Myria-
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Myria- (symbol my) is a now obsolete decimal metric prefix denoting a factor of 104 (ten thousand).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Brewster_1830">Template:Cite book</ref><ref name="Brewster_1832">Template:Cite book</ref><ref name="Lange_1956">Template:Cite book</ref><ref name="Dean_1973">Template:Cite book</ref><ref name="Cardarelli_2012">Template:Cite book</ref> It originates from the Greek μύριοι (mýrioi) (myriad). The prefix was part of the original metric system adopted by France in 1795,<ref name="fr">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> but was not adopted when the SI prefixes were internationally adopted by the 11th CGPM conference in 1960.
In 1685 John Wallis proposed the usage of myrio.<ref name="Wallis_1685"/> Also, in 19th century English it was sometimes spelled myrio,<ref name="Cooley_1889"/><ref name="Myriogram_1895"/> in line with a puristic opinion by Thomas Young.<ref name="Brewster_1830"/><ref name="Brewster_1832"/><ref name="Dingler_1823">Template:Cite book</ref>
The myriametre (10 km) is occasionally encountered in 19th-century train tariffs, or in some classifications of wavelengths as the adjective myriametric. The French mesures usuelles (1812–1839) did not include any units of length greater than the toise, but the myriametre remained in use throughout this period.<ref name="Appell_2009">{{#invoke:citation/CS1|citation |CitationClass=web }} (Website based on Alte Meß- und Währungssysteme aus dem deutschen Sprachgebiet, Template:ISBN.)</ref> In Sweden and Norway, the myriametre is still common in everyday use. In these countries this unit is called mil. Of units customarily used in trade in France, the myriagramme (10 kg) was the metric replacement for an avoirdupois unit, the quartier (25 pounds). Isaac Asimov's novel Foundation and Empire still mentioned the myriaton in 1952.
The myria's symbol of my ultimately led to its demise. In 1905 the Comité International des Poids et Mesures (CIPM) assigned it the symbol M, wishing to use only single-letter symbols. This meant that myriameter, for example, was abbreviated Mm.<ref name="Benoît_1905">Template:Cite book</ref> But in the first part of the twentieth century, electrical engineers began to use capital M for the prefix mega-, as in megawatt and megohm. This usage became so widely and firmly adopted that in 1935 the CIPM adopted the prefix “mega-” with “M” as its symbol, dropping the myria- entirely.<ref name="Procès-Verbaux_1935">Template:Cite journal</ref> In 1975, the United States, having previously authorized use of the myriameter and myriagram in 1866, declared the terms no longer acceptable.<ref name="Roberts_1975">Template:Cite book</ref><ref name="Judson_1976">Template:Cite book</ref>
See alsoEdit
- Myriagon, a polygon with 10,000 sides
- Myriapoda, a subphylum containing centipedes, millipedes etc.
- dimi- (aka decimilli-, a former French metric prefix denoting the inverse (10−4) of the myria- prefix up to 1961<ref name="Danloux-Dumesnils_1969">Template:Cite book (a translation of the French original Esprit et bon usage du systeme metrique, 1965)</ref>
- hebdo-, a prefix meaning 107
- Obsolete metric prefix