12. Davenport & Bridges, car builders of Cambridge, Massachusetts, in
1841, obtained a U.S. patent for a swing-beam truck.
13. Gustavus Weissenborn in his authoritative _American Locomotive
Engineering and Railway Mechanism_ (New York, 1871, p. 131),
stated that when in use the V's soon acquired a polished surface
which seemed to defy wear.