ruling pen
 直線筆
 Pen n.
 1. A feather. [Obs.]
 2. A wing. [Obs.]
 3. An instrument used for writing with ink, formerly made of a reed, or of the quill of a goose or other bird, but now also of other materials, as of steel, gold, etc. Also, originally, a stylus or other instrument for scratching or graving.
    Graven with an iron pen and lead in the rock.   --Job xix. 24.
 4. Fig.: A writer, or his style; as, he has a sharp pen. “Those learned pens.”
 5. Zool. The internal shell of a squid.
 6.  Zool. A female swan; -- contrasted with cob, the male swan. [Prov. Eng.]
 Bow pen. See Bow-pen.
 Dotting pen, a pen for drawing dotted lines.
 Drawing pen, or Ruling pen, a pen for ruling lines having a pair of blades between which the ink is contained.
 Fountain pen, Geometric pen. See under Fountain, and Geometric.
 Music pen, a pen having five points for drawing the five lines of the staff.
 Pen and ink, or pen-and-ink, executed or done with a pen and ink; as, a pen and ink sketch.
 Pen feather. A pin feather. [Obs.]
 Pen name. See under Name.
 Sea pen Zool., a pennatula. [Usually written sea-pen.]