I have seen several older masonry walls that have the appearance of running bond, yet do not contain any visible headers. In going over the walls with a metal detector, there is no indication of any wall ties.

Were these walls built without headers or ties?

The walls were probably built using a concealed header at every sixth course in a bonding pattern known as a diagonal or herring-bone. These diagonal or herring-bone headers consist of brick units that were installed at an angle, as shown in Fig. 1. The corners of the units in the face brick stretcher course are clipped off to accommodate this diagonal unit.

Another method for concealing headers involves splitting the face brick in half and then backing these split-face brick with a continuous row of header occurring every sixth course throughout the height of the wall, as shown in Fig. 2.

These methods are described in the book Masonry Carpentry Joinery - The Art of Architecture, Engineering and Construction in 1899 published by Chicago Review Press, which contains selections from the International Library of Technology published by the International Textbook Co., Scranton, Pa., in 1899.

In both methods the headers are held in by the mortar bond of the bed joint for the stretcher courses above and below the diagonal header or concealed perpendicular header. Because the headers are not visible on the exterior face of the wall, it gave an unusual appearance for the time period when most walls were built using exposed brick headers.

The running bond pattern, which is the most common appearance today, gained popularity with the use of steel wall ties.