These are the fold down flaps to permit viewing low to the North. Here they are in the down position - note that the metal cladding was yet to be fixed to the flaps. It is the second attempt - in the first attempt I constructed a single flap which I deemed too flimsy for its weight (flexed too much). The two flaps seen here were later fitted with gas struts to assist with opening / closing, and as a preventative mechanism against accidents in the dark (the flaps are reasonably heavy, especially after the metal cladding was fixed).