One of the greatest scholars of historic carpentry was Cecil Hewitt, who documented and catalogued English joinery from as early as the find at Sutton Hoo (dated to 670), to the later Middle Ages, covering everything from “secret-notched lap joints” to his favorite subject: the scarf joints where timbers could be joined end to end with such skill that they achieved the same strength as a solid piece. In chronological order, this joint evolved from a simple “edge-halved scarf with square abutment and two face pegs on its diagonal”, to the “apogee” reached at Place House, Hertfordshire (1295), that Hewitt describes as having “a stop-splayed and table scarf with sallied and under-squinted abutments, a transverse key, counter tongue and groove tables, four face pegs and two edge pegs.” In his enthusiasm for the perfection of this joint, Hewitt noted that: “[t]his form of the scarf achieved, as intended, high proportion of the strength of un-scarfed timber; two mechanical principles were utilized, the inclined plane and the wedge, and it therefore constitutes a mechanism. This was a scarf capable of resisting every known stress.”
Mysteries of the Carpenter 