ART / The crest of a wave: James Hall reviews 'The Great Age of British Water-colours 1750-1880'; plus the rehabilitation of the medium

Who needs enemies with friends like Adolf Hitler and Prince Charles? Both count as firm friends of the water- colour. The Fuhrer-in-waiting churned out water-colour views of listed buildings in Vienna and Munich; while the British heir-apparent is a prolific purveyor of traditional landscape and topographical water-colours. In such cases, the medium sends out an unmistakable message: in an age of instant photography, the use of a more labour-intensive medium signifies a sustained devotion to the motif, and a sense of historical place. Its apologists would have us believe that a sacred rite takes place. On a humble sliver of paper, material water gets turned into spiritual wine.

Plenty of these fogeyish forget-me-nots are advertised in the current issue of the Royal Academy Magazine. At Ackermann & Johnson, for example, we can wallow in 'Ken Howard RA - Venice Inspired: An Exhibition of Recent Water-colours'; at the Nevill Gallery we can thrill to the original water-colour illustrations from 'The Story of a Castle', by John Strickland Goodall RI RBA; at the exhibition of prints and water-colours by John Piper at the Berkeley Square Gallery, we can share his 'great love of Britain's castles, churches and houses . . .'

You would be forgiven for thinking that water-colours have become irredeemably wet. Forgiven, but mistaken. Water colour may now be the preferred medium of the professional and amateur heritage industries, but it has recently been given a new lease of life by some of the most celebrated contemporary artists. Its appeal to today's avant-garde lies in its expressivity and, paradoxically, its perceived status as an outmoded medium (see box, right). It is this that makes the Royal Academy's 'The Great Age of British Water-colours 1750-1880' so timely.

And what an ambitious show this is] Over 300 works by 88 artists have been marshalled into six thematic sections. Big names like Gainsborough, Turner, Constable, Girtin, Cotman, Martin, Palmer, Bonington and Whistler rub shoulders with many virtual unknowns. The last of these sections, 'The Exhibition Water- colour', is especially spectacular. It includes large-scale works, some of which are displayed in their original gilt frames. You are left in no doubt as to the heavyweight credentials of this most lightweight of media.

The development of water-colour in Britain is intimately bound up with the rise of the British Empire. Being portable and quick-drying, water-colour was good for recording far-away people and places. It was used by soldiers, sailors, traders and archaeologists. At the same time, increased prosperity and the start of a tourist industry at home created a market for views of English towns, architecture and scenery. These views were done by professionals and a small army of well-heeled amateurs, the latter schooled by specialist teachers and manuals.

The first room, entitled 'The Structure of Landscape: 18th-century Theory', includes work by pioneers such as Alexander Cozens and Francis Towne. Cozens, a drawing master at Christ's Hospital and Eton, is famous for his manual advocating the use of accidental inkblots for the suggestion of landscape motif to the aspiring amateur. The results are always eerie, and often rather ludicrous. In Mountain Peaks (c 1785), most of the 'peaks' point more or less in the right direction, ie upwards. However, muscling in from the left-hand side is another 'peak' that looks as though it has been turned on its side, defying gravity and geology. No wonder, then, that the out-stretched arms of the two noble Romans in Figures by a Pool below a Fortress in an Italianate Landscape point in different directions. Despite the detailed title, they are lost and don't know where to turn, like every day-tripper in Blotland.

Cozens worked in monochrome because he believed that the application of local colour would distract from the essential structure of a landscape. The technique of Exeter schoolmaster Francis Towne was more traditional than Cozens's, but he too avoided local colour for a similar reason. The Source of the Arveiron, painted in the Alps in 1781, epitomises the water-colourist's striving after truth and purity. The style, like the subject-matter, is suitably primal and virginal. A taut abstract pattern is built up from bold swathes and blocks of limpid colour. The logic of this minimalist design is made even more compelling by Towne's use of more than one piece of paper: the joins create a grid. Towne painted the picture using water taken from the source itself. Hence the secret credo of all later water-colourists - 'Water-colour: a Pure Medium in an Impure World'.

The next two sections - 'Man in the Landscape: The Art of Topography' and 'Naturalism' - deal with the more literal-minded delineation of places and things. The artist Henry Fuseli called topography 'the tame delineation of a given spot', and tame tends to be the operative word for the vedute of Paul and Thomas Sandby, James 'Athenian' Stuart, and Michael 'Angelo' Rooker. The 'Naturalism' section, full of effete nature studies and stuffy still-lifes, is text-book stuff (worthy but dull).

The show moves into higher gear in the following sections. 'Picturesque, Anti- Picturesque: The Composition of Romantic Landscape' focuses on Neo-Classical landscape water-colours in which the composition consists of austere, asymmetrical arrangements of a few basic elements. Surly, brooding monoliths loom up before us at regular intervals. In Storiths Heights, Wharfedale, Yorkshire (c 1802), Thomas Girtin creates Yorkshire's answer to Ayer's Rock. We peer over a sandy-coloured foreground towards a long, dark, squat mound. The scene shimmers in soft-focus, dry as dust. It is hard to know if it is a mirage; in Girtin's hands, this corner of Yorkshire takes on a sphinx-like inscrutability.

There is a flurry of Romanticism in the 'Light and Atmosphere' section. It is full of special sea and sky effects by Constable, Turner and Bonington, and there are several superb late works by John Sell Cotman. The saturated colour in the 244th work in the exhibition, Cotman's Study of Sea and Gulls (1832), is sure to inspire viewers who fear they have reached saturation point. A flock of white sea-gulls homes in on an isolated wooden promontory set against a turbid blue sea and sky. At top centre, the clouds part to admit a gash of white light and the gulls stir, imperceptibly.

In the final section, 'The Exhibition Water-colour', we see the way in which the water-colour strove to hit the big time. In 1804 the Society of Painters in Water-Colours was founded, largely inspired by the success of Turner. They held annual exhibitions in friendly rivalry with the Royal Academy. Works were mounted in sumptuous gilt frames, and they were frequently made on a pictorial scale. Turner's first large-scale water-colour, his full-frontal view of The Great Falls of the Reichenbach (1804), is presented as the fons et origo. Turner's brush seems to have tip-toed across the paper. He gives us the waterfall-as-fop. It drifts languidly through the rocky landscape, ruthlessly laid-back. Few of the Victorian water-colourists are content to display such a light touch. They start to use varnish, or bolster the texture of the paint by using gouache. The pictures become turgid, treacly, clotted, arthritic. Samuel Palmer's A Towered City (Illustration to Milton's L'Allegro), from 1868, has the consistency of a warm Cadbury's Flake. We hear the death-knell of the nimble English water-colour.

The organisers have been keen to include as much work as possible that can be dubbed 'proto-impressionist', but this orientation appears to have militated against the more visionary figure painters. Blake is represented by two minor late works, and the whole of English caricature is covered by Thomas Rowlandson's Skaters on the Serpentine, a work that will not even travel with the show when it transfers to Washington. Moreover, the topographical section would have been enlivened by architectural presentation drawings. J M Gandy's vast meditations on John Soane's architecture are among the most spectacular and visionary water- colours ever made. The inclusion of any of these would have been preferable to a re-run of the interminable English paternity-suit over French Impressionism.

(Photograph omitted)