In Germany in 2005, Cesco and I found a simple way of transforming a sha line to a sheng line . A week earlier with John Scudamore we had found that a CB placed on a sha line will transform it to a line of sheng line , but CBs are sometimes inconvenient to carry along with one.

          It is much easier to carry six TBs with one. The method is to place these six TBs uniformly on a circle centered on any point in the middle of the line:

          The effectiveness of this method depends, however, in being able to find the exact location of the sha line so as to center the TBs in the right place. It may also be necessary to change the diameter slightly, so that it is a little larger, or a little smaller than, a foot.