early eyedropper fillers that employed a device that withdrew the nib assembly into the barrel by turning a knob at the end of the barrel. When the cap was on tight, this prevented the pen from leaking.

the part of the pen at the end of the barrel that holds the nib and feed. Sections are either threaded into barrels or are designed to friction fit.

A term that was used to describe any pen that had a filling system, rather than being eyedropper filled.
Another definition I found reads: A pen that holds its own ink supply and refills the nib automatically rather than having to dip it. This is usually considered a criterion for a pen to be a "fountain pen." Waterman and several other companies designated pens as "self-fillers."

a model of the Parker 51 that had a gold-filled cap and barrel.

Wahl-Eversharp's modern designed pen of the '40s. The Skyline was a very popular pen and millions were produced in hundreds of variations. They were lever-fillers and are known as very good writers. P.S. If anyone finds a white one, call me.

yet another approach to operating a pressure bar against a sac. A sleeve was moved out of the way to reveal the pressure bar which was operated by the thumb.

any cap that friction fits to the barrel rather than being threaded.

a popular design of the early century for eyedropper pens. Parker's snake came in silver or gold-filled. Waterman's, which is much rarer, is only known in silver. The lowest priced snakes, in good condition, will bring over $10,000.

A filling system by Sheaffer from the early '50s. A knob on the barrel caused a metal tube to emerge from the feed so that the entire nib did not have to be immersed to fill.

The second style of Parker Vacumatic filler that did not have to be locked down.

Parker tried to register a "star" as a trademark and got turned down. They did produce some clips with this star mark before they came out with the blue diamond. "

Usually means a pen cap that is straight and the same size as the barrel. Associated with eyedropper filled pens.

A celluloid pattern

Conklin's entry into the field of streamlined pens introduced by all the major companies in the early '30s to replace the flat-tops of the '20s.

designed by Raymond Loewy, Symphony replaced the Eversharp Skyline. It featured a metal cap but used a nib/feed assembly like that of the Skyline.