The reference might be to a Mr. G.A.Weber's patent, #608088, issued on 26-Jul-1898. In fact, the entire class of patents after it are referred two as "Weber Insulated Joints". His original patent is for an insulated rail joint where, in addition to the two insulators that look like regular joint bars, there's another metal piece on the outside. It's an L-shaped piece that runs the length of the insulating joiner bars, and also fits under the rail to insulate it from below and to prevent flexing. The class of patents seems to focus around these joints where the outer metal joiner bar wraps around and under the rail.
I've attached an image of the drawing from the patent, and a link to the USPTO's scan of it. Warning, you'll need Quicktime, and probably IE. I couldn't get any other browser to load it.
It's a guess, and I'm not sure it's a correct one, since I can't imagine many Maine 2-footers having lots of insulated joints. Like I said, though, I might just be a generic reference to joints that include a support beneat the rail.
Nathan