This is a part of railroading that I've never known anything about. Is it possible to have a photo or a drawing of a heater posted. I'd love to see one. This, also, makes me wonder if the Boston & Maine used these heaters. I believe that I'd heard that potatoes had to be heated during shipping.
They may have been used on the B&M, but most of that road's potato traffic originated on the Bangor & Aroostook (BAR).