Name this tool....

[Oceans64]

   While emptying the drawer for the Hosman's thread, I came across this tool.  Never have known the name of it.  The end is a caliper I use to measure the diameter of anything round.  It came off my Grandpa's workbench.  He made lots of picture frames and was also a draftsman for Boeing tho this was only a few things he did -

[waywardangler]

I think you already named it...a carpenter's caliper rule.  Measures inside and outside measurements on one side and back side is a 6" rule.  Value ranges from $15 to $40 depending on condition.  The measuring tips on yours look a little dinged up but it may just be the light.  Probably made of boxwood.

[Oceans64]

Well good to know I was guessing right!  Think you got the value wrong tho.  It's priceless     and not because it was my gpa's - It's handy as heck!  The slide has the perfect stiffness so it doesn't slide back when removing it and you don't have to clamp tight so you risk scratching. 

[waywardangler]

I was just quoting replacement value in case you ever misplaced yours and needed another.    I also have some that are very similar to yours.  Very handy indeed.  I also have a little (about 8cm long) French watchmaker's calipers that has wood jaws and measures in mm's.  I am not sure how accurate the wood jaws are but they are non-marring.

[KC]

Love these type of items.  Handy to have around!  Agree...it is priceless!