english deutsch
The Bollman Truss
http://www.du.edu/~jcalvert/tech/bolltrus.htm
Essay featuring bridge types and materials, and principles and design .
Wendell Bollman - Civil and Constructing Engineer.
http://external.bcpl.lib.md.us/hcdo/cfdocs/photopage.cfm?id=11071
Facsimile of a mid-19th century advertisement from a City directory.