看了英文的faq,貌似亮着的煤气灯也是障碍物
About the gaslight, though... we had a session today, and my boyfriend insisted that lit gaslight don't stop Watson's light (the rules state unlit gaslight). I think that lit gaslights ARE obstacles, therefore they DO stop Watson's light from going any further. We played my way and I won, but I promised I would ask.
-Anything which blocks movement blocks Watson's light, so yes, a gaslight blocks it whether lit or not.