HELIX, in Geometry, a spiral line. The word is Greek, ἥλιξ, and literally signifies a wreath or winding, from ἵστασθαι, involve. In architecture, some authors make a difference between the helix and the spiral. A staircase, according
to Daviler, is in a helix, or is helical, when the stairs or steps wind round a cylindrical newel; whereas the spiral winds round a cone, and is continually approaching nearer and nearer its axis.