The chief led the boy to another portion of the floor.

"This sorter," he said, "can be set for thirteen different compartments.
In determining the country of birth, for example, at any given point on
the card, an electrically charged brush finds the hole punched and
directs the card in between two of those finely divided wire levels,
where a traveling carrier picks it up and runs it along to the point
where the wires stop, the top wire extending to the furthest
compartment. As the card falls, it is tilted into place against the pile
of preceding cards, an automatic receiver holding them together, the
operator clearing away the pile from each division as it becomes full.
As you can see, that feed knife moves so rapidly and the endless band
fingers carry the cards out of the way in such a hurry that they move
along in a steady stream. We have only twenty of these machines and they
handle all the cards."

"It's hard to believe," said Hamilton wonderingly, "that these machines
don't think."

"We're just building one in here," the supervisor replied, leading the
way into a little partitioned-off section of the room, "that has an
uncanny ingenuity. This machine feeds itself with cards, verifies and
tabulates at an incredible speed. It took some time to perfect all the
adjustments, but it is running finely now, and it will simplify the work
of the next census amazingly, just as the machines you saw have made the
old hand punching machines of former times seem very cumbersome. But
this one," he added, "is a gem."

[Illustration: PIN-BOX AND MERCURY CUPS. Details of mechanism which
almost magically detects mistakes in any census card. (_Courtesy of the
Bureau of the Census._)]

"It's a little like magic, it seems to me," said Hamilton, "to think of
every person in this whole country being registered on a card with a lot
of little holes in it, and practically the whole history on it. It
certainly is queer."

"There is something mysterious in it," the chief answered with a laugh.
"One feels as though all the secrets of the United States were boxed up
and in the storage vaults of the building. But the magician is the
Director. He is the man whose spells have woven this web of
organization, whose skill and knowledge have unlocked commercial
secrets, and whose perception has always seen the essential fact."

"It's great work to have a share in," the boy declared enthusiastically.

"To make us all feel that," his superior