Passing through the doors the passengers in small groups enter a horizontal cylindrical compartment containing seats on each side and a flat floor. It consists of knurled roller s that lock the elevator to its' guides should the elevator descend at an excessive speed, which is monitored by a governor device. The conveyor often includes partitions to prevent the material from sliding backwards. The first elevator shaft preceded the first elevator by four years. In the United States elevator safety codes began requiring various forms of corrosion protection for hydraulic cylinders. In addition passenger elevators are required to conform to the American's with Disabilities Act and other State and Federal civil rights legislation regarding accessibility. Even though the elevator is no longer daily necessity for neighbors since the rise of the automobile, it is still a popular tourist attraction and a unique part of the city.