Gravity fed watering????

I want to know if there is any plans out there for a gravity water feeder?

I am currently running a small soil grow. would rather make one tank and drip it, for emergencies. I also have done bubble ponics no watering problem there. just with soil.

Any help or suggestions welcome.

People are stopping by and I get no replys? Has any one used those water globes? do they work? I was going to try and base a sytem off that principle or theory.