Waves are produced by the friction of the air upon the water.
What causes the water to flow in creeks and rivers?
The attraction of gravitation, which causes water always to fall to its lowest level.
What retards the current of water in streams?
The friction, caused by the water rubbing against the banks and bottoms of the streams, retards their current.
In what part of a stream is the current the strongest?
It is strongest in the middle of a stream, because there is less friction there.
What retards the flow of water through a pipe?
The friction of the water against the sides of the pipe, retards its flow very much.
Why do sudden turns in a pipe check the flow of water through it?