This is my summary of the inventions and inventor I learned about in lessons six through nine. Lesson six was about the vapor-compression theory. Before it was invented by Oliver Evans, there was no air conditioning or refrigerators, so everything was hot in the summer. This was a miserable experience, as you can imagine! So thank Oliver Evans, who wrote a book containing the vapor-compression refrigeration theory in 1805. Evans never built the model he described in his book, but his invention is appreciated to this day.

How did Evans come to invent this theory? Well, he liked experimenting with high-pressure steam, and noted the effect a vacuum has on water- the water cools down. The theory of refrigeration needs four things to work: an evaporator coil, a compressor, a condenser coil, and an expansion valve.

Then, in lesson seven, I learned about Oliver Evans. I don’t have much to say about him, but he was an inventor. He was born in Delaware, and invented other things besides the vapor-compression theory previously mentioned. He started his inventing career by improving the flour milling process, then got involved with high-pressure steam technology. Lastly, he invented the refrigerating process we all use today.

Next, in lesson eight, I studied the percussion ignition system. John Forsyth, a Presbyterian minister, invented the percussion ignition system to solve his hunting problems. Due to how flintlock guns worked, the ducks he hunted were scared away before he could get a good shot. The system Forsyth invented was faster, made less smoke, and still worked in wet weather, giving it a large advantage over other gun systems. The percussion ignition system would eventually give way to the revolver.

Lastly, lesson nine was about the canning process. After the French Revolution, a new way to feed the soldiers was needed, so prize money was offered to whoever could invent a better method. In response, a French chef named Nicolas Appert invented the canning process. The canning process involves sealing food in glass bottles, then putting the jars in boiling water. This boils out all the bacteria, making canning a cheap and nutritious way to preserve food.