My guess on this is that the gas line connects to the valve and is lit directly, with the screw regulating the amount of gas/height of the flame. It would clamp to a table top and the articulated part just enables you to move it around, either for better light, to light a cigarette, or maybe for lighting a torch for welding, although it seems too ornate for that. I'm not sure of the purpose, but look to see if the underside is threaded like a gas line would screw into it.