If you did and need to find center between two points, wrap a string like this. Where they cross, will always be your center.
Years ago, before I began map and compass reading for wilderness hunts I was at work fabricating a small part off of a print. The engineer had specified the degrees and then 30 minutes! I asked my welding foreman “how do I measure minutes”. He said you don’t (Lol) ,set it as close to the degree and call it good, if they want it closer they should have specified (finish symbol) and had it machined.I don’t do much measuring larger than a micrometer.
About 20 years ago I found and old wooden 4’ level with brass inlays between the studs of a late 1800’s century home we tore down. It was made in Pennsylvania but looks like it came over on the Mayflower 😉If anyone is interested though I can tell you where I stored a good 4 foot spirit level in a shop I built close to 40 years ago now. Its in the SE corner, neatly encased in the corner studs. I stopped to visit the guy who currently owns the place a few years ago and told him where the level lives but he seemed uninterested in getting it out.