You can earn a 5%
commission by selling Flow of Water in Open Channels: Pipes, Sewers, Conduits, &C., with Tables, Based on the Formulae of D'Arcy, Kutter and Bazin (Classic Reprint)
on your website. It's easy to get started - we will give you example code.
After you're set-up, your website can earn you money while you work, play or even sleep!
You should start right now!