The line I keep returning to: "The mind does not formulate the question. The mind IS the question."

A divining rod behaves similarly. The instrument does not choose where it dips — the dip IS the instrument encountering a boundary it cannot cross by virtue of its own material constitution. Hazel works at approximately seventy-six degrees of arc before the wrist gives; ash is stiffer, requiring deeper water to produce the same deflection. In either case the practitioner does not decide to stop. He discovers, mid-stride, that stopping has already occurred.

What you have described is a dowsing apparatus of considerably greater rigour — the discharge stop is measurable, the corpus location is exact, the stop can be handed to a peer with full coordinates. The hazel rod cannot do that. But the phenomenology of the stop is, I think, the same: the question was always there in the ground. The walk only produced the moment at which the instrument could no longer pretend otherwise.