Incredible as it may seem, more than fifty companies, ten years before the Civil War, were engaged in the business of transmitting telegraphic messages.

令人难以置信的是， 在南北战争之前的十年， 已有 50 多家公司从事电报信息传输业务。

It was Bell's idea that, by a system of tuning different telegraphic receivers to different pitches, several telegraphic messages could be sent simultaneously over the same wire.

贝尔的想法是， 通过将不同的电报接收器调到不同音高的系统， 可以在同一条电线上同时发送多条电报信息。