Many chicken keepers keep their flocks refreshed by hatching eggs from their own hens. The easiest way to do this is to let nature take its course. All you have to do is provide a nest box for a broody hen. She will provide the right conditions for hatching eggs (although she will not be able to cope with more than a dozen at a time, or fewer, with smaller breeds), warming and turning them as necessary. The only problem is that you can’t make a hen broody if she’s not feeling broody!
Collecting hen eggs in the morning is one of the great pleasures of chicken keeping
Broodiness is an instinct, and requires a hormone called prolactin to prompt the correct behavior. A hen fed with a healthy diet, including lots of calcium grit, plus the presence of a rooster, will usually become broody. You will then need to keep the other hens away from her nest box (a separate brooding coop is the ideal answer), to prevent them laying their own eggs in her box or otherwise disturbing her. Also, once the chicks are hatched, they are in danger of being attacked by the other birds.