I believe it is spinning in the book, but not necessarily at this time as this picture is taken in 2007. Let's see, it took 23 hours to render with 'optimized' settings...adding motion blur for a spinning wheel will quadruple that-- but yours is a very good point!

I talked with the author of the book, and we've agreed to add some more detail in the image..which IMO it really needs. I think we'll add a rail and perhaps an overhead crane. I'll keep you posted.