Every wire that comes into the board is tasselled out into many ends, and by means of a "busy test," invented by Scribner, only one of these ends can be put into use at a time.

The normal limit of such a board is ten thousand wires, and will always remain so, unless a race of long-armed giantesses should appear, who would be able to reach over a greater expanse of board.

At present, a business of more than ten thousand lines means a second exchange.
The Multiple board was enormously expensive.

It grew more and more elaborate until it cost one-third of a million dollars.

The telephone men racked their brains to produce something cheaper to take its place, and they failed.