The base is a poured concrete slab over a buried circular wall of poured concrete 4 feet deep, 1 foot thick, 12 feet diameter. The circular wall above ground matches the one below but is made of 45-degree concrete blocks, filled with re-bar and concrete.
The "dome" is a square base 12 feet on a side sitting on a track of rolled angle iron. The wheels shown here were general-purpose replacement wheels from the local hardware store. They proved too flimsy and so many wheels tended to bind. I later replaced them with just three custom wheel assemblies I designed and had fabricated at a local welding shop. Each assembly held two wheels at right angles: one vertical and one horizontal. One assembly extended a shaft from the vertical wheel inside a few inches onto which I attached a small crank. The dome could be rotated easily with one finger.
There are two doors in the front which swing forward, and two on top which swing upward. The peak is not centered but is about 2/3 of the way back to afford a clear view of the zenith through the "slit".
Here you can see the asymmetric nature of the roof a little better. I don't know what that silly board is doing up there -- looks like it's about ready to slide down and konk me on the noodle.
The wheel skirt is in place, all finishing work is complete and the telescope has been moved in. At the bottom of the snapshot you can just barely see the top of a step I use to get in. Later I built a set of stairs the entire width of the building. This made it much easier to move to either side as I swung open the big doors on top. The entire project, from initial concepts to moving in the telescope, took me three years. Concurrent with this was the construction of the telescope.
I have been in many small circular domes and I would never want one after having used a square dome. The elbow room is far superior. There is room in each corner for shelves and storage which travel around with you. Thus, I can keep charts, eye pieces and like always in the same relative location throughout an observing session.
Now the rest of the story: I no longer have this observatory. I built it very permanently, as you can see, on a hill far back of my home at that time. When I divorced in 1991 I lost the home and hence the observatory. All I came away with was the primary mirror from the telescope. In June 1999 I had occasion to briefly revisit the site. The rotating wooden structure was gone entirely. The site was abandoned and had become heavily overtaken by dense vegetation. A large house has been built very nearby on what was then open pasture, forever ruining the clear views once enjoyed from the site.
A few other related links:
My Dobs telescope.
My resume.
Xephem, my astronomy program for X Windows.
email: ecdowney@ClearSkyInstitute.com