To get back on topic about babbage's drawings,
from what I read it was mechnical design that
could not be produced with 18th century mechanical
enginering.
There is some vague truth to this, but basically no, the technology
was indeed there. Almost.
During the 19th century, British precision machining was lacking, as
the machinists at the time were very reluctant to use many of the new
tools. The Germans, and especially the Americans, at the time very
eagerly embraced the new tools and left the British machinists behind.
Very few British machinists took up the new tools, and those that did
could have done the work. There is a very good book I once read about
this, and it slips my mind right now.
For a practical example - look at mid 19th century firearms at the
time: British interchangable parts aren't.
--
Will