In October 1774, Gluck was appointed Hofkompositor to the imperial court with a generous annual salary of 2000 fl (reduced to a net 1800 fl after the introduction of the Arrha tax in 1781). Although Gluck was never officially pensioned off, his transition to semiretirement in the 1780s meant his salary was inevitably understood on that basis and as a measure of his eminence in European musical life. When he died in November 1787, Joseph II took the opportunity over the next few months to reorganize the court music; this included the Hofkapelle (which had the principal duty of providing sacred music in the court chapel) and the Kammermusik (a small group which in theory provided personal service to the emperor). On 6 December Joseph appointed Mozart to his Kammermusik at a salary of 800 fl (net 760 fl). Because of the proximity of these events and the fact that both Gluck and Mozart were sometimes referred to as “(Kammer) Compositor”, many commentators have understood Mozart as Gluck’s “successor” in the position, with Mozart’s low salary perhaps a reflection of Joseph’s relative esteem for the two composers. But in fact Mozart’s position was a new creation, not equivalent to Gluck’s (see Link 2005), nor to Salieri’s nominal Kammer Compositor position which he had held since 1774 at a salary that was half Mozart’s.

The precise nature of Mozart’s duties as Kammermusicus are not at all clear, and the disposal of much contemporary documentation in the nineteenth century means it is now impossible to reconstruct the activities of the court music in the detail we would wish. What seems to be the first newspaper report on the appointment appeared in the Pressburger Zeitung on 25 Dec (Nr. 103, p. 4; also Auszug v.1237), citing “private letters” from Vienna of 22 Dec:

Wien, aus Privatbriefen vom 22 Decemb.
[...]
Der berühmte Musikompositor Mozard ist mit jährlichem 600 fl. [sic] Gehalt bey Sr. K. H. dem Erzherzog Franz zum Hofmusikus ernannt worden.

This report was repeated in the Prager Oberpostamtszeitung on 29 December (Berkovec 1989, 68; all these reports are missing in Dokumente and its supplements). Brauneis 2006 takes the reference to Archduke Franz seriously, viewing the appointment as Joseph’s initiative to provide his chosen successor with a small musical establishment. There is also the well-known comment by Count Johann Rudolph Chotek that Mozart was only given the post to keep him in Vienna (Dokumente, 388). As so often with the apparently arbitrary and disorganized employment practices of the court music, the decision to engage Mozart may have been the result of numerous factors both pragmatic and artistic.

This report from the Frankfurter Kayserliche Reichs-Ober-Post-Amts-Zeitung provides additional information on the appointment, stating that Gluck’s 2000 fl pension had been divided between Mozart and “other excellent musicians”. Interestingly, the dateline is 22 Dec, the same date as the “private letters” quoted by the Pressburger Zeitung above, which may suggest the reports had a common source. The correspondent was clearly well-informed, as the reference to “other excellent musicians” implies knowledge of developments that were then in discussion but not fully finalized until March the following year.

The Hamburg Reichspostreuter picked up the story on 9 Jan 1788, albeit with a slightly different wording:

Wien, vom 26 December.
[...]
Die ansehnliche Pension, welche der Ritter Gluck genoß, ist zwischen dem berühmten Herrn Mozart und einigen andern vortreflichen Musikern getheilt worden.

Who were the “other excellent musicians”? There were no additional musicians brought into the Kammermusik apart from Mozart and no increase in salary for those already there, so Mozart’s 800 fl accounts only partially for Gluck’s former pension if consideration is limited to the Kammermusik. It is more productive, however, to consider this report in the light of the wider reorganization of the Hofkapelle that was completed by March 1788. These reforms included the employment of some Hofkapelle musicians on annual contracts instead of the previous sessional arrangements, the transfer of the Hofkapelle from the office of the Obersthofmeister to that of the Oberstkämmerer, the pensioning off of Bonno (who passed away soon after), and the appointment of Salieri as Hofkapellmeister and Umlauf as his deputy.

Thus, while the report implies that it was a simple matter of dividing Gluck’s pension between new and perhaps existing musicians, the reallocation of the 2000 fl within the new structure means that the funds cannot be “traced” to a particular destination, and total expenditure on the court music did not remain unchanged but declined. This may be seen in the Hofkammer accounts from this time (ÖStA, Hofkammerarchiv; some but not all relevant entries are transcribed in Neddermeyer 2008):

Because the accounts used the military year (November to October) and the first few months of 1788 were under the previous arrangements, the most useful comparison is between the 1787 and 1789 accounts. While salary and pension costs increased due to the engagement of previously sessional musicians, operating costs declined to almost nil in consequence; they were perhaps further limited by a crackdown on additional hires and music copying costs ordered in February 1788 (transcribed in Link 2005, 176–77). Not listed here are costs for the trumpet and timpani players, who were members of the Oberststallmeisterstaab and paid a collective 2755 fl annually, but who had ceremonial responsibilities outside the Hofkapelle.

Mozart’s position was not immediately filled after his death, and it was not until August 1792 that Leopold Kozeluch was given the curious title of Kammerkapellmeister und Hofmusikcompositor at the enormous salary of 1500 fl (see Pfannhauser 1956, 11–12). If two newspaper reports are to be believed, Kozeluch’s salary was even higher; according to the Augsburgische Ordinari Postzeitung (1 Oct 1792):

Wien, den 24. Sept...An die Stelle des verstorbenen unvergeßlichen Kapellmeisters und Kompositeurs Mozart, hat der Monarch den Herrn Kozeluch mit einem jährlichen Gehalt von 2000. fl. zum Hofkammerkompositeur ernannt.

A slightly later report in the Gothaische gelehrte Zeitung (24 Oct 1792, 800) reads:

Wien. Die Stelle des verstorbenen k. k. Hofkapellmeisters und Concertcomponisten Mozart, hat der bekannte Componist Hr. Kotzeluch, um einen Gehalt von 2000 Gulden erhalten.

Neither report is in Dokumente or its supplements, but a similar notice from Der Heimliche Botschafter is in Addenda, 75.