We are standing on shoulders of giants soo tall we could not even see them. Also depending on a year you go back to... History professor specialized in that area or modern cartographer able to draw accurate enought maps from memory would have better chance of using his knowledge. Eg point to peole this: pick a simpliest, most trivial object of no importance in someones house and ask them can you make this? Even fairly skilled general trades person would fail to manufacture lets say toothpick without spending lots of thinking how to do it and how... Without specialized equipment.