I'd like to extend this question...
I know that knocker-uppers were employed in cities. People whose job was literally to knock on people's windows at certain times of the morning. And I know that there was a smaller set of people (knocker-upper-knocker-uppers?) whose job it was to stay up all night and wake the wakers.
But what I want to know, and I'm hoping somebody will chime in, is what sort of systems were in place outside cities? Were knocker-uppers still used? Did people just rely on the dawn or the rooster?
Were any pre-alarm-clock devices or conveniences used other than knocker-uppers?
FYI, you'll find a few more examples in the FAQ