The method and terms of "Dry Incubation" and "Dry Hatch" were a thing long before we came into chickens. If you read up on it, it is not without humidity. It still uses the 99.5 degree temp. You just don't put water in the incubator until lockdown. Days 1-18 the humidity is between 20-40%. At Lockdown, you then add water to raise the humidity. We do 65% at lockdown and it has worked well.