​MICROSCOPE, an optical instrument by which objects are so magnified that details invisible or indistinct to the naked eye are clearly seen. In a simple microscope the magnifying power is interposed directly between the eye and the object, in the manner of a magnifying glass; and though the power may consist of several lenses, they combine as one; a triple set, of which either lens can be used singly, or any two, or all in combination, is usual. In a compound microscope, an aërial magnified image of the object is projected by one lens in the manner of a magic lantern, and this image is looked at and further magnified by a second power as in the simple microscope.