A pointer on a dial before her swung to "O.K." Almost without stopping the motion of her hand, she inserted it into another gauge to see if it was too small.

Again the pointer swung to "O.K." The third test was to verify the angle of the cone, and for the third time the pointer said "O.K." The next moment the cone had been dropped into a box and another was going through the same course.
"How many have been rejected today ?" asked one of the visitors.
"Two," said the inspector.
These two unfortunates lay on a rack in front of her.

Interrupting her work she picked up one of them.

At the second operation the pointer turned to a red segment of the dial and a bell rang.
"I don't hear many bells ringing," commented the visitor, quizzically looking around the room.
Mary smiled with quiet pleasure.
"Next," she said, "I'm going to take you to a department where women never worked before." She led the way to one of the tempering buildings--a building equipped with long lines of ovens--each as large as a baker's oven--where metal cones were heated instead of rolls.
"Here, too, as you will see," said Mary, "we have tried to reduce the element of human error as far as possible.

In each oven is an electric thermometer and when the bearings have reached the proper degree of heat, an incandescent bulb is automatically lighted in front of the oven....
See ?" They made their way to the oven where a white light had appeared.