Lengths1 foot (Latin-pes) = 12 inches (Latin-uncia) since Roman times. History of the Inch An inch was the breadth of a man’s thumb at the base of the nail. To help maintain consistency of the unit, the measure was usually achieved by adding the thumb breadth of three men—one small, one medium, and one large—and then dividing the figure by three. During the reign of King Edward II, 1307-1327, the inch was defined as “three grains of barley, dry and round, placed end to end lengthwise.” At various times the inch has also been defined as the combined lengths of 12 poppyseeds. Since 1959 the inch has been defined officially as 2.54 centimetres. In Anglo-Saxon England, one Ell = 45 inches or 2½ Roman / Viking "cubits". A cubit was an elbow length of 18 inches that in Hebrew was called an
"am-mah".One garden yard was about 5½ ells, or about 20 feet. In 1100, King Henry I redefined a yard as "the distance from his nose to the thumb of his out-stretched arm", the length of a man's belt or girdle, 36 inches or 3 feet. 1 rod, pole, or perch = 5½ yards or 16½ feet. 1 chain = 22 yards or 4 rods. 1 furlong = 220 yards or 40 rods. 1 Roman mile was originally 1000 paces, and in 1592 it was fixed at 8 furlongs or 1,760 yards. 1 acre = 160 perches (square rods) or 4,840 square yards.
WeightsAbout 1300, the avoirdupois ("have of weight") system of 16 ounces to a pound was used to measure wool. Precious metals used 12 ounces (Latin-uncia) to a pound (Latin-pondus meaning weight or libra meaning scale), from Roman times. Today, the avoirdupois system of 16 ounces to the pound is used in Britain and the US. In Britain, particularly after 1835 when it was formalized, 14 pounds became the standard measure of one stone. The ton was standardized as 20 hundredweight, although the hundredweight could be 100 pounds (short US ton) or 112 pounds based on eight stone (long British ton).
VolumesWith regards to volume measurements, in 1824 twenty fluid ounces of water was standardized as the measure of a pint (568ml) in England, known as the imperial measure, while the US pint retained its earlier measure of one pound of water or sixteen fluid ounces (473ml). The imperial fluid ounce is about 4% smaller than the US fluid ounce. 1 gallon = 8 pints. 1 bushel = 8 gallons.
France and the Metric SystemOn the continent, one metre was originally defined in 1791 to be one 10-millionth of the circumferential distance of the Earth from pole to equator, in order that the circumference of the earth could be defined as being exactly 40,000 kilometres. After this theoretical length of the metre was published in 1795, it was subsequently reduced by a very tiny amount in 1799. It has since been found however to be fractionally incorrect, measured around the poles, the earth's circumference is 39,940.653 km (24,817.971 miles). Measured around the equator, it is 40,075.017 km (24,901.461 miles). Still, the length of the metre once it was defined and everyone started using it was left unchanged. 10,000 square metres (100 metres x 100 metres) was defined as a hectare. One gram was defined in Paris in 1795 as the weight of one cubic centimetre of pure water at 4 degrees centigrade which is the temperature of melting ice (the temperature of the maximum density of water). One kilogram of water equals one litre in volume. 1,000 kilograms of water (2,204.62 pounds or 1 tonne) equals 1 cubic metre in volume. Thus the gram and the litre which were old Greek and Latin words, were now being redefined anew as measuring weight and volume. History of Metrication Most of Europe converted to the French metric system during the following 80 years. The UK were supportive, but insisted that it not be made mandatory, which was also the approach of the US.
Japan switched to the metric system in 1868, followed by Russia and China in 1925. India switched over in 1956, followed by Australia and Canada and New Zealand in 1971 as those three English speaking countries introduced computerized records.
** End of Page