1800 was not so long ago, 7 generations or so. Yet it was a different world, one most of us would only dimly recognize and most of us would have great difficulty living in. Something less than a billion people lived on the globe. Almost all of those people lived short lives of great misery and toil, not much changed from centuries past. Lives were not much different from 1700 or 1600. Technological advances were speeding up, but were not affecting most people's lives.
England had far more green fields than satanic mills, and the 5 million in the USA lived mostly east of the Appalachian mountains, and much land even in the east was still wilderness.
True, there were signs of change. The Enlightenment had been gathering force for the previous two centuries, powered by science. Which in turn was powered by empiricism---observations, experiments, hypotheses and deductions. Science was (and is) a powerful way of discovering new knowledge. Even so, the Enlightenment in 1800 was more seeing the light at the end of the tunnel versus breaking out into the sun.
In 1800 people were ignorant about how the world worked. We had no idea how old the earth was (although some clever people realized that the world had to be over 6,000 years old) We had no knowledge of evolution, of plate tectonics. We didn't know about ice ages, or even if the climate had been different in the past. Most people, even scientists, didn't realize the climate could change, much less how it could do so.
And yet humanity may a factor in the climate even then. For thousands of years, wet rice paddy cultivation had released methane into the atmosphere, which may have prevented the earth from beginning to slide into a new ice age. I think that is likely, although it is not proven yet.
China had greatly increased the use of coal during the Song dynasty, but even so the impact of rice paddy agriculture and Chinese coal consumption was much smaller than what we do today.
In 1800 freedom and capitalism scarcely existed. Aside from Roger Bacon (who in the 1200s predicted television, telescopes, microscopes, spectacles, and airplanes) and Leonardo da Vinci, hardly anyone predicted much technological advancement. Far-seeing people perceived that the Americas would be much more developed but no one predicted the level of population and economic growth that the spread of capitalism and freedom over the next two centuries would bring around the world.
Our world today would simply be inconceivable to all those from 1800.
And yet this seems as good a time as any to begin, because a relevant scientific discovery was made in 1800.
William Herschel was the most famous astronomer of his time. In 1781 he had discovered the planet Uranus, doubling the diameter of the solar system. The fame from this enabled him to establish his own astronomical observatory, with the unsung help of his devoted sister, Caroline (a noted astronomer herself, who lived 2 months short of her 98th birthday and never had much of a life of her own)
The discovery that sunlight was a mixture of colors had been made by Isaac Newton, but for a century not much more was known about radiation---light was all that there was, as far as anyone knew.
Until February 11, 1800.
On that day, William Herschel was testing colored filters to observe the sun, looking for sunspots. He noticed that the light coming through the red filter was warmer than the other colors. William Hershel then took a large prism, and put thermometers into the different colors to see which thermometers grew warmest. An extra one was laying outside the spectrum of visible light, but on the red side.
To his surprise that thermometer got warmer than any of the others!
In addition to the planet Uranus, William Herschel had discovered infrared radiation! William Herschel investigated this new radiation and discovered that most of the heat energy came from beyond the red.
In a stroke, the known electromagnetic spectrum doubled, just like the solar system.
And the notion that this new form of radiation could have a role to play in our climate would soon be explored.
But I'll talk about that in the next entry.