Upvote:0
One of the reasons many of the works of Mozart and Beethoven had their premieres during Lent is that the church musicians weren't playing their usual jobs and became the pick-up orchestra for other concerts. The composer/conductor/soloist would go out and hire a bunch of musicians to play his concert. One of the reasons why the composer would sit at the harpsichord with a figured bass, was to fill in the missing parts he hadn't found players for. Mannheim, Germany, was one of the first cities to have a sitting orchestra.
The young Mendelssohn asked his banker daddy for an orchestra for Christmas and he got it, every Sunday, so he could conduct his compositions and others. He is credited with rediscovering Bach at theses concerts.
Upvote:1
It is indeed difficult to find the numbers for 19 or early 20s century, and it very much depends on the country. Here are some modern data:
https://en.wikipedia.org/wiki/List_of_symphony_orchestras_in_the_United_States
Please notice the RATE of decline!
Upvote:6
If we look just at the up-market classical composers we see the following pattern: Up until the end of the 18th century virtually all of them worked either as court musicians in the service of some king or nobleman, or else they were employed by the (Catholic or Protestant) churches. Bach, for example, was a court musician in the first half of his career, and a church musician in the second half. A notable exception was Handel, who set up a profitable opera company in London. After the French revolution, when the number of petty noblemen in Europe decreased, we find composers like Beethoven, who lived from giving public concerts in big cities and by writing “Hausmusik” (music performed by amateurs in their own homes) and selling it to publishers. They also worked as music teachers for rich urban patrons.
Alongside these you also have “folk” musicians traveling from place to place, playing at weddings and village feasts.