The Collaborative International Dictionary of English v.0.48:

Composing \Com*pos"ing\, a.
   1. Tending to compose or soothe.
      [1913 Webster]

   2. Pertaining to, or used in, composition.
      [1913 Webster]

   Composing frame (Print.), a stand for holding cases of type
      when in use.

   Composing rule (Print.), a thin slip of brass or steel,
      against which the type is arranged in a composing stick,
      or by the aid of which stickfuls or handfuls or type are
      lifted; -- called also setting rule.

   Composing stick (Print.), an instrument usually of metal,
      which the compositor holds in his left hand, and in which
      he arranges the type in words and lines. It has one open
      side, and one adjustable end by means of which the length
      of the lines, and consequently the width of the page or
      column, may be determined.
      [1913 Webster]