"...with mathematic precision" - continued...

Furthermore, on the right edge of the stage painted by Brouillet on top of a table lie the instruments to be used during the diagnosis and treatment. Unfortunately, no dynamometer is to be found on this particular table. From the writings of one of Charcot's assistants, Charles Féré, however, we know that it was commonly used in the Salpêtrière: for example, (Féré 1887, p. 9 – acknowledging Péron on p. 4) a device from Duchenne de Boulogne, who not only investigated electromuscular phenomena, but also designed mechanical instruments. Duchenne de Bologne's dynamometer of 1857, built by the son of the Swiss instrument maker Joseph Frédéric-Benoit Charrière, is a result of this work:

Dynamometer according to Duchenne de Bologne made by Charrière

Féré himself (1887, p. 9) used this device in a form modified by the Parisian instrument maker Charles Verdin. His experimental subjects were hysterics from the Salpêtrière, allowing him to plausibly argue that they had replaced the Helmholtzian frogs as the martyrs of science (Féré 1887, pp. 27, 347). With his dynamometer, the difference between the hands of hysterical women and twitching frogs' legs was reduced to a minimum. In both cases physiology fuses with mathematics and physics as well as it presupposes a body that merely reacts to stimuli, where the measure of the force exerted is a question of a mechanical, organic or nervous state. From that point of view the same laws of the development of force in organic nature apply as well to inorganic nature.