I'm not trying to belittle anyone but there is no such thing as "dry incubation" or "dry hatching"....and for certain, no "dry hatching"....unless you want 'shrink wrapped' chicks....ambient humidity is always present, if in an arid condition it may be very low, if in tropical conditions, it may be super saturated!
A better term would be limited humidity incubation.
Even in some 'tropical' conditions, small amounts of water must be added to keep the humidity stable.
Relative humidity isn't stable, even in a climate controlled environment. So, the incubation process must be monitored to be able to make adjustments as needed, either adding water or opening more vent to release moisture to obtain the optimum Rh%. There isn't a machine made that is truly automatic....'plug & play'!