A "Standing Order" exists in the English Houses of Parliament that in the cutting of canals, &c., the datum line employed shall be a "horizontal line, which shall be the same throughout the whole length of the work." Now if the Earth were a globe, this "Order" could not be carried out: but, it is carried out: therefore it is a proof that the Earth is not a globe.
In general, we at the Flat Earth Society do not lend much credibility to photographic evidence. It is too easily manipulated and altered. Many of the videos posted here to "prove a round earth" by showing curvature will show no curvature or even concave curvature at parts. The sources are so inaccurate it's difficult to build an argument on them in either case. Furthermore, barrel distortion and other quirks of modern cameras will cause a picture to distort in ways which may not be immediately obvious or apparent, especially without references within the picture. Photographs are also prone to distortion when taken through the bent glass of a pressurized cabin as well as atmospheric conditions on the outside. With this litany of problems, it's easy to see why photographic evidence is not to be trusted.
1.) The aeronaut can see for himself that Earth is a Plane. The appearance presented to him, even at the highest elevation he has ever attained, is that of a concave surface – this being exactly what is to be expected of a surface that is truly level, since it is the nature of level surfaces to appear to rise to a level with the eye of the observer. This is ocular demonstration and proof that Earth is not a globe.
108) The mariner’s compass is an impossible and non-sensical instrument for use on a ball-Earth. It simultaneously points North and South over a flat surface, yet claims to be pin-pointing two constantly moving geomagnetic poles at opposite ends of a spinning sphere originating from a hypothetical molten metal core. If compass needles were actually drawn to the North pole of a globe, the opposing “South” needle would actually be pointing up and off into outer-space.
15) If the Earth were truly a sphere 25,000 miles in circumference, airplane pilots would have to constantly correct their altitudes downwards so as to not fly straight off into “outer space;” a pilot wishing to simply maintain their altitude at a typical cruising speed of 500 mph, would have to constantly dip their nose downwards and descend 2,777 feet (over half a mile) every minute! Otherwise, without compensation, in one hour’s time the pilot would find themselves 31.5 miles higher than expected.

31) Quoting “Zetetic Cosmogeny” Thomas Winships states: “Let ‘imagination’ picture to the mind what force air would have which was set in motion by a spherical body of 8,000 miles in diameter, which in one hour was spinning round 1,000 mph, rushing through space at 65,000 mph and gyrating across the heavens? Then let ‘conjecture’ endeavor to discover whether the inhabitants on such a globe could keep their hair on? If the earth-globe rotates on its axis at the terrific rate of 1,000 miles an hour, such an immense mass would of necessity cause a tremendous rush of wind in the space it occupied. The wind would go all one way, and anything like clouds which got ‘within the sphere of influence’ of the rotating sphere, would have to go the same way. The fact that the earth is at rest is proved by kite flying.”

Due to special relativity, this is not the case. At this point, many readers will question the validity of any answer which uses advanced, intimidating-sounding physics terms to explain a position. However, it is true. The relevant equation is v/c = tanh (at/c). One will find that in this equation, tanh(at/c) can never exceed or equal 1. This means that velocity can never reach the speed of light, regardless of how long one accelerates for and the rate of the acceleration.
56.) The Sun and Moon may often be seen high in the heavens at the same time – the Sun rising in the east and the Moon setting in the west – the Sun's light positively putting the Moon's light out by sheer contrast! If the Newtonian theory were correct, and the moon had her light from the Sun, she ought to be getting more of it when face to face with that luminary – if it were possible for a sphere to act as a reflector all over its face! But as the Moon's light pales before the rising Sun, it is a proof that the theory fails; and is gives us a proof that the Earth is not a globe.
54) At places of comparable latitude North and South, dawn and dusk happen very differently than they would on a spinning ball, but precisely how they should on a flat Earth. In the North dawn and dusk come slowly and last far longer than in the South where they come and go very quickly. Certain places in the North twilight can last for over an hour while at comparable Southern latitudes within a few minutes the sunlight completely disappears. This is inexplicable on a uniformly spinning, wobbling ball Earth but is exactly what is expected on a flat Earth with the Sun traveling faster, wider circles over the South and slower, narrower circles over the North.
149) Throughout thousands of years the same constellations have remained fixed in their same patterns without moving out of position whatsoever. If the Earth were a big ball spinning around a bigger Sun spinning around a bigger galaxy shooting off from the Biggest Bang as NASA claims, it is impossible that the constellations would remain so fixed. Based on their model, we should, in fact, have an entirely different night sky every single night and never repeat exactly the same star pattern twice.
115) The existing laws of density and buoyancy perfectly explained the physics of falling objects long before knighted Freemason “Sir” Isaac Newton bestowed his theory of “gravity” upon the world. It is a fact that objects placed in denser mediums rise up while objects placed in less dense mediums sink down. To fit with the heliocentric model which has no up or down, Newton instead claimed objects are attracted to large masses and fall towards the center. Not a single experiment in history, however, has shown an object massive enough to, by virtue of its mass alone, cause other smaller masses to be attracted to it as Newton claims “gravity” does with Earth, the Sun, Moon, Stars and Planets.
58.) Astronomers have never agreed amongst themselves about a rotating Moon revolving round a rotating and revolving Earth – this Earth, Moon, planets and their satellites all, at the same time dashing through space, around the rotating and revolving Sun, towards the constellation Hercules, at the rate of four millions of miles a day! And they never will: agreement is impossible! With the a Earth a plane and without motion, the whole thing is clear. And if a straw will show which way the wind blows, this may be taken as a pretty strong proof that the Earth is not a globe.
The problem with the Globe Earth model is that it is completely the opposite of what the Bible says. In the Globe model, there is no separation of waters from the waters below. In fact, there are no waters above. Neither is there a barrier separating earths air from the vacuum of “space”. We are told that “gravity”, an invisible force even “scientists” do not understand, is what holds the air and the water onto the earth. But never has anyone ever been able to produce a real vacuum without a barrier around it to keep the air separated from the vacuumed space. There must be a solid barrier or it does not work. In this way, the globe makes no sense.
Astronomers tell us that, in consequence of the Earth's "rotundity," the perpendicular walls of buildings are, nowhere, parallel, and that even the walls of houses on opposite sides of a street are not! But, since all observation fails to find any evidence of this want of parallelism which theory demands, the idea must be renounced as being absurd and in opposition to all well-known facts. This is a proof that the Earth is not a globe.