WHAT WOULD THIS ADJUSTABLE TOOL BE USED FOR

[RAYWLI]

HI

I HAVE THIS BEAUTIFULLY MADE SMALL BRASS TOOL I HAVE INCLUDED SOME IMAGES AND WOULD APPRECIATE ANYONES INFORMATION. IT IS STAMPED 'W.M' AND HAS THE NUMBER '12200' STAMPED INTO THE BODY ALONG THE SIDE THERE IS AN ADJUSTABLE MEASUREING SCALE

REGARDS

[Papaw]

Perhaps a Butt Gage for door mortise work?
Some of our woodworkers will chime in soon.

[BruceS]

I'm thinking,  some sort of trammel point type attachment for measuring angles.   The scale is broken down into 5 degree increments.   With the pin and arch part missing a piece that would be an adjustable arm.  ONLY A GUESS.

[RWalters]

Almost looks like part of a gun sight.....

[rusty]

The scale is weird tho,

How wide are the lines between the numbers?
Sort of looks like mm , but I can't tell how big the thing is...