Compound lever the force of pushing back the stick to the levers and they rub against the wheels, using friction to slow and eventually stop the train. These are everyday applications of this mechanism. A piano key is a compound lever of the first-class, since the fulcrum is between the weight to be moved and the power. The purpose of this lever is to translate a small movement (depression of the key) into a larger and fast movement of the hammer on the strings. The quality of the resulting tone depends on whether the final speed is brought about by gradual or
Jan Lever about species constancy, and adhered to a kind of theistic evolution. Jan Lever Jan Lever (Groningen, 20 July 1922 - Amsterdam, 23 November 2010) was a Dutch biologist specialized in zoology, endocrinology and evolutionary biology. His ideas on evolution may be characterized as a form of theistic evolution. The Reformed Lever studied biology at Utrecht University from 1939 onwards. Lever obtained his doctorate in 1950. He served as a professor of zoology at the Vrije Universiteit Amsterdam from 1952 until 1986. In his inaugural lecture, he presented his belief that evolution was the way in which God had created the