When trying to push forward the boundaries of a subject of study its important to know something of its history, both to avoid pitfalls which have been made before, and to re-evaluate old ideas, to see if they might be of use. The measure of the universe
by John D. North provides a useful historical resource for the subject of cosmology, in particular that of the first half of the twentieth century. The book was written over 40 years ago, but I feel that this is a plus, as it meant it was closer to the action. Today we talk of the FLRW cosmological model, and this book looks at the contributions of each of these four scientists, as well as the Einstein- de Sitter model, the ideas of Milne and the later ideas of a steady-state universe. To get the most out of the book it is important to work through the mathematics in it, but this is generally fairly straightforward.
North is a philosopher, and the second half of the book is concerned with the philosophy of cosmology. I wasn't so keen on this part. North doesn't try to impose a particular view on the reader. This undogmatism is good, but sometimes I wished he'd try to make things clearer. For instance, there are a multitude of different ways of defining distance in cosmology. North seemed to be excessively worried by this, but my feeling is that it isn't much of a problem as its usually fairly easy to convert between them. Also, by the mid 1960's all sorts of interesting things were happening in cosmology, and I felt that North could have included more of these in his discussion.