Free Online stopwatch presentation that can be used in schools
The British government in 1714 had exposed a high price for the development of a method applicable to the lake for the accurate determination of longitude. Harrison's solution, an accurate clock, angry contemporary astronomers and scientists instead of other solutions astronomical (lunar distance) were looking for the problem. Although Harrison was ultimately successful, but his model was too expensive. One of the developments of the fourth and final model Harrison created 1778 watchmaker John Arnold (1736-1799), who in 1780 coined the term stopwatch in order to apply his instrument. Online Stopwatch Marine stopwatchs were widespread until the end of World War II and were then further used in the navies. The decline of the mechanical stopwatch came through the quartz crisis in the second half of the 20th Century, whose accuracy was better just around three orders of magnitude by the invention of the quartz watch. For the classic stopwatch as a navigational instruments no longer a need was present. Nowadays, ships use to navigate GPS (Global Positioning System), a system that also uses the exact a knowledge as possible of the time, but are means for determining the position of astronomical methods (tables and devices) remains compulsory. The default time is now determined using an atomic clock. • Even today stopwatchs are made for collectors and enthusiasts. Colloquially, the term stopwatch is often commonly used for high quality and precise timepieces. Officially, however, only a device called stopwatchs, when tested by an observatory or a transition official control body within a standardized measurement method. • As the official stopwatch, a clock may only call when their Swiss movement has passed an examination (by NIH 95-11 / ISO 3159) of the independent observatory Contrôle officiel suisse Swiss stopwatch (COSC). The plant receives a clock the COSC certification, the manufacturer usually provides the clock with the words stopwatch. • Several observatories offered stopwatch tests. The Paris Observatory (1671-1891) began with tests, followed by Greenwich (1675-1886), Liverpool (1843, with certification standards from 1893), Hamburg (1877), Yale (1879), Kew-Teddington (1883), Leipzig (1883) and Besançon (1885). • stopwatch certification in Switzerland • An officially full screen online stopwatch Online Stopwatch Timer Since September 2006, exists in the observatory works Wempe stopwatch Glash端tte i / SA, a German laboratory for stopwatch, which is operated by the jewelry and watch dealers Wempe KG. She was certified in cooperation with the State Agency for Metrology and Verification beings Thuringia and the Saxon State Agency for Metrology and Verification nature of the Physikalisch-Technische Bundesanstalt (PTB) as a calibration laboratory and field office for online stopwatch testing of the German Calibration Service (DKD). Comply with the limits for mechanical watches (DIN 8319-1) above the Swiss values. Differences for Swiss quartz movements there are audit, in which the following criteria.