Life and loves of the man in the white suit

A tantalising pre-title, "scientist, soldier, statesman, spy", scarcely needs supplementation; but, given the subject's proclivities as a master of mistresses and of molecular agitation, a further shot might have been "Rumford on heat". Famous for cannon-boring experiments in which the generation of heat through friction led to the hope that he would "live to drive 'caloric' off the stage", Rumford returns in George Brown's timely biography as an inventor so creative and energetic that he personifies the perpetual motion which, in his machines, eluded him.

The Royal Institution, recently celebrating its bicentenary, was his brainchild. So was an impressive series of devices, which promoted creature comforts both in elegant London homes and in the Bavarian workhouses he had invented to remove beggars from the streets. There was the Rumford stove for less smoky chimneys and the Rumford roaster for tastier meat. There was even Rumford soup, one of the recipes through which he heaped potatoes on Bavarians. A Rumford thermoscope compared the heat radiated by two different cylinders. Writing for a general audience, Brown nicely captures both the earnestness and eccentricity of the scientist who applied his science to himself. Believing that shiny surfaces radiated heat least quickly, Rumford would astonish onlookers by sporting white clothes and a shiny white hat in winter. One can imagine the hauteur of which his contemporaries complained and the peculiar style of philanthropy in which he loved humankind more than human beings.

Rumford had his rewards. Born Benjamin Thompson into a humble farming family in Massachusetts and having spied for British generals in Boston, his trajectory took him eastwards into polite London society and thence to Munich where his schemes for turning beggars into honest workers and for revitalising the elector's army were so successful that, in 1792, he was made a count of the Holy Roman Empire. Such was Carl Theodore's faith in his right-hand man that, in a moment of crisis in 1796, Rumford was saddled with defending Munich against the Austrians and the French. Brown tells the story delightfully - how the man who had never fought a battle in his life cunningly dissuaded the respective commanders from invading the city. In retrieving so eventful a life, it would have been tempting to overstate Rumford's scientific acuity. Brown is careful to record his limitations. He gives us warts and all, especially Rumford's penchant for other men's wives - including Lavoisier's widow who, on marriage, turned into a dragon.

One has to put up with cliches: how Rumford was always in the right place at the right time; how his ideas were ahead of their time, and a time when the sciences evinced a "confused state of understanding". A little unsophisticated perhaps; but a beguiling account of a man with a mission and a message - that the best formula for poor relief was the application of science.

John Hedley Brooke is professor of science and religion, University of Oxford.