I saw these 95-year-old cinderellas in an
ebay listing that looked quite colorful from the early days of stamp collecting (1916):

When I saw these, I decided to look up the convention being advertised. However, the account of the happenings as related in this philatelic journal, sounds as if it was as boring as any convention I've ever heard of, with the highlight being a dinner at a Chinese restaurant.
Certainly boring by today's standards...but then again, maybe this was considered something exciting 95 years ago?

