The first mention of the clavichord and harpsichord is found in the "Rules of the Minnesingers," by Eberhard Cersne, A. D. 1404. The celebrated musical theorist, Jean de Muris, of the University of Paris, writing in 1323, and enumerating musical instruments, mentions the four-stringed monochord, but says nothing of the clavichord or harpsichord. This gives reasonable ground for the inference that those instruments were either not invented at that time or had so recently appeared that they were not yet known in Paris, then the centre of musical culture. We are quite safe in assuming that both instruments date from the thirteenth century, and as they were the immediate ancestors of the piano, we must give them especial attention. The famous collection of Mr. Morris Steinert, of New Haven, contains examples in good working order of all the different kinds of clavichords, harpsichords, spinets, and early pianos, and it has been my privilege to examine and play upon all these instruments, thus obtaining a singularly effective object lesson in the history of the piano. The clavichord was always built in oblong shape, like our square piano. The keyboard was precisely like that now used, except that some builders made the naturals black and the sharps and flats white. The principle of the action remained that of the old monochord. The key was pivoted just inside of the front board of the case, and consisted of a single straight shaft of wood. On the inner end was a thin, slablike upright of brass, called a "tangent." When the player struck the outer end of the key, the tangent was driven upward against the string, causing it to vibrate. The tangent also acted as a bridge, and divided the string into two unequal parts, the longer of which gave out the tone. The shorter section was prevented from sounding by a narrow band of cloth interlaced with the strings at that end of the instrument. This band also acted as a damper, and caused the whole string to cease vibrating the moment the tangent was lowered. Clavichords made before 1725 (or about that year) had fewer strings than keys. One string had to produce two and sometimes three tones. This was accomplished by the use of the tangents, which divided the string at different lengths, as the violinist does with the fingers of his left hand. These instruments were known as "gebunden," or bound. About 1725 Daniel Faber of Crailsheim made instruments with one string for each tone, and such clavichords were called "bundfrei" (bound free) or "ungebunden" (unbound). In the latest clavichords each note had two strings tuned in unison,--a contrivance which gained power at the expense of some of the lovely expressiveness of the instrument.