This is my summary of the inventors and inventions I studied in lessons one hundred forty-six through one hundred forty-nine. In lesson one hundred forty-six, I learned about the invention of the crystal oscillator. The crystal oscillator was invented in 1918 by Alexander M. Nicholson, once it was discovered that solid objects such as quartz or ceramic will emit a small electric current when under extreme pressure. Crystal oscillators work by oscillating, or vibrating quickly, when electricity is introduced to it.

In lesson one hundred forty-seven, I studied George Washington Carver. George Washington Carver was born on an unknown date sometime in the 1860’s. He was born into slavery, but he was kidnapped as an infant. Moses Carver found him again, and he and his wife adopted George and raised him themselves.

George grew up to be a botanist. He got a good education and worked for Booker T. Washington in Alabama, where he did most of his research. He is most known for his work in crop rotation and popularizing peanuts.

In lesson one hundred forty-eight, I learned about the invention of the Yagi-Uda antenna. The Yagi-Uda antenna was invented by Shintaro Uda and Hidetsugu Yagi in 1926. It focuses the beam of a dipole antenna using reflectors and directors, and it was much more compact and efficient than other antennas at the time, as well as easy to make.

Last of all, lesson one hundred forty-nine was about the invention of penicillin. Penicillin is an antibiotic invented by Alexander Fleming in 1929. Fleming was a scientist who studied bacteria, and he discovered penicillin when he found mold that kept away bacteria growing one day. Penicillin works by stopping bacteria reproduction, which makes it easier to kill it.