Consider a sphere. Since a sphere has a consistent shape, no matter where on it you stand, you have exactly the same amount of sphere under you. (Imagine an ant walking around on a crystal ball. From the insect's point of view, the only indication of movement would be the fact the ant is moving its feet—the shape of the surface would not change at all.) A sphere's center of mass is in the center of the sphere, which means gravity will pull anything on the surface of the sphere straight down toward the center of the sphere. This will occur no matter where on the surface the object is located.
11.) As the mariners' compass points north and south at one time, and as the North, to which it is attracted is that part of the Earth situated where the North Star is in the zenith, it follows that there is no south "point" or "pole" but that, while the centre is North, a vast circumference must be South in its whole extent. This is a proof that the Earth is not a globe.

34.) If the Earth were a globe, there certainly would be – if we could imagine the thing to be peopled all round – "antipodes:" "people who," says the dictionary, "living exactly on the opposite side of the globe to ourselves, have their feet opposite to ours: – people who are hanging heads downwards whilst we are standing heads up! But, since the theory allows us to travel to those parts of the Earth where the people are said to be heads downwards, and still to fancy ourselves to be heads upwards and our friends whom we have left behind – us to be heads downwards, it follows that the whole thing is a myth – a dream – a delusion – and a snare; and, instead of there being any evidence at all in this direction to substantiate the popular theory, it is a plain proof that the Earth is not a globe.

Quite simply you cannot. It is widely stated you would need to be at a height of at least 40,000 ft to get even a hint of curvature if earth were round. Commercial aircraft are not allowed to fly this high. They are only allowed to fly just under this altitude. 36,000ft might be typical. In addition, the windows on commercial aircraft are small and heavily curved. Even if they flew high enough for a person to see curvature, it would still not be visible to passengers.
121) When you observe the Sun and Moon you see two equally-sized equidistant circles tracing similar paths at similar speeds around a flat, stationary Earth. The “experts” at NASA, however, claim your common sense every day experience is false on all counts! To begin with, they say the Earth is not flat but a big ball; not stationary but spinning around 19 miles per second; they say the Sun does not revolve around the Earth as it appears, but Earth revolves around the Sun; the Moon, on the other hand, does revolve around the Earth, though not East to West as it appears, rather West to East; and the Sun is actually 400 times larger than the Moon and 400 times farther away! You can clearly see they are the same size and distance, you can see the Earth is flat, you can feel the Earth is stationary, but according to the gospel of modern astronomy, you are wrong and a simpleton worthy of endless ridicule if you dare to trust your own eyes and experience.