This stop is listed only by Irwin, who describes it as a Plein Jeu constructed of harmonic-length spotted metal pipes. It is not clear how Irwin formed this impression. The Plein Jeu Harmonique was reportedly developed by Aristide Cavaillé-Coll, who used the word �harmonique� in his mixtures to indicate not harmonic pipes, but a type of mixture without breaks, in which the number of ranks increases as the stop ascends. Other stops of this type include Fourniture Harmonique and Cymbale Harmonique, which together form a Plein Jeu Harmonique. Cavaillé-Coll reportedly always made such stops of tin, not spotted metal. The name Harmonic Plein Jeu is mentioned only in passing by Irwin in his appendix on Mixtures, and is an inappropriate mixing of languages. We know of no examples of this name in actual usage.
Osiris contains nearly two dozen examples of Plein Jeu Harmonique. All but one are progressive in the number of ranks, ranging from II-V to III-VII. The earliest known examples are given below: