Lever fulcrum to where the output force is applied (point "B"), then the lever amplifies the input force. On the other hand, if the distance "a" from the fulcrum to the input force is less than the distance "b" from the fulcrum to the output force, then the lever reduces the input force. The use of velocity in the static analysis of a lever is an application of the principle of virtual work. A lever is modeled as a rigid bar connected to a ground frame by a hinged joint called a fulcrum. The lever is operated by applying an input
Jan Lever evolutie" (1956; English translation 1958 under the title "Creation and Evolution"). In 1970, Lever was elected member of the Royal Netherlands Academy of Arts and Sciences. In the early 1950s, Lever started research on the neuroendocrine system of the basommatophoran snail, "Lymnaea stagnalis". Lever himself found a particular kind of neurons in the ancylid snail "Ferrissia", and his student Joos Joosse demonstrated those neurons in other snail species. "Lymnaea" became the animal of choice for physiological research at the VU Amsterdam laboratory for decades. At the beginning of his career, Lever’s ideas about evolution and the species concept were inspired