Here's a very interesting 1951 paper on the construction of a complex
boolean logic unit using relays. It's contemporary with the more
better-known Kalin-Burkhart machine.
http://history.dcs.ed.ac.uk/archive/docs/mechanized_reasoning_screenres.pdf
This is the first time this paper has been put online. I received it
as a photocopy of the original from J B Smith's sister.
This is at screen resolution. I'll post a higher-res version later
for printing. (I had to clean up the paper considerably from the
original using Photoshop.)
If you're interested in the history of logic machines, you should also
look for machines by Alfred Smee (1851), and William Stanley Jevons
(1870)
Graham
References:
http://www.google.com/search?source=ig&hl=en&channel=2PSP&q=Kal…
http://www.google.com/search?hl=en&safe=active&q=%22mechanized+reas…