Ralph, these potash mines are quite remote and I could never get close enough to get some idea of dimensions of the domes so decided that I would make mine to fit in the space I had available. I started with an 8inch diameter circle on a piece of corrugated cardboard. I then marked the circumference into 45degree sections. I cut 8 sections of corrugated cardboard with a 90degree angle 4 inch base to go from the centre of the circle to the edge. The upright side is 4 1/2 inch high. I then cut a curve along the hypotenuse. Next I cut a piece of cerealboard wide enough to fit around the circumference between two sections. I lay it over the curved sections and used a pencil to draw the edges. No calculations here, just cut and fit. Once I had one piece cut that fit properly, I made 24 of them to go on the 3 domes.
Each dome is a scale 105 feet in diameter and 60 feet high.