I asked Mr.Carty to explain it.

He is our chief engineer; but he did not understand it.

We called the manager.

He did n't know, and called his assistant.

He did n't know, and called the local engineer, who was able to tell us what it was." To sum up this development of the art of tele-phony--to present a bird's-eye view--it may be divided into four periods: 1.Experiment.1876 to 1886.