Here are two photos, each showing both pens - capped and uncapped. Hopefully the second photo does a decent job of highlighting the hump fillers (and the barrel imprints as well).
The Evans is a small, stubby (4.25") BCHR pen with a nickel-plated clip and a bright red top. David Nishimura has one for sale at his marvelous website, and he dates it to around 1920. (He also reckons the red top is casein, which seems likely to me.)
My Evans is not a Frankenpen, but it is a hybrid of two different "parts" pens that arrived one day in an otherwise uninteresting lot. Neither Evans had a nib, sadly, but I was able to combine the various pieces to create a complete working pen. The restoration process was a vivid reminder that parts interchangeability, in the context of obscure, inexpensive early pens, exists only in an aspirational sense; I had a lot of filing, heat-setting, tweaking and trial-and-error hand-fitting to do before I coaxed all the components into harmonious coexistence.
The Evans uses the "WAWCO" filling system invented by William A. Welty (his monogram supplied the "WAW" of "WAWCO"). The WAWCO filler was first used on pens bearing Welty's own name; Richard Binder shows a lovely specimen at his website. While the Welty pens seem to have been relatively upmarket instruments, the Evans was decidedly a pen built to a price: one dollar. I'm afraid the pen betrays that fact in the general roughness of its fit and finish. By the way, the pen's substitute nib is a NOS (though unbranded) Welty nib; so while the nib is incorrect, it has, at least, a sort of family connection.
My Evans pen is imprinted "PAT. 10.30.06"; and this patent, issued to Mr. Welty on that date, does indeed detail the design and operation of the WAWCO filler. It's interesting to note, though, that there's also a later patent, issued to Welty on March 30, 1909, covering a hump filing system that predated - and was arguably similar to - the Grieshaber design discussed below (this latter Welty system involved a two-part rotating barrel - I wonder if any pens using that system were ever produced?).
Unlike a Conklin crescent, which it superficially resembles, the Evans's "hump" is a solid piece of metal attached to a pressure bar. It works much like the Conklin, though: one presses the hump in order to compress the sac; releasing it allows the sac to expand and draw in ink. To unlock the filler, one slides a rotating ring until its slot aligns with the hump; at that point the hump can be freely depressed. To lock the filler, one rotates the ring so as to move its slot away from the hump. Again, of course, this is very Conklin-like; the principal difference is that instead of moving straight down when pressed, the Evans's hump moves in and down (toward the section). So the Evan's rotating ring, instead of passing under the arc of a crescent to prevent motion, blocks the hump from moving downward. In practice, the system seems every bit as reliable as the Conklin system.
The Grieshaber is a different sort of pen. It's a BHR ringtop, but it's rather slender and elegant; the taper of the barrel and the gold-filled, floral-engraved cap fitting contribute to its svelte and sophisticated look, as does its length of 4.75". There don't seem to be an awful lot of Grieshaber hump fillers out there by way of reference, so I'll hazard a guess that this pen, too, dates from around 1920. Restoring this pen required the reshaping of the feed, whose leading edge had broken; in addition, the original nib proved to have a horrendous crack in the area hidden by the section, and so a suitable Warranted substitute was fitted.
The most obvious visual point of difference from the Evans isn't width, length or refinement of trim, however: it's the naked filling hump, with no provision for a locking ring. An odd look, to be sure.
To lock and unlock the Grieshaber's hump, one rotates a knob at the end of the barrel; it looks for all the world like a twist-filler knob. Rotating that knob turns a sliding sleeve inside the barrel. There's a notch on the hump and a notch in that sleeve; when the notches align and lock together, the hump is prevented from traveling inward. When they're not aligned, the hump (which is attached to a pressure bar that acts on the sac) can be readily depressed for filling. Perhaps this patent, issued to Benjamin Grieshaber on May 3, 1910, will give a better idea of the mechanism's operation than my poor description. Note, however, that this patent describes a system in which one actually rotates the barrel itself, relative to the section, in order to turn the inner sleeve; there's no barrel-end knob. (I was unable to locate a patent for my pen's specific design, notwithstanding the reference, in the imprint, to a patent issued 3/12/12.)
How well does this interesting arrangement work? Well, the twist knob is far more elegant than a bulbous locking ring (if "elegant" can be reasonably applied to any pen with a great honking semi-circle of metal protruding from its side), and the inner sleeve is a novel solution to the locking/unlocking challenge. In fairness, though, I somehow feel that the Grieshaber system fails to lock the filler quite as securely as does the Evans system. It's important to keep in mind, naturally, that one is dealing with an 80-year-old pen, and decades of wear may have compromised the precision of the parts. Still, I suspect the twist knob would accidentally turn, in a pocket, more readily than the Evans's simple barrel ring.
Elegance vs. utility: that's an old tug-of-war, of course. The Evans is somewhat crude, but it gets the job done. The Grieshaber is rather sophisticated, but that sophistication comes, perhaps, at the expense of security. One thing's for sure: each of these pens is interesting and fun to play around with. Apart from their inherent mechanical fascination, they have endeared themselves to me during the course of a rather demanding restoration process, and I'm delighted to have them both in my collection.
I hope there's something of interest here. I would be thrilled to have the benefit of additional historical context, further patent citations, etc., from my FPN colleagues.
Cheers,
Jon