In 1780, when he had more patients than he could treat individually, Mesmer introduced the method of collective healing known as the “tub” with which he could treat more than 30 people at the same time.
The patients, connected to each other by ropes, sit around a round oak box with holes in the lid
and from which metal rods emerge that can come into contact with various diseased parts of the body.
In the bottom of the box, on a layer of crushed glass and iron filings, rest symmetrically lined up, filled bottles, some pointing to the center, others to the edge.
Mesmer, in a robe of lilac silk, and his assistants, whom he has chosen to be young and handsome, are armed with a ten to twelve inch iron rod with which they touch diseased parts of the body.
Mesmer usually accompanies his magnetism sessions by playing the fortepiano or the glass harmonica. (Glass harmonica, invented by Benjamin Franklin in 1762).