The magnifying glass is one of the oldest devices used to improve sight. Historians seem to agree that the Romans were the first to discover glass in the first century AD. The Egyptians had discovered an almost clear crystal, called obsidian that was used to view small objects
The Romans were probably looking through the glass and discovered that the objects looked larger. They experimented with different shapes and found that glass that was thicker at the center and thinner on the outside magnified the object that was being observed. They also discovered that the suns rays could be concentrated sufficiently to start a fire. They called these glasses “burning glasses”. These glasses were similar to the shape of lentils, and so the word “lens” comes from the latin word for lentil. The benefits of these lenses were not appreciated until the 13th century, when scientists used them to study tiny insects. They were then called “flea glasses”.
During the 16th century, the first primitive microscopes were invented using multiple lenses and so a new industry was born. Magnifying glasses continued to be used for low levels of magnification, when compared to the magnification ability of the microscopes. Telescopes were soon invented using lenses that were just arranged differently within a tube..
Modern magnifying glasses are double-convex lenses and they make the objects appear larger. The lens is convex on both sides, ie. thicker in the middle. When viewing objects the light rays are bent towards the center of the lens, making the object look larger than it is to the eye. Each magnifying glass has a focal length, which is the distances from the optical center of the lens to the point where the light rays converge. The focal length of any lens is determined by the radius of the curve on the face of the lens. The mathematics that describe magnification is relatively straight forward and can be found in comprehensive physics textbooks.
Magnifying glasses are now manufactured with many configurations. The basic magnifying glass has the glass attached to a handle, which may be made from almost any stiff material. Many different sizes are available form the small round compact pocket magnifying glasses to the large rectangular full-page magnifiers. Many have built-in lighting systems to allow the user to see objects better.
The magnifying glass would have to be one of the most simplest aids available today for people who want to study small objects, for people who have trouble seeing the text in newspapers and books as well as handy tool to take to the outdoors as a fire starter.
Magnifying glasses of almost any configuration are available from many shops and online.
Magnifying Glasses are sometimes a little difficult to obtain. For more information about magnifying glasses and different configurations go to http://groovyideas.googlepages.com
Tags: folding magnifying glass, large magnifying glass, lighted magnifying glass, magnifying glass
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