The Glass Bathyscaphe

This review originally appeared in the Sunday Times on 28 July 2002.

Alan Macfarlane and Gerry Martin, The Glass Bathyscaphe: How Glass Changed the World, Profile Books, £15, pp. 255

There’s a disturbing aside in one of Descartes’s Meditations, in which he entertains the delusion that his body is made of glass. To sustain the fantasy at length, he explains, would be taken as a mark of insanity, whereas his ability to entertain it fleetingly serves as a reassuring demonstration of the unique and separate quality of the human mind. Images of glass, and of its special fragility, have recurred throughout the literature of philosophy, and one of the many pleasures to be had from The Glass Bathyscaphe is the appreciation of why that might be so: glass, as Alan Macfarlane and Gerry Martin demonstrate on every page of this fascinating book, is one of the great technologies of thought.

Yet it arose as a technology of enchantment. The precise origins of glass making are unclear, although it seems to have first appeared somewhere in the middle East or the eastern Mediterranean between five and ten thousand years ago. By the time of the collapse of the Roman Empire, the practices of glass making, including glass blowing, had spread to every civilisation in the known world. Yet its use was restricted to the manufacture of small, decorative objects, such as drinking vessels, beads and jewellery. Even in ancient Rome, the most glass-soaked culture that the world has ever seen, there were few if any glass windows, and mirrors were made from sheets of polished metal.

And then something curious happened. Some time between the ninth and eleventh centuries, while western Eurasian cultures were finding new, practical uses for glass technology, India, China and Japan ­— the world’s first great technological cultures — stopped making it. It was an extraordinary parting of the ways: just as European builders were beginning to pierce their walls with window glass, and Islamic scholars in the near and middle East were developing the new science of optics with the use of lenses and prisms, the great Asian cultures were turning their backs on glass in favour of other materials such as porcelain and paper. These events, and their global consequences, make a riveting story, and Macfarlane and Martin’s explanations for them are wide-ranging and ingenious.

Take wine-drinking, for instance, which had spread throughout Europe under the influence of the Romans. The pleasures of wine are enhanced by good-quality glass, through which one can admire its clarity and colour, as well as monitor its improvement in the bottle. The great Asian cultures, however, were tea-drinking cultures, and their demand was not for glass but for porcelain. Neither did their climate require plate glass windows, which were anyway unsuited to a traditional architecture that was built until recently of paper and bamboo. Glass windows, too, are susceptible to earthquakes, whereas Japanese mulberry paper screens, which let a beautifully diffused form of light into a room, bend gently to the tremors of the earth. These and other factors form a matrix of connected reasons why Eastern civilisations abandoned glass, but Macfarlane and Martin’s most surprising claim concerns the issue of comparative eyesight.

Estimates suggest that between seventy and eighty percent of the Japanese and Chinese populations are affected by myopia, or short-sightedness. The myopic individual, however, is not actually prevented from reading and writing, or from doing other close work, but merely has to draw ever nearer to the page. The populations of the West, on the other hand, are correspondingly affected by presbyopia, or long-sightedness, especially as they pass middle age. The presbyopic individual, unlike the myopic, is prevented from reading and writing, since they need to draw back so far from the page that any script ceases to be legible. The invention of spectacles with bi-convex lenses in late thirteenth-century Italy thus extended the working lives of millions of European clerks, lawyers, administrators, teachers, and writers. Petrarch, the fourteenth-century Italian poet, wrote the second half of his output wearing spectacles. The economic impact of the bi-convex lens was immense, halting the early retirement (due to failing eyesight) of many of the most experienced and valuable members of the European professional classes. Spectacles were not invented in medieval Asia because there wasn’t a pressing need; they were invented in medieval Europe because that need was all too apparent, and clear glass was already a widespread commodity.

Later experiments in Italy using different kinds of lenses led to the invention of the microscope and the telescope in the early seventeenth century. As had been the case with the invention of spectacles, the development of this new generation of scientific instruments depended upon a reliable supply of high quality glass of the kind that had been manufactured in Venice for centuries. Thus did the Roman love of wine contribute to the dawning of the scientific revolution in which, according to Macfarlane and Martin, “that strange, light-bending transparent substance, glass, gave people new eyes to see and what they saw changed the whole world.” And it must have seemed to many that there was no limit to the possibilities of a technology such as glass. The bathyscaphe of the title, a glass diving bell, was an early modern example of the imaginary machine. It appears on the cover of this delightful book, in a medieval miniature depicting Alexander the Great, crowned, robed and safely submerged, gazing through the glass at the creatures of the deep.

The Glass Bathyscaphe presents a set of intriguing arguments, which range generously and enjoyably over a wide field of enquiry: there cannot, after all, be that many books in which Eeyore and Thomas Edison sit next to one another in the index. And although much of the argument is necessarily speculative, it is presented with energy and insight. By piecing together “the shattered history of this extraordinary substance,” Alan Macfarlane and Gerry Martin have made a valuable contribution to the wider social history of technology.

Richard Hamblyn

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