Since the beginning of the 19th century dynamometry was a common method to measure human body strength. Instruments were described by J.-B. Regnier, G.B.A. Duchenne de Boulogne, V. Burq et Mathieu, and unauthorized copies of different size were also being used. Although it is not clear which instrument exactly Sigmund Freud used when trying to measure the effects of cocaine on grip strength in 1884, it seems that he used copies like those maintained in the Museum on the History of Medicine in Ingolstadt.Attempts of quantification seem to belong to the scientific tendencies in mid and late 19th century medicine. It can be demonstrated, that the roots of dynamometry go back to the first decades of the century and belong to the conceptions derived from Mesmerism and Animal Magnetism.