SMT007 Magazine

SMT007-Sept2019

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36 SMT007 MAGAZINE I SEPTEMBER 2019 Units of Measurement Naturally, as humankind transitioned to agri- cultural societies, and trade routes were estab- lished, standards for measurement became important in wider and wider circles [5] . "The earliest recorded systems of weights and measures originate in the third or fourth millennium B.C. Even the very ear- liest civilizations needed measurement for purposes of agriculture, construction, and trade. Early standard units might only have applied to a single community or small region with every area developing its own standards for lengths, areas, volumes, and masses. Often, such systems were closely tied to one field of use so that volume mea- sures used, such as for dry grains, were unrelated to those for liquids with nei- ther bearing any particular relationship to units of length used for measuring cloth or land. With the development of manu- facturing technologies, and the growing importance of trade between communities and ultimately across the Earth, standard- ized weights and measures became critical. Starting in the 18th century, modernized, simplified, and uniform systems of weights and measures were developed with the fun- damental units defined by ever more pre- cise methods in the science of metrology. The discovery and application of electric- ity was one factor motivating the develop- ment of standardized internationally appli- cable units." This trend to have local "flavors" of units of measurement is a common theme throughout history. For example, the yard (the introduction of which is unclear) was localized through- out Britain until it was standardized sometime after 1100 A.D. to be the distance from King Henry I's nose to the end of his thumb (or so the story goes). Other sources (from the reign of Edward I or II, around 1300 A.D.) suggest that "three grains of barley dry and round do make an inch," and that all other measure- ments of length build up from this reference length [6] . The imperial yard, however, goes on to play a key role in standards for length mea- surement. In 1758, the legislature required the con- struction of a standard yard, which was made from the Royal Society's standard and was deposited with the clerk of the House of Com- mons; it was divided into feet, including one of the feet into inches, and one of the inches into tenths. A copy of it, but with upright cheeks between which other measuring rods could be placed, was made for the Exchequer for com- mercial use [7] . In 1760, this standard yard was certified as the "imperial standard yard" from which all other imperial units of measurement then were derived. Of note is the exacting specifi - cation applied to the definition of this yard standard [7] : "…the straight line or distance between the centres of the two points in the gold studs of the straight brass rod now in the cus- tody of the Clerk of the House of Commons whereon the words and figures 'Standard Yard 1760' are engraved shall be and the same is hereby declared to be the origi- nal and genuine standard of that measure of length or lineal extension called a yard; and that the same straight line or distance between the centres of the said two points in the said gold studs in the said brass rod—the brass being at the temperature of 62 degrees by Fahrenheit's thermometer— shall be and is hereby denominated the imperial standard yard and shall be and is hereby declared to be the unit or only stan- dard measure of extension, wherefrom or

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