By the definition of using light you can quanify a foot or yard by a
division of that length. In a way the scientific advances that allowed
the modern definition of the metre also made the most accurate yard length
ever, thanks to the very concept of the metre.
Accurate in relation to what?
Accurate in relation to the conversion factor to the metre becoming more
accurate (as technology allows).
But what I am trying to say that at some point the yard was compared to
the metre to set-up a conversion factor.
It would be interesting to know how they actually went about doing this.
Did they physically take a metre stick to the official yard at Trafalgar
square?
I doubt it.
A prototype kept out in the open exposed to the elements is hardly sensible
for the purposes of modern metrology.
With all due respect you haven't grasped the key point here. The statement
"1 yd = 0.9144 m" is not just a conversion factor.
It is a *definition* of the term "yard".
The yard has no other form of existence in the modern world, it is
numerical only.
"You doubt it" - which means that the view your expressing is an opinion.
Other more 'pro-metric' people have picked up on how an imperial measure of
length can be based upon the same light technology that the metre is defined
against.
As far as I can see 2yds = (0.9144 x 2) metres. That looks like a
conversion factor to me.
I guess both yard and metre used to be physical - now neither are.
Fortunately I have no emotional attachment to the yard so I can put it on
either side of the equation.
