This construction is based on the drum and dome of the Variation of Chapel 10.
The drum, now the main body of the building, has been extended from three to five levels. A section of the dome has been removed and three other sections have been slightly modified to form the slot in the dome, that is, the window through which the telescope watches the sky. Finally, 16 feet has been added to the lower ring of the drum (see below).
The telescope itself is a tube made of hexagonal antiprisms resting in another similar, longer tube, although it is obvious that it could rest in a variety of structures.
Two more views of the construction:
Each sphenocorona of the lower ring rests on a cube through a square pyramid. The wedge made of two squares prevents the cube from rotating: