THEATRE / The appliance of science: Paul Taylor on Tony Harrison's Square Rounds at the National's Olivier Theatre

THE REVOLVE on the stark-white Olivier stage is fringed with black so as to evoke a conjuror's top hat. The precise species of animal Tony Harrison proceeds to pull out of this headgear is not at all easy to define. An earnest polemical panto would be one way of describing Square Rounds, his new venture for the National, though there are times when it resembles a choreographed oratorio or an agit-prop magic show. Whatever it is, it remains, for the most part stubbornly inert.

Written in verse and played by a large cast of women (some of whom have to get in drag to play the male boffins), the piece is a theatrical exploration of the double-edged nature of 'scientific progress'. The creative-destructive gifts it brings are gruesomely epitomised here by the fact that artificial fertiliser and TNT were derived from the same processes: 'Nitrogen as nitrates could make all Europe green / But it blasts in even blacker as Tri-ni-tro-to-lu-ene'. Focusing on Fritz Haber, the pioneer of chemical warfare, and Sir Hiram Maxim, the inventor of both the machine-gun and the inhaler (or 'pipe of peace'), Square Rounds examines, too, the responsibility of scientists for the lethal applications of their discoveries.

The uncomfortable link between the desirable evolution of synthetic dyes and the invention of poison gas is adumbrated in one of the most charged and powerful passages in a script that too often relapses into dogged doggerel: 'the green of a chemise / borne as deadly poison on the breeze . . . Those materials that lovers' hands would stroke / wafted as miasma and making young men choke'. The poetry images the scientific development from dye to poison gas almost as though it were an eerily beautiful magician's stunt, and it is as a speeded-up metaphor for the (often tragic) transformations wrought by science on people's lives that the tricks (with which this spectacular piece is tricked out) work best.

Giving a new twist to the idea of lavatory humour, the show begins and ends with a centre-stage toilet cabin used by the women working on munitions in the First World War. The loo (a British invention) has a lot to answer for, it seems; hence its prominence in the play. Thanks to latrines, soil-enriching excrement was, for the first time, literally flushed down the pan. The resulting need for nitrates led to the discovery of TNT.

This and the other paradoxes and contradictions the piece pinpoints (such as Sir Hiram's belief that his machine-gun is a great lifesaving invention or Fritz Haber's conviction that his poison gas is humanly preferable to gunfire because it leaves the relations with an intact corpse), are all intriguing, but Harrison's verse thumps away at them in a laboured, repetitive, lecturing manner. It's the sort of piece that has you worried that they are going to spring a compulsory comprehension test on you at the end.

Apart from Haber (Sara Kestelman) and his scientist wife (a sweetly-voiced Maria Friedman singing Dominic Muldowney's haunting tunes) who commits suicide in protest at his use of chemistry to kill men, there is a dearth ofrelationships you could describe as dramatic and, in terms of pace, some of the proceedings seem to have been tuned to the pulse of a zombie.

And the role and responsibility of governments is under-explored. Indeed, the enormous political problem of what sort of constraints to put on, and directions to give, 'pure' research, is scarcely addressed. Instead, the finale takes us back to old China and leaves us with the problem of how to dismantle the first rocket by freeing the flame from the claws of the dove of peace. Instead of feeling stirred by this, you may well end up feeling patronised.

Square Rounds continues at the Olivier, National Theatre, South Bank, London SE1 (Box office: 071-928 2252).