Eratosthenes discovered the earth was round, about 240BC by using simple tools. He measured the suns movement and did his calculations.
ED had some interesting views on astronomy, and drew his conclusions from his own experiments. ED Leedskalnin discovered how earth moves through space by using celestial alignments in relation to earth (his tools).
Ed mentions.. have a look at the drawing on the red door, (shows earths path as an angular curved orbit around the sun not flat) the polaris telescope/sextant (tracks the movement of polaris star all year round marking absolute north proves earths axis does not shift) and the sundial/Curved Surface Analamatic 9-4 and see how they would effect science.
have a look at Coral Castle researcher R.L. Poole YouTube video posted by TalkingToLeedskalnin
The next video is yet to be posted..