John Clinton, a musician and theorist, published this essay in 1845 with the aim of introducing flutists who were reluctant to change fingerings to the Boehm flute and appreciating the qualities of this innovative flute. A few years later, he developed his own flute, which he called the equisonant, aiming to create an instrument that combined the advantages of the Boehm flute with those of the "old system" flute. The copy of the treatise I present is legible and free of stains; only the binding is slightly loose, and the cover bears the marks of ancient battles. The first two pages of the preface are missing (photocopied for reference), but the text of the treatise is present in its entirety.