what is the historical origin of the wearing of the triple tau in the royal arch

The triple tau, formed by three tau crosses conjoined at their feet, serves as the badge and emblem of Royal Arch Masonry 1. Its symbolic origins draw on several ancient traditions, particularly the Hebrew concept of the tau as a mark of preservation and salvation 1. In biblical tradition, Ezekiel speaks of the tau cross as a mark distinguishing those who were to be saved 1. Based on this allusion, Albert Mackey suggests the emblem was adopted in the Royal Arch as a mark designating those who know and worship the true name of God 1.

In English Royal Arch lectures, the symbol is explained geometrically: its intersecting lines form right angles that can be taken in five regular combinations, which were likened to the five Platonic bodies representing the four elements and the universe 1. English Masons historically termed it the "Emblem of all Emblems" and the "Grand Emblem of Royal Arch Masonry" 1. While its early historical adoption remains tied to these symbolic lectures, it was formally codified in regalia over time, such as in 1859 when the General Grand Chapter of the United States prescribed the triple tau inside a triangle and circle for the flap of the Royal Arch apron 1.