In order to make sense of our own environment and that of the universe beyond, we need agreed scales of measurements which allow us to quantify the tangible and the intangible. Whether you are baking a cake or estimating the fuel requirements of a jumbo jet embarking on a transatlantic flight, you need a precise understanding of the volume of the raw materials involved and to be able to factor in variables of weight, time and temperature. You need measurements.
It wasn’t until people abandoned nomadic lifestyles for settled communities that the need arose to measure. They had to measure out individual plots of land, which gave rise to basic geometry (from Greek ge, land, and -metria, a measuring of), and they needed to weigh out the grain they grew for sale or barter. The human body provided a ready, common scale, so horses were measured in hands (and still are, although the hand has been standardized to 4 inches), while different gauges were made by other body parts, such as the thumb, foot, forearm from fingertip to elbow and the span of outstretched arms. Each early settlement must have used a rock or stone as a grain weight – hence the imperial weight unit of a stone – but as this would have varied in size, standards to codify scales of weight and volume had to be introduced. As commerce expanded and found itself in need of employees, time itself had to be measured to make sure the labour force turned up on time and worked the agreed number of hours.
As with many other basic features of everyday life, such as language, regional codes of measurement developed into national ones, as it became essential to understand what vendors were offering and to have an appreciation of size and value. It may strike some readers that the following pages are biased towards the imperial and metric scales, but these are the measurements by which most of the world now runs. With the possible exception of the ancient Malay unit kati (600 g / 1 ⅓ lb), which gave us the tea caddy, few exotic and obsolete measurements would even be recognized in their country of origin, so their inclusion in this book could hardly be justified.
Other current units – no pun intended – such as the volt, amp and ohm have also been excluded because, after the complexity of their definition is explained, there is little of interest to say about them. Much the same reasoning was behind the exclusion of units such as the pascal, the erg, the dyne and the atmosphere, which are more familiar in the fields of science and engineering than in everyday life.
The origins of many standard measurements are intriguing. The boxing ring became square and has the dimensions it does today because of the length of the four-horse coaching whip, while the shape and dimensions of the modern tennis court originate in the old manorial courtyard. Tennis’ somewhat eccentric scoring derives from the face of the old courtyard clock. But why are clock faces traditionally round? And what determined clockwise rotation? The answers lie in the sundial: had mechanical clocks been invented in the southern hemisphere, then clockwise would denote a rotation to the left.
European shoe sizes – 38 or 40, for example – equate to the number of barleycorns laid end to end, while the mile is based on one thousand (mille) full marching paces of a Roman legionary. The format of the periodic table was based on that of the card game solitaire, or patience. Zero degrees on the original Fahrenheit scale was determined by the temperature of ice in Danzig (now Gdańsk, Poland) during the unusually severe winter of 1708–9, while its upper marker of one hundred degrees was the temperature in Frau Fahrenheit’s armpit.
It is probably fair to say that we all take measurements for granted; a yard is a yard, a kilogram is a kilogram and so what? But as with so many other seemingly mundane subjects, when you delve into the history and origins of measurements you are in for more than a few surprises.