What the companies starting out in series fountain pen productionin the 1880s were soon discovering was that if you put a feed under the nib, and a channel in the feed, the feed will feed ink in a metered amount to the paper because air passes up the channel into the reservoir (in the opposite direction to the ink) in equivalent amounts at the same time.
The fact is that if you merely fill a long thin reservoir with ink and stick a 'nib' at the bottom, ink will not flow smoothly (or at all) to the paper.
This was not obvious at all to those who had been studying quills for numerous thousand years, and who saw a point with what seemed like a reservoir behind it.
It seemed obvious that one should be able to produce a pen with an artificial reservoir by adapting what nature had already designed, and what the whole world was using. The fallacy was that nature had not actually designed the quill for use as a writing instrument. What was not noticed was that there were no cases on record of long-feathered birds ever having written anything of import since the dawn of time.
EARLY FOUNTAIN PEN MECHANISMS
Based on this elementary misconception, artisans had since the 1780s been trying to produce pens which did not need dipping into ink every few characters.
As the pens so produced did not actually work, these immensely gifted craftsmen had to concentrate on making the items so produced as beautiful as possible in the hope that someone might buy them, and possibly order more. As may be reasonably expected, these pens were often thrown away in disgust by their owners, and few survive today. Their value tends to be gigantic, as when they are uncovered today, in default of a nib, they are not often recognised as pens.
None of these manufacturers made any money, and no companies grew rich by producing beautiful and remarkably well crafted pens which did not write.
At any rate, such early artisans' ingeniousness in following these (as turned out) wrong principles knew no bounds. Fine cotton was pressed into service to attempt to get a flow of ink, and the problem of the ink leaking all over the paper out of the silver vessel was corrected by using a pigs bladder to contain the ink. Rudimentary metering of the ink supply to the paper was (or more accurately wasn't) effected by filling the bladder with balsa wood slats; this made these early concepts similar in form, if entirely different in concept from the 20th Century pens using rubber sacks.
When it was noticed that the ink did not actually flow from these beautiful implements, devices were designed to force the flow. This either by putting a button on the side exerting pressure on the reservoir (making the process of writing a relatively fatiguing one), or by means of a rudimentary feed which metered ink to the paper on down strokes.
Thus, it was thought, a quarter of the problem was solved, which was presumably better than no solution at all.
Sooner or later, the problem of the ink flooding the paper fell to be considered, and this challenge was met by means of the sponge inserted between the nib and the reservoir, filled upon exhaustion by the ubiquitous button pressing on the reservoir.
It was in this way that a few faintly workable fountain pens were made individually in the early days; Thomas Jefferson certainly had a writing instrument which he used, and which presumably satisfied his needs in not needing dipping into ink every few characters. However no patents were taken out on that implement. It worked. (much like the water supply from the river to Jefferson's estate at Monticello) by a capillary-like process whereby the ink was held at a higher level than the 'nib' and the feed fed ink through a slit which may be familiar to today's colloctors to a collecting area on the nib. From this collecting area, another slit fed that ink to the paper. Although it probably did not have a channelled feed, it is certainly noteworthy that Jefferson's manuscripts are not overly characterised by the presence of undue plethoras of ink blobs. The only conclusion which one can reasonably draw is that either it did work in some way or he did not use it much for formal purposes.
When the Daughters of the Revolution had taken whatever they wanted from Jefferson's estate for putting in various museums and the remainder of his estate fell to be disposed of in the thirties, the actual pen he used to write the Constitution was thrown into the bottom of a box of general merchandise and was bought by a private collector in whose estate it now lies.