I wouldn't call this book "practical," and its usefulness certainly isn't confined to inventors; this is an exhaustive look at electronics and electricity, from principle and theory to application. If you want a single book that will teach you most of what you need to understand before working with electronics, this is it. HOWEVER, at nearly 1,000 pages, and written by someone with an obviously exhaustive knowledge of the subject, this is not light reading and will take a commitment to work through. I am using it alongside other books that give a more casual explanation of components and projects so that I can better understand what is going on inside of the components.
If you know nothing about electronics, and you want two years worth of electrical engineering crammed in your head within a few weeks, this is the book for you. If you would rather get right into building circuits or soldering IC's to do specific tasks, I would consider a simpler text (but still get this as an essential reference!)