Discovery School - 100 Greatest Discoveries - Earth Science
1. Earth's Core (1906) Seismologist Richard Oldham determines that earthquake waves move through the central part of the Earth much slower than through the mantle around it. He surmises that the Earth has a core composed of liquid.
2. Earth's Inner Core (1930s) In 1936, Inge Lehmann documents that some seismic waves from deep inside the Earth's core do not pass through, but are reflected back. It becomes clear that the Earth has an inner core consisting of a small, solid iron sphere that is surrounded by a thick outer core composed of liquid iron.
The Economist is a global weekly magazine written for those who share an uncommon interest in being well and broadly informed. Each issue explores the close links between domestic and international issues, business, politics, finance, current affairs, science, technology and the arts.
Discovery School - 100 Greatest Discoveries - Chemistry
1. Oxygen (1770s) Joseph Priestley discovers oxygen; later, Antoine Lavoisier clarifies the nature of elements. Priestley produces oxygen in experiments and describes its role in combustion and respiration. Then, by dissolving fixed air in water, he invents carbonated water. Priestley, oblivious to the importance of his discovery, calls the new gas "dephlogisticated air." Lavoisier gives oxygen its name and correctly describes its role in combustion.
Video Collins Workplace English 1 Meet Jasmine Goodman, personal assistant. She answers the phone, writes emails, manages her boss’ schedule and looks after visitors to the company.
1. Microorganisms (1674) Microscope lens grinder Anton Van Leeuwenhoek accidentally discovers microorganisms in a drop of water. He observes sperm, bacteria and red blood cells.
2. The Cell Nucleus (1831) While studying an orchid, botanist Robert Brown identifies a structure within the cells that he terms the "nucleus."
3. Archaea (1977) Carl Woese discovers bacteria are not the only simple-celled prokaryotes on Earth. Many of the organisms classified in the new kingdom of Archaea are extremophiles.
