Ernst Mach (1838-1916)

Mach was an Austrian physicist who gave his name to the Mach number. This number is a method of relating an object's speed to the speed of sound in a particular medium, usually air.
He also worked on shock waves and inertia, coming to conclusions that conflicted with Einsteins' theory of relativity.

Speeds
Below Mach1 called subsonic.
Above Mach1 called Supersonic
Above Mach5 called hypersonic


Wikipedia

Milestones in Medicine

Milestones in Medicine

2000BC Medicine practised in China and India.
1651 William Harvey describes the circulation of the blood
1700s John Hunter perfects surgical techniques
1846 William Morton uses ether as an anesthetic.
1895 Wilhelm Roentgen discovers X-rays
1920s Frederick Banting and Carles Best use insulin to treat diabetes.
1960 Albert Sabin develops oral polio vaccine.
1967 Christiaan Barnard carries out the first human heart transplant.
1985 Lasers are used during surgery to clean out clogged arteries.