"By your discoveries you have greatly furthered the cause of Science. You must try to revive the grand traditions of your race which bore aloft the torch light of art and science and was the leader of civilization two thousand years ago. We, in France applaud you." This fervent appeal, we shall see, as we proceed, did not go in vain.
He was next invited to lecture before the Universities in Germany. At Berlin, before the leading physicists of Germany, he gave an address on Electric Radiation, which was subsequently published in the Physikaliscen Gesellschaft Berlin, in April 1897.
FURTHER RESEARCHES ON ELECTRIC WAVES
Having received the most generous and wide appreciation of his work, Dr. J. C. Bose continued, with redoubled vigour, his valuable researches on Electric Waves. He studied the influence of thickness of air-space on total reflection of Electric Radiation and showed that the critical thickness of air-space is determined by the refracting power of the prism and by the wave-length of the electric oscillations. He next demonstrated the rotation of the plane of polarisation of Electric Waves by means of pieces of twisted jute rope. He showed that, if the pieces are arranged so that their twists are all in one direction and placed in the path of radiation, they rotate the plane of polarisation in a direction depending upon the direction of twists; but, if they are mixed so that there are as many twisted in one direction as the other, there is no rotation.[9] He communicated to the Royal Society the results of his new researches. And the Royal Society published, in November 1897, his papers 'On the Determination of the Index of Refraction of glass for the Electric Ray' and 'On the influence of Thickness of Air-space on Total Reflection of Electric Radiation' and, in March 1898, his further contributions 'On the Rotation of Plane of Polarisation of Electric Waves by a twisted structure' and 'On the Production of a "Dark cross" in the Field of Electro-magnetic Radiation.'
SELF-RECOVERING "COHERER"
The study of Electric Waves by Dr. J. C. Bose led not only to the devising of methods for the production of the shortest Electric Waves known but also to the construction of a very delicate 'Receiver' for the detection of invisible other disturbances. The most sensitive form of detector hitherto known was the "Coherer." One of the forms made by Sir Oliver Lodge consisted simply of a glass tube containing iron turnings, in contact with which were wire led into opposite ends of the tube. The arrangement was placed in series with a galvanometer and a battery; when the turnings were struck by electric waves, the resistance between loose metallic contacts was diminished and the deflection of the galvanometer was increased. Thus the deflection of the galvanometer was made to indicate the arrival of electric waves. The arrangement was, no doubt, a sensitive one, but, to get a greater delicacy, Dr. Bose used, instead of iron turnings, spiral springs which were pushed against each other by means of a screw.[10] Still the arrangement laboured under one great disadvantage. The 'receiver' had to be tapped between each experiment. So something better than a 'cohering' receiving was needed—something that was self-recovering, like a human eye. To discover that something, Dr. Bose began a study of the whole theory of 'coherer action.' It was hitherto believed that the electric waves, by impinging on iron and other metallic particles in contact, brought about a sort of fusion—a sort of 'coherence'—and that the diminution of resistance was the result of that 'coherence.' To satisfy himself as to the correctness of this theory, Dr. Bose engaged himself in a most laborious investigation to find out the action of electric radiation not only on iron particles but on all kinds of matter and ultimately discovered the surprising fact that, though the impact of electric waves generally produced a diminution of resistance, with potassium there was an increase of resistance after the waves had ceased.[11] This discovery at once showed the untenability of the old theory and pointed to the conclusion that the effect of electric radiation on matter is one of discriminative molecular action—that the Electric Waves produced a re-arrangement of the molecules which may either increase or decrease the contact resistance. It may be incidentally mentioned here that this detection of molecular change in matter under electric stimulation has given rise to a new theory of photographic action.
As a result of his painstaking investigation on the action of Electric Waves on different kinds of matter, Dr. Bose invented a new type of self-recovering electric receiver, "so perfect in its action that the Electrician suggested its use in ships and in electro-magnetic light-houses for the communication and transmission of danger-signals at sea through space. This was, in 1895, several years in advance of the present wireless system." Practical application of the results of Dr. Bose's investigations appeared so important that the Governments of Great Britain and the United States of America granted him patents for his invention of a certain crystal receiver which proved to be the most sensitive detector of the wireless signal. Dr. Bose, however, has made no secret at any time as to the construction of his apparatus. He has never utilised the patents granted to him for personal gain. His inventions are "open to all the world to adopt for practical and money-making purposes." "The spirit of our national culture" observes Sir J. C. Bose "demands that we should for ever be free from the desecration of utilising knowledge for personal gain."[12]
HIS RESEARCHES TAKE A NEW TURN
This inquiry which Dr. J. C. Bose started for the purpose of ascertaining 'coherer action'—why the "receiver" had to be tapped in order to respond again to electric waves—took him unconsciously to the border region of physics and physiology and gave an altogether new turn to his researches. "He found that the uncertainty of the early type of his receiver was brought on by 'fatigue' and that the curve of fatigue of his instrument closely resembled the fatigue curve of animal muscle."[13] He did not stop there but pushed on his investigations and found "that the 'tiredness' of his instrument was removed by suitable stimulants and that application of certain poisons, on the other hand, permanently abolished its sensitiveness." He was amazed at this discovery—this parallelism in the behaviour of the 'receiver' to the living muscle. This led him to a systematic study of all matter, Organic and Inorganic, Living and Non-Living.
RESPONSE IN LIVING AND NON-LIVING