Note on the April 2020 publication:
This Technical Paper, revised by Jacqueline Challet-Haas, Raphaël Cottin and Noëlle Simonet, has been copied as close as possible to the original, while harmonizing the typography. The kinetograms have been revised as well as certain reformulations which seemed to us to contribute to greater clarity. The original paper can be consulted on request in the CNEM archives, deposited at the library of the Centre National de la Danse in Pantin, France.