Before we had things in the sky to take photos of the world and show us exactly what it looked like, what kind of crazy math, technologies or techniques did cartographers use to try to make their maps and charts as accurate and to scale as possible? I’m especially interested in mapmaking techniques from the 17th and 18th centuries (and double especially interested in maritime charts from that time), but if anybody has knowledge of earlier time periods I’d be interested in that as well.