I didn't wanna say anything really cos it is a good idea I just don't know how reliable it can be.
It would be interesting to see some of the results of peoples measurements.
And probably very funny to read the ensuing arguments over 0.02 of an inch or mm.
Please don't let me put you off of a wonderful time consuming excersize.
The cold winter nights are not far away and you must have something to occupy your mind init?