At a local auction today I picked up a box lot of canning jars and a few tobacco tins because down in the bottom there were two glass nob insulators. They are embossed THE E. S. G / & CO., Aqua, and 1 3/4" X 1 1/2 " and although they are known to collectors are still unlisted in the Briel Price Guide. Definitely a fun find. Both have that sooty grim so I think they were used in proximity to steam locomotives.