"A flurry of patents [for roller coaster designs] issued in 1884 coincides approximately with Thompson's ride at Coney Island. The patents of Wood (US #291,261 Circular Gravity-Railway) and Stevens (US #298,710 Roller Coasting Device) describe roller coasters which are extremely similar. In both cases, the layout is a full circle, with adjacent passenger loading and unloading platforms. The platforms are within the circle and accessible by stairs. In both cases, the passengers are seated facing sideways. The former patent relies on precisely determined distances and heights such that the car stops on a level stretch of track, while the latter patent allows the car to stop on the final upgrade, where it is held by an anti-rollback pawl. The inclusion of exact dimensions in Wood's patent suggests that an experimental prototype had been built, although it may not have been full-size. Although it has been suggested that Wood never built a ride that was operated for the public, construction of a ride at Ponce de Leon Springs (Georgia) was reported in the Augusta Chronicle and the New York Times ["Sliding Up Hill," New York Times, June 27, 1884]. Wood's obituary [Toledo Blade, May 4, 1909] indicates that he licensed his patent for as much as $17,000 in a single year, strongly suggesting that multiple rides based on his invention were built by others. A possible example may be a ride at Oakland Beach, Conneaut Lake, Pennsylvania. An 1885 advertisement for this ride is reproduced in Bush & Hershey's book [Lee O. Bush & Richard F. Hershey. Conneaut Lake Park, The First 100 Years of Fun. Amusement Park Books, 1992] about Conneaut Lake Park. The drawing in the ad appears to match the Wood and Stevens patents quite closely, and the description of the ride as a "circular gravity railway or roller coaster" is remarkably similar to the titles of both patents."

- Victor Canfield. 2001. "U.S. Rollercoaster History From Patents" from http://www.personal.psu.edu/faculty/v/a/vac3/history.html)