Mechanical Acoustic Telephones

It would take about two hundred years before the tin can phone as we know it made another appearance.

Origins of Telecom: Mechanical Acoustic Telephones

Mechanical acoustic telephones

Remember making a “telephone” with tin cans and a string as a child? While tin can phones may be considered fun and games today, they were a big deal back in the mid-1800s.

The first acoustic string phone is believed to have originated in the 1660s when British physicist Robert Hooke first tinkered with a conical glass hearing aid in an attempt to improve it. He experimented with various apparatuses and wire to send sound across a long distance (in this case, from one room to another). Using two hearing aids connected by an insulated, stretched wire, he was able to send sound to his assistant in another room. He started by playing a musical note on an instrument. His assistant heard it perfectly. Next, he spoke into the conical glass hearing aid, and once again, his assistant heard him perfectly.

As far as Hooke, was concerned, the experiment was a success. However, all he did with it was make note of it in the preface of his book, Micrographia, where he wrote, “I can assure the Reader, that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light, at least, incomparably swifter then that, which at the same time was propagated through the Air; and this not only in a straight line, or direct, but in one bended in many angles.”

It would take about two hundred years before the tin can phone as we know it made another appearance. This time, the inventor was Amos E. Dolbear. He used regular string and two cylindrical containers. As you know, this is about as simple a device as you can create, perhaps too simple. Dolbear approached Western Union with his device but was promptly dismissed due to its simplicity and Western Union’s interest in a competing technology, the telegraph.

Admittedly, it’s hard to capitalize on something as simple as two tin cans and a string. Hooke’s invention was not a commercial success, but it did find an audience among regular people, in particular, lovers. In fact, the tin can phone is often called the “lover’s phone.”

The December 1889 edition of Science magazine describes a demonstration of a simple wire acoustic telephone outside a railway near London. A wire stretched along telegraph poles made it possible for passengers to speak across the distance using nothing but the wire and a standard hat placed against it. The hat served as the receiver/transmitter, amplifying the sounds from the wire. When the passengers arrived at their destination, a local hotel, similar wires were present throughout the property. These lines included a wooden box at each end that acted as both a transmitter and receiver. This simple mechanical acoustic telephone by the British Pulsion Telephone Company worked much like the tin cans, but included a metal diaphragm held in place by clips and screws as well as a few “resonators” on the diaphragm such as springs, which were thought to re-enforce the sound vibrations.

Mechanical acoustic phones were marketed as a niche alternative to Bell’s electrical telephone but failed to gain a major following due to limited range and increased competition once Bell’s patents expired.

A January 1890 article in Hawke’s Bay Herald covering this same demonstration suggests that the Pulsion telephone would “produce a complete revolution in telephonic communication.” Of course, by this time, Bell’s telephone had been patented 14 years prior and was in use by tens of thousands of subscribers.

Mechanical acoustic telephones are an interesting blip in the history of telecommunications.

Sources: (Micrographia)