Abstract: A robotic tractor that travels on rails forming a grid over a crop field and automatically performs tasks in the field is described. The tractor is supported on extendable legs that carry dual tandem perpendicular wheel sets. A rotary implement bed supported by the tractor is adapted to carry implements.

Abstract: A light-transmissive solar insulating block assembly comprising: light-transmissive insulating block means defining at least one internal cavity for insulating the interior of a structure to be heated; a housing having a light-transmissive cover providing an exterior surface and a plurality of support walls extending between and separating said cover and said block means, said housing cooperating with said block means to define a circulation chamber therebetween, said support walls defining a plurality of passageways for ingress and egress of air into and out of said chamber; and control means operatively pivotally connected to said housing for reflecting radiant heat back into the interior of the structure being heated controlling the amount of light passing through said chamber, and structures constructed from an array of said block assemblies.