[Editors note: [todo: how this treatise was found].
This manuscript is now the last piece of known writing by Carnot before his death in 1832. The most notable thing about this manuscript, from a historical physics perspective, is that Carnot seems to have developed a much more sophisticated and modern understanding of thermodynamics since his 1824 treatise. It's known that Carnot had moved pass his caloric theory by the time of his death. But it was not known until now that Carnot seems to have connected the idea of temperature with microscopic motion, and has some understanding of entropy as a one-way process!
On the other hand, his signature "clarity of thought" is gone. There is a confusion of ideas demonstrated here, relating temperature and pressure of gasses with "temperature" and "pressure" in the social sense. It shouldn't need to be said, but human societies don't obey the ideal gas law. Is this an honest attempt to understand the French Revolution via physical laws, or something else? Is this analogy how he came to think of temperature as microscopic motion? We will probably never know.
The idea of interpretting social movements through a physics lense wasn't unheard of in Carnot's day. For example, this manuscript quotes Lettres d'Un Habitant de Genève À Ses Contemporains, written by Henri Comte de Saint-Simon in 1803, which advocates for scientists to play a larger role in society, and uses words like "la force d'inertie" to describe social "inertia". But honestly, trying to draw a line between these two works feels reductionist. This manuscript is on a whole other level. I'm not aware of any contemporary work with remotely similar subject matter. [todo: find a better example]
The other striking thing to note is the writing style. His usual first-person, conversational, sans-culottes style is still present. The [todo]
[todo: talk about how odd this way of writing is. Or maybe not.]]
Every one knows that gunpowder can produce motion. That it possesses vast motive-power for both shells and people no one can doubt, in these days when the story of the Revolution is everywhere so well known.
[todo]
The National Assembly saw the spontaneous physical separation of republicans and royalists. What mechanism can cause this?
The manuscripts in their hands are a sieve, a sort of reverse osmosis, a one-way barrier for people and minds. It couldn't have been more effective if they had printed their enlightenment thoughts on cheesecloth. The delegates there understood this too, for they then wrote the Declaration of the Rights of Man: a sieve that, with the right pressure applied, could separate an entire nation.
[todo]
Let me engage in some suasoria. Gaius Pontius, meddix of Samnium, you've defeated the Romans at Caudine Forks. Surrounding them in the valley, containing them, that was good. A drop of oil in water will contain itself and not disperse, but that doesn't work with Romans and Samnites. You're not very different from them, you're both descendants from the Umbrians. If you want to them contained, and eventually removed in an irreversible way, you need an impermeable membrane. Preferably made of spears.
You can transport the Roman army, contained in their spear bubble, back across the Apennines. This translation requires 0 work, because the bubble doesn't change volume or pressure. Alternatively they can be killed.
The worst option would be to create a valve at the border, increase pressure, and squeeze the Romans through it. The army that exits the other side will have a very high temperature, and will raise the temperature of the Romans on the other side. Living next to hot Romans is a bad idea.
[todo: comment on reversible processes?]
[todo]
In this city all the little particle people moved more rapidly then. Their thoughts and manuscripts passed from hand to hand, the particles passing around their own little bits of caloric. No amount of work can push the Seine one centimeter, the volume remains constant. $PV \propto NT$, so the only way to keep the pressure from reaching criticality is to reduce the number of particles in Paris.
[todo: the bit about chess between Murat and _]