True to its title, this chapter has not so much a historical as a scientific background. As Prince Alex is trying to understand what is the nature of heat and cold, I found myself asking much the same question, only with an 18th century twist. What DID they know about those things back then? What would Prince Alex glean as he begins to obsessively measure temperatures of snow — and himself? I was lucky to get advice of Dr. Hasok Chang, a historian and philosopher of science at the University of Cambridge. My simple-minded question to Dr. Chang was, “what did they think of temperature, back in the late seventeen hundreds?” Turns out, Dr. Chang had written a whole book about this and other matters, called Inventing Temperature. He also had taken part in the NOVA series The Quest for Absolute Zero . He directed me to his and others’ writings, which informed much if not all of my understanding of the subject.
Absolutely fascinating.
Insofar as I understand it, the great scientific minds of the period were engaged in choosing between the “particle” or corpuscular theory of warmness and coldness, and what can be described as a prototypic wave theory of the same. In its extreme, the corpuscular theory regarded heat as something like an atom, which, when joined with other, atoms, like iron, or sulfur, made them heat up. Antoine Lavoisier (who, tragically, lost his head to the guillotine of the French Revolutionary government in the 1790s) was an adherent of this one. The proponents of the “wave” theory, on the other hand, were groping their way towards the appreciation of radiant heat, which was of course, spot on, we now call it infrared radiation. One opinion is, if not for Lavoisier’s charisma and polemic ardor, physical science would have gone less atomistic and more wavy earlier than it did.

Portrait de Monsieur et Madame Lavoisier by Jacques-Louis David.

More to the point, if there was radiant heat, there had to be radiant cold. In fact, a Swiss scientist, named Marc-Auguste Pictet (who has a Moon crater named after him), was demonstrating to everyone an experiment that proved its existence. This marvelous series of experiments in fact can be and have been recreated in our day, and it still works as advertized. I describe it in the story The Colors of Cold, which is a tie-in to the novel. The gist of it is, you can put a cold object in a focal point of one mirror and it will send something, waves of cold, one presumed, to a second mirror, in a focal point of which stands a thermometer. This thermometer promptly registers the wave of cold.
Pictet was not as charismatic as Lavoisier, but someone named Sir Benjamin Thompson, Count Rumford, was. The Massachusetts-born Count of the Holy Roman Empire was quite a character – just look up his Wikipedia page (which is where you learn why his aquiline profile still adorns our cans of baking powder manufactured by a company called — yes, Rumford). And by the way, he married Lavoisier’s widow.
At any rate, Count Rumford believed in Pictet’s experiment and developed a theory where heat and cold were just motion — vibrations in space, like sound. One frequency – and it is hot, another frequency – and it is cold. Sounds familiar, doesn’t it?
Prince Alex would have wished cold radiation indeed existed.