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Sunday, August 28, 2011

Coherer, iron and mercury:he Bengali physicist Jagdish Chandra Bose. ..FATHER OF RADIO.



J.C. BOSE: CAN WE CALL HIM THE FATHER OF RADIO?

JCBOSE.jpg (4465 bytes)Jagdish Chandra Bose (1858-1937)
Born 30 November 1858 (Mymensingh, Bangladesh)
Died 23 November 1937;
D.Sc. (1896), University of London, UK
Specialization:
Optics, Electromagnetic Radiation,
Plant Physiology
            Sir J.C. Bose did his original scientific work in the area of Microwaves. He made his own equipment by employing an illiterate tin-smith whom he trained up to do the job for him. He produced extremely short waves and done considerable improvement upon Hertz's detector of electric waves. He produced a compact appratus for generating electromagnetic waves of wavelengths 25 to 5 mm and studying their quasioptical properties, such as refraction, polarization and double refraction. These could be demonstrated by his compact apparatus mounted on an ordinary spectrometer table. The most satisfactory polarizers and analyzers were made out of pressed jute fibres or books with laminated pages. He could even produce rotation of plane of polarization by transmission of electric rays through bundle of twisted jute fibres. The originality and simplicity of his apparatus were its remarkable features. Bose's research on response in living and non-living led to some significant findings: in some animal tissues like muscles, stimulation produces change in form as well as electrical excitation, while in other tissues (nerves or retina), stimulation by light produces electric changes only but no change of form. He showed that not only animal but vegetable tissues under different kinds of stimuli-mechanical, application of heat, electric shock, chemicals, drugs- produce similar electric responses.

BOSEtrasmitter3.jpg (7201 bytes)
The Microwave receiver developed by Bose

            The receiver which was made by Bose represented a great advance compared to that of even Hertz. He was said to be the first to employ a semi-conductor like galena as a self recovering detector of electric rays.
galena.jpg (1085 bytes)



The Galena detector developed by Bose

                Bose could successfully produce a flash of radiation by pressing a key; the waves were only about half an inch in length; while the receiver was so sensitive that it responded to the feeblest electric reaction. In the year 1895, at the Presidency College, Calcutta, Bose demonstrated the possibility of signalling by ether waves, message to a distance. In the Calcutta Town Hall also, before a large gathering, he transmitted waves through the body of the chairman of the meeting, the Lieutant Governor of Bengal, and then through a solid wall, displacing a heavy weight, a mine placed in closed room.


bose.jpg (3405 bytes)
The Microwave transmitter developed by Bose

            Nearly 100 years after Guglielmo Marconi's first transatlantic wireless communication, a group of scientists of the US-based Institute of Electronics and Electrical Engineers (IEEE) reported that -"the origin and first major use of the solid state diode detector devices led to the discovery that the first transatlantic wireless signal in Marconi's world famous experiment was received by Marconi using the iron-mercury-iron coherer with a telephone detector invented by Sir J.C.Bose in 1898".

                Bose's invention of the "mercury coherer with a telephone" which Marconi used was published in the Proceedings of the Royal Society, London, on April 27, 1899, over two years before Marconi's first wireless communication on December 12, 1901, from NewFoundland, now in Canada.
                Investigations by the IEE group show that both Bose and Marconi were in London in 1896-97. The Italian was conducting wireless experiments for the British post office and Bose was on a lecture tour. Both the scientists were interviewed by McClure's Magazine (now defunct) in March 1897.
                In the interview, Bose came out with high praise for Marconi, then under attack from established British scientists who doubted his credentials. Marconi never could make it to college because of his poor high school record. Bose also said he was not interested in commercial telegraphy and that others could use his research work.

                In 1899, Bose unveiled his invention of the mercury coherer with the telephone detector in a paper at the Royal Society.
Brilliant Marconi quickly grasped the commercial importance of Bose's invention and began to explore it secretly. His childhood friend Luigi Solari started experimentally with Bose's invention and presented Marconi with a slightly modified design in the summer of 1901 for use in the upcoming transatlantic experiment.
The Chronology:
1895 
J.C. Bose ignites gunpoder and rings a bell at a distance using electromagnetic waves, proving for the first time in history communication signals can be sent without using wires.
1896
Bose is in London on a lecture tour and so is Marconi, who is conducting wireless experiments for the British post office. In an interview, Bose also says he is not interested in commercial telegraphy and others can use his research work.
1899
Bose announces the invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at Royal Society, London.

Sources: 
" Discovery of Millimeter Waves by Sir J.C. Bose" by Prof. P.K. Ray, Director, Bose Institute, Calcutta : Hamfest India'96 Souvenir
Bose invented Marconi's wireless"- by Mita Mukherjee : The Telegraph, Calcutta, Saturday 1 November, 1997.
"Fellows of the Indian National Science Academy" Vol.1 (Diamond Jubilee Compendium),1994, Indian National Sci