As students of harp history know, Erard made harps with fourchettes, Cousineau with béquilles and most others with crochets. However, several exceptional harps remind us that harp makers were not as ideologically rigid as we imagine them to be, sometimes experimenting with the innovations of their competitors.
The first of these is a 43-string green and gold harp preserved in the Camac collection. It is stamped 'NADERMAN A PARIS', bears the number 301, and curiously, has fourchettes instead of the crochets that one would expect from this maker. Similar 43-string Naderman harpes à fourchettes can be found in the Musée de la Musique, Paris and in a private collection in Italy.
Cousineau, who made almost exclusively harps with his béquilles mechanism also made at least two harps with fourchettes. A 42-string Cousineau harpe à fourchettes is today preserved in the Fernanda Giuilini collection and a 39-string harp dating from around 1810 was sold at auction at Koller in Zurich on 28 March 2001. [I am grateful to Beat Wolf for sharing this information.]
But perhaps the most interesting example of this mechanical borrowing is revealed in the ledgers of the Paris branch of the Erard firm. On 1 and 12 November 1814, they manufactured two single-action harpes à crochets (n° 466 and 467, respectively).
We know that Sébastien Erard was ready to abandon his fourchettes mechanism as early as 1800, when he built his first double-action harp using Cousineau's system of chevilles tournantes. However, it is unclear why he decided to experiment with Naderman style harps. The Erards repeatedly criticized the harpe à crochets as old fashioned, and believed that it presented numerous flaws that the fourchettes were designed to overcome (cf. Pierre Erard, The Harp in its Present Improved State, 1821). In a recent posting to this forum, Beat Wolf points out the commercial motivations behind the Erards' critiques of the harpe à crochets. Nevertheless, whether or not these critiques were objectively valid, the Erards themselves believed them to be, and it is therefore all the more surprising that they would make and sell even two harpes à crochets.
It is almost certain that Erard's harpes à crochets n° 466 and 467 were not made as special orders from musicians, as they were made in a close temporal proximity for two customers who probably have no connection to each other: the Marquise d’Epinay in Paris (not the famous writer of the same name, who died in 1783) and Mr Gayer in distant Moulins. It would have been a remarkable coincidence indeed if these two customers, spontaneously and almost simultaneously, specifically requested that Erard make them harpes à crochets.
It is possible that Erard’s harpes à crochets are related to an English patent (no 3835) entitled ‘Improvements in musical instruments’ that Sébastien Erard applied for on 4 August 1814. English patent law required that the applicant submit the detailed specifications for the patent within six months, which this time Erard failed to do. As a result, the patent application is blank, and we have no clue as to the content of his intended (and subsequently abandoned) patent. We can assume that he was continuing his work on harp innovations during this period, and that this patent might be related to his experiments with harps n° 466 and 467.
I would be interested in hearing from others who have identified similar harps with mechanical systems atypical of their maker. (I am excluding from consideration Cousineau harpes à crochets made prior to his invention of the béquilles. At that time, use of crochets was not a form of homage or borrowing, but rather the only choice a harp maker could make.)