I think the addition of fillports was an 1880-1881 thing for Dietz and S.G.&L (half owned by Dietz). Remember that they had no significant competition at that time. Patents for spring-loaded hot blasts persisted into the late 1890's. The oldest catalog that I have is the 1883 S.G.&L. which shows fillports on all lanterns and a few spring-top models available as well as a few blowholes that are illustrated.