Under pressure

Robert Morgan explains how a valve was the last piece in the jigsaw that created the sophisticated, and expensive, pneumatic airgun

- Robert Morgan

Last month we looked at the origins of airguns (Sporting Gun, March). In particular, we looked at how the earliest examples — ignoring the humble blowpipe — were either bellows or spring operated. The only type not looked at was the true pneumatic, whether precharged or multi-pump.

True pneumatics were the last type to appear, but the time frame between all was very small, less than 100 years. The reason pneumatics were last is a simple one: all materials and technologies existed when spring and bellows airguns appeared; the bellows were modified items commonly used for fires and the springs were modified from existing ones meant for clocks, so all it took was a clever person to utilise these to power projectiles, either directly or by a piston.

The pneumatic was different, though. A major component had to be invented before it could work, and that was the valve.

Early versions

Compression (and vacuum) pumps had been around for centuries. The mechanical genius Ctesibius of Alexandria constructed one in 3 BC and a pupil of his, Philo of Byzantium, used his pump idea to make an ‘air-pressure catapult’, although from surviving records it sounded extremely impractical and was probably never fired in anger.

No other mention of any potential pneumatic weapon appears in antiquity. Leonardo da Vinci did not design an airgun of any sort, although he did design a steam gun. However, even this remarkable piece of ingenuity did not use a valve.

No one actually knows who invented the first valve, but an educated guess says it was probably the man who invented the first documented pneumatic airgun. That was a Frenchman called Marin le Bourgeoys, a gunmaker from Lisieux, Normandy.