A simple device invented by the Count de Tromelin, described in his book Les Mysteres de l'Univers (ca. 1908). It was supposed to demonstrate the existence of human energy emanations analagous to the subtle "fluid" of animal magnetism. It was composed of a paper cylinder about two inches in diameter, open at each end and crossed diametrically at its upper part by a piece of straw. A needle was stuck through the middle with the point resting on the bottom of a small, inverted porcelain or glass jar. The paper cylinder was suspended outside and concentric with the inverted jar, the point of the needle acting as a pivot and enabling it to turn easily under the slightest impulse.
Count de Tromelin claimed that if the right hand was placed behind this apparatus it would turn counterclockwise. If the left hand was placed behind, it would turn in the other direction. W. Warcollier, writing in the Annals of Psychical Science (August-September 1908), observes that this motion has nothing to do with the polarity of the two hands. The left hand produces the same effect as the right in the same position, writes Warcollier; moreover the heat of the hand is sufficient to create an air current that is capable of producing the rotation.
A more satisfactory instrument of this kind was invented by Paul Joire and was known as a sthenometer.
(See also biometer of Baraduc ; magnetometer )