The Count de Tristan found out the key to this anomaly.
He had discovered that a thick cover of silk upon the handles of the divining fork, like Mr. Fairholm's coating of sealing wax, entirely arrested its motion. Then he tried thinner covers, and found they only lowered, as it were, and lessened it. The thin layer of silk was only an imperfect impediment to the transmission of the influence. Then he tried the effect of covering one handle only of the divining rod with a thin layer of silk stuff. He so covered the right handle, and then the enigma above proposed was explained. The divining fork, which hitherto had gone the usual way with him, commencing by ascending, now, when set in motion, descended, and continued to perform an inverse rotation.
I think this is the place for mentioning, that when the Count walked over the exciting soil, rod in hand, but trailing likewise, from each hand, a branch of the same plant, (which therefore touched the ground with one end, and with the other touched, in his hand, the magic fork,) the latter had lost its virtue. There is no motion when the ends of the divining rod are in direct communication with the soil. The intervention of the human body is necessary for our result.
Then we are at liberty to suppose that the two sides of our frame have some fine difference of quality; that there is in general a sort of preponderance upon the right side; that in general, in reference to the divining rod, there is a superior vigour of transmission in the right side; that _this difference_, whatever it may be, of kind or degree, determines a current, causes motion, in the unknown fluid, which, in a simple arched conductor, with its ends upon the soil, remains in equilibrium. To explain the result of the last experiment I have cited of the Count de Tristan, no difference in quality in the two sides of the body need be assumed. Difference in conducting power alone will do. Then it might be said, that by covering the right handle of the divining rod, he checked the current rushing through the right side of the frame, and so gave predominance to the left current. One cannot help conjecturally anticipating, by the way, that with left-handed diviners, the divining rod will be found habitually to move the wrong way.
