Lufkin 7172 - An odd Ruler

[PsRumors]

This was in my grandfather's stuff and I've never been able to figure out its use nor found any reference on line.

From left to right each section measures

0 - 2 ft 2 inches
6 ft - 4 ft 1 inches
4 ft 1 inches - 2 foot 2 inches

At first I thought it must be assembled incorrectly but there is no way to assemble it where it would run 0 to 6 feet.

Any thoughts on why it would be set up in such a fassion?

 

[gamescastspencer]

My guess is you’d telescope the right side out (the reverse reading side) into a jamb or opening, two points, then the number at the joint is your measurement. Kind of like using a caliper for an inside measurement.

Here is a cut from their 1920 catalog.

 

[RTM]

My guess is you’d telescope the right side out (the reverse reading side) into a jamb or opening, two points, then the number at the joint is your measurement. Kind of like using a caliper for an inside measurement

Great for door jambs, windows etc, but wonderful for making sure something is square, by measuring the diagonals.

 

[Beerhippie]

For inside measurements for door or window casings, I use a sliding rule as a story pole--just transfer the measurement directly from the rule to the casing. Using numbers always means compromising, whereas directly transferring is accurate to sub-RCH levels.

 

[PsRumors]

I'll be darn. I now understand how it works, what its for and it makes perfect sense.

Thank you all