The Mersenne Clavichord Project
The reconstructed Mersenne clavichord in my workshop
Marin Mersennes description of a manicordion, with its accompanying engraving, was published in the 1630s in two versions, one with a text in Latin and the other in French. [Click here for a picture of the engraving as it appears in both texts: opens in a new window].
The instrument is unusual in several respects, and Mersenne’s account of the clavichord has been dismissed as inconsistent and vague; however, Maria Boxall showed in an article in the Galpin Society Journal in 2001 that it is, in fact, both precise and detailed, and the engraving shows the instruments true proportions in a form of isometric projection. Such inconsistencies as there are can be fairly easily resolved.
Marias analysis was so convincing that in 2010 I decided to attempt a reconstruction of the instrument. Extracting a plausible design was not too difficult: I have described the process in a paper which was delivered at the 2011 International Clavichord Symposium in Magnano and published in De Clavicordio X; this paper is now available on-line in PDF format. Of course it is too much to hope that I have got every detail right, but theres a reasonable chance that the design resembles the instrument Mersenne was observing in more ways than those in which it differs.
It required some determination to persist in following the evidence, when the design was so strikingly different from that of most surviving clavichords: most of them are, of course, much later in date, and their qualities and parameters are now fairly well understood. By comparison, Mersennes clavichord was terra incognita. It is much larger, for its compass, than a typical late seventeenth- or eighteenth-century instrument: the case is, in particular, very much deeper. It is obviously related to certain early ones in having several bridges, each arranged at right angles to the axis of the case, without any bridge-pins, so that the strings must press down on the bridges to maintain firm contact. But none of these early examples have as many as five separate bridges, like Mersennes.
Details which could not be derived from Mersenne were sometimes provided from surviving contemporary French harpsichords; where this was not possible, inventiveness had to be called into play.
Having derived the design, the next stage was to construct the instrument. I did not make things easy for myself: for example, there are no fewer than twelve dovetail and through-tenon joints to be made, and the sides overlap the bottom, which nonetheless has to fit precisely. Key-guidance is by means of metal pins working in a rack, a system quite usual on harpsichords but rare on clavichords: it needs to be made with extreme care in order to avoid introducing excessive action noise.
A well-functioning stringing had to be found, essentially by trial and error, since Mersenne does not go into string gauges or even string material. With five separate bridges you have two special difficulties: (1) the equivalent scale does not progress smoothly, and (2) a larger number of courses than usual may suffer from bridge-end effect. Both these make it difficult to produce any kind of homogeneity in the sound from note to note.
Finally, the instrument had to be set up to play as well as it could: this involved fitting listing, in the red cloth presecribed by Mersenne, and careful voicing of the unusually tall tangents with their hand-forged heads.
The instrument has been used several times in performances, and can be heard, played by Terence Charlston, on the CD Mersennes Clavichord. It is now available for sale or hire: for details click here.
Terence Charlston with the Mersenne clavichord
in the recording studio at the Royal College of Music
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Updated August 2018