where did the office of Principal Sojourner in a Royal Arch chapter come from and what are his actual duties

The title and character of the Principal Sojourner derive from the biblical narrative of the Babylonian captivity, drawing on the Hebrew term ger, meaning a man residing outside his own country 1. In the narrative of the degree, he acts as the spokesman and leader of a party of three sojourners who return to Jerusalem to assist in rebuilding the temple 12.

Regarding the historical institution of the office itself, the supplied sources do not provide a date or record of its administrative origin. They do, however, outline a distinction between ritual systems: in the English system, three officers act as Sojourners, whereas in the American system, the candidates themselves represent the three historical sojourners, and an officer called the Principal Sojourner represents their supposed leader 1.

In terms of duties, the Principal Sojourner acts as a Conductor, fulfilling a role analogous in certain respects to that of the Senior Deacon in a Craft lodge 1. When a chapter is opened on any preliminary degree in the American system, he occupies the Senior Deacon's office 1. In vestments, he wears a dark robe featuring a tessellated border, accompanied by a slouched hat and a pilgrim's staff 1.

From an allegorical perspective, Walter Leslie Wilmshurst interprets the triad of sojourners stationed in the West as representing the candidate's psychic and materialized pole, mirroring the spiritual pole represented by the three Principals in the East 2.