Sentence:  On the wall, in an ornate fixture of darkening bronze, a gas jet burned, <WSD>laminar</WSD> and gently singing — adjusted to what scientists of the last century called a "sensitive flame": invisible at the base, as it issues from the orifice, fading upward into smooth blue light that hovers several inches above... 
Meaning of the word marked with <WSD> tags:  Of fluid motion, smooth and regular, flowing as though in different layers.