There he sold fountain pens of the time to the students too. The idea of a fountain pen was popular with the students, but the pens were continually giving dissatisfaction. The principal trouble was that there was no provision in them for a steady flow of air up into the ink chamber as the ink flowed out. The pens alternated between no flow of ink at all when the air was trying to force its way up there, or too abundant flow when it had forced its way up.
To Parker, forced to live with the students he had sold the pens to, it was a very great difficulty indeed. He saw the need for a new sort of feed-shaft, so he got a scroll saw, a file, and some other simple equipment and tinkered until he had made up a shaft that would let the air up more steadily.