing the Sun.
O. Transit of Venus—An observer sees Venus transit the Sun at the predicted time and along the predicted path.
P. Phases of Venus—An observer sees Venus as predicted as a partially illuminated disk with the illuminated portion facing the Sun.
III. Radio
A. Ham Radio Distance—A listener can hear ham radio stations from around the world.
B. Commercial Radio Distance—A listener cannot hear commercial radio stations beyond a predicted distance during daylight.
C. Nighttime Distance—A listener can hear commercial radio stations during nighttime that he or she could not hear during daylight.
IV. Foucault Pendulum—An observer will see that a Foucault Pendulum’s motion rotates predictably over the course of a day based on latitude.
V. Parallax
A. Moon Distance—Two coordinated observers separated by large distance will obtain predicted angles to consistently determine the distance to the Moon.
B. Sun Distance— Two coordinated observers separated by large distance will obtain predicted angles to consistently determine the distance to the Sun.
C. ISS Distance—Two coordinated observers separated by large distance will obtain predicted angles to consistently determine the distance to the ISS.
D. Iridium Flash Distance—Two coordinated observers separated by large distance will obtain predicted angles to consistently determine the distance to the flash off one of the antenna dishes of an Iridium satellite.
VI. Rotation of the sky
A. Northern Sky Rotation—An observer in the Northern Hemisphere will observe that the stars appear to rotate about a fixed point in the northern sky.
B. Southern Sky Rotation—An observer in the Northern Hemisphere will observe that the stars appear to rotate about a fixed point in the southern sky.
VII. Angle of Polaris
A. North Pole—An observer at the North Pole will see Polaris directly overhead.
B. 45 Degrees—An observer at 45° North will see Polaris at 45° above the horizon.
C. Equator—An observer at the Equator will see Polaris at the horizon.
D. South—An observer south of the Equator will not see Polaris.
VIII. Angle of Polaris
A. North Pole—An observer at the South Pole will see Crux directly overhead.
B. 45 Degrees—An observer at 45° South will see Crux at 45° above the horizon.
C. Equator—An observer at the Equator will see Crux at the horizon.
D. South—An observer north of the Equator will not see Crux.
IX. Intensity of the Sun—An observer will measure the predicted solar intensity on a cloudless day, regardless of the time of day or season.
X. Cavendish Experiments—An observer will measure the same value of G for any sizes or shapes or materials used in a Cavendish device.
XI. Lake—An observer will measure the predicted angle of deviation from level of a line of sight over a given, large distance over a still body of water
XII. Zodiac—An observer will determine that the Sun appears to moves in relation to the Zodiac in the predicted manner.
XIII. Photographs—The observer will see the Earth as a sphere in photographs taken for sufficiently high altitudes.
XIV. Man to moon
A. Earthrise—The observer on the Moon will see the earthrise at the predicted time and angle.
B. Distance—Using the equipment left on the moon by the Apollo project, an observer will accurately measure the predicted distance to the Moon.
XV. Transits of the ISS
A. Sun—An observer will see the ISS transit the Sun at the predicted time and along the predicted path.
B. Moon— An observer will see the ISS transit the Moon at the predicted time and along the predicted path.
XVI. Launch—An observer will see in the sky a satellite following a successful space launch following the predicted course.
XVII. Meteors—An observer will see the meteors from a predicted shower or storm radiate from a predicted point in the sky.
XVIII. Lunar Eclipse Shadow—An observer will always see a round edge to the shadow on the Moon during a Lunar Eclipse.
XIX. Commercial flights
A. Great circle—An observer will notice that long commercial flights travel mostly along great circle routes.
B. Times—An observer will notice that commercial flight times will not be less than a predicted minimum.
XX. Transverse the Globe—An observer may circumnavigate the globe in any direction.
XXI. Surveyors—When surveying large features, surveyors must account for the curvature of the Earth.
XXII. Mountaintops—A pair of coordinated observers on two distant mountain tops within visual range of each other will both measure by line of sight the other’s position to be lower than it is measured by the other.
XXIII. Latitude Lines—An observer will notice that latitude lines are always straight and equidistant.
XXIV. Longitude Lines—An observer will notice that longitude lines are always straight and diverge and then converge, going north to south (or visa versa).
XXV. Tides
A. Daily—An observer will notice that there are two high tides and two low tides at predicted times and the Moon is high is the sky during one high tides each day and low on the horizon at all low tides at many locations.
B. Monthly—An observer will notice spring and neap tides each twice during the lunar month, with spring tide during new and full moons and neap tide during the first and third quarter at many locations.
XXVI. Auroras—An observer will notice auroras near the poles, and they will occur at around both poles with nearly the same intensity and duration.
XXVII. Modern navigation
A. Gyroscopes—An observer will note that modern navigation when aided by gyroscopes provide readings consistent with predicted results.
B. GPS—An observer will note that modern navigation when aided by GPS provide readings consistent with predicted results.
XXVIII. Weather patterns
A. Weather Fronts
1. Speed—An observer will note that weather fronts move with about the same speed in either hemisphere and in line with their internal wind speeds.
2. Polar Origins—An observer will note that weather fronts originate from both poles with approximately the same frequency and intensity.
B. Trade winds—An observer will note that the trade winds in both hemispheres blow at approximately the same speed, but in opposite directions.
C. Large Storm Systems
1. Speed—An observer will note that large storm systems move with about the same speed in either hemisphere and arrive predictably across great distances.
2. Direction—An observer will note that large storm systems are about of equal intensity in either hemisphere, but tend to move in opposite east versus west directions within the same latitude bands.