This is a CD 145.6 Boston Bottle Work in nice blue color (much lighter than the screw top) with considerable milky amber swirls. It's {MLOD} and has four-segments with the embossing "Boston Bottle Works - Patent Applied For -" on the inner skirt. This insulator was found on the Central of Georgia Railway South of Fort Valley and North of Marshallville, GA. The line was on the West side of the track and the insulator was on the fourth tier and had heavy old rusted iron wire on it. Note - all up and down the line the top tier was inactive with some of the wire cut and others still had spans that had not been cut as was the case here. At one time, Ray K. told me that the Boston's were used on a Postal Telegraph line which existed for only a few years. Space was rented on the Western Union Telegraph line - I really don't know why Western Union would give their competitor any leverage. If anyone has any information on the Postal history in Georgia it might be of interest to the hobby. I did find evidence of a one-tier line on the East side about 50 yards from the track in an area near Byron, GA which had CD 210 Postal and CD 145 Hemingray 21's. This would have to be much later than the early line which contained the Boston Bottle Works.