Before the installation of "mine telephones" underground to maintain contact with the General Office, for example, messengers were employed. A clerk rode a saddle-horse daily into North Sydney three miles away from Sydney Mines and papers were carried by locomotives hauling coal between the different areas.

Underground communications with the surface was an urgent factor when considering the isolation and other problems with which the miners could be confronted. Often, "speaking tubes" at the mine shaft were used but a more reliable and effective means of communication was desirable.

The opportunity came in the person of Gardiner G. Hubbard. Mr. Hubbard, the father-in-law of Alexander Graham Bell, was the trustee and business manager of all telephone patent rights. He was also a partner with the New England associates in coal mining and shipping operations in Cape Breton.

The telephone was invented in 1874, and three years later, in 1877, the first underground telephone network was installed in the Caledonia Mine, Glace Bay, Nova Scotia. In the course of a regular inspection trip to Glace Bay in that year, Hubbard installed the phones so that some means of communication with the surface was available. The Caledonia mine phones were the first regular commercial or industrial telephones in Canada and the oldest electrical coal mine telephones in the world.

The telephones at Caledonia were made of wood. They were cylindrical in shape in a pattern known as the "butter stamp," because of their resemblance to a butter-maker's tool used to imprint a trademark or decorative design in freshly-moulded butter.

They were designed to be held in one hand and the person would talk into the "mouthpiece" which was then held to the ear and used as a receiver, or "earpiece." Four slightly differing styles were produced during the latter half of 1877. Later, a separate transmitter and receiver replaced the inconvenient alternating of one piece between mouth and ear.

The inspector of mines at that time, Henry S. Poole, had the opinion that the telephones were of "no practical value" because there was no calling device to alert the called party. For the user of the network, it was difficult to adjust his hearing to catch the faint sounds coming from the instrument. But, overall, Poole was very enthusiastic about the prospects of the new invention and borrowed two more telephones from Hubbard, which Poole proceeded to demonstrate all over Nova Scotia.

Because of the Glace Bay demonstration, orders for telephones from two other mining companies in Nova Scotia were placed, and the telephones were installed the following year. Hubbard brought five more telephones, more advanced, from Boston and leased them to the General Mining Association, to be used in Sydney Mines.

The installation of five stations linked the GMA's General Office with the mine office, shipping pier, railway and the manager's residence. The area covered was four to five miles in circumference, and the communication system was considered to be the largest telephone installation in Canada at that time. It was also the first railway telephone in the Dominion and the second in North America.

The following is a description of the underground telephones installed in the Caledonia Mine:

The long handle section of the telephone was hollowed out to contain the single pole bar magnet. The instrument, then flared out to form a chamber for the voice coil, the coil of wire around the end of the magnet which activated the instrument. The chamber was enclosed by a thin metal disc, or diaphragm which produced the sounds as a receiver picked up the vibrations of the voice when used as a transmitter. A cup shaped wooden cap held the diaphragm in place and, when placed against the ear, formed the necessary acoustic chamber between the diaphragm and the ear. The instrument was completed by two metal wire terminals on the smaller end which served as connections for the two line wire when the telephone was in use. - The Bulletin (Maritime Tel & Tel)