Silvanus Phillips Thompson (1851-1916) is perhaps best known as a professor of physics at the City and Guilds Technical College in Finsbury, London, and for his work as an electrical engineer and author. What is possibly less well known is his involvement with the manufacture of telephones and his, ultimately unsuccessful, challenge to the telephone patents of Dr Graham Bell and Thomas A Edison. Some recently discovered letters, found amongst S P Thompson’s pamphlet collection in the IET Archives, has helped to bring this story to life.

S P Thompson’s Involvement with ‘Telephone Instruments’

Thompson’s early researches included the subject of ‘binaural audition’ or ‘hearing with two ears’. During these researches he made use of the telephone invented by Graham Bell in 1876 and Thompson tried to work out a mathematical theory for it which led to him corresponding with Bell in 1878 and 1879. Thompson also invented an instrument which he called a Pseudophone which helped him to investigate the laws of binaural audition.

In 1882 Thompson took out a patent for ‘improvements in telephone instruments’ at a time when he was considered an expert on the subject as a result of him lecturing on the subject of telephony in various parts of the country. He also wrote the book, ‘Philipp Reis: Inventor of the Telephone’, which was published in 1883.

Challenge to Bell and Edison Patents

In the early 1880s the United Telephone Company (UTC) was endeavouring to create a monopoly in Great Britain with the patents of Bell and Edison. As UTC refused to sell its instruments, and charged a very high rent for them, many business people were interested in obtaining a cheaper form of telephone which could be used between their private homes and offices, and their factories.

By 1884 Thompson produced a new telephone with a valve transmitter and Reis receiver, both of his design, and this resulted in the formation of a syndicate to buy the patents from Thompson. The Attorney-General of the day gave his opinion that the telephones invented by Professor Silvanus Thompson did not infringe any patent rights held by UTC. The New Telephone Company (NTC), was the company set up to take over Thompson’s patents (paying Thompson a royalty), and it published its prospectus in November 1884 and began to advertise its instruments which it sold outright to its customers under licence from the Postmaster-General.

One of the newly discovered letters (image below), written in May 1886 by J W Barnard, the Secretary of NTC, and sent to Thompson, shows the headed paper of NTC and includes the sentence, ‘under license from the Postmaster-General’.


Another letter dated June 1886 and sent to Thompson by the Darlington based firm of Cox-Walker & Co (electrical engineers and manufacturers), illustrates the corporate tensions between the players involved in the telephone business. Cox-Walker asks Thompson to persuade NTC to sell them receivers alone not just NTC’s complete telephone. Cox-Walker’s problem was that its customers, who were using receivers not made by UTC, were receiving ‘threats’ from UTC who were demanding that those receivers be sent to UTC (part of letter shown below).


Once NTC’s instruments began to be installed and its commercial prospects appeared bright, UTC brought an injunction against NTC for infringement of its patents. Then followed a lawsuit in Chancery in which NTC was defeated. This was taken to the Appeal Court where Lord Justice North gave the decision against NTC. This decision killed NTC’s prospects and its directors soon wound up its affairs and the company went into bankruptcy which was finally settled in 1889.

Justice North’s decision focussed on Thompson’s transmitter which used a valve rather than a diaphragm for the transmission of speech, and Justice North judged that, “every surface which can vibrate is a diaphragm”. This was a view that Thompson could not understand and thought was “most monstrously unfair”.

A Footnote!

One of the other ‘newly discovered letters’, shown below, was sent from Lord Thurlow at his home Dunphail, Scotland, to Thompson (dated August 1886). The letter discusses an NTC shareholder whose shares Lord Thurlow wanted to buy out or have cancelled, and also talks about methods of paying to achieve this end such as selling NTC’s foreign patents which Lord Thurlow didn’t think were being exploited by NTC.


Clearly Lord Thurlow was not the most successful person when it came to business and financial affairs and associations. Not only did NTC go bankrupt in the late 1880s, but he was made personally bankrupt in 1894 (assets £30,000, liabilities £430,000). Lord Thurlow (Rt. Hon. Thomas John Howell-Thurlow-Cumming-Bruce), 5th Baron Thurlow (1838-1916), was a British Liberal politician who became Paymaster-General briefly in 1886 in William Gladstone’s Ministry, which was returned to power in February 1886, but which lost power again in August 1886. Later in 1886 Thurlow was appointed Lord High Commissioner of the General Assembly of the Church of Scotland, and also appointed a member of the Privy Council.

For those interested in reading more about S P Thompson’s life and his telephone research, the book, ‘Silvanus Phillips Thompson: His Life and Letters’, By J S Thompson and H G Thompson, published in 1920, can be consulted in the IET Library. A physical example of S P Thompson’s ‘valve’ telephone can be found in the collections of the Science Museum and is described on its website.