Arguably the best
fountain pen ever made. Manufactured by
Parker, its name came from the desire to ensure that it meant the same thing in any
language. It was released in
1939, in honor of the company’s fifty-first
anniversary.
The pen is characterized with a plastic body and a metal cap. The nib is “hooded,” such that only the very tip is exposed. This was to prevent the ink from being exposed to the atmosphere until the last possible moment, to minimize evaporation. This design is now a classic, and regarded as characteristic of twentieth century design.
The first incarnation of the 51 used the “Vacumatic” filling system (created for its predecessor). The back end of the barrel would unscrew, and reveal a plunger used to draw ink into the pen. While this maximized the ink capacity, over time, the diaphragm of the pump would eventually fail.
The second generation, released in 1948, of the 51 had the “areometic” filler. The section of the pen would unscrew, revealing a bladder that could be compressed by a pressure bar. This was the basis for the pen (and its derivates, the 41 and 21) until production stopped in the mid-seventies. If you can find one of these pens, very little would be required to coax it into working again (perhaps a soak overnight in water).
The Parker 51 is the most numerous pen in my collection, including a Vacumatic, a desk pen, and a “demi.”