In America, this is a very important length.  It was the distance between
Benjamin Franklin’s wrist and his elbow, and is the basis of the now defunct
system of measure that he devised.  He based this system on the cubit mentioned
in earlier texts, but later found that it was the ideal length of the key that
he strung from his kite to prove that electricity resided in the sky.  Turns out
it is an exact fraction of the length of a lightning bolt and worked like a
harmonic to attract those bolts..

These little red marks are now more a matter of tradition than actual function,
although I have found them handy when I am making windsor chairs, using this
length as the height of the back of the seat off the floor.  Occasionally I find
that it is also the depth of a table or the width of a drawer, and then they
come in handy for repeatability.

Safe to ignore them.

Ed Minch





On Apr 17, 2014, at 6:34 AM, John Holladay  wrote:

> 
> 
> Purchased a MF No 1506 tape measure, arrived today.  Every 16” is marked
> with two red triangles..
> 
> https://dl.dropboxusercontent.com/u/37914238/wood/MF%201506%20marks.J
PG">https://dl.dropboxusercontent.com/u/37914238/wood/MF%201506%20marks.JPG
> 
> Any clues as to why every 16” is marked this way ?
> 
> 
> Cheers
> Mal
> Oz
> (Perth to be more precise)