It's true that there were such precursors around the time of the First World War, but the great expansion - the invention, it seemed at the time - of this way of working took place in the five years after 1968. The reasons seem pretty straightforward. The first, often advanced by the artists themselves, was that there was a reaction away from formal concerns - these were seen, rightly or wrongly, as hierarchical and elitist. Second, I suspect that the triumph of vanguardism opened up so many new spaces and opportunities that galleries were eager to try anyone who seemed novel. But the third reason for the success of installation art is the crucial one. It's easy to do.
Of course the organisational problems can be immense. Think of the effort expended in bringing to the gallery all the heaps of sand, horses, boulders, slide projectors, display cabinets, automobiles and cages that we have seen over the years. But still it's easy to get an effect, so long as some drama is included. I used to think of installations as distant cousins to sculpture. Now I think of installation art as a substitute for theatre. Stagey set-ups, dramatic lighting, music, the air of a performance about to begin, the feeling that the spectator is a member of an audience - all these things ally installation with the performing arts.
Because making installations was easy, art was put was more within the capacities of anyone who wished to be an artist. This ease of access was a tenet of the post-1968 generation, but a look through the pages of this book makes me wonder how much was gained. Just as conceptual art produced no masterpieces, so also installations seem unable to convince us that any one work is utterly perfect and necessary to our conception of the art of our time. They lack aesthetic finality.
The leading players of the movement, to judge from Installation Art, are Richard Long, Giuseppe Penone, Sol LeWitt, Joseph Beuys, Rebecca Horn, Robert Gober, Sherrie Levine and Helen Chadwick. They have certainly been more prominent than their contemporaries, but it's hard to say that they are better artists than people with less respected names on the vanguard circuit. They have just had a more powerful way of employing the lingua franca of installation, a set of conventions that were immediately disseminated through the art magazines of 20 years ago.
Such magazines - Artforum, Arts Magazine, Art in America - are hung from the wall in Serge Spitzer's exhibition at the Henry Moore Institute in Leeds, as though in homage or in ironic reference to their power. Spitzer's name is not to be found in the pages of Installation Art, but obviously it belongs there. Romanian- born, he came to the West in 1972, and after periods in Jerusalem and Berlin finally settled in New York. In his work there is no trace of either his native land or of memories of any art other than early-Seventies conceptualism.
His exhibition and its catalogue covers work since that period. So here are lengths of rolled- up linoleum, dismembered painting-stretchers strewn on the floor with sheets of linen, photographs of the artist playing with long poles on a lonely beach, rooms redesigned to make it
difficult to see their full extent, slide projections directed toward awkward corners, the
imitation tank that he once placed on the roof of a Jerusalem theatre, heaps of rubber, conveyor-belts going round and round, 'their endless purposeless motion intended as a parody of the movement of capital through the world's banks', as the Henry Moore Institute's publicists respectfully explain.
Whether these ideas were borrowed from other people does not particularly concern me. The point is that they became cliches two decades ago and are doubly cliches today. Spitzer's drawings, which were hardly worth framing, show that he has had difficulty in becoming an individual artist. His new installation is still in the grip of outdated 'subversive' art. Here, once more, is a conveyor-belt running through three galleries, associated with a towering structure made of 100 metres of I- beam in a continuous loop. This tower is the best thing in the exhibition. But it is more like a parody of sculpture than sculpture itself.
After such a disappointment in Leeds it is good to see Richard Wilson's installation at Matt's Gallery. Wilson became celebrated five years ago for his piece 20/50, now familiar to visitors to the Saatchi Gallery. This was a metal walkway through a huge tank filled with sump oil, which perfectly and uncannily reflected the roof above you. Space wasn't really transformed, but the illusion was magic. Wilson hasn't done anything comparable since, but watertable has a memorable quality of its own.
A billiards table has been sunk into a rectangular hole in the gallery floor. At one side of the table a big concrete drainage pipe invites you to look down. And there is water, lapping and gurgling in its mysterious way. Wilson has descended by just three metres to find London's water table. One would never have dreamt that it might be so close. In this bizarre fashion the artist suggests how fragile is the basis of our crummy civilisation. Most installations are quickly forgettable, but this one is likely to remain in our minds.
'Installation Art' is published by Thames & Hudson, pounds 28. Serge Spitzer: Henry Moore Institute (0532 343158) to 11 June. Richard Wilson: Matt's Gallery, E3 (081-983 1771), to 15 May.