Escalators

• Both these types of escalators can be made to move up or down by aid of a swinging switch, or two of them can be placed side by side, one moving upward and the other downward. 佚名. 神奇的知识之书.
• The Story in Elevators and Escalators[15] 佚名. 神奇的知识之书.

校对:佩德罗