A little while back, Bernie Maopolski of the Fan of History podcast and I discussed some recent research into the use of hydraulics at the step pyramid of Pharoah Djoser. 
Well, lordy lordy, we received an email from a hydraulic engineer who said that the original researchers were barking up the wrong tree. Let's see what he had to say. 
You can find Bernie's show at https://shows.acast.com/history.