what is the historical origin of the skirret and pencil in craft masonry and how do preston and mackey explain their symbolic use

The skirret made no official appearance in English Masonic ritual until after the Union of 1813, when it was sanctioned alongside the pencil and compasses under the Lodge of Reconciliation as the symbolic working tools of a Master Mason, replacing elements of William Preston's earlier 18th-century lecture system post-Union as recorded in a paper read before Quatuor Coronati Lodge.

Operatively, the skirret is an implement rotating on a centre pin from which a line is drawn, chalked, and struck to mark out the ground for a structure's foundation, as Albert Mackey explains in a paper read before Quatuor Coronati Lodge. Symbolically, he reads it as pointing to that straight and undeviating line of conduct laid down in the Volume of the Sacred Law, a definition he aligns with its use in the English working tools.

The pencil represents the tool used by the architect to sketch plans upon the tracing board for the guidance of the craftsmen, as recorded in a paper read before Quatuor Coronati Lodge. Albert Mackey notes that in the English system it symbolically teaches that all human words, thoughts, and actions are continuously recorded by the Almighty, to whom an account must ultimately be rendered 1, though he observes that the pencil is not specifically recognized as a working tool in the American system 1.