The Junior Deacon of a Masonic Blue Lodge is an assistant officer of the Lodge. He sits to the lower right of the Senior Warden. The Junior Deacon's principle roles are to assist the Senior Warden by carrying messages from the Senior Warden in the West to the Junior Warden in the South and to guard the inner door of the Lodge. It is his duty to ascertain at all times whether the Tiler is guarding the door and only allowing visitors to enter after they have been properly vouched for. The Junior Deacon and the Tiler communicate with each other by knocking on the door (the Tiler from the outside...and the Junior Deacon from the inside). Some jurisdictions split this position into 2 positions...that of the Junior Deacon and the Inner Guard. The Junior Warden's position is similar to a Manager.
. . .
Like his senior counterpart, the Senior Deacon, the Jewel of his office is the Square and Compass, however the Junior Deacon's Square and Compass has a moon in the center (rather than a sun), which signifies that he is in the West.