I'm interested in the influence semi-automatic routing procedures in telegraphy (e.g. Western Union's Plan-55 <http://en.wikipedia.org/wiki/Plan_55-A>) may have had on the mathematicians and engineers who developed packet-switching standards and algorithms. Davies, Baran, and Kleinrock all seem to have been familiar with telegram routing. Kleinrock mentions Plan-55 <http://dspace.mit.edu/bitstream/handle/1721.1/11562/33840535.pdf> in "*Message Delay" *(1962). In *Distributed Communication Networks *(1964) Baran mentions that "Torn-tape telegraph repeater stations and our mail system provide examples of conventional store-and-forward switching systems". Davies' mother worked for the British postal system <https://books.google.com/books?id=RLKxSvCBQZcC&pg=PA65&lpg=PA65&dq=donald+davies+store-and-forward&source=bl&ots=1Mlb5RdpKa&sig=MHkb264Q1_ufWupKiHMD16-lMZE&hl=en&sa=X&ei=z9uuVJDrGtDhsASJj4LQDg&ved=0CE4Q6AEwBw#v=onepage&q=donald%20davies%20store-and-forward&f=false>, and his first exposure to queuing theory was through a book she brought home from work. In a CBI oral history <http://conservancy.umn.edu/handle/11299/107241>, he portrays the influence of torn-tape systems on researchers in general as quite strong, but says little about how they influenced him: I think the reason [the software problems of packet switching were
difficult] was that message-switches were being made to try to operate like a torn tape centre. In other words they were trying to emulate the human system, which was really quite complex and involved a certain amount of subtlety in dealing with particular kinds of failures. The idea of sending messages - packets - and relying on lack of any response to send them again was unlike the way human systems work.
I'm looking for any tips the list can offer in determining when these researchers first became acquainted with torn-tape or postal systems, and in what manner. Observation of installations? Product manuals? Conversations with engineers who designed such facilities? What institutional connections were there between their employers (NPL, RAND, MIT) and the operators of semi-automatic message-switching systems? When Baran was at RAND, was Western Union's contract with the Air Force to build and operate a Plan-55 system an influence on research? Would RAND fellows have been in touch with Western Union engineers? Cheers, Bjorn