This is a good account by Swade if you have IEEE access: 
The Construction of Charles Babbage&#x27;s Difference Engine No. 2<p><a href="http:&#x2F;&#x2F;www.computer.org&#x2F;csdl&#x2F;mags&#x2F;an&#x2F;2005&#x2F;03&#x2F;man2005030070-abs.html" rel="nofollow">http:&#x2F;&#x2F;www.computer.org&#x2F;csdl&#x2F;mags&#x2F;an&#x2F;2005&#x2F;03&#x2F;man2005030070-a...</a>