The images of science are not always what they seem. Our popular conception is that they explain the findings of scientists and exemplify the way science interprets reality. This may not always be the case. Sometimes, scientific findings are exaggerated in order to appear more glamorous than mere realism. Others are made hard to interpret, confusing and disenfranchising the tyro spectator. On other occasions they are distorted to fit scientific preconceptions. In some instances, there has been a mistake in an early published drawing which is copied by others until it enters the vernacular of science as reality and can be hard to correct. The publication of a drawing has the effect of dignifying the spurious and perpetuating inaccuracy.
Scientific illustration suddenly emerged, in its modern guise, during the mid-eighteenth century. This was the era of a miraculous flourishing of scientific endeavour in Europe, with the emergence of the concepts and insights on which today's science is predicated. Until that time drawings were hesitant and often inaccurate. Attempts towards realistic portrayal were bravely made by such great workers as Leonardo in the sixteenth century, but in the mid eighteenth century accurate portrayals - of a standard rarely surpassed - finally appeared. Many of them could well feature in modern texts and would be well adapted for digitization. Not only is the accuracy and clarity vivid and memorable, but modern students would be reminded of the majestic achievements of their predecessors.
When did scientific illustration begin? Some of the earliest portrayals of the world were made in order to record reality through two- or three-dimensional media. Models were moulded in clay or carved from bone or ivory. Sketches were painted on the cliff faces. Outlines were scratched on bone or bark. The earliest cave paintings portray scientific reality, for these were didactic images, not merely decorative additions. We may deduce this from the fact that many of the images are found in secluded regions deep within a cave, where initiates might be admitted. Further substantiation lies in the way that arrows are sometimes used to draw attention to a significant structure - a target for which the hunter should aim, for example. The earliest such images date from 20,000 years ago, and examples are found in the caves that have been discovered in an area extending across the boundaries of France and Spain.
We do not have to confine our studies to prehistoric tribes, for contemporary peoples still produce drawings of entrancing simplicity and with intriguing resonances of their scientific knowledge. Bark drawings, scratched by aboriginal tribesmen in Australia, show some hints of internal anatomical structure and their portrayal of features of everyday life, fish species for example, may well have an educational purpose. Such portrayals have not been seen as scientific illustrations. Yet is science naught but our key to understanding. As truth emerges and the need exists to explain it to a new generation, visual aids are an inevitable development in all human societies. The bark drawings of the modern Australian peoples, like the entrancing images from the caves at Lascaux, derive from the state of knowledge. They are aids to teaching comparable to the over-head projector films and the computer-generated color slides of the modern lecture theatre.
Many of the most exciting early images date from the era of ancient Egypt. Here the illustrations served to celebrate daily life, and as such are invaluable documentation. We may see how hunters worked in the verdant swamps of the Nile delta, using a hunting cat much as more modern traditions use dogs. Paintings show how gardens were laid out, and we can still identify the plants, the birds and the fish with which the Egyptians surrounded themselves. Sometimes we see their instruments, the earliest known portrayals of scientific apparatus. A wonderfully crafted balance, for example, is used to weight the heart of a deceased nobleman and we may compare it with instruments of more recent vintage. From the vase decorations of ancient Greece one can obtain information on the technology of the era, including modes of transport, methods of hunting and techniques of spinning and weaving cloth.
With the decline of those great civilisations, knowledge of the sciences passed to the Arabian and Persian scholars. Perhaps the greatest of these was Abu Sina (980-1037) born at Bakhara, known by the bowdlerised version of his name as Avicenna. The middle eastern scholars had a considerable understanding of chemistry and astronomy and many modern words derive from those traditions - alcohol (al-kul), algebra (al-jabr) and alchemy (al-chimie) for example. Their anatomical studies were hampered by the strictures imposed by the teachings of Islam. Like many Christian traditions, these orthodoxies proscribed pictorial representations. The convention spread across a wide range of subjects, including human anatomy. Many pioneering studies of vision were made by middle eastern scholars, including the optic chiasma (where the optic nerves cross over). Though these were illustrated in the manuscripts of the time, they were portrayed in a heavily stylised and diagrammatic form. This reduced the risk of action from th the religious authorities, but demands considerable interpretive skills from modern scholars in trying to understand the true extent of knowledge in the past.
The earliest graphical records of human anatomy are found in the Pyrennean cave paintings in sites such as Gargas. The painters dabbed at their hands, leaving behind clear silhouettes. They provide a haunting point of contact with our forebears. Some of the outlines show hands with missing digits. Were these a record of mutilation, perhaps of ritualised punishment? In ancient Rome organs of the body were modelled in clay and fired in the kiln. These strange representations were of eyes or ears, for example, and were associated with charms which could lead to good health. There are bas-relief images of medical science, carved in wall decorations, showing how a physician would examine a patient.
As is well understood, the early teachings of Aristotle, Plato and Hippocrates were watered down and misinterpreted by later writers and it was not until the eleventh century that British physicians began to compile documents on the techniques they used in practice. Cautery was widely used - an intriguing anticipation of aseptic technique which was not to become established for a further eight centuries, and with hints of the laser cauterisation used in the modern world. Surgical operations for piles were recorded. By the fourteenth century the physician John of Arderne (fl 1370)was publishing his surgical techniques for treatment of anal fistula. He developed probes, scalpels and protective spoons to explore the rectal wall. Even at the time his success rate was widely acclaimed. His fees were œ5, and sometimes as high as œ40, for a single operation - the cost of a house. The diagrams that remain convey the drama and bravery of his techniques, and are powerful images from the dawn of surgical medicine.
The finest anatomical drawings were made by Leonardo da Vinci (1452-1519), who used dissection to improve his knowledge and diligently recorded what he saw. But his studies were kept in his own files, and were not intended for publication. They now reside in the Queen's library at Windsor Castle, England. Perhaps the most influential medical scholar of the time was Andreas Vesalius (1514-1564) who, in 1543, published De Humani Corporis, a magnificent work heavily influenced by practical study of the human body. The studies were complemented by brilliantly life-like diagrams by the Flemish artist Jan Stefan. It was claimed that Vesalius corrected over 200 erroneous beliefs about the body - stemming from the traditional teachings of Galen - in publishing his book.
During the following centuries, medical illustration reached a pinnacle of perfection. The Scottish brothers William (1718-1783) and John Hunter (1728-1793) published the most enthralling images of human anatomy. William Hunter was responsible for the establishment of obstetrics as a science, and his published studies of the gravid uterus are of unimpeachable realism. The greatest and most successful work on the subject is Gray's Anatomy. Its author, Henry Gray, set out to describe human anatomy in clear language supplemented with detailed and painstakingly accurate illustrations. The first edition appeared in 1858 and contained 363 superb studies drawn by H. Vandyke Carter. Some of the original figures have still been reproduced in the editions published during the 1990s. The clarity of illustration from the 18th and 19th centuries has rarely been surpassed.
Portrayals of the animal world are, without doubt, the most memorable features of the great prehistoric cave paintings. Great horses and cattle, wild animals under attack by the hunters, loom from the cave walls in beautiful colour. Their didactic force must have been overwhelming. The vivid pictures of birds, mammals and fish in the Egyptian wall paintings were not so obviously educational, but seem to have been of a more decorative purpose. Here the art was used to record reality as then perceived. Aristotle (384-322 BC) is said to have made many drawings of animals. None have survived, though we can see the emergence of representative delineation in the images that have survived from ancient Rome. There is a vivid mosaic which was made in Populonia in around AD 100, which features spiny lobster, an octopus, scorpion fish and wrasse. Though an image of great beauty, it may also have served a purpose as an instructional aid.
Most interesting are the images of non-existent creatures. Dragons and sea-serpents, mermaids, unicorns and gryphons, illuminate many early texts. Most of them were entirely imaginary, and were based on earlier representations of fantastical creatures invented in folk-lore. Sometimes they were substantiated by evidence, for strange creatures were invented for collectors. Strange and half-mummified corpses were sold as evidence that mermaids existed, and skates and rays, dissected and dried, have been made to look like strange, mythical creatures.
As late as the seventeenth century, serious scholars were studying animal life and claiming personally to have seen dragons. Johann Johnston (1693-75), a doctor of medicine, published his celebrated De Serpentibus et Draconibus in 1653. It featured a host of non-existent creatures, all - as the author insisted - painstakingly `drawn from life'. Many of the earliest zoological images were inaccurate, though the lapses are more understandable when the artists have been unable to observe their subject. Thus, an early portrayal of elephants dating from circa 1230 shows them like boars with extended snouts. The artist, lacking a specimen from which to work, had extemporised on a familiar creature. Not until Matthew Paris, a monk of St Albans, drew an elephant from life in 1255 did the recognisable appearance become available to English naturalists.
In much the same way, legends about the rhinoceros had given rise to the classical unicorn - this time based on a conventional horse with a horn at the end of the snout. But in 1515 Albrecht Dšrer (1471-1528) based a drawing on descriptions of a rhinoceros brought to Italy for Pope Leo X. The creature is unmistakable in this image, and the illustration was plagiarised for centuries. Curiously, the Dšrer illustration showed a second, smaller, central horn adjacent to the scapulae. It projects forward, and is less than one-tenth the size of the existing horn. As the image was copied by successive illustrators, the relative size of this imaginary horn increased. By the time Fran‡ois Legaut published his Voyages et Aventures in 1708, the rhinoceros illustrations (clearly based on Dšrer's original) show the imaginary horn to be the same size as the existing one. In this instance the debt owed to the originator is clearly visible in the work of the plagiarists. Here too, the later writers insist that their work is original, and based on personal observation. A similar sequence can be traced from drawings by the Swiss physician Konrad Gesner. His drawing of a mandrill baboon - wrongly identified as a `hyena' in the original - appears in successive books including those of William Topsell (1607) and Johann Johnston (1653). A particularly amusing example of plagiarism is that of the great auk which featured in Ole Worm's Museum Wormianum of 1655. Worm trained his auk to come for a walk at the end of a ribbon lead. The lead was attached to a collar fixed round the bird's neck. The collar shows as a pale band encircling the auk's throat, and in succeeding portrayals of the great auk for many years a neck band was featured, as though it was a distinctive marking of the species.
The emergence of accurate representation in the 18th century gave rise to some of the most stunning and captivating portrayals of animal life. George Stubbs (1724-1806) was the son of a leather-dresser who set out to document the anatomy of the horse. He lived with an assistant, Mary Spencer, in a remote farm-house in Lincolnshire and methodically dissected horse cadavers suspended on wires from the beams of the ceiling. The odour was said to have been offensive for miles down-wind, but he single-mindedly prosecuted the task. He engraved the resultant drawings, which appeared in The Anatomy of a Horse (1766). After moving to London, Stubbs became one of the most popular painters of his era. But his studies of the horse skeleton are dedicated and precise and established an unsurpassed example of zoological illustration.
There are also vivid images of plants in the Egyptian wall-paintings, as we have seen, and the great Greek philosopher Pedanius Dioscorides (c AD 20-70) wrote copious notes on plants as agents of medical treatment about the year AD 50 in his De Materia Medica. The earliest surviving papyrus showing plant specimens dates from about AD 400. But the drawings are clearly taken from previous accounts, rather than from life. Throughout the middle ages, herbals were produced in which the images of plants bear little resemblance to the species they are intended to portray. I now believe there was a purpose in this. The special conventions of science are often used, not to facilitate communication, but to but to hinder it: to excommunicate the tyro. This is true of the use of specialist terms, which serve to maintain the distance of scientific discourse from the public arena, and also applied to the unrecognisable herbs in the herbals. Plant species were supposed to be prescribed only by the specialist, to whom the uinitiated were obliged to turn for advice. A stylised and distorted vision of reality served to maintain the exclusivity of botanical knowledge.
Interestingly, the evolution of representationalism can best be observed in the non-scientific media of the time. Jacobo Filippo, a monk of Padua, included in his writings a beautiful Viola odorata painted in the 1390s. Filippo translated the herbal studies of the Arabic writer Ibn Sarabi, whose great treatise on medicinal plants was completed about AD 800. The pages of the Books of Hours contain countless realistic images of plants. So do altar paintings and still life studies. Many of these aspire to greater aesthetic heights than the plants portrayed in herbals, and offer greater insights into plant cultivars as they were introduced into horticulture.
The middle years of the eighteen century gave rise to an explosion of captivating images of limpid clarity. Georg Ehret's Plantae Selectae (1750-73) and Ferdinand Bauer's Flora Graeca (1806-1840) are fitting examples of the new age of realism, and many of Ehret's insightful engravings have the same dramatic sense of depth as a modern photograph, but the greater resolution and depth of field conveys an unmistakable sense of realism.
Even in the works on mechanics and the physical sciences are images of great beauty. A wonderful book on practical mathematics was the Pantometria of Leonard Digges (?-1571), which was published by his son Thomas (c 1546-1595) in the year of the father's death, 1571. Thomas, an adherent of the Copernican system and a pioneer of the concept of an infinite universe filled with stars, had the book illustrated with dramatic, stylised wood-cuts. The trigonometrical calculations exemplified in the diagrams include many features of sixteenth century life, with castles and houses, boats and people, all carefully delineated in their natural environment. As I pointed out in 1985, it was the Digges family which first described the principles of a telescope: "By these kinds of [concave and convex glasses] yee may ... represent before your eye the lively image of every Towne, Village &c. and will also dilate or augment any parcell thereof ... as plainley as if you were corporally present, although it be distante from you ".
Within a century, clear diagrams were being published as technology advanced. Christiaan Huygens (1629-1695) published his design for a clock with a pendulum escapement in the Horologium oscillatorium of 1673. It is a clear example of draughtsmanship, and can be set in interesting juxtaposition with the far cruder woodcuts of Ren‚ Descartes' Discours sur la M‚thode published in the same year. Chemists used clear engravings to demonstrate their methods, and Joseph Priestly (1733-1804) took pains to ensure his diagrams were accurate. The prolific output of Antoine Lavosier (1743-1794) was illustrated by his wife Marie-Anne [n‚e Paulze].
Images from the geological sciences can be observed as they slowly unravelled. There are many engravings of interesting minerals in the early books from the newly-born Royal Society (including Robert Hooke's Micrographia (1665) and Nehemiah Grew's Catalogue (1681)) whilst Cuvier and Brongniart's Essai sur la G‚ographie Min‚ralogique des Environs de Paris (1811) promulgated the study of what lay beneath the surface of the earth. Their pioneering maps showed the recurrence of strata around Paris. But it was the British `navvy' [=navigator] William Smith (1769-1839) who produced the most beautiful pioneering geological maps one could imagine. Smith was a farmer's son with little education and he became involved in the construction of the network of canals which covered Britain in the years before the railways were widespread. He noticed the recurrence of rock layers as he travelled across Britain, and wrote copious notes. His findings were published as A Delineation of the Strata of England and Wales with part of Scotland (1815) and the book contains a host of highly detailed maps, each delicately hand-coloured.
We may exemplify the birth of a single discipline, and the images it created, by a survey of the microscope. The first microscopes are believed to have been made in the Netherlands around 1590. An early study made with the aid of a primitive microscope was Francesco Stelluti's portrayal of the honey-bee Apis mellifera which dates from the 1620's. The compound eye, the bee's sting, and the fine details of the proboscis are clearly the result of microscopical examination. Several members of the early Royal Society of London (including Christopher Wren and Nehemiah Grew) used microscopes and one was obtained by Robert Hooke (1635-1703) who started his observations in the Spring of 1663. He published his results in a large folio volume entitled Micrographia (1665 and 1667). Hooke's images are detailed and memorable. Some, like his stunning etchings of the human flea and the head-louse, were taken from the book by many purchasers and hung on the wall as decoration. Hooke's vivid picture of the ant, and the under- side of a nettle leaf, with prickles almost glowing against the background, are as eye-catching and revealing as modern scanning electron micrographs.
In my view, this important volume was the first modern popular science book. It is wide-ranging and written in a style that attracts the general reader. The pictures are of every-day objects shown in a new light, and Samuel Pepys records that he sat up all night reading it, and couldn't put it down. There are many lessons we can learn from Micrographia, and one of those is the way that a personality can mould a book, and can shape the way it seems to embody truth. Hooke himself was a troublesome character, and frequently complained that he was not given proper priority for his work. His concepts were indeed picked up by others. In Micrographia appear many images of snowflakes. They decorate a portion of a section on frozen figures observed in water. The flakes included by Hooke are not based on close observation but are idealised, even caricatured, snowflakes. Careful study of the images which Hooke published reveal that he himself was not above plagiarism. Surprising as it seems, the snowflakes that feature in Micrographia were themselves taken by Hooke from an earlier book, written by a different author. The curious style of snowflakes had been adopted originally by the Danish anatomist Thomas Bartholin (1616-1680). His De Nivus usu Medico Observationes Variae of 1661 included several studies of snow and those used as references by Hooke appear as Figure 1.
Even Bartholin was not the first to publish an image of the six-sided snowflake. The first such portrayal I have been able to find was published by Olaus Magnus (1490-1557) in an article De variis figuris Nivium published in 1555. The six-pointed snow-flake is illustrated with deliberate care, and becomes the earliest recorded image of an essentially microscopical object. Hooke was not the last to use the Bartholin conventions, either. The design was been passed on ever since, and even appears in modern type fonts and graphic sheets. At the time of writing there are cans of anti-freeze spray in a local store which bear snowflakes clearly descended from this publication over three centuries ago.
Images of scientific objects are frequently used by artists as objects to copy as they prepare new illustrations. The object may not be directly plagiarised, but used more as an aide memoire or a guide. In formal scientific publishing, acknowledgement is offered to the originator (had Hooke observed such a convention, he would have published a note that his snowflakes were "modified, after Bartholin" in his book). In popular publishing, it is more usual to use the earlier image without acknowledgement. An illustration thus utilised is said to be a reference for the later image. Illustrators are accustomed to ask - if no original art-work is available - whether there is a published image which might be "used as a reference". In this form, as an object for an illustrator to copy, these artistic references will need to be recognised as legitimate intellectual property.
We have seen how this unacknowledged usage has caused problems in the history of scientific images. Worm's auk, with the pale neck band the species did not possess, became a feature of bird books. In the field of microbiology a fine study of the amoeba Allogromia by M S Schultze became the norm for that organism, appearing more recently in a popular work for children. But as the re-use of a reference goes on, the accuracy declines. Once published, an erroneous structure is perpetuated by the act of publication and it can become hard to remove an inaccurate image from the hierarchy of scientific illustrations.
An example dogged my heels during the compilation of The First Encyclopedia of Science, published in 1993. I had been offered a file illustration for the section on steam power. It showed a cut-away diagram of a coal-burning locomotive. Curiously, a [non-existent] central fly-wheel was visible within the mechanism. The drawing was rejected as being inaccurate. However, it did not disappear, for when the page proofs began to arrive the imaginary fly-wheel was still apparent in the art-work. A note from the art editor said that this had been checked with earlier reference books, and found to be correct. I rejected it again, anxious that time was running out, yet found that the same art-work came back on the final page proofs. The technical consultants had checked it again, and decided that (as it appeared in several leading publications) it was clearly correct. At this stage I insisted it be withdrawn, but publication scheduled stood to be jeopardised. And so, a compromise as reached. The erroneous art-work did appear in the printed version of the Encyclopedia, but re-labelled as the 'crank' assembly! Because of the derivative nature of many popular reference works, many errors in modern printed books are now being subsumed by the CD-ROM generation of reference works.
This is an important consideration, for it make one realise how the images we create acquire their own heady momentum that can transcend reality. We must further understand how they reflect the values of the era in which they are made. For many decades illustrations were prepared in a style that was terse and strictly didactic. A high premium was placed on the ability of a student to interpret an image, and aesthetic considerations were largely omitted. The best-selling text, Clapham, Tutin and Warburg's Flora, has almost no illustrations at all. The mind of the scholar was expected to interpret reality through terse written designations, not pictures. In recent decades, the development of image processing has given rise not only to a renaissance in picture-book instruction, but has popularised techniques for adding spurious color to images. In consequence, this technology is reflected in the many gaudy and unrealistic images which now appear in magazines and journals. Not only are these testimony to the ava ilability of graphics software, but the added impact of brightly colored virus particles on a deep and sombre cell helps to clarify details that may not be so apparent to a less educated mind.
Elsewhere, technology has been used to provide vivid images that were previously unavailable. Those who have seen the grazing brachiosaurs of 'Jurassic Park' could be forgiven form believing they had once seen dinosaurs. But that is a benefit of technology - there are also drawbacks. For example, some CD-ROM encyclopedias have assembled hasty and inaccurate visual information. We may thus perceive fashionable aspects of society and the constraints of currently available technology when we look at the images of science.
What of the future? Ours is an era predicated upon the works of science, yet in many ways the public are disenfranchised from what it means. The images of space travel, brought to television screens in earlier decades, triggered an unprecedented level of public interest, and support for, science and technology. The public are familiar with sights like the lunar landscape, or the rings around Saturn. Through fashionable molecular modelling they would recognise the double helix of DNA. But - at the other end of the scale - in vitro microscopy is rather less fashionable. In consequence, the nature of life, and the appearance of a fundamental concept - the living cell - is rarely presented to the public. Few would recognise a microbe, being more conversant with the caricatures of bug-like monsters which feature on television advertisements. We are constructed of living cells, yet few could draw an image one of those.
Until we use images, good images, to promulgate the realities of science, we will never produce a generation which is properly qualified to understand what goes on. And until we have new generations who feel comfortable with scientific realities, we face growing dangers of mis-use or misunderstanding. Science is too important to be ignored, and the images which convey its current truths deserve our urgent attention.
Brian J Ford