The wrest jjlank is siipijortcd by two cud blocks, 

 against which the partition behind the action (called 

 the belly rail) is also placed. The soundboard is glued 

 to the top of the belly rail. The wrest plank is 

 veneered with cypress, giving the appearance that the 

 soundboard extends over it. The jack guides also rest 

 on the end blocks in the space between the wrest plank 

 and the belly rail. Figures 8 and 11 clarify the 

 arrangement of these structural features. 



Figure 10 shows the layout of ribs, bridges, and 

 strings on the soundboard. The soundboard is about 

 's" thick. The bridge on the wrest plank tapers in 

 height from fi" in the treble to Xe" in the bass and 

 in width from %/' to Ke"- The soundboard bridge 

 measures about ^s" by %" and has virtually no 

 taper. The soundboard does not have a rose, although 

 that decorative device is fairly common on Italian 

 harpsichords. 



The jack guides are built up of spacer Ijlocks held 

 together by thin strips along the sides. There is now 

 no provision for moving the guides, althoua;h plugged- 

 up holes visible in the right end of each guide suggest 

 that they originally could be disengaged. In Italian 

 harpsichords generally, the jack guides were con- 

 trolled by knobs projecting through the sides of the 

 case. Sometimes these harpsichords had levers 

 pivoted on the wrest plank and attached to the guides. 

 The Ridolfi case has not been patched and there are 

 no holes in the wrest plank where levers could have 

 been attached; so, the guides proliably were not 

 intended to be movable. 



The jacks are simple slips of walnut measuring 

 about fU" by Yn" by 3%" . The arrangement of 

 the tongue, spring, plectrum, and damper are shown 

 in figure 11. The dampers arc small pieces of buck- 

 skin held in slots at the tops of the jacks. The plectra, 

 perhaps not original, are of leather. Of course, there 

 are no adjusting screws or capstans of any \ariety. 



The direction in which the plectra of each row of 

 jacks should be pointing is not known. Two claxicy- 

 theria having two registers of strings and a single row 

 of double tongue jacks have been examined by the 

 author. Each of these jacks has two plectra, one 

 pointing to the right and one to the left. Turning 

 these jacks around does not alter the order of direc- 

 tion. The plectra nearest the keyboard points the 

 same way whether the jack is upside down or not. In 

 the clavicytherium at the Smithsonian Institution the 

 plectra nearest the keyboard points to the player's left. 

 In a clavicvtherium at the Boston Musemn of Fine 



Arts the opposite is true. Probably l^oth arrange- 

 ments were used in harpsichords also. 



String Lengths and Pitch Standards 



The vibrating lengths of the strings of the polygonal 

 \irginal and of the Ridolfi harpsichord can be roughly 

 determined from the drawings. For purposes of com- 

 parison, a tabulation of the vibrating lengths (in 

 inches) of the C strings on both instruments follows: 



The lengths shown for the harpsichord represent the 

 shorter of the two strings with which each key is 

 provided. 



In order to produce a uniform tone color throughout 

 the compass of a stringed instrument, it is necessary, 

 among other things, to have the tension of all the 

 strings reasonably uniform. In the treble this is 

 accomplished by varying the string lengths. Since 

 the length of a vibrating string is inversely propor- 

 tional to its frequency, each string is made about half 

 as long as the string an octave below, two thirds as 

 long as the string a fifth below, etc. This principle 

 cannot be carried all the way into the bass since the 

 lowest strings would be inconveniently long, so some- 

 where below middle C the strings are gradually 

 shortened and the diameters of the wires are increased 

 in compensation. 



As the above comparison shows, the string lengths 

 are approximately doubled at each descending octave 

 down to c' on the virginal and c on the harpsichord. 

 The shape of the case allows the harpsichord to ha\'e 

 longer bass strings than the virginal; between c' and 

 c the string length is doubled in the harpsichord. 

 However, in the virginal the c string is considerably 

 less than twice as long as the string an octave above. 

 In fact, the bass strings of the virginal are shortened to 

 such an extent that the lowest string of the harpsichord 

 is much longer than the lowest string of the virginal, 

 although in the treble the virginal has longer strings 

 than the harpsichord. 



If the length of one treble string of an instrument of 

 this sort is known, the lengths of all but the bass strings 



102 



BULLETIN 225: CONTRIBUTIONS FROM THE MUSEIIM OF HISTORY AND TECHNOLOGY- 



