John W. Farrell is the author most recently of The Clock and the Camshaft: And Other Medieval Inventions We Still Can't Live Without (Prometheus Books). His other writings can be found at www.farrellmedia.com.
John W. Farrell is the author most recently of The Clock and the Camshaft: And Other Medieval Inventions We Still Can't Live Without (Prometheus Books). His other writings can be found at www.farrellmedia.com.