On a hygrometer:
I bought three at a local hardware store and tried all three in the bator.
all three gave different numbers and were basically useless
the only reliable system is a wet bulb
My advice, where in the house the bator is placed makes a big difference in humidity. I used mine in the basement (in Canada we all have concrete wall basements) for years and had good hatches without adding any water to the bator.
If the bator is an a room without a window or direct sunlight, then
you should be ok to hatch in spring.
In spring, March through May anywhere, the moisture is high and you probably won't need to add any water. In summer when its hot and dry you'll have to add water. do add water when its time to hatch.
its better to be dry than wet, from a dozen eggs you'll get something at least
for a wet bulb: get a container you can fill with water and seal other than a hole you drill to put a small cloth through (i use an old spice container) : the cloth is wrapped around the base of the thermometer so that the thermometer (wet bulb) measures the rate of evaporation. I bought a wet bulb at a hardware store or you can order from many mail order places; they charged an extra $5 over the price of the thermometer and it was the same thermometer with a dinky cloth on it
good luck, Bert
