This is my summary of the inventions I learned about in lessons sixty-six through sixty-nine. In lesson sixty-six, I studied the invention of the safety elevator. The elevator had been around for a while, but it was only a very simple version. In the 1800’s,steam power and counterweights were added to the existing elevator, as well as hydraulic pumps. However, they were still unsafe, and elevators were usually avoided. This meant the maximum height a building could reach was about six stories, since that was as far as people were willing to climb.

In 1852, Elisha Otis invented the safety elevator. He was looking for a better and safer way to lift scrap wood in the factory he was managing. The mechanism in the safety elevator stops the elevator from falling to the ground if the supporting cable breaks. The elevator is positioned between two vertical beams with small teeth cut into them every few inches. If the cable snaps, it releases a safety arm that catches on the little teeth. This holds the elevator in place, and is called the ratchet system.

In lesson sixty-seven, I learned about the invention of the syringe. Before the syringe was invented, inserting medicine into the veins was dangerous. Doctors used scalpels to cut your skin and the vein open. A Scottish inventor nake Alexander Wood changed this when he invented the syringe in 1853. The syringe was inspired by the stinger of a bee, which is a hollow tube with a sharp point.

In lesson sixty-eight, I studied the Bessemer process. After having a discussion with Napoleon III, Henry Bessemer invented his process for making steel in 1855. Henry Bessemer was the son of an inventor. Weapons made of steel would be stronger than those made of iron, but steel was harder to make.

The Bessemer process converts pig iron into steel by blowing hot air through the molten pig iron, increasing its temperature. This burns off the impurities, leaving the right amount of carbon behind to create steel.

Last of all, lesson sixty-nine was about the invention of the egg-beater. The egg-beater consists of two beaters that are turned by a hand crank. The egg-beater makes it easier to mix baking ingredients together thoroughly.