The use of simple geometry and the local unit of measurement in the design of Italian stringed keyboard instruments:

an aid to attribution and to organological analysis


Grant O'Brien


A virginal dated 1641 by Stefano Bolcioni, Florence, in the Musikinstrumenten­museum, University of Leipzig

          The virginal by Bolcioni in the Musikinstrumentenmuseum at the University of Leipzig[39] is in a fairly ruinous state, but very interesting as a result of never having been restored in modern times[40].  This instrument is signed ‘Stefanus bolcionius Pratensis 1641’ written in cursive script in ink on the back of the namebatten[41].  The compass is C/E to f 3 with a broken short octave with split D/F#, E/G#, and then split g#/ab and g#1/ab1, giving it altogether 54 notes.  The c2 string scaling is 328mm, apparently based on 12 Florentine soldi = 328.09mm (see footnote 35), or, equivalently, of f1 = 18 Florentine soldi. 

          It is a rectangular virginal with the right rear corner missing from the rectangle so that, placed in its outer case, the empty space provides a toolbox in the normal way.  Here the only triangle which can be used to make an initial estimate of the unit of measurement is that of this rear toolbox space.  A summary of the original measurements of the baseboard and case height is given in Table 9.






                                                                           Length:               1592

                                                      Length of rear spine:               1244

                                                           Baseboard width:                424

                                                     Short right-hand end:                136

                                                Case left of the keywell:                384

                                                                        Keywell:                 710

                                              Case right of the keywell:                498

                                                           Keywell projects:                117

                 Component of toolbox side along the spine:                348

           Component of toolbox side along the right side:                287

                                                    Angle of toolbox side:               50½º

                                                      Height of case sides:                210


tan 50½º = 1.213 1.214 =                = 1.2125

Table 9

Baseboard dimensions and case height

Rectangular virginal by Stefano Bolcioni, Florence, 1641

Musikinstrumentenmuseum, University of Leipzig

(On loan from the Leipzig Museum für Kunsthandwerk)




Analysis of the unit of measurement used in the construction of the Leipzig Bolcioni rectangular virginal:

          The procedure for determining the local unit used to construct this virginal begins with the measurement of the toolbox angle at the rear right-hand corner of the instrument.  The tangent of this angle is tan 50½º = 1.213 ≈ 1.214 =  and this suggests that the two sides of the triangle that form the toolbox are 12¾ soldi and 10½ soldi which, mathematically, would form an angle of 50.53º.  This angle is very close to the measured angle of 50½º.  Measurement in millimetres of the length of the two orthogonal components of the toolbox side gives an approximate estimate of the size of the soldo.  Table 10 shows the calculation of the unit of measurement used in the Bolcioni rectangular virginal based on the assumption that the sides of the toolbox at the rear right-hand side of the instrument were constructed geometrically using lengths of  12¾ soldi and 10½ soldi.



                                                                                   Measurement          Local                             Length of

                                                                                               in mm          unit                                  soldo

                    Toolbox angle component parallel to spine:           348    =    12¾ soldi                    »    27.29

         Toolbox angle component perpendicular to spine:           287    =    10½ soldi                    »    27.33

                                                                     Total length:         1592    =    58¼ soldi                    »    27.33

                                                        Length of rear spine:         1244    =    45½ soldi                    »    27.34

                                                             Baseboard width:           424    =    15½ soldi                    »    27.35

                                                       Short right-hand end:           136    =    5 soldi                         »    27.0

                                                  Case left of the keywell:           384    =    14 soldi                       »    27.43

                                                                           Keywell:           710    =    26 soldi                       »    27.31

                                                Case right of the keywell:           498    =    18¼ soldi                    »    27.29

                                                             Keywell projects:           117     =    4¼ soldi                     »    27.53

                                                        Height of case sides:           210    =     7soldi                     »    27.39

                                                                                Total:         5950    =    217soldi       Average:   27.34mm

Table 10

Calculation of the local unit of measurement

Rectangular virginal by Stefano Bolcioni, Florence, 1631

Musikinstrumentenmuseum, University of Leipzig

(On loan from the Leipzig Museum für Kunsthandwerk)



          These measurements are shown in the diagrams of Figure 11 where the actual measurements in millimetres are shown in the top diagram, and the measurements in units of the Florentine soldo are shown in the diagram at the bottom.  The value of the length of the soldo found for this instrument is very close both to that found for the Yale Bolcioni single-manual harpsichord (error 0.04%) and to the reference values already discussed for the previous instrument (see footnotes 37 and 38).  This excellent agreement helps to confirm both that the instruments are made by the same maker and that their design is based on the Florentine soldo.




Figure 11

Baseboard measurements in millimetres (above) and in Florentine soldi = 27.34mm (below)

Rectangular virginal by Stefano Bolcioni, Florence, 1641

Musikinstrumentenmuseum, University of Leipzig

(On loan from the Leipzig Museum für Kunsthandwerk)


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[39] This instrument does not bear a Leipzig Musikinstrumentenmuseum catalogue number as it is on loan from the Leipzig Museum für Kunsthandwerk.  My thanks to Ezster Fontana and Klaus Gernhardt of the Musikinstrumentenmuseum of the University of Leipzig for their help and co-operation in allowing me to examine this instrument.  Please note that this instrument is not listed among the other instruments by Bolcioni in Donald H. Boalch, Makers of the Harpsichord and Clavichord, 1440-1840, (3rd Edition, Clarendon Press, Oxford, 1995) 248‑9.  I do not want here to digress into the intricate reasons why both this instrument and the virginal in Munich (see footnotes 31 and 74) were thought by Hubert Henkel not to be by Bolcioni.  As mentioned in footnote 31 I see no reason to doubt the signatures nor the authenticity of either of these two instruments for all of the usual reasons - the workmanship, materials, mouldings, unit of measurement, etc. are similar for all of these instruments.

[40] The jacks, for example, have beautifully-cut plectra which may well be original eighteenth-century French raven quills!

[41] The signature is incorrectly given as “Stefanus Colcionius Pratensis 1641” by Hubert Henkel in Kielinstrumente.  Katalog des Musikinstrumentenmuseums der Karl-Marx Universität Leipzig, Vol. 2 (VEB Deutscher Verlag für Musik, Leipzig, 1979) 112. 

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