The pictured insulator is a nice blue aqua CD 158.9 Boston Bottle Works Screw-top. This is the shorter version of the CD 158.9s. The insulator was dug by a bottle collector about a year ago from a vacant lot in a known dump in downtown Augusta, Georgia. The digger advised that his research showed that the lot once belonged to the railroad. He could not remember the name of the railroad at the time of my acquisition. I asked him what else he had found and he said that he had found some rare very early 1870's bottles. Given this time frame I can't help but speculate that the CD 158.9 may have been the forerunner of all segmented insulators produced by the Boston Bottle Works. I asked the digger, as he continued to dig, to keep an eye out for anything that might screw down on the top and notify me. I have not had a response.