where did the office of principal sojourner come from in the royal arch and what are his duties

The office of Principal Sojourner derives historically and allegorically from the leader and spokesman of the three sojourners who returned from captivity in Babylon to Jerusalem to assist in rebuilding the Temple 1. According to Masonic tradition, these figures returned to aid Zerubbabel, Jeshua, and Haggai, and their work amidst the ruins led to the discovery of the subterranean vault and the stone of foundation 1.

In the English system, three distinct officers serve as Sojourners: the Principal Sojourner and two Assistants 1. In the American system, the candidates themselves portray the three historical sojourners, while the Principal Sojourner serves as an officer appointed to guide them 1.

The Principal Sojourner's primary duties are to act as a Conductor to guide candidates through the degree, fulfilling a function similar to that of a Senior Deacon in a Symbolic Lodge 1. Within the narrative of the degree, he acts as the chief spokesman for the returning travelers presenting their discoveries 1. Symbolically, Wilmshurst views the triad of sojourners stationed in the West as representing the psychical and materialized aspect of the candidate's nature, acting as a lower reflex to the spiritual pole occupied by the Three Principals in the East 2.

In traditional Chapter working, the Principal Sojourner is distinguished by wearing a dark robe with a tessellated border, a slouched hat, and carrying a pilgrim's staff 1.

The duties of the Principal Sojourner are those of a Conductor, which resemble in some respects those of a Senior Deacon in a Symbolic Lodge 1. In systems where a Chapter opens on any of the preliminary degrees, the Principal Sojourner occupies the office of Senior Deacon directly during those proceedings 1.