Double Zero - I have in fact met Mr Farley at a lecture he gave some 16 years ago. We had a chat afterwards and it remains one of the most informative and well explained lectures on aviation I have ever been to. I don't expect him to remember a little boy at North Weald asking him about Ski jumps for the Harrier, but I remember it well!
The reason I ask here is because I know that with people like John and the others on this forum, I will get a decent well explained response that will make me think, rather than uninformed speculation.
John - Thanks for explaining that, I've not seen the instrument which you describe. The one I saw was decidedly odd. I thought it had toppled, but apparently not. I'll see if I can find one to look at.
Kind regards.