Bernard, the ‘lonely trademark on the opalescent 1315’ is on the side of the interior of the ‘bowl’, and I attach a photo in confirmation.
Might I say that I have never purported to be any sort of authority or expert on Sowerby glass (or any other kind of glass for that matter). I am merely an amateur researcher into many aspects of glass design (mainly British Victorian moulded glass designs, especially those from registered designs, and glass trinket sets), and am a seeker after knowledge and truth, not accolades. I think it was Isaac Newton who said “If I have seen further it is by standing on ye sholders of giants”, and I pay due obeisance to those who truly are ‘giants’ in my various fields of interest.
I use the GMB as a resource to further my own research and am incredibly grateful for the input of other participants in those discussions (and try to express my gratitude as appropriate).
During the course of my research I have built up a large photo reference database as a useful primary source of information. Many of the photographs are of pieces that are rare, uncommon, or unusual. Some of photographs are of pieces that seem never to have been to have been in the public domain before. On occasion, I submit information to other members to [hopefully] assist them in their queries or research and hope that participants in the various discussions may gain some benefit.
Fred.