Microscope

 The first microscope to be developed was the optical microscope, although the original inventor is not easy to identify. Evidence points to the first compound microscope appearing in the Netherlands in the late 1590s, probably an invention of eyeglass makers there:^[3] Hans Lippershey (who developed an early telescope) and Zacharias Janssen (also claimed as the inventor of the telescope). There are other claims that the microscope and the telescope were invented byROGER Bacon in the 1200s,^[4] but this is not substantiated. Giovanni Fabercoined the name microscope for Galileo Galilei's compound microscope in 1625 ^[5] (Galileo had called it the "occhiolino" or "little eye"). In 1648 in Amsterdam, van Leeuwenhoek saw a simple microscope, a magnifying glass mounted on a small stand used by textile merchants capable of magnifying to a power of three. He was 14 years old when he soon acquired one for his own use. In 1654 he left Amsterdam and moved back to Delft, and started his own lucrative drapery business there. In 1660 van Leeuwenhoek was appointed chamberlain of the Lord Regents of Delft. It is believed that soon after 1665, he read a book byRobert Hooke, titled Micrographia, which dealt with Hooke's observations with the compound microscope. His reading of Hooke's book is believed to have roused an interest in van Leeuwenhoek to use his microscopes for the purpose of investigating the natural world beyond the mere quality of the fabrics he sold. In 1669, he obtained an academic degree in geography, leading to his later appointment as geographer in 1679.Van Leeuwenhoek's interest in microscopy steadily grew until he was spending most of his nights and free time grinding his own lenses, improving the quality of his microscopes, and studying everything he could beneath them. Although he is sometimes erroneously referred to as "the inventor of the microscope," compound microscopes (with two lenses mounted together) had existed since 1595. However, they were very crude because the technology used made it difficult to build them properly. Van Leeuwenhoek's genius was developing his skill to grind single lenses very precisely. It is likely that his microscopes were powerful magnifying glasses, not compound microscopes.Van Leeuwenhoek also carefully documented many of his observations. He soon developed what is believed to have been the highest-powered microscopes of his day, magnifying up to 500 times. He retained some of his methods of microscope construction in secret, “which I only keep for myself.” While scientists agree that many of his observations would have required a 500-power microscope, exactly how he constructed such a microscope remains unknown. Van Leeuwenhoek's microscopes were small, generally only about two inches long and one inch across. The microscope held at the Utrecht museum has a magnification factor of about 275x with a resolution of about one micron.

Source: http://www.newworldencyclopedia.org/entry/Anton_van_Leeuwenhoek