Originally Posted by Maelochs

I did okay with geometry but trig kicked my butt right out of the math program.

That si excellent and all, but the issue is making sure the measurements are taking perfectly horizontally and vertically. That is my I mess with boards, and a giant metal right angle (18x12 inches or so) and all that other stuff.

A plum bob (weight on a rope) is the best ... well, simplest---way to determine the vertical ... hold the rope at the top of the ruler and it will always hand perpendicular tot eh center of the Earth. Piece of string and a washer works fine.

Finding the horizontal is important and more complicated ... but a simple spirit -level (bubble level, carpenter's level) works fine.

Not everyone cars if the measurements are half an inch or an inch off I suppose.

Not saying this way is not good or any other way is better. I know that I made some faulty measurements because what looked vertical to my crooked eye was actually not vertical to the rest of the world, and thus every measurement or calculation made off that measurement was wrong and had to be redone.