Niépce's Pyréolophore demonstrated on the Saône

Background. The Pyréolophore was an early internal combustion engine invented by the Niépce brothers in the early 19th century. It was the first internal combustion engine made to power a boat. The brothers conceived, created, and developed the device together, and in 1807 they constructed a prototype to demonstrate its practical application.

Demonstration on the Saône. To prove the engine's utility to the patent commission, the brothers installed the Pyréolophore on a boat. The engine successfully powered the vessel upstream on the river Saône. The demonstration is dated to 1807 by inference from the patent grant chronology rather than by an explicit statement about the demonstration itself. It followed earlier presentations to the Academy of Sciences in 1806, which described the engine's operation.

Patent Grant. Following the successful demonstration, a patent was granted in 1807. The patent was signed by Emperor Napoleon Bonaparte and dated 20 July 1807. It was issued by the Bureau of Arts and Trades in Paris for a term of ten years, recognizing the Niépce brothers' invention.