This concerto, kept under the name Rosetti in the library of Stift Melk, is not known until today as a concerto for solo horn and orchestra.

Sterling E. Murray describes in his catalog of 1996 ("A Thematic Catalog: The Music of  Antonio Rosetti (Anton Rösler), ca 1750-1792)" this work  as the concerto for two solo horns where the part of the first solo horn is missing. How was this wrong assumption made by the correct title "Concerto pour le cor"? The reason lies in the heading of the solo horn part, namely "Corno 2do Prinzipale in Dis". One possible conclusion would be, that this concerto was written for two solo horns, but the first horn part is missing. 

The other possible interpretation of the heading is certainly the correct one, that this work was written for one horn of the deep register, formerly named as the corno secundo. I was easily recognizing this interpretation by playing the solo horn part, which is not at all incomplete.

At the time of the Wallerstein Court, there were two excellent horn players, Joseph Nagel and Franz Zwirzina. The estate of Zwirzina keeps several solo and double horn concerti composed for these two hornists by Rosetti as well as by other composers, like the here edited  Concerti for two horns of Hoffmeister. In these concerti as well as in the very virtuoso harmony music, Zwirzina showed probably also a very virtuoso deep register. Rosetti dedicated Zwirzina or another second horn player one special concerto for their register. The title is here the same as for the second horn part in a double horn concerto, that is Corno 2do principale. The confusion is only recognizable by examine the music itself. 

The authorship is questioned, but I am convinced that this concerto was composed by Rosetti. The evidence lies in the bar 84 to 87 where the humorous Rosetti cited with Bohemian wit the theme of the double horn concerto E flat major of his orchestra colleague and composer Joseph Fiala, as well Bohemian. Both together started their employment at the court of Wallerstein in 1773. Certainly, they knew each others compositions and were amused by this quiet quotation. 

ROM 36

ROM 36a

ROM 36b