Shelford Bidwell
Encyclopedia
Shelford Bidwell was an English
physicist
and inventor. He is best known for his work with "telephotography", a precursor to the modern fax
machine.
in 1873, he practised as a barrister on the South Eastern Circuit for several years before becoming interested in electronics.
He married in 1874 Anna Wilhelmina Evelyn, daughter of Edward Firmstone, rector of Wike. He died at his home in Weybridge, Surrey and was buried at Walton cemetery.
photocells. In one experiment, he duplicated the "photophone
" originally created by Alexander Graham Bell
. This device used sound to vibrate a mirror. Variations in light intensity reflected from the vibrating mirror were detected using a selenium photocell which was then connected to a telephone. This showed that voice communication could be transmitted using light beams with a photocell used to convert it to an electrical signal. In another experiment, Bidwell placed a selenium photocell inside a rotating cylinder. A small hole in the cylinder allowed the photocell to scan an image on a brightly illuminated glass slide. Another rotating cylinder was covered with a paper treated with potassium iodide. The electrical signal from the photosignal was sent to a platinum
wire that darkened the paper when current was applied. Bidwell's device did not solve the problem of synchronizing the transmitter and receiver. Both cylinders were on the same shaft. Similar devices for transmitting images had previously been demonstrated by Alexander Bain
and Frederick Bakewell
, but Bidwell was the first to use a photocell to scan the image.
Bidwell reported his results in an article entitled "Tele-Photography" in the February 10, 1881 issue of Nature
. His device is dispayed in the London Science Museum. In 1886 he was elected a Fellow of the Royal Society. He was president of the Physical Society from 1897 to 1899.
In the June 4, 1908 issue of Nature, article "Telegraphic Photography and Electric Vision", Bidwell reported on "telegraphic photography" experiments by other scientists and commented on the greater difficulties faced by those wishing to develop "distant electric vision". He pointed out that besides the problem of synchronizing the transmitter and receiver, there was a much larger problem in transmitting the extremely large volume of data at a rate that would create a continuous image to be viewed. He estimated that each image would need to have 16,000 to 150,000 "elements" (pixel
s in modern terminology) and a minimum scan rate of 10 times per second would be required. He suggested that this high rate of data transmission would require a separate circuit for each line scanned or possibly a separate circuit for each point in the image. This large number of circuits would result in a large, complex and expensive device. This article illustrates some of the problems in creating television and the possible solutions that were being considered in the first decade of the 20th century. This article is also noteworthy because it prompted a response by Alan Archibald Campbell-Swinton
, who suggested that the problems would be best solved by using cathode ray tube
s instead of mechanical devices.
"Bidwell's ghost" is a visual phenomenon associated with after-images produced by alternating flashing lights.
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
and inventor. He is best known for his work with "telephotography", a precursor to the modern fax
Fax
Fax , sometimes called telecopying, is the telephonic transmission of scanned printed material , normally to a telephone number connected to a printer or other output device...
machine.
Private Life
He was born in Thetford, Norfolk the eldest son of Shelford Clarke Bidwell, a brewer, and his wife Georgina, the daughter of George Bidwell of Stanton, Norfolk. He entered Caius College, Cambridge, graduating BA (1870), MA (1873) and LLB (1873).Called to the bar from Lincoln's InnLincoln's Inn
The Honourable Society of Lincoln's Inn is one of four Inns of Court in London to which barristers of England and Wales belong and where they are called to the Bar. The other three are Middle Temple, Inner Temple and Gray's Inn. Although Lincoln's Inn is able to trace its official records beyond...
in 1873, he practised as a barrister on the South Eastern Circuit for several years before becoming interested in electronics.
He married in 1874 Anna Wilhelmina Evelyn, daughter of Edward Firmstone, rector of Wike. He died at his home in Weybridge, Surrey and was buried at Walton cemetery.
Researches
In the late 1870s, he carried out a number of experiments with seleniumSelenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
photocells. In one experiment, he duplicated the "photophone
Photophone
The photophone, also known as a radiophone, was invented jointly by Alexander Graham Bell and his then-assistant Charles Sumner Tainter on February 19, 1880, at Bell's 1325 'L' Street laboratory in Washington, D.C...
" originally created by Alexander Graham Bell
Alexander Graham Bell
Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator who is credited with inventing the first practical telephone....
. This device used sound to vibrate a mirror. Variations in light intensity reflected from the vibrating mirror were detected using a selenium photocell which was then connected to a telephone. This showed that voice communication could be transmitted using light beams with a photocell used to convert it to an electrical signal. In another experiment, Bidwell placed a selenium photocell inside a rotating cylinder. A small hole in the cylinder allowed the photocell to scan an image on a brightly illuminated glass slide. Another rotating cylinder was covered with a paper treated with potassium iodide. The electrical signal from the photosignal was sent to a platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
wire that darkened the paper when current was applied. Bidwell's device did not solve the problem of synchronizing the transmitter and receiver. Both cylinders were on the same shaft. Similar devices for transmitting images had previously been demonstrated by Alexander Bain
Alexander Bain (inventor)
Alexander Bain was a Scottish inventor and engineer who was first to invent and patent the electric clock. Bain installed the railway telegraph lines between Edinburgh and Glasgow.-Early life:...
and Frederick Bakewell
Frederick Bakewell
Frederick Collier Bakewell was an English physicist who improved on the concept of the facsimile machine introduced by Alexander Bain in 1842 and demonstrated a working laboratory version at the 1851 World's Fair in London.-Biography:Born in Wakefield, West Yorkshire, he eventually moved to...
, but Bidwell was the first to use a photocell to scan the image.
Bidwell reported his results in an article entitled "Tele-Photography" in the February 10, 1881 issue of Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
. His device is dispayed in the London Science Museum. In 1886 he was elected a Fellow of the Royal Society. He was president of the Physical Society from 1897 to 1899.
In the June 4, 1908 issue of Nature, article "Telegraphic Photography and Electric Vision", Bidwell reported on "telegraphic photography" experiments by other scientists and commented on the greater difficulties faced by those wishing to develop "distant electric vision". He pointed out that besides the problem of synchronizing the transmitter and receiver, there was a much larger problem in transmitting the extremely large volume of data at a rate that would create a continuous image to be viewed. He estimated that each image would need to have 16,000 to 150,000 "elements" (pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s in modern terminology) and a minimum scan rate of 10 times per second would be required. He suggested that this high rate of data transmission would require a separate circuit for each line scanned or possibly a separate circuit for each point in the image. This large number of circuits would result in a large, complex and expensive device. This article illustrates some of the problems in creating television and the possible solutions that were being considered in the first decade of the 20th century. This article is also noteworthy because it prompted a response by Alan Archibald Campbell-Swinton
Alan Archibald Campbell-Swinton
Alan Archibald Campbell-Swinton, FRS was a Scottish consulting electrical engineer. He described an electronic method of producing television in a 1908 letter to Nature.-Biography:...
, who suggested that the problems would be best solved by using cathode ray tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
s instead of mechanical devices.
"Bidwell's ghost" is a visual phenomenon associated with after-images produced by alternating flashing lights.