Jay Eanes, age 11, of Thomasville, N.C., for his question:

HOW DOES AN ELEVATOR WORK?

Early elevators were lowered and raised by a system of ropes and pulleys attached to a hydraulic cylinder. A plunger or steel column below the car required a pit below the building as deep as the building was tall.

Newer elevators do not require the deep pits. Instead, a counterweight hangs at the back of the elevator shaft and balances the weight of the car. An electric motor is at the top of the shaft, and this is used to raise and lower the car. The motor shaft has a set of pulleys and steel cables run from the top of the car, around the pulleys and down to the counterweight. When the car moves, the counterweight moves in the opposite direction. When the car goes down, the counterweight goes up.