Jul 202018

On this date in 1807 a patent was granted by Napoleon Bonaparte for the Pyréolophore, arguably the world’s first internal combustion engine, after it had successfully powered a boat upstream on the river Saône. It was invented in the early 19th century in Chalon-sur-Saône by the Niépce brothers: Nicéphore (who went on to invent photography) and Claude. The Pyréolophore ran on what were believed to be “controlled dust explosions” of various experimental fuels. The fuels included mixtures of Lycopodium powder (the spores of Lycopodium, or clubmoss), finely crushed coal dust, and resin. This prototype was not a commercial success because it was grossly inefficient: the brothers did not combine the controlled explosions with compression.

Operating independently of the French brothers, the Swiss engineer François Isaac de Rivaz built the de Rivaz engine, a hydrogen-powered internal combustion engine, also in 1807. These practical engineering projects may have followed the 1680 theoretical design of an internal combustion engine by the Dutch scientist Christiaan Huygens. The separate, virtually contemporaneous implementations of this design in different modes of transport means that the de Rivaz engine may be correctly described as the first use of an internal combustion engine in an automobile (1808), whilst the Pyréolophore was the first use of an internal combustion engine in a boat (1807).

In 1806 the Niépce brothers had presented a paper on their research to the French National Commission of the Academy of Science (French: Institute National de Science). The Commission’s verdict was:

The fuel ordinarily used by MM. Niépce is made of lycopodium spores, the combustion of which is the most intense and the easiest; however this material being costly, they replaced it with pulverized coal and mixed it if necessary with a small portion of resin, which works very well, as was proved by many experiments. In MM. Niépces’ machine no portion of heat is dispersed in advance; the moving force is an instantaneous result, and all the fuel effect is used to produce the dilatation that causes the moving force.

To prove the utility of the Pyréolophore to the patent commission, the brothers installed it on a boat, which it powered upstream on the river Saône. The total weight was 2,000 lb (910 kg), fuel consumption was reported as “one hundred and twenty-five grains per minute” (about 8 grams or 0.28 ounces per minute), and the performance was 12–13 explosions per minute. The boat was propelled forward as the Pyréolophore sucked in the river water at the front and then pumped it out towards the rear. Thus, the Commissioners concluded that “the machine proposed under the name Pyréolophore by MM. Niépce is ingenious, that it may become very interesting by its physical and economical results, and deserves the approbation of the Commission.”

The operation of the Pyréolophore was first described in a meeting at the Academy of Sciences on 15th December 1806. Lazare Carnot noted that “there was a bright flash of the ‘spores of lycopodium’ inside their sealed copper machine… The Niépce brothers, by their own device and without using water, have managed to create a commotion (explosion) in a confined space which is so strong that the effects appear to be comparable to a steam engine or fire pump”.

The Pyréolophore operated as a series of discrete burns at a frequency of about 12 per minute to power a boat. Power was delivered in pulses, each pulse forcing water from the engine’s tail pipe set under the boat and pointing towards its stern. The boat was pushed forward at each pulse by the reactive force of the ejected mass of water. A Pyréolophore engine consists of two principal interconnected chambers: a firelighting chamber and a combustion chamber. There is also a bellows for injecting air, a fuel dispenser, an ignition device, and a submerged exhaust pipe. There is a means of storing energy at each explosion in order to work the mechanism as it prepares itself for the next cycle. A mechanically operated bellows injects a jet of air into the first chamber where ignition will take place. Mechanical timing lets fall a measured amount of powder fuel into the jet so that it is blown along and mixed with it. Under the control of the mechanical timing mechanism a smoldering fuse is introduced to this fuel air jet at the precise moment it passes the fuse location. The fuse then withdraws behind a metal plate. The now burning ball of powder and air travels through a wide nozzle into the main combustion chamber where a fast, almost explosive, burn takes place. The whole system now being almost airtight, a build-up of pressure follows. The pressure acts against the column of water in the exhaust pipe and expels it from the system. As the flow of exhaust gas moves into the tail pipe, it moves a loose piston in the combustion chamber which extracts and stores sufficient power to work the machine’s timing mechanisms. Energy from this piston is stored by lifting weights attached to a balance wheel. The return of this wheel to its lower position under the pull of the weights governs the timing for the next cycle by operating the bellows, fuel dispenser, the fuse and valves at the correct points in the cycle. The tail pipe, being under the boat, fills with water ready for the next discharge. The fall of the timing piston also expels the exhaust gases via a pipe above the ignition chamber, which is closed off by a valve during the burn part of the cycle.

On 24th December 1807, the brothers reported to Lazare Carnot that they had developed a new, highly flammable fuel (powder) by mixing one part resin with nine parts of crushed coal dust. In 1817 the brothers achieved another first by using a rudimentary fuel injection system. By 1817 there was insufficient progress to attract subsidy and investment, so the ten-year patent expired. Worried about losing control of the engine, Claude traveled first to Paris and then to England in an attempt to advance the project. He received the patent consent of King George III on 23rd December 1817. Over the next ten years, Claude remained in London, settled in Kew and descended into some kind of insanity or mental delirium. In the process he squandered much of the family fortune chasing inappropriate business opportunities for the Pyréolophore. Nicéphore, meanwhile, was also occupied with the task of inventing photography.

By 1824, after the brothers’ project had lost momentum, the French physicist Nicolas Léonard Sadi Carnot scientifically established the thermodynamic theory of idealized heat engines. This highlighted the flaw in the design of the Pyréolophore. It needed a compression mechanism to increase the difference between the upper and lower working temperatures and potentially unlock sufficient power and efficiency.

There are a great many specialties from the Saône-et-Loire department where the brothers were born and worked to develop their internal combustion engine. I was once a fan of warm chocolate tarts. I’ve never made them myself because local bakers do such a great job. Here’s a traditional recipe I have translated for you from what appears to be a dialect of Langue d’oïl. It should be serviceable.

Tartelettes chaudes au chocolat

For the pastry
125 gm butter, softened
30 gm ground almonds
90 gm icing sugar
2 tsp bitter cocoa
250 gm flour
1 egg

For the filling
150 gm dark chocolate, cut in small chunks
5 eggs
125 gm butter
90 gm sugar
90 gm flour

For the decoration
1 egg white
powdered sugar
mint leaves


For the pastry: Put soft butter, sugar, ground almonds and cocoa in a stand mixer. Mix until creamed and light. Add the flour and the egg and mix until you have a dough. Wrap with cling film and refrigerate.

For the filling: Melt the chocolate pieces with the butter in a double boiler. Meanwhile, beat together the eggs and sugar in a stand mixer. Add in the flour and mix again. Then pour in the melted chocolate and butter, and whisk well.
Assembly: Preheat the oven to 170°C.
Butter and flour 6 tartlet moulds.

Roll the pastry dough on a floured surface so that you can cut our 6 round tart shells. Place the pastry rounds in the tartlet moulds, shape to fit, prick the pastry with a fork, cover each one with a circle of baking parchment, and fill with dried beans (i.e. to bake blind). Cook 12 minutes.

Take the tartlet shells out of the oven. Remove the dried beans and the parchment. Divide the chocolate mixture between the 6 moulds. Raise the oven to 240°C, and then cook the filled tartlets for 4 minutes. Remove the tartlets from the oven, unmould and decorate them.

To decorate: Whisk an egg white until it forms soft peaks. Brush the egg white on clusters of currants and mint leaves. Sprinkle with powdered sugar. Let them dry on paper towels, then decorate the tartlets with these “crystallized” fruits and leaves.
Serve warm.

 Posted by at 7:56 am

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