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.
The metronome was invented by Dietrich Nikolaus Winkel in Amsterdam in 1812. A man called Johann Maelzel copied Winkelâs ideas and improved them. He made a small, portable metronome which was patented in 1816. The metronome made it possible for a composer to show the performer what speed he wanted. If the composer writes at the top of his music: Crotchet (quarter note) = 76, for example, then the metronome can be set at 76 and it will tick at the right speed for that piece of music. Sometimes they write MM76.