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Filling System Histories: Getting Over the Hump

(This page revised July 4, 2015)

Reference Info Index | Glossopedia  ]

This article is a revised and expanded version of one that first appeared in the February 2014 issue of Pen World Magazine.

Conklin Advertisement featuring Mark Twain, 1904
This 1904 Conklin ad from McLure’s Magazine (top page) shows Mark Twain, with part of a testimonial letter referring to Conklin’s pen as a pro­fan­i­ty saver.


In 1897, Roy Conklin of Toledo, Ohio, invented a self-filling fountain pen. The next year, he founded the Self Fountain Pen Company and became its secretary/treasurer. He didn’t get around to filing for a patent on his design, however, until 1901, when he and his co-investor C. B. Gundy changed their company’s name and incorporated as the Conklin Pen Manufacturing Co., with Conklin as president. Conklin’s first patent, (U.S. Patent No 685,258), carries a date of October 19 in that year. Conklin’s design wasn’t the first successful self-filler — that honor goes to Woodruff Post’s pull filler — but Conklin’s pen enjoyed runaway sales, with celebrity endorsements from the likes of Samuel Langhorne Clemens (better known as Mark Twain, seen in the Conklin advertisement shown to the left), who referred to it as a “profanity saver” because it would not roll off the user’s desk. (During his lifetime, Clemens owned several different pens; from 1904 to 1907, according to Dr. Ron Dutcher, Conklin’s Crescent-Filler, Model S, was his constant companion.)

Crescent and lock ring

Conklin’s Self-Filling Fountain Pen would not roll off the desk because the filling mechanism featured a crescent-shaped metal hump protruding from the side of the barrel, as illustrated by the photo above and the portion of Conklin’s patent drawing shown below.


To prevent accidental pressing of the crescent filler, which soon edged out “Self-Filling” in the product name, Conklin used a lock ring that rotated around the barrel. The ring was not a complete circle; a portion was removed, leaving a C-shaped ring. When the filler was locked, part of the ring passed through the opening in the crescent. To unlock the crescent, the user turned the ring until its opening was under the crescent, allowing the crescent to be pressed into the barrel to compress the sac.

Crescent and lock ringTo prevent competitors from immediately developing systems based on his concept, Conklin included in his patent application two additional variations of the design. These both used a solid blade, notched at the ends, coupled with lock rings having notches that engaged the notched ends of the blade in much the same fashion as the notches at the ends of flaps on a small paperboard box such as many pen companies use to protect their pens’ display cases during shipment. Shown here is one of these alternate implementations as drawn in the patent papers.

In 1903, Conklin patented an improvement on his design (U.S. Patent No 745,481). Initially, the lock ring had been free to rotate all the way around. In use, the ring tended to rotate when it wasn’t supposed to, exposing the pen to the very problem it was supposed to prevent. Conklin changed the ring slightly, so that it would jam under the crescent when rotated to lock the filler.

Fountain pen
Fountain pen
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The popularity of Conklin’s pen spawned a number of imitators. The important thing for the second guy in line at the Patent Office to remember is that he must make his design different enough that it doesn’t infringe on the patent rights of the first guy. Some of the imitators didn’t manage that feat — in fact, some seemed not to care, as they produced pens with fillers identical to Conklin’s. At least one of these upstarts, the Skidmore Fountain Pen Company, also of Toledo, sold a high-quality copy of the Crescent-Filler until 1924, when a court order put the Skidmore brothers out of business.

Other imitators, more ingenious, managed to produce pens that did pass muster. Their pens, as well as Conklin’s, are classified under the general heading of “hump fillers.”

Variation I

One of the best-known companies to produce a hump filler was the Paul E. Wirt Fountain Pen Company of Bloomsburg, Pennsylvania. Wirt sold pens built to U.S. Patent No 852,369, issued to Wirt himself in 1907. Wirt’s design, a slight variation of his U.S. Patent No 852,368, used a round knob attached to the pressure bar as its hump; a sliding bar, actuated by a knob at the end of the barrel, blocked the movement of the hump by slipping into a notch in the hump itself, as can be seen in his patent drawing.


The actual implementation didn’t quite match the patent, in that the round knob became a hard rubber hump, like Conklin’s, and the slider became a J-shaped bar whose end wrapped around the end of the barrel slot to lie along the outside surface of the barrel as shown by the photos below.

Fountain pen
Fountain pen

Making the locking bar as he did allowed Wirt to simplify the machining of the barrel, thus reducing cost. He also placed a threaded knob at the back end of the barrel to move the bar, probably because a simple push-pull knob would not stay pushed in reliably.

Variation II

In 1910, Benjamin Grieshaber of Chicago, Illinois, received U.S. Patent No 956,895) for his hump filler, which was in essence an improved version of Wirt’s design. Instead of a sliding bar, Grieshaber used a rotating sleeve (part 13, in cross-section in Figures 2 and 3 below, fully exposed in Figure 4) within the barrel. His patent drawing shows the shape of the sleeve’s end; when rotated in one direction, the sleeve locked the hump by fitting into a slot in the hump as did Wirt’s; when rotated the other way, the sleeve retracted from the slot, releasing the hump.


Grieshaber’s patent shows the sleeve attached to the gripping section — with the entire barrel, rather than the sleeve, free to rotate. In production, however, Grieshaber followed Wirt’s lead, consciously or not, by reversing the mechanism, and attaching the sleeve to a knob at the end of the barrel. The knob was not threaded, as it did not need to move longitudinally in the barrel.

Fountain pen
Fountain pen

Variation III

One of the more forthright copies came from the mind of William A. Welty of Waterloo, Iowa. In 1906, Welty patented a design that he called the WAWCO filler (for William A. Welty COmpany). Welty’s design, U.S. Patent No 834,542, featured a hump and a lock ring almost exactly like Conklin’s. The difference lay in the actual locking mechanism: instead of slipping the ring through an opening in the hump, Welty made angled notches on each end of the hump. The ring slipped into one of the notches, sliding the hump (and with it, the pressure bar) slightly toward the back end of the barrel, so that the second notch in the hump would latch onto a beveled surface at the end of the slot in the barrel.

Fountain pen

Welty’s pen, which he also called WAWCO, naturally attracted the attention of Conklin, who sued Welty for patent infringement. Welty prevailed. In 1915, his company changed its name to the Evans Dollar Pen Company (in recognition of Patrick H. Evans, who had provided an infusion of cash after Welty won the lawsuit brought by Conklin) and began selling a reduced-quality version of the WAWCO pen. Welty himself patented a completely different filling system, apparently setting up a new company that took his name for the filler as its own, becoming the Servo Fountain Pen Company, with offices in Waterloo, Iowa, and a factory (maybe not its own) in Boston, Massachusetts. He later moved to Chicago and went on to produce a line of high-quality lever-filling pens under the Welty’s brand.


About a decade after the Welty contretemps, Conklin began producing a reduced-cost pen called the Conklinette. In the Conklinette, a small button replaces the crescent; the metal lock ring has a keyhole-shaped opening through which the button protrudes. The button is grooved so that when the ring is rotated one way, the narrow part of the keyhole engages the groove to keep the button from being depressed. When the ring is rotated the other way, the wider part of the keyhole encircles the button without engaging it, and the button can be depressed.

Fountain pen

To avoid devaluing his brand, Conklin soon renamed the Conklinette to become the Jaxon Pen. He did not, however, want to lose the connection to the Conklin Pen Company’s reputation for quality, and the Jaxon Pen was advertised as being made by Conklin.

Conklin’s attorneys apparently thought that this design was similar enough to Roy Conklin’s original design that it did not warrant filing for a new patent, and the Conklinette- and Jaxon-branded variants both bear the 1901 date of Conklin’s original patent.

Variation IV

By the mid-1920s, Conklin’s patents had expired, leaving bottom feeders free to get into the market. One such was Frank Spors, of Le Sueur Center, Minnesota. Disabled and unable to work in any of the jobs that would otherwise be available to him, Spors set up a business to import all sorts of cheap East Asian merchandise, which he advertised in the back sections of magazines such as Popular Mechanics. Among the items he sold were Japanese fountain pens, in both lever-filling and crescent-filling models. Made of the thinnest celluloid, and fitted with glass nibs and wooden inner caps, these pens wholesaled for 67¢ each, to retail for $1.25.

Fountain pen


By 1930, the age of hump fillers was over. For a while, that is. With the resurgence of fountain pens in the 1990s, Italian manufacturers Stipula and Visconti issued models featuring the venerable and still clunky — but nonetheless fascinating — crescent-filler mechanism. The Stipula Saturno and the Visconti Copernicus and Millennium Arc found a market in the modern world, and the name that started it all was reborn in a new Conklin Pen Company that has offered Crescent-Fillers almost since its 2000 founding.

Fountain pen
Fountain pen
Fountain pen
Fountain pen

The information in this article is as accurate as possible, but you should not take it as absolutely authoritative or complete. If you have additions or corrections to this page, please consider sharing them with us to improve the accuracy of our information.

This article is also available as a chapter in The RichardsPens Guide to Fountain Pens, Volume 3, an ebook for your computer or mobile device.

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