"I spoke to a FLight Deck Engineer who invented the display layout - & he told me that this is the way the thing is supposed to work ! "
U2FB....
The only way it could work was if the V/S scale was linear... at least on the type shown in the pic.
I now recall that a variation of this trick could be used to scale down/up drawings (a tip from my Technical Drawing classes in High School).
Notso....
You are a gentleman and a scholar. All is forgiven.
Regards.
Q.