Is there a small instrument that you could lay on a map or any other page that has angled lines and make a fair estimate of the angle sizes? Example: Two streets cross each other but not at right angles. We had occasion to wonder about this with two highways yesterday. Would be nice to be able to lay an instrument on the map an get a close estimate. Same with measuring steeples on tall buildings or -- whatever. It would not give perfect angle measurements but close.
If there is such an instrument, what would I ask for and where might I find one? Thanks.