BALL RESERVOIR AIRGUNS

Pneumatic airguns, that is "pump-up" airguns which employ pre-compressed air as their propulsive force, may go back to ancient times. Leonardo da Vinci considered pneumatic devices, but Arne Hoff, surely the dean of airgun history, notes (Hoff, 1972, 1977) that proof is lacking that da Vinci, or any other ancient artist/inventor ever invented an airgun. Hoff reported that the French gunmaker, Marin le Bourgeoys, made the first airgun with an air reservoir about 1605, only a decade or two after the very first known mechanical airguns (as contrasted to blowguns), powered by an internal bellows. These early pneumatic guns stored their compressed air in internal vessels. The earliest surviving pump-up airguns, from about 1640, employed a "barrel reservoir", a long tube concentrically sealed around the barrel. Others had an air reservoir built into the buttstock, sometimes in combination with a built-in air pump. These built-in reservoirs suffered from having two valves, one for air input from an internal or external pump, and one for air release at the moment of firing, as well as having the handicaps of difficult construction and lack of flexibility.
In the early 1670s, a young Frenchman, Denis Papin, experimented with using vacuum to drive a bullet, but his big contribution to airguns came about 1675 when he moved to London to work with Sir Robert Boyle. This was a detachable ball-shaped reservoir. His idea of using the barrel as both barrel and pump-cylinder (!) was impractical, but the ball reservoir opened a new century of airgun development. In 1686, John Evelyn demonstrated the first practical airgun utilizing a pre-charged ball reservoir, a gun apparently made in Amsterdam by an unknown maker (probably Andreas Dolep, a Dutchman who later worked in London), at the Royal Society in London. The ball reservoir required only one valve. Perhaps even more important, it could be instantly replaced by another ball with a fresh charge of air. A small supply of pre-charged balls added huge convenience to the field use of an airgun. A bonus was the instant replacement of the air valve. This freed the shooter from the sudden and acute problem of the failure of a valve buried within the gun. Airguns with built-in butt reservoirs and airguns with barrel reservoirs continued to be made into the 1700s but ball reservoir airguns, independently developed by several makers, came to dominate airgun design. Airguns with unscrewable butt-reservoirs that provided many more shots per reservoir, but whose reservoirs were heavier and more difficult to build, joined them.
Ball reservoir airguns did not develop in a clear evolutionary lineage, but rather represent several independent lines. A simplified classification is presented here.