The Serpentine Railway, built in 1885 at Coney Island, was the 1st gravity roller coaster to tie the track end together and return passengers to their starting point without them needing to disembark while the car was placed on the return track. The train, with its passengers seated sideways on a wooden bench, ran atop an undulating wooden structure. The train was slow and took several minutes to complete its circuit. Sounds scary to me.

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