A roller coaster inversion is a roller coaster element in which the track turns riders upside-down and then returns them to an upright position. Early forms of inversions were circular in nature and date back to 1848 on the Centrifugal railway in Paris. These vertical loops produced massive g-force that was often dangerous to riders. As a result, the element eventually became non-existent with the last rides to feature the looping inversions being dismantled during the Great Depression. In 1975, designers from Arrow Development created the corkscrew, reviving interest in the inversion during the modern age of steel roller coasters. Elements have since evolved from simple corkscrews and vertical loops to more complex inversions such as Immelmann loops and cobra rolls. The Smiler at Alton Towers holds the world record for the number of inversions on a roller coaster with 14.[1][2][3]