Bass- added later to give more "meat" to the bass line, it's aslo known for burning longer than a cello.
Cello- originally was the instrument to play the bass line, later was used by composers like Ceaikovski (spelled Tchaikovsky for English people) to play melodies together with violins in BIG unisons.
Viola- people had to invent that in order to laugh of viola players (who wouldn't exist without viola)
The legend says that viola was invented when Antonio Stradivari being drunk, was trying to build a violin case.
Violin- That's the trumpet of the bowed strings instruments !
Brass & Woodwinds
All the things you should know about brass and woodwinds is told by Wynton Marsalis:
Wynton Marsalis telling the truth
Well, he's talking more about the Jazz Marching Bands (that's why he said about saxophones and don't mention bassoon, oboe and english horn).
So here's the explanation on the instruments not mentioned there.
Oboe - used to imitate duck sounds, in the lucky days oboe sounds like horny ducks, in less lucky days, oboe sounds like dying ducks and in worst days the oboe player is dying and oboe don't sound at all. That's the worst because you're stuck with viola jokes again :(
English Horn - A woodwind that got its name because it's neither English nor a horn. Not to be confused with French horn, which is German.
From the shape and sound, everybody expect that to lay eggs.
Here's a more serious guide to instruments.