The Multiple boards swallowed up capital as a desert swallows water, but THEY SAVED TEN SECONDS ON EVERY CALL.

This was an unanswerable argument in their favor, and by 1887 twenty-one of them were in use.
Since then, the switchboard has had three or four rebuildings.

There has seemed to be no limit to the demands of the public or the fertility of Scribner's brain.

Persistent changes were made in the system of signalling.

The first signal, used by Bell and Watson, was a tap on the diaphragm with the finger-nail.