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The front of Jens Olsen's World Clock The back of Jens Olsen's World Clock. Jens Olsen's World Clock or Verdensur is an advanced astronomical clock which is displayed in Copenhagen City Hall. [1] [2] The clock consists of 12 movements which together have 15,448 parts. [3] [4] The clock is mechanical and must be wound once a week. [5]
Antonie van Leeuwenhoek (1632–1723). The field of microscopy (optical microscopy) dates back to at least the 17th-century.Earlier microscopes, single lens magnifying glasses with limited magnification, date at least as far back as the wide spread use of lenses in eyeglasses in the 13th century [2] but more advanced compound microscopes first appeared in Europe around 1620 [3] [4] The ...
The World Clock (German: Weltzeituhr; German pronunciation: [ˈvɛltt͡saɪ̯tˌʔuːɐ̯] ⓘ), also known as the Urania World Clock (German: Urania-Weltzeituhr), is a large turret-style world clock located in the public square of Alexanderplatz in Mitte, Berlin.
A microscope slide (top) and a cover slip (bottom) A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then both are inserted together in the microscope for viewing. This ...
A clock or chronometer is a device that measures and displays time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, and the year. Devices operating on several physical processes have been used over the millennia.
Standard-quality 32 768 Hz resonators of this type are warranted to have a long-term accuracy of about six parts per million (0.0006%) at 31 °C (87.8 °F): that is, a typical quartz clock or wristwatch will gain or lose 15 seconds per 30 days (within a normal temperature range of 5 to 35 °C or 41 to 95 °F) or less than a half second clock ...
The company of Carl Zeiss exploited this discovery and becomes the dominant microscope manufacturer of its era. 1928: Edward Hutchinson Synge publishes theory underlying the near-field scanning optical microscope; 1931: Max Knoll and Ernst Ruska start to build the first electron microscope. It is a transmission electron microscope (TEM).
Lens clock. A lens clock is a mechanical dial indicator that is used to measure the dioptric power of a lens.It is a specialized version of a spherometer.A lens clock measures the curvature of a surface, but gives the result as an optical power in diopters, assuming the lens is made of a material with a particular refractive index.