I read in a thread on this forum that you're planning two books perhaps, one for the general public and one for trainers/science-tech people, or to put it better those with an understanding of the principles you'll be writing about that's far above the layman's. There may be a better approach. i've read quite a few science popularization books, and they follow an interesting format. The topics are covered in a way that goes from less to more technical, from basic concept to in depth study and explanation. This works great because once the reader hits the limits of his own ability to understand the material, he goes on to the next topic which is handled in the same way. This might be a way for you to avoid writing two books and repeating yourself quite a bit in both, and also reach a broader audience with just one effort.