The orchestra was rather small at this time, maintained by noble families for private concerts. Handel had as few as 30 players. Bach usually used about 18 players.
The violin family displaced the viols as the principal strings of the orchestra (except the double bass which came from the viols family).
In the strings, a division into four parts had become standard: first and second violins, violas, and cellos + double basses playing the same part.
Woodwinds usually included two oboes (or sometimes flutes) and a bassoon.