What was this tool used for

[znamien]

here is a large wood,  looks like scribing tool, it has a name W. Thompson on it, has a curved blade, the stop moves, it is 22 inches long, does anyone know what this was used for, thank you

[Bill Houghton]

Could be a panel gauge (like a marking gauge but for marking the final width of a panel, as for frame-and-panel construction), or it could be a similar tool used in leather work.

[wvtools]

I have always called them all panel gauges when they were that size, no matter what the cutting blade looked like.  Salaman (1990 reprint of 1975 original; Dictionary of Woodworking Tools) calls the large gauges with a knife type blade cutting gauges, and the ones with a scribe tip panel gauges.  He calls your style a slitting gauge. 

Cutting gauges are used for deep scoring lines and cutting veneer or thin strips of wood.  Slitting gauges can be used to cut thin wood such as drawer bottoms.

[Branson]

It's the knife like blade that makes this a slitting gauge.  As WV pointed out, these can be used to cut, rather than saw thin stock.  (They'll do wonders on up to 1/4 inch thick plywood, too.)  It's designed to cut rather than simply mark, like the little cutters on dado planes, butt gauges, and some rabbet planes (and the Stanley #45 and #55).  This one would be excellent at laying out the center of a raised panel, as it will actually cut a crisp shoulder and prevent tear-out.

This one is much more rare than the usual panel gauge.  I don't believe I've ever run across one -- at least I never got one (can't imagine I would have passed one up).

[znamien]

thank you all ,for your help, znamein