Josef Ressel: the inventor of the propeller

Josef Ludwig Franz Ressel was born on June 29th, 1793 in the Bohemian town of Chundrum. His mother was Marija Ana Konvichkova, a Czech, and his father Anton Hermann Ressel, a German. He came from a poor family that couldn’t sustain his studies at Vienna University, and for this reason he had to sustain himself (and even his family) with his works of calligraphy and drawings. One of his drawings was admired by Emperor Franz I who decided to pay for his studies in the newly founded Forestry Academy. Once finished, he became District Forester in Pleterje and later in Trieste (from 1821 to 1835).

Trieste at that time was the main port of the Austro-Hungarian Empire, a melting pot of cultures coming from all the corners of the Empire. In some aspects it was one of the most advanced technological centers: since 1818 the first steamship served the line from Trieste to Venice and in 1819 the first industrial steam engine was built in Trieste, which fed all the port infrastructures.

The latter was an impressive hydrodynamic system which furnished, through a series of steam machines, the energy needed to change the pressure of the hydrodynamic system; it was able to feed one hundred cranes and fifty lifts in various storehouses. Although in 1930s some power lines were substituted with electric engines, the remaining of the system was in use for over one century.

In a city so stimulating from the cultural and technological point of view, Ressel developed his most famous invention: the screw propeller. The idea to use a propeller (screw propeller, spiral wheels or similar concept) was not new to the epoch. David Bushnell designed his first submarine, The Turtle, with manual screw propulsion in 1775, but Ressel was the first one to patent his invention (“A never-ending screw which can be used to drive ships both on sea and rivers”). The Privilegium, the Austrian patent, was released on February 11th, 1827.

He did first experiments with ship models in his fishpond, but in the Trieste gulf he rigged and ran the first civil ship with propeller, the Civetta, in 1829. The Civetta was a 48-ton ship with a steam engine featuring a Fichtner boiler and cast iron pipes capable of generating up to 6 horsepower (4,4 kWh); the propeller had a diameter of 1,58 meters.

During the experiment the ship reached a speed of 6 knots (11 km/h). Unluckily, a soldered connection gave way and the steam conduits exploded. While it was not a dysfunction of the propeller, authorities prohibited him to perform other experiments with this new technology.

There are many reasons why the authorities prohibited him  from developing this technology. First, there was the opposition of everyone who had interests in the construction of paddle and sail ships; second, the authorities had a constant fear of anarchic terrorist attacks and for this reason they preferred to avoid anything which may have frightened the population. Last but not least, all new technologies were viewed with suspicion. For example, many years after the introduction of steam engines on aquatic vessels, ships still had masts for navigation with sails.

After the sea trial, Ressel dedicated himself to other activities and retook the experiments years later. He continued to develop the screw propeller with new inventions, which allowed, for example, turning the propeller in order to use it as a helm. However, with the prohibition of the authorities and the lack of commercial investments, Ressel soon abandoned further developments of his propeller. Frustrated and embittered, he started working full time as forest officer.

When in 1839 the British steam ship Archimedes arrived in Trieste, Ressel could recognise his propeller design, retaken and improved by Francis P. Smith without being credited. In the same year, the first screw-propeller powered ship designed by Smith performed the crossing of the Atlantic in forty days.

When the British government announced a competition for the inventor of the first propeller, Ressel sent all his documentation to British Admiralty but the package got lost. Only after his death was he acknowledged as inventor of the screw propeller.

Working as a forest officer, Ressel came in contact with another important issue for his epoch: the deforestation of the Karst.

The Karst was a forest region extending from the Trieste Gulf to the Vipava Valley, which throughout centuries had seen its oak woods plundered for burning, pasturing, and shipbuilding.

It was an environmental and cultural disaster. The deforestation caused bad harvests, earth erosion and climate change, leading many farmers to poverty.

As Forester, Ressel first tried to reduce the consumption of wood suggesting more iron to be used for shipbuilding; successively he started a major reforestation of Karst planting the Austrian Pine. He started a reasonable forest management, which allowed them to save the environment and people living in it and to supply enough wood for commercial purpose.

The versatile curiosity and vast knowledge of Josef Ressel led him to patent inventions in many fields. He is remembered for an air cooling system for steam engines, a chemical compound able to preserve the wood used for shipbuilding, and even a press-roller for oil and wine.

Josef Ressel has been compared many times to another genius, Leonardo DaVinci; but while DaVinci left us only sketches of his machines, and it is still under discussion if his machines were ever realised, Ressel actually built, tested and spread his inventions.

Although he was at the service of an Empire which was, under some aspects, oppressive, Josef Ressel tried to use his genius to both serve the Empire and help the people and the communities where he lived.