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Sydney has recently experienced a festival - dare I say a frenzy - of precision measurement. Length, height and speed have been joined by measurements of chemical composition. But what of the role of measurement in the past? What were the metrological characteristics of the ancient olympics? What, you might ask, were the dimensions of the ancient velodrome? (slide) In truth, I cannot say what the particulars of the classical olympic stadium were. Some time back I visited Turkey where I saw some impressive stadiums.

Possibly the best preserved Graeco-Roman stadium in the world is at Aphrodisias. It could seat 30,000 spectators. The Roman stadium, by the way, was a unit of length consisting of 125 paces each of five Roman feet amounting to a total of 184 metres.

I also saw evidence to suggest that Cleopatra might have exhibited some prowess in swimming the hundred metres.

But if Cleopatra is famed for her beauty, then what of Helen of Troy?

The plain seen from the hill of Troy

It is said Helen had a face that launched a thousand ships - leading to the proposal that the unit of beauty be defined as the millihelen: beauty sufficient to launch one ship!. Well, this is an old joke, and I suppose not politically correct - so enough of ancient frivolity.

In the next few minutes I want to look at

• the rise of measurement - both the variety of things measured and the precision of measurement
• the conflict between two different concepts of nature as applied to measurement
• a number of units of measure named after people
• a particular person who had a broadranging and inventive approach to measurement
• and conclude with a poetic coda on traceability

Sign over the Market Hall at Greenwich, London

Over the last couple of thousand years, and especially in recent centuries, technologists have developed ever greater precision in the production of devices for measurement. This has not been a smooth and steady progression, but has been a combination of dramatic breakthroughs and incremental refinements. This has been exhibited for example in the development of precision weighing. (OH Graph of the increase in accuracy of the measurement of mass) The development of time measurement exhibits the same pattern. (OH Graph of the increase in accuracy of the measurement of time)

Measurements were developed to serve the needs of the society in which they were made. The division of the calendar and measurement of time structured the cycles of agricultural production and interconnected religious observances. In a settled society with division of labour, issues of ownership and exchange needed to be defined. The determination of land ownership produced such measures as the hide - literally the amount of land bounded by a single cow hide cut into a single continuous strip. One can almost surmise that this was the invention of the earliest members of the legal profession.

Standards were adapted to convenience and circumstance. In the University Museum in Utrecht is a rectangular brass plate ruled with about a dozen different foot measures, the longest about 50% greater than the smallest. For local purposes a local standard was sufficient.

Here we see sixteen feet in their Sunday best randomly selected as they emerge from church. Given the relative genetic stability of local populations for most of history, sixteen men - you see they were all men - probably averaged the same length on successive occasions, at least so far as the community required.

Public Standards of Length by Troughton & Simms
On the wall beside the gate to Old Greenwich Observatory, London

We can see the same principal of adapting means to circumstances in New Zealand after European contact. F.E. Maning, (Old New Zealand (1887), pp. 69-70) described an impromptu unit - the stocking of gunpowder: "a quantity as much as a stocking would hold, which was the regular standard measure in those days in that locality".

Earlier I made whimsical reference to the measurement of beauty. But concepts to be measured gain clarity with hindsight. Consider the long period required to differentiate the concepts of temperature and heat. In the fourteenth century, as the spirit of measurement began to grow upon Europe, scholars wondered about quantifying certitude, virtue and grace along with motion, light and colour.

The later Middle Ages saw a great upsurge of economic activity. The six annual fairs of the Champagne district of France are particularly notable. These fairs were the meeting ground for merchants from the Low Countries to the north and Italy to the south. This ‘regionalisation’ of business - like ‘globalisation’ today - created the need to find a common aggreement on language, quantity and money. Two standardised systems of weights emerged: avoirdupois for goods such as wax and spices (measured by weight rather than volume), and Troy weights - nothing to do with the previously mentioned Greeks and Trojans, but named for Troyes, one of the towns where the regular fairs were held - a weight scale for precious metals.

NATURAL MEASURES

These days much is made of the ‘natural’ qualities of commercial products - foods, medicines, cosmetics - yet these are generally mass-produced, highly manufactured products. The concept of naturalness can be viewed from very different perspectives and serve very different ends. The great diversity of local units of measure sanctioned by custom could be said to be the natural development of local circumstances. On the other hand the ‘scientific revolution’ of the sixteenth and seventeenth centuries created the quest for revealing uniformity in nature - universal laws and principles. In such a conception, ‘natural’ units of measure should be grounded in universal properties of nature. This type of distinction is characteristic of the transformation from the medieval to the modern world view. Such a transformation does not come ‘naturally’. It comes at the expense of habit and comfortable tradition. There is much resistance and winners and losers (as we see today in the process of ‘globalisation’).

The spirit of the ‘scientific revolution’ was to explore nature to reveal, define and quantify its properties. (slide) Here we see the French Academy of Sciences in 1698. By the late eighteenth century, with its emphasis on systematised univeral knowledge, the tide of measurement was in full flood. This led to the desire to construct a system of weights and measures founded on a universal and hence replicable basis. The introduction of the metre in France at the end of the eighteenth century - supposedly representing the ten millionth part of a quadrant of the circumference of the earth - was partly a reflection of this desire. (slide) To encourage the adoption of the new units of measure in revolutionary France various forms of propaganda were employed.

MEASURING THE MINIATURE

Early measures were derived from human anatomy - inch, foot - or from steps - the Roman passus. For very small units, plant seeds were convenient - three barleycorns to the inch or 12 poppyseeds. With increasing precision, finer degrees of measurement were required. For practical purposes the head of a pin was considered the smallest unit in the early modern period except to specialists such as apothecaries. Medieval philosophers may have whiled away their monastic lives debating how many angels could fit on the head of a pin but they did not worry too much about a standard pinhead, let alone a standard angel. The problem is illustrated in the earliest quotation in the Oxford English Dictionary, dating from 1662: ‘No more than a pin-head, and not a great one neither, but about one quarter of a grain’.

Early microscopes were in use by this time. Robert Hooke published his Micrographia in 1665. This and other works focused new attention on the miniature and especially on the details of living things. The compound microscope really came into its own in the nineteenth century with the solution to various optical problems. This led to an explosion of microscopic activity both scientific and recreational. (slide) This microscopic picture of birds at a bird bath is one of the more eccentric applications of recreational microscopy. This picture is constructed from butterfly scales. (slide)

Perhaps most remarkable of all was the development of techniques for miniature writing engraved with a diamond stylus on glass. One of the most accomplished of these miniature writers was William Webb who devised a special writing machine. (slide) His products were sold by a leading London retailer of prepared microscope slides in the later nineteenth century, Edmund Wheeler. Wheeler offered The Lord’s Prayer (227 letters), The Creed (480 letters) and even the entire Second Chapter of St John (2070 letters). The price was proportional to size given at a most unusual unit of measure. A slide of the Lord’s Prayer cost £1 at a scale of five bibles to the square inch and £10 at a scale of ten bibles to the square inch.

UNITS AND PEOPLE

UNITS AND SCALES NAMED AFTER PEOPLE

Now it occurred to me that some of you might be hoping to discover a property to which your name could be applied. So I made a tally by quarter century of year of birth of scientists whose names were given to units of measure. The optimum quarter century in which to be born was 1775 to 1799. After that came the first and third quarters of the nineteenth century. While this is a bit flippant it does point to the enormous expansion of significant scientific work in the nineteenth century. It also reminds us how recent is the American dominance of world science, the only American being Joseph Henry, though perhaps one should add the Croatian-born Nikola Tesla. Delving into more obscure units one could add the mooney, a measure of the plasticity of such things as pre-vulcanized rubber. This is named after the American physicist Melvin Mooney (1893-1968).

Someone after whom no unit has been named (so far as I know), although he had a rich and inventive engagement with measurement, was Francis Galton. (slide) Galton was Charles Darwin's cousin and took a keen interest in heredity, becoming a founder of the eugenics movement. He measured everything. When travelling among the Hottentots in southern Africa in the 1850s he came across an outstandingly steatopygous woman - the projecting form of the posterior being a notable feature of those people. "I profess to being a scientific man [he wrote], and was exceedingly anxious to obtain accurate measurements of her shape." Wishing to avoid the difficulties of explanation and interpretation - his interpreter was a missionary - he stood at a distance and used his sextant and trigonometry to achieve the desired result. On later occasions, at meetings of the Royal Geographical Society, he measured the boredom of members of the audience by counting the number of their fidgets. "The use of a watch attracts attention, so I reckon time by the number of my breathings, of which there are 15 in a minute." (slide)

These examples indicate something of Galton's eccentricity, but also his inventiveness. He made a number of important contributions to meteorology and statistics, and was largely responsible for the introduction of fingerprints for identification. Very much influenced by his cousin's Origin of Species, he believed strongly in the dominant role of heredity in the nature of a person's physical and mental characters. He published Hereditary Genius in 1869. Galton set out to measure every possible character of man. (slide) He set up an anthropometrical laboratory at the International Health Exhibition held in London in 1884. (slide) Here we see the portrait of Galton painted by Charles Wellington Furse in 1903. During the course of an earlier portrait by Gustav Graef in 1882, Galton occupied himself counting the brush strokes - some 20,000. Twenty years later he observed that Furse used a different technique, but also took 20,000 brush strokes (although the portrait was not quite complete). Much more could be said about Galton and measurement, but I leave that for you to explore.

CONCLUSION

As an outsider to metrology the lesson to me of all this is that metrology is an intensely human activity. Although a concern with machines and precision is often portrayed in popular culture as contrasting with social and human values, this is a gross distortion. Science, not least the science of measurement, has its origins in practical purposes. Metrology underpins the warp and weft of our society in ways most of us are completely oblivious of.

Let me now conclude - lest you start to practice Galton’s fidget measure - with some brief comments on traceability. How do we know that an inch here is an inch somewhere else, or a kilogram, or a volt? Careful systems have been established for the comparison and transmission of physical measures. Just as the regular fairs in the Champagne region of France led to standardisation for long-distance international commerce, so globalisation today requires consistent and reliable systems of measurement. Where the components for complex manufactured goods such as cars or computers are produced in many different countries and then brought together for assembly, all the different manufacturers stamping, pressing, molding, casting, machining components must ensure that they are not only using the same units of measure, but that these units of measure represent the same physical quantities. National measurement laboratories and national standards authorities provide an essential bridge between the abstract concept of a unit - and sometimes its physical embodyment - and the diverse applications of measurement to daily life.

I leave the last words on measurement and traceability to the poet John Keats (from ‘A song about myself’):