THE TELEPHONE HANDSET
Although the first telephones worked, they were uncomfortable to use. Watson described using Bell's "gallows" telephone as like holding a packing case in your hand. More work had to be done on the ergonomics. This was limited in the United States by the size of the transmitters- they were so large that they had to be mounted on (or in) large wooden wall boxes. The widely used Blake transmitter needed a box of its own. Even the White Solid Back transmitter that replaced it was inconveniently large for a handset.
In spite of this, people saw the advantage of having the transmitter and receiver combined. As early as February 3, 1880, Robert G Brown received a U.S. Patent for an "Electric Speaking-Telephone" that was simply a handset. (1). In his claim, he stated "I do not broadly claim the combination in one instrument of two so arranged that when one is applied to the mouth the other will be applied to the ear as I am aware such subject-matter is not new". Brown's patent was for an arrangement of the receiver that allowed it to be adjusted to the user's head length, and a semi-pivoting transmitter whose angle would adjust somewhat to face the user's mouth. We have no information on who first suggested joining two instruments, but the concept was well known to Brown. He built some of his telephones for Western Union's Gold and Stock Exchange, for whom he worked. His invention was viewed with an almost total lack of interest so he went to France and became a General Engineer for Societe Generale des Telephones. They liked the handset idea and produced their first model in 1879. It was rather sensitive to vibration, but this helped reduce packing of the carbon granules so was not as much of a drawback as it seemed.
Brown was preceded by two British inventors, Charles McEvoy and G E Pritchett. Both received patents in 1877 for handsets. McEvoy described a Butterstamp receiver with a speaking tube attached to it that reached down in front of the user's mouth. The tube attached to another Bell transmitter at the telephone end.
Pritchett described a surprisingly modern-sounding handset in general terms, but since practical hardware did not exist at the time to build it his patent did not attract interest. (2)
This is a good time to examine the problems of handsets, as compared to the separate transmitter / receiver.
Size: the components of the time were bulky, but good engineering and refinement was reducing the size. Europe had the advantage of having many inventors and companies working on the problems, but in the U.S , because of the patent issues and the capital demands of an ever-growing telephone system, research funds were limited. French inventor Mercadier showed that a receiver could be scaled down to quite a small size, provided critical ratios such as diaphragm gap to magnet assembly were maintained. This allowed Ader, particularly, to develop a watchcase receiver that was quite efficient and small enough to use on a handset. The Hunnings, Berliner and Edison carbon transmitters, although rather ignored by Bell in the U.S., were developed into practical small transmitters in Europe. Even Berthon's carbon pencil transmitter was miniaturised to handset size.
Sidetone: this is the effect caused when sound going into the transmitter is fed back into the receiver. It distorts the received sound, making it sound "tinny" and less clear. The effect was usually electrical and applied to separate transmitter/receiver telephones as well, but the tubes in early handset were also a major cause of acoustic feedback which also generated sidetone. At worst the sound could then feed back into the transmitter, be regenerated back into the receiver, and generate a howling noise that made conversation impossible. By 1918 Western Electric had developed an anti-sidetone circuit to remove this problem.(3)
Efficiency: Since the sound waves did not strike directly onto the diaphragm, in spite of the cup mouthpieces used on many handsets, the output from the transmitter was lower than the wall-mounted transmitters. Ralph Meyer (3) notes that Kellogg used a retardation circuit in its early phones, and this combined with the lower level of signal reduced the acoustic feedback in Kellogg's Grabaphone. The different lengths of the users' heads could also place the transmitter in a less-than-optimal position. Some companies experimented with variable length transmitters (as described in Brown's patent) to overcome this.
Packing: Like the wall-mounted transmitters, handsets suffered when the carbon granules packed down to the bottom of the transmitter. In some cases they could fall away from the center electrode and interrupt the conversation. The movement of the head and the pickup and replacement of the handset usually kept the granules from packing, so this was not a major problem. Even so, Berthon Ader issued an instruction leaflet with their telephones to show users the best angle for the handset. In the late 1890s - early 1900s Bell Telephone Manufacturing in Antwerp developed a small Solid Back capsule transmitter that effectively removed the packing problem from its handsets. In spite of this, it was not introduced into the U.S.
In 1892 L M Ericssons in Sweden released their Model AC110 "Skeletal" or "Eiffel Tower", featuring a well-designed and efficient handset. A similar handset was released by Bell Telephone Manufacturing on their "Eiffel Tower" phone some years later, and handset telephones became a familiar sight in Europe. During World War 1, U.S. servicemen saw these telephones and christened them "French" phones, a name which is still inaccurately applied to handset phones by eBay sellers today.
Now let's look at some of the significant early handsets.
These were built somewhat similar to Brown's pattern, with a large flat steel handle, but without using the handle as a magnet. They did not follow Brown's "pivoting" transmitter.
The large transmitter was a three-carbon-pencil model. The right angle shape of the handset meant the sound waves from the voice worked directly onto the diaphragm. The receiver was a conventional Ader watchcase receiver, and the whole handset was fairly rugged and efficient.
L M Ericsson
The success of Ericsson's 1890 handset depended on the reliable transmitter. This gave a compact well-balanced handset that worked particularly well, and had a style about it that many early handsets lacked. Poole (4) described the transmitter in detail. His description is available on this website.
Ericsson broke the metal tube into two short pieces joined into an ebonite handle. This reduced acoustic feedback and sidetone usefully. A pushbutton fitted to some handsets cut out the transmitter on noisy or faint lines.
There were complaints in Britain that the transmitter was relatively insensitive, but this seems hard to justify as it was quite adequate on lines of over 30 miles in Australia. Possibly to overcome the problem, an improved transmitter was introduced progressively in models built after the First World War.
The Monophone, by Kellogg and many others, was mostly only seen in Europe. It was a response to outbreaks of tuberculosis, a respiratory disease that was often fatal. The monophone design allowed the speaking trumpet to be sterlilised safely. Similar styles of handset were built using Berliner transmitters, and they were particularly popular in France.
Acoustic feedback should have been a major problem with such a design In fact the Phonopore company did use such a device to generate a feedback howl for signaling. In use, however, this does not seem to have been a problem as the style was quite widely used. Partly this may be due to a French modification that cut small slots into the trumpet near its base. This reduced the pressure on the diaphragm and cut acoustic feedback.
Bell Telephone Manufacturing Company. Antwerp
BTMC had access to much new technology that never made it back to the United States, and so were able to produce some technically advanced phones. Their handset was made in polished aluminium, a new metal for telephones. Aluminium was less resonant than the usual brass or steel, and feedback does not seem to have been a problem. The handset grip was available in a plain style not unlike Ericsson's, or an ornate floral-patterned "deluxe" :style.
It was issued in a number of styles over the years, but its strong point was that it had one of the first capsule transmitters. This proved less susceptible to sidetone and feedback. It was based on an improved Hunnings design, the White Solid Back.
In the United States the handset did not go unnoticed. WE engineers had experimented with the style since the 1890s, and some models went into very limited production. They seem to have made every mistake that their European counterparts had already worked around - all-metal cases, one-piece tubes that maximized feedback and sidetone, and large bulky transmitters. The disadvantages of sidetone and acoustic feedback soon became apparent and production was eventually stopped on the instruction of J J Carty, the Chief Engineer. Although an anti-sidetone circuit was designed as early as 1918, handsets did not go back into production until the first E1 bakelite models appeared.in 1927.(3). The No. 2 handset shown in the center featured a built in switch attached to the suspension ring at the top. Taking the handset "off hook" released the switch, which was probably a better arrangement than other companies' "press to talk" switches.
When Western Electric did not proceed with handsets in the U.S., it was left to their competitor Kellogg to produce the first commercial production handset phone in 1905. They called their earliest handset the "microtelephone", but after redesigning the handset for mass production it was renamed the Grabaphone, and fitted it to a number of models.
Kellogg was selling telephone parts into Europe through agents, and were made aware of the handsets in use. Their first handset was based initially on Ericsson parts but was soon redesigned and improved into a simpler, more rugged model. It, too, disappeared when bakelite handsets finally appeared.
This was WE's first bakelite handset, designed to house their new No. 395 transmitter. The receiver was the usual efficient watchcase design. They went to a lot of trouble over the handset, measuring average head sizes to get the best handset length. The anti-sidetone circuit designed to go with it was not yet ready but the bakelite handset moulding proved excellent at reducing acoustic feedback (and so sidetone).
The rather ungainly transmitter was actually an advantage as it put the diaphragm of the transmitter closer to the user's mouth for a better signal.
M Ericsson 1001
In 1932 L M Ericssons started production of their first bakelite phone, the DBH1001. Initially it was made by their Norwegian subsidiary, Elektrisk Bureau, since it had been substantially designed by Johann Christian Bierknes, one of EB's engineers and Norwegian designer Jean Heiberg. It was a little more angular than the Western Electric E1 and used a more compact transmitter capsule.
It became Ericssons' standard handset for many years and was only seriously redesigned after the Second World War.
Siemens No. 162 Telephone
In 1924 the British Post Office and Siemens reexamined the handset as a basis for new telephones to replace their standard candlestick-style desk phones. Siemens developed a new telephone, christened the Neophone, in bakelite with a new handset. The transmitter and receiver were reliable capsules designed for long life and fast changeover. Its only disadvantage was a triangular cross-section grip, which some found uncomfortable. It was successful, however, and customers became used to the convenience of handset telephones. It was widely exported and became the standard telephone for most British-influenced countries.
The 162 and its 1937 replacement, the 300 series, lasted successfully until the 1950s. The handset, now listed as the No. 164, was then replaced with a smoother, more rounded Ericsson handset which finally did away with the scooped mouthpiece and the strengthening ridge along the top of the handle.