When the Royal Academy of Arts was founded in London under the patronage of King George III in 1768, the painters, sculptors and architects who made up the pioneering group had to decide on a suitable president to represent them on the public stage. The obvious candidate was the portrait painter Joshua Reynolds: accomplished, highly successful, and with a wide circle of eminent and learned friends.

Reynolds represented and advocated the academic principle of respect for the Old Masters of Italy, Spain and the Netherlands and a preference for serious literary and historical subjects. (He considered his own speciality, portraiture, second best.) He set out this high-minded programme in his Discourses to the students, but in his own earnest efforts at history painting he almost always failed.

It was part of his pre-eminence that he took a creative interest in the actual techniques of painting. Striving after grand effects, he was always experimenting with new materials, and his most ambitious canvases are now illegible ghosts because of his inventive adoption of substances such as bitumen and wax, which he mixed with his pigments to enhance their depth and glow. Go to Petworth House in Sussex, and see one of the biggest of them, Macbeth and the Witches. It covers a large wall, and is an almost indecipherable, darkened wreck, a monument to his laudable curiosity.

He was far from being the only experimenter. There is a picture in the Tate by a history painter of the next generation, William Hilton. It is a night scene, a dramatic historical subject: Editha and the Monks Searching for the Body of Harold, and it measures an appropriately enormous 334× 243 centimetres. Hilton showed it at the Academy in 1834. But it cannot be exhibited now. It is the sad remains of an experiment similar to Reynolds’s Macbeth: the semi-liquid bitumen with which it was painted — the ‘mummy’ in which the ancient Egyptians embalmed their dead has never dried, and the canvas has to be turned like a mattress every few years so the pigment can flow back to its proper place.

The spirit of invention and exploration among the Academicians is wonderfully spoofed in the great satirist James Gillray’s print Titianus Redivivus (Titian Reborn), published in 1797. It shows several leading artists taken in by a spurious ‘Venetian Secret’, concocted and promoted by a young woman, Mary Anne Provis, and her father. Several of them had paid ten guineas apiece for this quack recipe. Others, including the 22-year-old J. M. W. Turner, are not fooled. Reynolds, who had died in 1792, is present as an appalled spirit, but one cannot help wondering if he might have been attracted to the claim that the methods of one of the greatest painters of the Italian Renaissance had been revealed to Miss Provis, and been tempted to try it, simply for the sake of experimenting.

A student at the Academy Schools was the young William Blake. He came to despise the institution and wrote scurrilously about Reynolds as a traitor to the art he practised. He never became a member, but he followed Reynolds’s lead in trying out materials that proved disastrous for his pictures. He invented a medium that he called ‘fresco’, a version of tempera, not much related to the system the Renaissance Italians had used to cover their walls and ceilings. The elaborate subject-pictures that he painted using it — The Spiritual Form of Pitt Guiding Behemoth and The Spiritual Form of Nelson Guiding Leviathan, among others — have deteriorated just as much as Reynolds’s much larger works, to become cracked and blackened wrecks. But he had more success with a highly idiosyncratic version of the medium of etching, for the purpose of printing his own Prophetic Books of visionary poetry, which he (or his wife Catherine) would colour by hand and issue in tiny editions for the few people interested in his now much-prized arcana.

The fact is that the Royal Academy, like its products, like the country as a whole, was a technological melting pot. It was the youngest of the artists’ academies established in Europe over the past 200 years to embody and promote their professional aspirations and status. They had all laid down standards that ensured the quality of work remained high. In London, the same objectives held good, and it was clearly understood among the artists that their aims were more refined, more exclusively aesthetic, than the mere mechanical crafts. But London was not Rome, Copenhagen or Paris. It was the capital city of a country caught up in the civilisation-altering toils of the first Industrial Revolution. Only a few years earlier, a Society for the Encouragement of Arts, Manufactures and Commerce had been founded in London, awarding premiums for works of scientific invention and ingenuity as well as for essays in design and draughtsmanship. It was a leading institution of the Age of the Enlightenment. In the year of the Academy’s first exhibition, 1769, Thomas Arkwright unveiled his spinning machine which was to help revolutionise the manufacture of cloth. Earlier in the decade, in 1763, James Hargreaves’s spinning jenny had started the process. In between, in 1765, James Watt had invented his condenser, which ten years later was to produce the first steam engine.

Also in 1769, Josiah Wedgwood opened his Etruria pottery works in Burslem, Staffordshire, an initiative that married technology with art and design in ways that survive today. A very early academician straddling the two disciplines was George Stubbs, the renowned painter of horses, who executed pictures in enamel, a very unconventional medium, on thin ceramic panels that Wedgwood produced specially for him. Stubbs exhibited the resulting paintings at the Royal Academy in 1782, where they caused a furore. And his attitude to his art was scientific; he brought a dead horse into his Lincolnshire barn and dissected it over many weeks, making careful drawings of the anatomy. These he published for their informative value in their own right.

Much of the impetus for the technological revolution of the age came from the newly expanding cities of the Midlands, with their coal and steel industries, where groups of businessmen, industrialists and scientists met to exchange ideas about science and technology. The Lunar Society is the best known of these groups. It came into existence in the mid-1760s, and Josiah Wedgwood was one of its early members, as were Richard Arkwright, the chemist Joseph Priestley, the industrialist Matthew Boulton, and Erasmus Darwin, Charles Darwin’s grandfather. Closely associated with several of these was the Derby painter Joseph Wright, who was elected an Associate of the Royal Academy in 1781. Shortly after, he celebrated the cotton mills that Arkwright had built a decade earlier in a view of them by the light of a serene full moon. The unromantic, eminently functional factory buildings are presented as the focus of an atmospheric night scene.

Moonlight, firelight, candlelight: Wright painted all these effects in a spirit of investigation, of scientific research, even while making the most of their value as visual poetry. This double intention lies behind his famous depictions of an orrery — a model of the solar system — and An Experiment with the Air-pump, both seen by candlelight, with all the expressive human nuances of fascinated faces seen in chiaroscuro. In the Air-pump, the scientist — or is he a magician? — working the contraption, a seventeenth-century invention, is about to turn off the supply of air to a white bird in a bell-like glass receiver. A scientist takes notes, an old man ponders the idea of death, children try not to watch, lovers take advantage of the darkness to canoodle. It’s a disquisition on human nature in relation to the achievements of science. This and The Orrery are among the greatest and most original paintings of the age.

An art form that developed astonishingly in this period was landscape. It lent itself particularly to experiments with media and methods. One of its greatest exponents, the Suffolk-born Thomas Gainsborough, forged his career by painting portraits but, like Reynolds, always wanted to do something else. In his case, it was landscape he experimented with, not only painting specific places but inventing compositions that obeyed rules of harmony, proportion and balance as true abstractions. For these explorations he sometimes painted on glass, so that the luminous sky could be presented with real light by holding the pane up to a candle. The theory of abstract design in painting had been laid out and published by an art master at Eton, Alexander Cozens, whose son, John Robert, reversed the process and applied it to real places, such as scenes in the Alps or the Italian Campagna.

It was inevitable that the theatrical possibilities of light and landscape should break out from their confinement on canvas or paper and become three-dimensional experiences. Philippe-Jacques de Loutherbourg, a painter from Alsace who became a full academician in 1781, created a theatre stage ten feet by six feet wide that he called the Eidophusikon, in which he showed scenes that were not stationary but presented altering phenomena: Aurora, or the Effects of Dawn; Tangiers at noon; Naples with a sunset; or a view of London from Greenwich Park. There was a storm at sea with thunder and lightning, using a battery of equipment including moving scenery, coloured slides and mirrors, as well as musical accompaniment. These dramatic scenes chimed with the current fashion for ‘the Sublime’, a notion considered important and much discussed in contexts both philosophical and aesthetic.

Other artists enlarged the technical range of picture-making along similar lines by developing the Panorama — a complete 360-degree circular painting that you stood or sat in the centre of and could imagine yourself present at an actual event, whether the meeting of all the devils in the Pandemonium of Milton’s Paradise Lost, or a tranquil morning on the roof of a tall London building. Several academicians contributed sensational, enormous paintings to the repertoire, notably ‘mad’ John Martin, whose vision of Belshazzar’s Feast was a typical specimen of his heightened vision. The word ‘panorama’ was invented (or stolen from the Greek) in 1791, and as a form of popular entertainment and instruction it spread throughout Europe and America and begat even more elaborate devices that were the forerunners of cinema.

Many artists experimented with transparencies — either on glass, or sheets of paper painted to be partly opaque, so that when a candle was placed behind them an illuminated scene appeared; a cottage by moonlight, for instance. As a young man, Turner tried his hand at a few of these. Another landscape painter who used sheets of glass for his studies was John Constable, who emphasised that he saw his own art as part of the scientific endeavour of the age. He thought of his pictures, small or large, as scientific experiments, not only his rapid notes of meteorological effects but even the full-size sketches for his six-footers, which he kept simply as trials for the finished works he would send for exhibition at the Academy. The comparison between the sketches and the finished pictures reveals how much his experiments taught him, with the final version embodying much of the impromptu technique and vibrancy of the sketch. This was the dawn of a totally fresh approach to painting, a new union of technique and emotion, parallel, we might say, to the experiments in verse that Wordsworth and Coleridge made in their Lyrical Ballads of 1798. ‘Painting is but another word for feeling,’ observed Constable — a truly modern idea! It is no coincidence that he was popular in France, where his Hay Wain won a medal at the Paris Salon in 1824. Impressionism was not far down the historical line, but Constable had already got there.

He distanced himself from the academicians who took a long time electing him one of their number, and did so only grudgingly in the end. He laughed at what he called the ‘high-minded’ members ‘who stickle for the ‘elevated & noble’ walks of art – i.e. preferring the shaggy posteriors of a Satyr to the moral feeling of a landscape’. By comparison, Turner (a year older) thought of himself as continuing the great European tradition, treating landscape as grandly as if it were history painting.

But in a quite different way he, too, was technically extremely adventurous. By the age of 25 Turner had developed watercolour into a new medium, capable of much the same expressive power as oils, and he used it to paint grand historical subjects too. The large watercolour views he made in North Wales in 1798 are among the great landscapes of European art. He would have been a major master if he had died in 1800. But he lived another half-century, constantly expanding the technical range of his work.

He kept his methods to himself and people were correspondingly keen to find out how he did it, whether in oil or in watercolour. He was seen as a wizard in both media, and there are excited reports from lucky witnesses of his procedures. A boy who was allowed to watch him painting a watercolour of a huge battleship (from memory) told his family: ‘He began by pouring wet paint until it was saturated, he tore, he scratched, he scrubbed at it in a kind of frenzy and the whole thing was chaos – but gradually and as if by magic the lovely ship, with all its exquisite minutia, came into being…’

Much later in his life he took to performing these kinds of transformation scenes in public, or at least in front of his fellow academicians, who crowded around (while pretending not to look), on the ‘varnishing days’ before the annual exhibition opened, rather like the audience gathered around Wright of Derby’s scientist (or conjuror?) with his air pump, or the visitors to De Loutherbourg’s Eidophusikon. In 1835, Turner submitted one of his two spectacular treatments of The Burning of the Houses of Lords and Commons, and a fellow academician reported: ‘…the picture when sent in was a mere dab of several colours, and without form and void, like chaos before the creation…since he began in the morning — he never ceased to work, or even once looked or turned from the wall on which his picture hung…A small box of colours, a very few small brushes, and a vial or two, were at his feet, very inconveniently placed… In one part of the mysterious proceedings Turner, who worked almost entirely with his palette knife, was observed to be rolling and spreading a lump of half-transparent stuff over his picture, the size of a finger in length and thickness…presently the work was finished: Turner gathered up his tools together, put them into and shut up the box, and then, with his face still turned to the wall, and at the same distance from it, went sideling [sic] off, without speaking a word to anybody…All looked with a half-wondering smile, and Maclise, who stood near, remarked, “There, that’s masterly, he does not stop to look at his work; he knows it is done, and he is off.”’

Turner transformed his own paintings into performance art but, as we have seen, that was exactly in the spirit of the times.