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Carl Friedrich Christian Mohs (/ m oʊ z / MOHZ, German: [ˈfʁiːdʁɪç ˈmoːs]; 29 January 1773 – 29 September 1839) was a German chemist and mineralogist. He was the creator of the Mohs scale of mineral hardness. [1] Mohs also introduced a classification of the crystal forms in crystal systems independently of Christian Samuel Weiss. [2]
Quartz clocks and quartz watches are timepieces that use an electronic oscillator regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency , so that quartz clocks and watches are at least an order of magnitude more accurate than mechanical clocks .
1822 - Friedrich Mohs attempted to bring the molecular approach of Haüy and the geometric approach of Weiss into agreement. [18] 1823 - Franz Ernst Neumann invented a system of crystal face notation, by using the reciprocals of the intercepts with crystal axes, which becomes the standard for the next 60 years. [19]
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The first clock known to strike regularly on the hour, a clock with a verge and foliot mechanism, is recorded in Milan in 1336. [96] By 1341, clocks driven by weights were familiar enough to be able to be adapted for grain mills, [97] and by 1344 the clock in London's Old St Paul's Cathedral had been replaced by one with an escapement. [98]
For example, some sources have assigned a Mohs hardness of 6 or 7 to granite but it is a rock made of several minerals, each with its own Mohs hardness (e.g. topaz-rich granite contains: topaz — Mohs 8, quartz — Mohs 7, orthoclase — Mohs 6, plagioclase — Mohs 6–6.5, mica — Mohs 2–4).
Johannes Sayler (1597–1668), German watchmaker, Ulm, rolling ball clock, turret clocks, table clocks. Nicolas Lemaindre (1598–1652), French clockmaker, Blois, clockmaker of the court. Jost Bodeker von Wartbergh, German vicar, Osnabrück. craft clock with a centrifugal pendulum (1578 to 1587).
In the 1960s, Kienzle produced dashboard clocks for Mercedes-Benz, Rolls-Royce and Bentley: both Series 1 Silver Shadow, and Bentley T models were fitted with Kienzle clocks. [5] In the 1960s and 1970s, Kienzle became a market leader in Germany. In 1972, the first solar watch, "Heliomat", was produced as well as the first quartz movements. [6]