I've been saying it for years, the knowledge base in this form never ceases to amaze me. But this time I think I've got a serious curve ball...

Found in an old barn.  It's comprised of both ferrous and nonferrous metal, possibly brass, I haven't dug into it...

It's a light or lantern of some sort. It has an igniter, similar in principle to the ones in old Coleman lanterns...

Any thoughts/ideas on what these were for? Is it simply some kind of old outdoor (or indoor) light? Was it fixed to a horse drawn carriage? What kind of fuel might it have used? Any help is appreciated.

gas lamp, turn of the century 1900coal gas or natural gas most were in cities aka city gas

Right, gas lamp, most likely in a home.  Hung down from the ceiling,  ceilings were tall, nine to ten foot in the latter half of the 19th century.   The ring supported a glass globe to diffuse the light.   The small ring on the valve was for turning on the gas.  Could be lighted from the floor with a hook tool on a pole.  A neat find.  Have been in a couple of homes that still had the gas lamps. 

It's late hon, just let me blow out the light. Opps. We are gathered here today to pay---------------------------------------------

EvilDr235

Our 1907 Post Office still has some of the gas light valves on the lobby walls.  When I explain to people what they are and why the lobby ceiling is so tall some of them start to take a serious look.  My house has some gas light piping buried in the walls & ceilings from an early 20th Century remodel, but none of it is exposed or visible. 
The old "town gas" generation plant building is still standing in York & a local businessman has remodeled it into a private club.  Instead of charging for drinks, he just has a donation jar on the bar -- does not need a liquor license that way.

Thanks for the help! I might be guilty of overthinking this one a bit lol

Interesting stories, too! Thanks!