Just been having an interesting conversation about the history of communications and the subject came up about old interconnected networks.

Now, I was sure there used to be a system that used the sewers of Paris - got confused with Minitel - and then stumbled across this post by Molly Wright Steenson who is writing on the origins of the pneumatic tube network.

http://www.activesocialplastic.com/2009/01/pneumatic_post_in_paris.html

A really interesting read and a very good blog too!