How was the electric motor invented?

Thomas Davenport of Vermont invented the first official battery-powered electric motor in 1834. This was the first electric motor that had enough power to perform a task and his invention was used to power a small scale printing press.

they created rotating discs or levers that swayed back and forth

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

answer; i believe that the correct answer is (scientific approach)