If our eyes only saw frames (IE: 30 images a second), like a single lens reflex camera, we'd see images pop in and out of existance and that would really be annoying and not as advantagous to us in our three dimensional space and bodies.
In the Vienna of the second half of the 18th century, in addition to Haydn and Mozart, three symphonic composers, namely Leopold Hoffmann, Carl Ditters von Dittersdorf and J.B. Vanhal helped further the development of the symphony.
Beethoven's Fifth Symphony (1809) is the earliest use of the trombone in any symphonic work that is ever performed anymore, although the Third Symphony of the little-known Swedish composer Joachim Eggert (1807) appears to be worth reviving.