Originality and Influence: Charles Gröll’s Role in the Invention of the Double-Action Harp

Sébastien Erard (1752–1831) is widely considered the father of the modern harp, in part because of his invention (c. 1786) of the forked discs that shorten the vibrating length of the strings by a semitone, but above all for his 1810 invention of the double action, a mechanical system that allows the harpist to play in all keys and which has been used on virtually all concert pedal harps for the past two centuries. However, Erard’s double-action harp model was similar to that of the Warsaw-born artist and inventor Charles Gröll (1770–1857), who had submitted his patent in 1807, almost three years before Erard. Moreover, Erard bought the rights to Gröll’s patent prior to finalising his own. For these reasons, some critics since the nineteenth century have called into question Erard’s claim to authorship of the double-action harp, suggesting that Gröll was its true inventor. The purpose of the present article is to clarify Gröll’s role by placing it in the context of the evolution of Erard’s ideas, established by a number of sources that have recently come to light. Gröll’s patent is more heavily indebted to Erard’s inventions than Erard’s patent is to Gröll’s. Indeed, the only elements from Gröll’s patent that remained in Erard’s 1810 patent were elements that had in fact been invented by Erard: the double-notched pedal box and the forked discs. The linkage between the pedals and the forked discs was the weakest part of Gröll’s patent, one that was conspicuously not adopted by Erard, undoubtedly due to the excessive friction inherent in its construction. Erard’s 1810 patent has endured because it proved itself to be the first satisfyingly functional double-action system. However, Gröll’s doubling of the forked discs can be seen as a crucial step in the evolution of the double action, as long as one keeps in mind that Gröll’s is a composite invention whose individual parts had all been invented by others: the double mechanism by Cousineau, and the double-notched pedal box and forked disc by Erard. In conclusion, if we continue to consider Erard the father of the double-action harp, we might at least allow for Georges Cousineau to be its spiritual godfather, and for Charles Gröll to be its Polish uncle.