It is hard to believe the misting cannot be cured, I understand all the excuses about temperature differentials - yawn - but in all the years of flying in Tiger Moths all year round I never once experienced this phenomena, or in any other light aircraft for that matter.
It'll be interesting if Kerry can add some input on this one about older aircraft too.
I’m pretty sure by the 1930’s Smiths Aero instruments will have been hermetically sealed