An early apparatus developed to detect the existence of an external psychokinetic energy generated by animals, primarily humans. The sthenometer was created by 19th-century psychical researcher Paul Joire, a professor at the Psycho-Physiological Institute in Paris, France. Joire believed that the energy he was attempting to measure was produced by the human nervous system.
The simple device consisted of a dial marked out in 360 degrees. A light needle or pointer (usually a piece of straw) was balanced on a pivot in a glass support. The dial and the needle were then enclosed in a glass cover. Joire discovered that, if the extended fingers of the hand was brought close to the glass cover at a right angle to the needle, the needle would be attracted by the hand and would move toward it. Movement would also take place if certain objects previously held in the hand were brought close to the cover. Cardboard, wood, linen, and water caused the needle to move, but tinfoil, iron, and cotton did not.