You can always count on Chris Rowell (Baltimore) and others for researching and stirring up points about the bottles we collect that I quite honestly, know very little about. That is what is so great about our hobby. So much depth and variety. Here you will see a few pictures of a shard that Chris dug with an illustration of a glass production flaw that we sometimes see.
I have also included two screen captures of some spirited dialog from the facebook Bottle Collectors page that is centered around the three pictures that Chris posted.