There were plane landings on each side on every floor and on the roofs of buildings higher than five floors. Beside the moving stairways in these buildings, and in all other large buildings, alongside the moving stairways were two elevator shafts, one used solely for up traffic, the other for down. They were each large enough to hold one of our freight cars, for they measured sixty feet by ten feet. Used exclusively for freight, these elevators were only platforms supported by wheels eighteen inches in diameter. They also had gear wheels on each corner and on the middle of each side. Running up and down the walls of these shafts were six full-length geared metal beams. When a platform was in the shaft, the gear wheels closely fitted into the cogs or gears of the shaft beams and the platform gear wheels operated either up or down. Weather conditions in re to expansion and contraction did not loosen or tighten the hold that these gear wheels had on the beams. Strong springs helped to keep the hold constant. These platforms were not attached to or supported by cables. They were not permanent inside fixtures of the shaft; many elevators could operate at the same time in one shaft, as many as there were floors. Automatically, they traveled in the shaft at a certain distance from each other so that they could not collide. When one of them reached its given floor, the whole line of elevators stopped in the shaft until this one vacated it. The shaft floor doors opened and released three rails from the floor into the shaft to support the elevator, while it released itself from the beams, gears. The elevator then rolled on its flat wheels onto the rails and then onto the floor. When the rails snapped back into position, the doors closed, and the other elevators in the shaft continued on their way to their floors. Now the released elevator with its load propelled itself to the place of unloading. On the floor of this elevator were four movable belts. They were used for loading (pulling on) and unloading (pushing off) a full load, four units, when all four belts operated, or a half load, two units, when two belts operated; or a quarter load, one unit, when one belt operated. One unit was the equivalent of the minimum size of a load of heavy merchandise that we handle. When this elevator reached the place of unloading, it hooked onto the permanent loading platform against the wall, eighteen inches from the floor. These permanent platforms had metal movable belts for loading and unloading and when the elevator was hooked to one of them, the belts on both moved into action. The elevator belts pushed off while the platform belts pulled on the load. These loading and unloading belts were on all the freight cars, loading platforms, and on every deck, on both sides, of our air and sea freight ships.