The Earliest Microscopes and Pond Ecology

The earliest microscope magnified the object ten times the actual size. They were made up of a tube with a plate for the object at one end and, at the other, a lens which magnified the object. In 1609, Galileo worked with the lenses and made more advanced instrument with a focusing device. Anton van Leeuwenhoek taught himself methods of polishing tiny lenses of extreme curvature which gave best magnification of that time up to 270 diameters. This led to the building of his microscopes and his discoveries. He was also the first to see and explain yeast plants, bacteria, life in a drop of water, and the circulation of blood corpuscles in capillaries. In his life, he used his microscope to make lots of discover on living and nonliving things. Robert Hooke who came after Leeuwenhoek improved his discoveries using his copy of microscope. In 19th century, Charles A. Spencer build a microscope that gave magnification up to 1250 diameter with lights. He also founded an industry that created microscopes (Bells, History of Microscope, About.com).

A light microscope cannot show objects that are smaller than half the wavelength of light. As a result, Electron microscopes were invented in 1930s by Germans, Maz Knoll and Ernst Ruska. They were awarded Nobel Prize for physics in 1986 for this invention. The way this work microscope worked was by speeding up the electrons in a vacuum until their wavelength got very short, only one hundred-thousandth that of white light. The fast moving electrons beams are focused on cell and absorbed or scattered by the cell’s parts so as to form an image. Electron Microscopes can enlarge objects as small as diameter of an atom. Unfortunately, there is a disadvantage that ...

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...an them up which takes plenty of time depending on the specimen. The pros are you can see fresh and alive specimen unlike permanent slide. Permanent slides last a long time and are made with special liquid and uses different cover slip. They are usually brought from a science labs and other places. Two most used slides are flat and concave. Flat slides are rectangular with 90 degrees corners. they have to handle them with care to avoid minor finger cuts. The concave slides contain surface depression for liquid and larger specimen. These slides can be used without a cover, but you have to be careful to not make contact with lenses. Cover slips are used to cover the specimen and to keep it in place. The cover slip is square, thin, and transparent. They come in two sizes identified as number 1 and 2. Number 1 cover are .13-.17mm thick and number 2 covers are .17-.25mm.