Electromagnetic flow meter for water | One week paper introduction in Science (published) | Gas flow meter

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Who knows the history of the invention of telescopes - in English

A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century. "Telescopes" can refer to a whole range of instruments operating in most regions of the electromagnetic spectrum.The word "telescope" (from the Greek tele = "far" and skopein = "to look or see"; teleskopos = "far-seeing") was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei"s instruments presented at a banquet at the Accademia dei Lincei.[1][2][3] In the Starry Messenger Galileo had used the term "perspicillum ".The earliest evidence of working telescopes were the refracting telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals: Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, and Jacob Metius of Alkmaar.[4] Galileo greatly improved upon these designs the following year.The idea that a mirror could be used as an objective instead of a lens was being investigated soon after the invention of the refracting telescope.[5] The potential advantages of using parabolic mirrors, primarily reduction of spherical aberration with no chromatic aberration, led to many proposed designs and several attempts to build reflecting telescopes. [6] In 1668, Isaac Newton built the first practical reflecting telescope that bears his name, the Newtonian reflector.The invention of the achromatic lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter

, more functional refracting telescopes. Reflecting telescopes, though not limited by the color problems seen in refractors, were hampered by the use of fast tarnishing speculum metal mirrors employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857,[7] and aluminized mirrors in 1932.[8] The maximum physical size limit for refracting telescopes is about 1 meter (40 inches), dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors. The largest reflecting telescopes currently have objectives larger then 10 m (33 feet).The 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937. Since then, a tremendous variety of complex astronomical instruments have been developed.The name "telescope" covers a wide range of instruments and is difficult to define. They all have the attribute of collecting electromagnetic radiation so it can be studied or analyzed in some manner. The most common type is the optical telescope; other types also exist and are listed below.Optical telescopes50 cm refracting telescope at Nice Observatory.Main article: Optical telescopeAn optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet). Optical telescopes increase the apparent angular size of distant objects as well as their apparent brightness. In order for the image to be observed, photographed, studied, and sent to a computer, telescopes work by employing one or more curved

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