Inspired by the "Odyssey" thread I decided to elaborate a little on different styles of catenaries and power pickups. I know three basic types of catenaries, all of which are used for tramway and subway systems in central Europe.
I don't know the correct English terms, but literally translating it's single catenary, flat chain catenary and high chain catenary. Single means there's just one single copper wire held by suspension wires running from pole to pole or from the houses across the street.
High chain is what you see in the picture, the power wire and above a second arched wire that gives mechanical strength.
Flat chain is high chain turned 90 degrees.
Now to the power pickups. The oldest ones are the lyra pickups.
They were used until about 1930. In 1925 so-called scissor pickups made their appearance in Vienna. They were first used on the type N Stadtbahn cars (a former urban steam railway system was converted to electric operation with tramway-like 2-axle cars seen in the first picture for "high chain catenary", the dirty brown cars).
After 1964 they were surpassed by standard pantographs.