My friend Nancy recently acquired a “glass-threaded” EAPC Lamp. In her search for a burner that would fit, we’ve been learning more about oil lamps. My apologies. I think you’re correct. That there may have only been one type of EAPC Oil Lamp. Those we think are glass-threaded may indeed be just lamps whose brass collars have come loose.

From what we’ve learned so far, dimpling along the top is all that holds the collar to the lamp. If the burner rusts and gets stuck to the collar, the collar can come out with the burner when unscrewing the burner.

We’re still researching this to be certain, but I think you’re right.

Actually, there are both types. EAPC Oil Lamps with a glass-threaded collar have glass threading inside the collar. Lamps with brass inserts have brass threading and the inside of the collar is smooth glass, not threaded, into which a brass or brass-plated burner can be inserted. So there are two types.