But it was not the final type.

It was preliminary only, the best that could be made at that time.

Not one is in use to-day.

In 1888 Theodore Vail set on foot a second series of experiments, to see if a cable could be made that was better suited as a highway for the delicate electric currents of the telephone.

A young engineer named John A.Barrett, who had already made his mark as an expert, by finding a way to twist and transpose the wires, was set apart to tackle this problem.