It must be repaired or improved by a sort of vivisection while it is working.

It is an interlocking unit, a living, conscious being, half human and half machine; and an injury in any one place may cause a pain or sickness to its whole vast body.
And just as the particles of a human body change every six or seven years, without disturb-ing the body, so the particles of our telephone systems have changed repeatedly without any interruption of traffic.
The constant flood of new inventions has necessitated several complete rebuildings.

Little or nothing has ever been allowed to wear out.

The New York system was rebuilt three times in sixteen years; and many a costly switchboard has gone to the scrap-heap at three or four years of age.

What with repairs and inventions and new construction, the various Bell companies have spent at least $425,000,000 in the first ten years of the twentieth century, without hindering for a day the ceaseless torrent of electrical conversation.
The crowning glory of a telephone system of to-day is not so much the simple telephone itself, nor the maze and mileage of its cables, but rather the wonderful mechanism of the Switchboard.