If we define a music box to have a tuned steel comb then Kevin Kline
is correct about the official birth date (1796) but it cannot be the
gold seal of the former Guido Reuge collection.

The official document (in French) made up by the Geneva Arts Committee
is copied in "The History of the Musical Box"  by Alfred Chapuis.
It speaks of "une boïte de fer blanc".  Eduard Saluz gives a German
translation of the document in the fine "Klangkunst" catalogue of 1996,
commemorating 200 years of the music box; it reads:

"15 Februar 1796, Protokoll der Genfer Société des Arts.  Musikwerk,
erfunden von Hernn Favre.  Herr Descombaz berichtet, dass Herr Favre
die Möglichkeit gefunden hat, Musikwerke ohne Glocken und Hämmer zu
bauen.  Er zeigt eine Dose aus Eisenblech, welche ein solches nach
dieser Bauart enthält......."

Translated, it reads: "15 February 1796, protocol from the Geneva Arts
Society, music movement, invented by Mr. Favre.  Mr. Descombaz reports
that Mr. Favre found the possibility to make music movements without
bells and hammers.  He shows a box made of tinplate, which houses one
made this way."

In a further report from 7 March 1796 it is stated that the movement
plays 2 airs, imitates the sound of a mandolin and that it is built
in a "tabatière" of normal size.

The music box with its hardened and tempered tuned steel comb was
only possible after the start of the industrial fabrication of useable
steel, almost certainly Swedish iron or refined in English blast
furnaces. After 1815, when it became widely available, the music box
came to glory.

Niko Wiegman