This really is a book that you can judge by its cover.
As a child, Bill Bryson was fascinated with a cutaway diagram of the Earth in a science textbook that showed the various layers of mantle and molten core beneath his feet and wondered, not unreasonably, "How do they know that?". As an adult he resolved to spend some years in reading and research to find answers to some of the questions that had always niggled him and how people had figured them out.
Bryson manages to cover just about every field of natural history and physical science in a little under 700 pages in an engaging and informative manner. Starting with the big bang and matters cosmological, the structure of atoms, the formation of the Earth (and the process by which its age was finally calculated), paleontology, geology and finally covering the processes involved in the creation of life and its evolution into the diverse forms we see today. He charts the development of scientific thought in each field and does not shy away from the limits of current knowledge where we realise how much there is that we don't know. He summarises the debate about the nature of the dark matter that comprises between 90% and 99% of the universe as a choice between WIMPs (for Weakly Interacting Massive Particles) and MACHOs (MAssive Compact Halo Objects - black holes, brown dwarfs and the like), before concluding that we may as well call them DUNNOS (for Dark Unknown Nonreflective Nondetectable Objects Somewhere).
The book really comes to life in the telling the stories of the scientific minds involved in the process of discovery and their various eccentricities. The Reverend Buckland, a pioneering geologist and fossil hunter was renowned for carrying out his field work properly attired in an academic gown and once woke his wife in the middle of the night to conduct an experiment involving flour paste, the family tortoise and a series of footprints across the kitchen floor. Another memorable story involves the huge personal risks of a certain JBS Haldane who constructed an early pressure chamber to investigate the effects of decompression on divers and submariners. He simulated a dangerously hasty assent to see what would happen. What happened was that the dental fillings in his teeth exploded. 'Almost every experiment ended with someone having a seizure, bleeding or vomiting'. Lest we forget, the notebooks of Marie and Pierre Curie still have to be stored in lead lined boxes due to the dangerous levels of radioactive contamination.
Bryson also talks to various modern scientists and personalities, including the Reverend Robert Evans, an amateur astronomer whose talent for spotting supernovae has been compared to looking at 1500 dining tables with black table cloths and a random sprinkling of salt on each one and being able to find the single additional grain added between one night and the next.
One of the themes of the book is the fragility and brevity of human existence. If the planet were a touch closer to, or further away, from the Sun, or if various chemical processes had not occurred, or if any number of comets had not struck the Earth at particular times, or if evolution had taken a different tack then we would not be here today. We've had a lot of lucky breaks along the way. If the history of the planet is represented by your arm span then life has only been visible for the width of your hand, and human existence by the sliver of a finger nail. We are causing the extinction of hundreds of species and tinkering with the climate with no idea of the possible consequences - as Edward Wilson expressed it in his book The Diversity of Life : 'One planet, one experiment'.
Well worth reading, if you have any scientific curiosity at all.