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A '''microscope''' is an instrument that enables the user to view objects smaller than can be seen with the naked eye. The word ''usually'' refers to an optical compound microscope.  

A '''microscope''' is an instrument that enables the user to view objects smaller than can be seen with the naked eye. The word ''usually'' refers to an optical compound microscope.  

[[Leeuwenhoek]] made one of the earliest practical microscopes and observed tiny "animalcules" under its high magnification (270X). No one knows why he did not realize that these were [[germs]]. Two centuries would pass before [[Pasteur]]'s [[germ theory of disease]].  

[[Leeuwenhoek]] made one of the earliest practical microscopes and observed tiny "animalcules" under its high magnification (270X). No one knows why he did not realize that these were [[germs]]. Two centuries would pass before [[Pasteur]]'s [[germ theory of disease]]. Based upon vague written descriptions, some scholars contend that the [[Etruscan]]s produced compound lens as early 800 A.D. However, there are no known physical examples.

==Optical compound microscopes==

==Optical compound microscopes==