In dome 1 the sides are divides in three parts and opposite sides are connected by 2 ribs. In The points on the side of the basic square are connecte in a way that they form 2 smaller, slightly rotated squares.[br]The ribs perpendicular to the sides mark a smaller central square as base for a second dome.[br]In the applet below you can see how this confiuration looks like in 3D.