Last week I completed Bill Bryson's Short History of Nearly Everything. It is a good book that tries to cover in one sweep the evolution of natural sciences. It starts of from the creation of the universe and goes on to explain the universe, planetary systems and other celestial phenomenon. It then moves on and covers diverse topics like Physics, Chemistry, Biology and Geology. It takes the user through a journey of how each of these subjects of study evolved over a period of time and also it's more illustrious practitioners.
The book has very nice glimpses, in the form of anecdotes, into the lives of great scientists. It is a very good read and is sure to engage readers who are scientifically inclined.