Perhaps this may help. This is a 1852 map from Wikipedia showing the line: http://en.wikipedia.org/wiki/File:Harva ... ilroad.jpg
I just discovered this 1940 map showing the Harvard Branch overlaid onto Harvard University buildings! Astounding!
The full article is also excellent:
http://www.cambridgehistory.org/content ... -1849-1855" onclick="window.open(this.href);return false;