Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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The use of, or investigation by means of, a microscope. A microscope consists of an optical device containing one or more lenses and is used to view minute objects, generally those larger than .005 mm. A one-lens instrument is known as a simple microscope, while one with two or more lenses is called a compound microscope. Instruments which interpose oil of the same refractive index as glass between the object and the objective are used for high power work. The limit of resolving power is equal approximately to the wavelength of the light source used, i.e., points separated by 4 X 10-5 cm. Objects smaller than this can be detected as bright points in the ultramicroscope, while their actual shape and dimensions can be examined in the electron microscope, in which a beam of electrons is used in lieu of light and is focused by electrostatic or magnetic fields. Resolution down to 5 X 10-8 cm is theoretically possible with such an instrument, which is, however, difficult to use because of the necessity of mounting the specimen in a vacuum. The microscope is a valuable instrument for the study of paper and leather fibers, etc. (195 )

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