さっそく情報提供をお願いしたところ、学芸員 ケネス・ムア氏（(Mr. J. Kenneth Moore)からご丁寧な情報をいただいた。
Information of the Arpeggione;
Mr. J. Kenneth Moore
Frederick P. Rose Curator in Charge
Department of Musical Instruments
Metropolitan Museum of Art
New York City, New York 10028-0198
Object Name: Arpeggione
Maker: Johann Georg Staufer
Date Label: 1831
Object Place: Vienna, Austria, East, Europe
Medium: Wood, various materials
Description: Spruce belly, 2-piece back of figured maple, ribs of figured maple, lowest rib in 2 parts separated by purfling strip, hard, brittle, yellow varnish with fine craquelle; hardwood neck stained black and varnished, grafted pegbox of hardwood (pear?) stained black and varnished, escutcheon-form head with inlaid ring 6-point star of black abalone and mother-of-pearl, fingerboard of back-stained pear? with 23 inlaid German silver frets, patent mechanism maple? pegs stained black with inlaid ring of mother-of pearl with black dot, pear? tailpiece stained black, stained beech and maple purfling with 3 stripes of equal thickness, spruce corner blocks and linings, maple? upper block, later synthetic endpin holder.
Dimensions: Total L.: 115.7 cm (45-9/16 in.); Body L.: 68.2 cm (26-5/8 in.);
Widths: UB. 33.3 cm (13-1/8 in.): MB. 23.2 cm (9-1/8 in); LB. 39.5 (15½ in.); Sto. 34.2 (13-3/8 in);
String L. 60.4 (23½);
For other measurements see department file.
Mark(s): (printed on label) Joannes Georgius Staufer/fecit Viennae anno 18(MS)31; (stamped) "D.R.G.M."
Notes: In 1832 Staufer and his son patented a model for bowed instruments having the bridge positioned exactly at middle of belly length; therefore F holes are higher than normal. This instrument seems to have such proportions and so may combine the idea of the improved violoncello with the arpeggione, invented in 1823. The adjustable neck and patent pegs are typical for Staufer. (Rudolf Hopfner, March 1997.)
The stamped mark D.R.G.M on the endpin clamp refers to a design registered by the Deutsches Reichs Gebrauchs Muster, in effect until World War Two.
Constructed according to Viennese inch measure.
Catalogue information compiled by R. Hopfner (1997).
From Harvey Turnbull's The Guitar from the Renaissance to the Present Day: "In 1822 the German violin and lute maker George Staufer was granted a license to work in collaboration with Johann Ertel on improving the construction of guitars. Two of their improvements were the raising of the fingerboard above the table to create a better tone and the use of an alloy of brass, copper, silver and arsenic -- used by button makers in the manufacture of white buttons -- instead of silver or ivory for the frets to provide a more durable material." (See references card)
The arpeggione's adjustable neck is very similar to those seen on early C. F. Martin guitars (from 1834 on); C. F. Martin, the famous American guitar maker, worked with Stauffer (sic) in Vienna, becoming foreman of Stauffer's shop before migrating to New York in 1833. Stauffer was originally a guitar maker. See Mike Longworth, Martin Guitars; a History (1975), pp. 3, 16-17.59.105
"no reason to question its authenticity" F. Hellwig (May 1978).
For information on Staufer's invention and description of another arpeggione, see Georg Kinsky, catalogue of Musikhistorisches Museum von Wilhelm Heyer in Cöln, vol. 2, p. 174-175; further on Staufer in Paul de Wit, Geigenzettel alter Meister...(2nd ed., 1910), part 1, p. 14 and table 33; see also Anthony Baines, European and American Musical Instruments, p. 23, and ill. 141.
Black and White Negative: 170739
Credit Line: Purchase, Rogers Fund, 1959