Books: Shale of the century

Yorkshire's rock stars began the revolution in geology. John Gribbin discovers our learned friends in the north

The Floating Egg: episodes in the making of geology

by Roger Osborne

Cape, pounds 15.99

I have to declare an interest in this book - or rather, a disinterest. It is not what I would call a "real" book, but a book of bits, or a bit of a book. Roger Osborne has strung together a range of items: straightforward historical accounts, scientific description, lengthy quotations from other sources, and slightly cringe-inducing attempts at fictionalising true stories in the vein of those historical bodice-rippers about Mary Queen of Scots, told from the viewpoint of a lady in waiting. It is just the sort of book I would usually fling down with disgust. And yet, I don't.

The redeeming feature of The Floating Egg is the material that is mistreated in this way. Osborne tells a genuinely multi-faceted story, built around the geology of the north-east of England, starting with alchemy and proceeding historically to end (if we ignore the last and weakest of his attempts at faction) with real science.

This works because the region really was of key importance in the development of the science of geology. There are long stretches of cliff along the Yorkshire coastline, for example, where strata are exposed to view and provide a laboratory for testing ideas about the evolution of the Earth.

We meet William Smith, the canal builder who invented the study of this kind of stratigraphy at the end of the 18th century; we uncover strange fossils of what are now known to be dinosaurs; we follow, in one of the best sections, the saga of stones that fall from the sky, and we even journey with Captain James Cook around the world (which is a bit of a cheat, even though he did hail from Whitby).

The episodic structure of the book, and much of its style, would make it an excellent basis for a radio series, but the whole thing has a disjointed feel. Of course, it may just be that I am being unperceptive and that the ragged edges are intentional, like the careless windswept look on an actress that takes hours to achieve in make-up. The author tries to encourage such a belief by stating in his Preface that "in the next few hundred pages all is not quite as it seems". But I have been unable to uncover any hidden depths, so if they are there they must be buried very deep.

Where do floating eggs come into the story? Right at the beginning, with the alchemists involved in extracting alum (invaluable in the cloth and leather industries) from the shales of the Yorkshire cliffs in the 17th century. The key to their success in producing alum on an industrial scale was to boil a solution of several salts until evaporation had raised its density to a critical value. Then, when the broth cooled, alum, and alum alone, would crystallise out of the stew, leaving unwanted contaminants in solution. The whole process depended on some unknown genius who realised that if a hen's egg were placed in the boiling vat, it would float to the surface at the precise moment that the density of the liquid had reached the optimum level.

Where Osborne's storytelling technique works well, as in this example, he is as good as James Burke at his best. Where it doesn't work, he falls flat on his face. But the structure of the book in 25 self-contained chunks means that you can skip the ones that don't appeal.

Resisting heroically any temptation to mention curates and their breakfast fare, I am more than a little surprised to find myself recommending The Floating Egg as, on balance, a Good Thing. It does make science accessible, it does provide entertainment, and it does portray the scientists involved in the geological revolution as human beings. It's a pity it doesn't often manage to do all three tricks at once, but I've a suspicion that I will like the package more next time I read it.