Why did they call the roller coaster a roller coaster?

The first roller coaster was actually a coal mining car in NY in 1895 that ran 18 miles down hill and would hit a 100 MPH. People came up to the hill where it was located and rode it down. Roller coasters became popular after WW1 and there were over 2,000 built in the United States in the early 1900's. In 1927 the Coney Island roller coaster opened. The early Roller Coasters were very dangerous and many people got hurt on them. They are called roller coasters because wheels are used for them to coast on a track. It is all done with gravity.