That's partly my point Al, Lord Kelvin perpetuated production of the dry card compass for far longer than it should have been made purely for commercial reasons, they do wobble around a bit, a spirit or oil fill compass dampers the movement down and is far easier to use. Try using a WW1 prismatic marching compass and then switch to a Mk3 Prismatic WW2 jobby, a world of difference, the former is dry, the latter is alcohol filled. My father made full size ships compasses for LIlley and Reynolds ltd, they had to be tested at the National physical laboratory at Teddington, they froze them then boiled them to make sure they were unburstable! I do work now for one of the few surviving compass adjusters left in the Uk. They talk a different language, heeling error, swinging the compass, azimuth etc etc.
