The baryton can be viewed as a sort of augmented bass viol. It is similar in size to the latter instrument and likewise has six or seven strings of gut, arranged over a fretted fingerboard and played with a bow. The instrument is held vertically and is supported by the player's legs (rather than with an endpin as in the modern cello).
The baryton differs from the bass viol in having an additional set of wire strings. These perform two functions: they vibrate sympathetically with the bowed strings, enriching the tone, and they can also be plucked by the left thumb of the performer, creating a contrasting tonal quality. As can be seen in the illustration, the bowed strings are placed on the right, where they can be easily fingered by the player's left hand. The plucked strings are on the left; they were reachable by the player's thumb from the rear, where the back of the instrument's neck was left open.
Of the repertoire for this instrument, the best known works are the 175 compositions written by Joseph Haydn for his patron, Prince Nikolaus Esterházy, who enjoyed playing this instrument. Of these, 126 are trios for viola, cello and baryton. They were written in the earlier part of Haydn's career, from 1762 to 1775.
The historical baryton 
There are only about 50 historical barytons for which we have evidence, either in the form of documents or the instrument itself. Many of the latter have been modified from their original form. Thus, tracing the history of the baryton is a difficult task.
Concerning the origin of the baryton, Pamplin suggests that "the instrument probably originated in England in the early 17th century when the characteristics of two instruments, the viola da gamba and the bandora, were combined into one hybrid instrument." Early evidence for the existence of the baryton is found in Marin Mersenne's work Cogitata Physico-Mathematica (1644). According for Fruchtman, "Mersenne stated that the English constructed a viol or lyre much admired by King James. The instrument had six bowed strings as well as metal strings behind the neck. The thumb of the left hand plucked the metal strings, which were made to sound with the bowed notes. If this information is accurate, the baryton must have been known in England before 1625, the end of King James' reign." The earliest baryton that survives today dates from 1647; it was made by Magnus Feldlen in Vienna and is currently in the musical instrument collection of the Royal College of Music in London.
The instrument was never particularly popular, but "it acquired a certain cachet in courtly circles, particularly in south Germany and Austria" (Pamplin). The compositions for the instrument by Haydn and his students and colleagues represented a last hurrah for the baryton; by the early 19th century it had gone out of style and ceased to attract new compositions. The Haydn-era baryton was different from earlier versions in a crucial respect; the sympathetic strings were tuned a full octave higher than previously. This helped the baryton to stand out from the other instruments (viola, cello) in the baryton trio, the primary form in which Haydn wrote. Since the Haydn oeuvre tends to dominate the field today, the Haydn-type tuning has become the standard.
Modern revival 
The baryton was "completely neglected" (Hsu) in the nineteenth century, but in the twentieth, with the rise of the authentic performance movement in classical music, new barytons were built and played. Initially, these instruments were heavily constructed, more in the manner of a cello than a bass viol (they were thus sometimes called "cellitons"), but (much as with the parallel history of the harpsichord revival) eventually lighter instruments were constructed that more closely followed their historical antecedents.
Probably the first person to initiate the revival of the baryton was Christian Döbereiner in Munich. In 1934 he ordered a copy of an instrument by Simon Schödler (1782) from the renowned luthier, Ferdinand Wilhelm Jaura in Munich. The first performance in modern times on that baryton took place in Munich in 1936, which featured a trio by Haydn. This instrument forms part of the Vazquez Collection of Historical String Instruments and is frequently employed in performance by the Orpheon Foundation. A complete documentation of the Jaura Baryton is available at the Orpheon Foundation web site.
Among the modern active baryton players are Jeremy Brooker, Kazimierz Gruszczyński, Balasz Kukak (Haydn Baryton Trio of Budapest), José Manuel Hernández, John Hsu, Roland Hutchinson, José Vázquez, and Kenneth Slowik.
With the revival of the baryton, a body of recorded work has gradually emerged. Several ensembles have produced recordings of individual works, and the Esterházy Ensemble (Michael Brüssing, baryton) has issued a set of recordings that cover the entire Haydn oeuvre.
The Swiss composer Klaus Huber has written an important solo part for the instrument in his work ...à l'âme de marcher sur ses pieds de soie... (2004).
According to the Oxford English Dictionary, the name of the instrument is a loan word from French baryton or Italian baritono, and ultimately derives from Greek bary- + tonos 'deep-pitched'. Alternate spellings include: bariton, barydon, paradon, paridon, pariton, viola paradon, viola di bordoni, [Italian] viola di bardone, [German] viola di bordone.
- Gartrell (2003: 117) discusses the evidence for four-string barytons. Evidently all such cases either are barytons that were converted into cellos, or (in one instance) show evidence in the form of filled-in peg holes of an original form with six strings.
- Strunk (1932, 218)
- Hsu, cited below
- Gartrell (2003: 116). Fruchtman (1962, 2) writes, "the history of the baryton is a curious assortment of isolated facts."
- Pamplin (2009)
- Fruchtman (1962, 3)
- Pamplin (2009)
- Quoted in Warwick William Wroth and Arthur Edgar Wroth, The London Pleasure Gardens of the Eighteenth Century, 1896:96.
- Pamplin (2009)
- Pamplin (2009)
- Pamplin (2009)
- Sadie and Pamplin (no date)
- Fruchtman, Efraim (1962) The baryton: its history and its music re-examined. Acta Musicologica 34:2-17.
- Gartrell, Carol (2003) Towards an inventory of antique barytons. Galpin Society Journal 56:116-131.
- Hsu, John (1986) Program notes for his performance of trios #97, 111 87, and 101 with violist David Miller and cellist Fortunato Arico on ASV (GAU 104, 1986).
- Pamplin, Terence M. (2009) "Baryton", in David Wyn Jones, ed., Oxford Composer Companions: Haydn. Oxford: Oxford University Press.
- Sadie, Julie Anne and Terence M. Pamplin (no date, accessed 20 February 2012) "Baryton", in Oxford Music Online.
- The first modern Baryton, by Ferdinand Wilhelm Jaura
- Döbereiner and the Baryton by Ferdinand Wilhelm Jaura
- Roland Hutchinson and the Baryton (demonstration video at YouTube)
- Burgksteiner: Divertimento for baryton trio (performance on YouTube)
- Songs with baryton accompaniment by Prince Pal Esterhazy (performance on YouTube)
- International Baryton Society
- Baryton by John Pringle
- Esterházy Ensemble
- Haydn Baryton Trio Budapest