George S Duncan built the first pull curve in Dunedin, New Zealand, for the Roslyn Tramway, which had to carry cars over a climbing curve around Saint Joseph's Cathedral. The pull curve is complicated because it needs a series of small horizontal sheaves placed close together to keep the ...
[题目] People in several American states may be surprised to see cars on city streets without a driver. Experimental driverless vehicles now are legal in Florida, Nevada and California. They are pointing the way to a future that is not far down the road.