The Principles and Practice of Ornamental or Complex Turning by John Jacob Holtzapffel is one of those rare books that will completely blow your mind. A compilation of techniques for doing ornamented woodturning, which is dependent on a highly complex apparatus for the wood lathe, ornamental turning is to regular turning as a Rolls Royce is to a Taurus.
Half of the techniques are routing around the periphery and across the face of work held in the lathe, using chucks and spindles that can eccentrically, geometrically, linearly, spherically present the work to the cutting tool. Oh right, I forgot, and elliptically! True Victorian madness. A great read for its own sake as well as for techniques that you can add to your “simple” wood turning.