This book tells the story of scientific understanding of the stratospheric ozone layer. It is certainly not the first work to be written on this subject! But the approach here is somewhat different. We are looking at the story of a series of scientific investigations. And we are looking at them from the point of view of evidence: what conclusions were drawn, and when? How were experiments designed to try to sort out the different possibilities? What happened to cause scientific opinionon certain issues to change? The first part of the book sets out the history, with these sorts of issues in focus.

This then sets the basis for the second part. Philosophers of science have tried to analyse the way that science is conducted. They have written about the way that theories are devised, become consensually accepted, and then may be revised or even overthrown in the light of new evidence. The history of stratospheric ozone is full of unusual twists and changes. So in this work it is used as a case study: an example we can use to examine how some philosophical accounts of evidence in science might compare with the actual conduct of modern science. The example even suggests some new aspects that differ from the philosophers' accounts.

Does that mean that this is a work without a clear focus? A book that is trying to tackle two quite separate issues, rather than concentrating on one of them? I would certainly hope not.