The ability to tilt the Cirkut, thus keep the horizon level, was patented by Eugene Goldbeck. With the patent number one can download the original patent. ( I'd give you the number, but I must find it !) The mechanism is fairly simple, essentially like the drive shaft on an automobile. Say a square shaft sliding in a square tube, one end of each with a universal joint. Add a pair of boards with a hinge along one edge and a couple of thingies to hold/attach the magic shaft and walla, or voila'. Oh yes, some brackets and thumbscrews to hold the angle you want between those boards.