Unlike chickens, geese are waterfowl, and the shell on goose eggs is very thick. People recommend a higher humidity towards the time of hatching for goose eggs, so we needed a way to know what the humidity actually was.
I developed a sensor that is connected to the Internet to make display easier, so here is the humidity of our gosling incubator

humidity of the gosling incubator (this is %RH and the x-axis is time, over a 24h span)
Unlike temperature, controlling humidity is low-tech – bar towels soaked in water and a water spray.