Brief sketches of ten men who developed important scientific theories and inventions: Ernst Mach and his number, Gergor Mendel and his laws, Christian Johann Doppler and his effect, Hans Geiger and his radiation counter, Nicholas Sadi Carnot and thermodynamics, Gustave, Gaspard de Coriolis and his force, Andrija Mohorovicic and the Moho, James Van Allen and the radiation belts, Rudolph Mossbauer and nuclear resonance, Alfred Noble and his prize