This is my summary of the inventions I learned about in lessons forty-one through forty-four. In lesson forty-one, I learned about the invention of the steel plow. The plow slowly improved over time as new soils were discovered that the current plow couldn’t get through. The steel plow was the same way. The iron plow didn’t work well in the sticky soils of western America, so John Deere invented the steel plow to do what the iron plow couldn’t.

John Deere was a blacksmith who moved west to make a better living. He heard the local townspeople complaining about the sticky soil, and remembered from experience that polished steel is very smooth. He built a plow out of polished stainless steel in 1837, and it became the steel plow. The main benefit of the steel plow is that it can slice through the prairie soil without the soil sticking to it.

In lesson forty-two, I learned about the invention of the steam shovel. Before steam technology, construction equipment was powered by people or animals. In 1835, William Otis Smith applied steam power to digging machinery, thus inventing the steam shovel.

William Otis Smith was born in Massachusetts, and grew up in a culture that valued education. Smith observed workers digging paths through the wilderness to lay down railroad tracks, and was inspired to invent the steam shovel because of it. The steam shovel recreated the motion of a digging worker, only it used a bigger shovel and was powered by steam. Much deeper and wider holes could be dug with the steam shovel in the same time it took a human worker to dig a smaller one.

Lesson forty-three was about the invention of the postage stamp. The UK postage system of the 1800’s was corrupt. So, in 1838, Rowland Hill started to reform the system, beginning with the postage stamp. The postage stamp proves that the piece of mail it’s on has been paid for.

Last of all, in lesson forty-four, I learned about the invention of vulcanized rubber. An entrepreneur named Charles Goodyear invented vulcanized rubber almost by accident. He was trying to invent a way to make rubber permanently unsticky, when some of the rubber he was working with fell onto the hot stove.

Rubber vulcanization is the process of mixing natural rubber with a chemical- such as sulfur- and heating it all together. It makes a chemical reaction that causes the rubber to stop sticking, melting, and getting brittle permanently.