Popular Mechanics (South Africa)
Time machine: Fascinating stories from the PM archives.
Duluth Aerial Bridge Ferry
More than 100 years ago, this cover story told of the Duluth aerial ferry, which was the first structure of its kind in America. The steel-trussed superstructure spanned the Duluth shipping channel, and loads of up to 50 US tons could be transported from tower to tower by means of powerful electric motors.