Are there any books out there that talk about the lives of mathematicians? I recently read lots about the discovery of calculus of variations. The maths of this period is outstanding, however almost from what I can gather was the lives of Newton, Leibniz, the Bernoullis etc and how these problems were discussed. However I can only find scraps and it's almost as if its thrown in and the authoer is embarrassed to do.
I guess I am looking for something similar to that you would find of the lives of Shelly, Byron, Coleridge. However rather than romantic poetry, I would like something similar on the mathematicains during the discovry of calculus of variations. Maybe I am failing with my keywords and/or the stores in which I am looking, however so far I have drawn a blank.

Men of Mathematics by E. T. Bell, as mentioned by ThomasGrubb, is appropriate for reading about mathematicians up to the 19th century.  In particular: Newton, Leibniz, Bernoulli, Bernoulli. Great for learning about them, if you know next to nothing about them.  (But more sophisticated readers should note that Bell romanticized some of the stories.)
In some cases there are book-length scholarly biographies that you can find if you want more, after the introduction in Bell.  In particular, of course, Newton and Leibniz have many such biographies.
